Research Article
Fatemeh Khedri; Ainaz Khodanazary
Abstract
Introduction: The mackerel (Scomberomorus commerson; Scombridae) also known as "Sheer fish" in Persian, is the most popular fish in Iran with the highest economic value. This fish is mainly offered on the Iranian market as skinned and boneless fillets. Major changes occur in proximate, microbiological, ...
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Introduction: The mackerel (Scomberomorus commerson; Scombridae) also known as "Sheer fish" in Persian, is the most popular fish in Iran with the highest economic value. This fish is mainly offered on the Iranian market as skinned and boneless fillets. Major changes occur in proximate, microbiological, chemical and sensory composition of fish fillets during storage in the refrigerator. To preserve the fish fillet, antioxidant additives prior to packaging is a common practice used in food market to extend the shelf life of aquatic products. Currently, synthetic antioxidants such as butylated hydroxyanisole (BHA) and butylated hydroxytoluene (BHT) frequently have been used prior to packaging. However, recently the consumers’ demand has ben changed to fillets with natural preservatives such as green tea extract (GTE), usually packaged in vacuum packaging (VP). Green tea is a good source of polyphenolic compounds such as catechina having strong antioxidant and antimicrobial properties. Incorporating GTE as a food additive due to its antioxidant activities is a growing interest in the seafood industry. GTE can improve the marketing potential of various seafood products and can effectively be used in the packaging food industry.Materials and method: Mackerel, Scomberomorus commerson was purchased from a local fish market in Abadan city, Khozestan province, Iran. Fish were freshly caught and completely free of additives. The fish samples were kept in ice with a fish/ ice ratio of 1:2 (w/w) and transported to the seafood processing laboratory within one hour. Upon arrival, fish samples were washed in cold water and each sample was carefully filleted by hand. Two fillets were obtained from each fish after removing the head and bone. Mackerel fillet were soaked with 1 g GTE/ L solution at a fillet/solution ratio of 1: 2 (w/v) for 15 min at 4 °C, followed by draining on the screen for 3 min at 4 °C. The trays of containing samples were then vacuum- packaged (VP).Results and discussion:The results indicated that the bacterial experiments (total count and pscychrotrophic bacteria) showed the antibacterial effect of green tea extract. Lipid oxidation value experiments (peroxide and thiobarbituric values) showed lower oxidation value in fillets treated with GTE, compared to fish kept under vacuum packaging without treatment and the control (P
Research Article
Orang Khademi; Younes Nemati
Abstract
Introduction: There are two types of Japanese persimmon (Diospyros kaki Thunb.), astringent and non-astringent, based on the degree of astringent taste at maturity state. Fruits of either type are strongly astringent when small and immature, but non-astringent type loses its astringency during development ...
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Introduction: There are two types of Japanese persimmon (Diospyros kaki Thunb.), astringent and non-astringent, based on the degree of astringent taste at maturity state. Fruits of either type are strongly astringent when small and immature, but non-astringent type loses its astringency during development on the tree, still with firm flesh. However, the astringent type keeps its astringency and is inedible even when fully colored. It loses its astringency when becomes over-ripe with extremely soft flesh. At this stage, the fruits are usually over ripe with poor quality. Astringency in persimmon is caused by soluble tannins present in the fruit flesh. One mechanism useful in artificial removal of astringency from persimmon fruit is condensation or polymerization of soluble tannins into insoluble non-astringent forms, by acetaldehyde, which is being produced in the fruit flesh during different treatments. Acetaldehyde accumulates in the fruit flesh during its exposure to ethanol vapor or high level of carbon dioxide (CO2) gas, Hence, constant temperature and short duration (CTSD) is the preferred method of CO2 treatment used to remove astringency of persimmon fruit. It involves holding the fruits in ≥95% carbon dioxide atmosphere for a short duration at constant temperature of 20-30°C then transferring to normal atmosphere. However using CO2 treatment as gas form is expensive and needs special equipment. However, solid CO2 (dry ice) is easily available in Iran with low price. It release CO2 gas and can be used for removing astringency in persimmon fruit. The response of persimmon to de-astringent treatment depends on the cultivar. In this study two persimmon cultivars namely: ”Karaj” and ”Japanese” were harvested at maturity (full coloring) stage and treated with dry ice and ethanol vapor to remove astringency and the quality of treated fruits were evaluated.Materials and methods: Astringent persimmon fruits cvs ‘Karaj’ and ‘Japanese’ were harvested at maturity stage and transported immediately to the Department of Horticulture Science, University of Shahed and treated with either ethanol or dry ice. Both ethanol and dry ice treatmenttreatments were applied in low-density polyethylene bags with 0.05 mm thickness and polyethylene container with 3 mm thickness. In the polyethylene container, dry ice was applied at amounts of 3, 5 and 7% per kilograms of fruit and in the polyethylene bags dry ice was applied at amount of 0.16, 0.25 and 0.33 per kilogerams of fruits. For ethanol treatment, in both polyethylene bag and polyethylene container, 10 ml of 36% ethanol per kilogram of fruit was sprayed. Thereafter, bags and containers were sealed completely and kept for 48 hours at 25°C and 80% RH. After removing from the closed bags and containers, fruits were held in air at 25°C, 80% RH for completing astringency removing. After astringency removal treatmenttreatments, soluble tannin contents, astringent taste degree, fruit firmness, total soluble solid and ascorbic acid content were measured. The content of soluble tannin was determined by Folin-Denis method and the degree of astringency was determined by panel test. The experiments were conducted in a completely randomized design (CRD) and analysis of variance (ANOVA) was performed and the means were compared using LSD Test.Results and discussion: After performing the astringency removal treatment, fruits containing less than 1000 ppm of soluble tannin on a fresh weight basis showed no astringency. Results presented here showed that, dry ice treatment, especially at higher concentrations such as 7% in both cultivars, causes removal of astringency and decreases soluble tannin contents below the threshold of 1000 ppm, but ethanol treatment was effective only in Karaj persimmon for the removal of astringency. Similarly, it was indicated that CO2 treatment removed the astringency more easily in some Chinese cultivars than the ethanol treatment. The response of persimmon cv. Karaj was similar to a leading cultivar Hiratanenashi in Japan, for astringency removal by both CO2 and ethanol treatments, while, according to this results, Japanese cultivar had not shown suitable response to ethanol, while it successfully responded to dry ice treatment.Treatments to remove astringency of persimmon fruit often cause fruit softening. Astringency removal treatment induced ethylene production in persimmon which causes to the fruits softening. In this study, the firmness of both cultivars decreased significantly after treatments, however, the average of flesh firmness was significantly higher after dry ice than after ethanol treatments.Total soluble solid contents under the astringency removal treatments in both cultivars reduced significantly. This reduction is due to the removing of soluble tannins responsible for fruit astringency, since they are included in SSC measurements when not polymerized. Moreover, the results showed that ascorbic acid content is not affected by astringency removal treatments.Conclusions: The results presented here showed that removing astringency from persimmon cvs. Karaj and Japanese were achieved by postharvest application of dry ice in the poly ethylene container. Results also showed that dry ice was more effective than ethanol in astringency removal and retained higher quality of fruit. Dry ice is available treatment in Iran and it can be commercially used for removing astringency of Iranian persimmon.
Research Article
Seyed Ali Jafarpour
Abstract
Introduction: The use of computer vision technology has been highly successful in food classification in the past and it has continued this success in recent times. However, a number of opportunities to progress computer vision technology exist which are critically examined based on cost and feasibility. ...
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Introduction: The use of computer vision technology has been highly successful in food classification in the past and it has continued this success in recent times. However, a number of opportunities to progress computer vision technology exist which are critically examined based on cost and feasibility. A range of hardware options are considered along with a range of software options. The economic cost of implementing new hardware continues to prove a major impediment. Thus future efforts need to be focused on maximizing the potential benefits of the existing hardware framework and instead concentrate on developing improved software. Of the improved software available the aspect that offers the greatest promise is more efficient analysis of food surface texture attributes which will lead to more powerful understanding of the relationships between quality factors and experimentally measured food quality. Materials and Methods: In this study, the efficiency of IMG-Pardazesh instrument in color measurement in comparison with CIE L*ab, Hunterlab and Patch Tool color systems was evaluated. The IMG-Pardazesh instrument was designed and manufactured based on CIE 45/0 standard and all measurements were performed based on the ColorChecker® 24 Patch Classic target which is an array of 24 scientifically prepared natural, chromatic, primary and gray scale colored squares in a wide range of colors. Many of the squares represent natural objects, such as human skin, foliage and blue sky. Since they exemplify the color of their counterparts and reflect light the same way in all parts of the visible spectrum, the squares will match the colors of representative sample natural objects under any illumination, and with any color reproduction process.Results and Discussion: According to the results, the regression value (R2) of L*a*b* resulted from IMG-Pardazesh compared to CIE L*ab recorded at 0.996, 0.998 and 0.980, respectively. In comparison withHunterlab, the values were equal to 0.983, 0.981, 0.871, and compared to Patch Tool system were 0.935, 0.881 and 0.953, respectively. However, to base an unbiased conclusion it is necessary to consider the numeric value of data that can be calculated in form of Root Mean Square Deviation (RMSD) rather than the similarity of color changes pattern.Therefore, as much as the RMSD value becomes smaller, the validity of color measuring instrument become greater compared to the standard system. RMSD was calculated following below formula:RMSDL= √((∑_(i=1)^n▒(L_i^*-L_(p )^* )^2 )/n)RMSDL= √((∑_(i=1)^n▒(a_i^*-a_(p )^* )^2 )/n)RMSDL= √((∑_(i=1)^n▒〖(b_i^*-b_(p )^*)〗^2 )/n)Which Li*,ai*,bi* are color parameter from Patch Tool system and Lp*,ap*,bp* are color parameters from other color systems.By calculating the RMSD index, it was revealed that numeric value of L*a*b* from IMG-Pardazesh was slightly lower than that of CIE L*ab. Compared to Hunterlab system, apart from a* value, the RMSD was remarkably lower in L* and b* values. By calculating the normalized error of means (e), the values of eL, eaandeb from IMP-Pardazeshwereequal to 0.776, 1.184 and 0.968, respectively, whereas, the same parameters for CIE L*ab were recorded as 0.882, 1.243 and 1.124, respectively, and for Hunterlab system were found to be 1.085, 0.933 and 1.423. Furthermore, computingthe average normalized error of means (e ̅) in CIE L*ab compared to L*a*b* from IMG-Pardazesh indicated that all color parameters had higher total average error and it terms of Hunterlab again L* and b* showed higher error. In a study conducted by Mendoza et al. (2006) on application of image analyzing for evaluation of food items color, the authors stated that that sRGB standard (linear signals) was efficient to define the mapping between R′G′B′ (no-linear signals) from the CCD camera and a device-independent system such as CIE XYZ. The CVS showed to be robust to changes in sample orientation, resolution, and zoom. However, the measured average color was shown to be significantly affected by the properties of the background and by the surface curvature and gloss. Thus all average color results should be interpreted with caution. L*a*b* system is suggested as the best color space for quantification in foods with curved surfaces. In another study on evaluation of L*a*b* units from RGB parameters, Leon et al. (2006) presented five conversion models as: linear, quadratic, gamma, direct, and neural network. Additionally, a method was suggested for estimating the parameters of the models based on a minimization of the mean absolute error between the color measurements obtained by the models and/or usinga commercial colorimeter for uniform and homogenous surfaces. In the evaluation of the performance of the models, the neural network model stands out with an error of only 0.93%. the same authors also stated that on the basis of the construction of these models, it is possible to find a L∗a∗b∗ color measuring system that is appropriate for an accurate, exacting and detailed characterization of a food item, thus improving quality control and providing a highly useful tool for the food industry based on a color digital camera.In conclusion, the IMG-Pardazesh instrument have lower error in determination of L*a*b* parameter from RGB of digital image compared to the other tested systems.
Research Article
Najmeh Molaahmadibahraseman; Reza Farhoosh; Ali Sharif
Abstract
Introduction: Medical benefits of Omega 3 fatty acids have appealeda lot of research to be done on of fish oil. Among marine fish, kilka has the most industrial application. Kilka oil contains significant amount of omega-3 fatty acids. In this study, physiochemical properties, fatty acid composition ...
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Introduction: Medical benefits of Omega 3 fatty acids have appealeda lot of research to be done on of fish oil. Among marine fish, kilka has the most industrial application. Kilka oil contains significant amount of omega-3 fatty acids. In this study, physiochemical properties, fatty acid composition and stabilization of kilka oil were investigated. p- hydroxy benzoic asid, its methyl ester and alpha-tocopherol as control were compared to each other.Materials and Methods: Crude Kilka fish oil was supplied by Khazarcompany (Babolsar, Iran). All chemicals and solvents used in this study were of analytical reagent grade and purchased from Merck (Darmstadt, Germany) and Sigma–Aldrich (St. Louis, MO). 200 ppm of the mentioned antioxidants was added to the purified oil and kinetic regime of oxidation at temperatures of 35, 45 and 55°C was prepared. After monitoring theoxidation over time using peroxide test, graph of peroxide changes over time was plotted and induction period and kinetic parameters (F, ORR and A) were calculated. In order to compare the performance of antioxidants in oil and water, 10% emulsion of Kilka oil-in-water was prepared and 200 ppm of antioxidant was added to it and its oxidation process was monitored at 55°C.Results and Discussion: Results showed that the fatty acid composition of this oil contains a variety of unsaturated fatty acids, saturated and polyunsaturated (mainly linoleic, eicosapentaenoic and docosahexaenoic acids). Temperature had significant effect on oxidation. p-hydroxymethylbenzoate, a little more than p-hydroxybenzoic asid, could increase oxidative stability of oil. Alpha-tocopherol had better performance as compared with other antioxidants. Performance of methylp-hydroxybenzoatewas better in emulsion than oil. In general, the emulsifier and emulsion preparation as compared with antioxidant had a more prominent role in the oxidative stability of Kilka oil.
Research Article
Arash Koocheki; Abdollah Hematian Sourki; Mohammad Elahi; Seyed Mohammad Ali Razavi
Abstract
Introduction: β-glucan is the most important water soluble fiber found in cell wall of some cereals such as barley, oat, wheat and rye, that are composed of β-D-glucoseunits with (1→4) (70%) and (1→3) (30%)anomericbonds(Benito-Román, Alonso, & Cocero, 2013).β-glucan ...
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Introduction: β-glucan is the most important water soluble fiber found in cell wall of some cereals such as barley, oat, wheat and rye, that are composed of β-D-glucoseunits with (1→4) (70%) and (1→3) (30%)anomericbonds(Benito-Román, Alonso, & Cocero, 2013).β-glucan is regarded as a dietary fiber in functional foods. It can act as a hydrocolloid due to its thickening characteristic in aqueous phase and can be used as a stabilizer in some foods such as sauces, salad dressing and ice cream (Dawkins & Nnanna, 1995; Kontogiorgos, Biliaderis, Kiosseoglou, & Doxastakis, 2004; Temelli, 1997; Wood & Webster, 1986). Hull-less barley is a barley variety that has no hard coat around its’ seeds. The content of soluble fiber e.g. β-glucan in hull-less barley is higher than of ordinary barley varieties. Hull-lessbarley cv. Lut is the first commercial hull-less barley in Iran registered in 2013 by SPII(Seed and Plant Improvement Institute). Lut is a kind of spring barley cultivar which is precocious and resistant to lodging. It’s average yield is 6.425 t/ha and it is suitable to cultivation in temperate regions of Iran (SPII, 2013).This type of barley contains about 6% β-glucan and thus is a good source for β-glucan extraction.To date no research has been conducted on properties of β-glucan from this cultivar of barley.Considering high technological properties of β-glucan, the present study was carried out to determine the optimal condition for extraction of β-glucan from hull-lessbarley using hot watermethod to achieve the highest qualitative and best functional properties.Materials and methods: Barley flour was obtained by grinding whole kernels of cv. Lut in a laboratory mill and sieved through a 0.50 mm screen. Prior to the extraction procedure, 50 g of barley flour was suspended in 200 ml of aqueous ethanol (80%, v/v) and stirred under reflux for 3 h to remove most of the lipids and inactivate the endogenous β-glucanases. The liquid phase was separated by vacuum filtration and dried at 40 °C for 12 h. 50 g of dried defatted barley flour was suspended in specified amounts of distilled water (solven:flour ratio = 6:1, 8:1 and 10:1) in a 1000 ml beaker. pH was adjusted to the designed levels (5, 7, and 9) by 0.1 N HCl and 0.1 N NaOH solutions. Extraction procedure carried out at 50±1°C for 30, 60 and 90 minutes. Total β-glucan content was determined by the specific enzymatic method of McClear and Glennie-Holmes (1985) using the mixed linkage β-glucan assay kit (K-BGLU 07/11) supplied by Megazyme International (Wicklow, Ireland). The colour of β-glucan gums was measuredusing a Hunter-Lab Colour Flex 45 spectrophotometer (Hunter Associates Laboratory, Inc., Reston, VA, USA). The L*a*b* (CIELAB space) colour space measurement was used for colour analysis of β-glucan samples. Emulsion stability (ES) against high temperature was determined by heating emulsions in a water bath at 80 °C for 30 min followed by centrifuging at 1200 g for 10 min. For foam stability, ovalbumin was dissolved in distilled water and added to β-glucan solution and then whipped vigorously with a laboratory rotor-stator homogenizer at room temperature. Flow behaviour measurements were done by a Brookfield viscometer. The flow behavior index (n) and consistency coefficient (k) values were obtained by fitting the power law model. All chemicals, reagents and solvents were of analytical grade and obtained either from Sigma-Aldrich Co (Deisenhofen, Germany) or from Merck (Darmstadt, Germany).Results &Discussion: Results showed that the extraction time, solvent: flour ratio and pH had significant effect on extraction yield, purity, foam and emulsion stability, consistency coefficient (k), flow behavior index (n) and colour. Increasing the extraction time had significant effects on β-glucan’s yield and purity and improved the emulsion and foam stabilizing effect of β-glucan. Increasing the pH from 5 to 9 significantly enhanced the purity, consistency coefficient (k), foam and emulsion stability. At higher pH levels, extraction yield, flow behavior index (n) and L* decreased. With increasing solvent:flour ratio, extraction yield, purity, consistency coefficient (k), foam and emulsion stability significantly increased. In contrast, the flow behavior index (n) decreased as a result of increase in solvent: flour ratio. However, solvent: flour ratio had no significant effect on L*, a* and b*. Models presented in this study were highly significant and the correlation coefficients could be used for optimization of ß-glucan extraction from hull-less barley. Considering the importance and desirability of the response variables, the best results were obtained when the extraction time, solvent: flour ratio and pH were 90 min, 10:1 and 7.33 respectively. At the optimal condition, extraction yield, purity, foam stability, emulsion stability, consistency coefficient (k), flow behavior index (n), L*, a* and b* were 4.12%, 69.11%, 86.95%, 88.77%, 1.51 Pa.sn, 0.62, 73.42, 0.81 and 8.72 respectively.
Research Article
Najmeh Molaahmadibahraseman; Reza Farhoosh; Saeid Johny; Ali Sharif
Abstract
Introduction: Medical benefits of omega-3 fatty acids have led to a lot of research on fish oil. Among marine fish, Kilka has the highest industrial applications. Kilka oil contains significant amounts of omega-3 fatty acids. In the present study, oxidative stability of Kilka fish oil based on the Schaal ...
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Introduction: Medical benefits of omega-3 fatty acids have led to a lot of research on fish oil. Among marine fish, Kilka has the highest industrial applications. Kilka oil contains significant amounts of omega-3 fatty acids. In the present study, oxidative stability of Kilka fish oil based on the Schaal oven test and the use of two phenolic acid derivatives (syringic and vanillic acids) was investigated.Materials and methods: Crude Kilka fish oil was supplied by Khazar company (Babolsar, Iran). All chemicals and solvents used in this study were of analytical reagent grade and purchased from Merck (Darmstadt, Germany) and Sigma–Aldrich (St. Louis, MO). Free radical scavenging activities of phenolic compounds was measured by reading the absorbance of methanolic solutions of the antioxidants containing 1,1-diphenyl-2-picrylhdrazyl (DPPH)at 517 nm. The partition coefficient (log P) of the antioxidants was measured in terms of the maximal UV absorbance of aqueous (0.3 mM) and 50:50 aqueous/acetate buffer (0.1M, pH =5.5) solutions. In order to study the antioxidant activity in lipid systems, peroxide value of the chromatographically purified Kilka fish oil as well as its 10% oil-in-water emulsion containing 200 mg/kg of antioxidants was monitored at 55 °C. Results and discussion: Syringic acid with two methoxy groups showed higher scavenging activity (IC50) than vanillic acid with one methoxy group (54.2 vs. 418.2). Radical scavenging activity in phenolic acids had direct relationship with the type and number of electron donor groups on phenolic ring. Peroxide values changed exponentially. Despite the relatively high polarity (Log P = – 0.65) and high scavenging activity, the performance of syringic acid in Kilkafish oil was degraded as affected by inter-molecular interactions and was not in accordance with the "polar paradox" hypothesis. Antioxidant activity of syringic acid in emulsion increased significantly as compared with oil and it was similar to α-tocopherol. It was concluded that the type of emulsifier and also the way of emulsion preparation as compared with antioxidant had a more prominent role in the oxidative stability of Kilka fish oil.Introduction: Medical benefits of omega-3 fatty acids have led to a lot of research on fish oil. Among marine fish, Kilka has the highest industrial applications. Kilka oil contains significant amounts of omega-3 fatty acids. In the present study, oxidative stability of Kilka fish oil based on the Schaal oven test and the use of two phenolic acid derivatives (syringic and vanillic acids) was investigated.Materials and methods: Crude Kilka fish oil was supplied by Khazar company (Babolsar, Iran). All chemicals and solvents used in this study were of analytical reagent grade and purchased from Merck (Darmstadt, Germany) and Sigma–Aldrich (St. Louis, MO). Free radical scavenging activities of phenolic compounds was measured by reading the absorbance of methanolic solutions of the antioxidants containing 1,1-diphenyl-2-picrylhdrazyl (DPPH)at 517 nm. The partition coefficient (log P) of the antioxidants was measured in terms of the maximal UV absorbance of aqueous (0.3 mM) and 50:50 aqueous/acetate buffer (0.1M, pH =5.5) solutions. In order to study the antioxidant activity in lipid systems, peroxide value of the chromatographically purified Kilka fish oil as well as its 10% oil-in-water emulsion containing 200 mg/kg of antioxidants was monitored at 55 °C. Results and discussion: Syringic acid with two methoxy groups showed higher scavenging activity (IC50) than vanillic acid with one methoxy group (54.2 vs. 418.2). Radical scavenging activity in phenolic acids had direct relationship with the type and number of electron donor groups on phenolic ring. Peroxide values changed exponentially. Despite the relatively high polarity (Log P = – 0.65) and high scavenging activity, the performance of syringic acid in Kilkafish oil was degraded as affected by inter-molecular interactions and was not in accordance with the "polar paradox" hypothesis. Antioxidant activity of syringic acid in emulsion increased significantly as compared with oil and it was similar to α-tocopherol. It was concluded that the type of emulsifier and also the way of emulsion preparation as compared with antioxidant had a more prominent role in the oxidative stability of Kilka fish oil.
Research Article
Neda Nayyeri; Mohammad Reza Edalatian Dovom; Mohammad Bagher Habibi Najafi; Masoumeh Bahreini
Abstract
Introduction : Nowadays, attention to foods free from chemical preservatives is on the rise. Recently, consumers have concerned about foods containing these preservatives in their formulation .Therefore,the use of antimicrobial peptides produced by Lactic acid bacteria (LAB) are strongly highlighted. ...
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Introduction : Nowadays, attention to foods free from chemical preservatives is on the rise. Recently, consumers have concerned about foods containing these preservatives in their formulation .Therefore,the use of antimicrobial peptides produced by Lactic acid bacteria (LAB) are strongly highlighted. Ribosomally-synthesized peptides, which possess antimicrobial properties, are produced by a vast range of organisms including prokaryotes and Eukaryotes.Yeasts are the most important microorganisms which are responsible for fruit juice and soft drink spoilage. In case of growth and production of by-products like CO2, acid and other contaminants, the spoilage will be visible.Lactic acid bacteria isolated from natural, local sources such as dairy products have presented potentially antifungal features against food spoilage fungi. Among these, Rodotorula and Penicillium are regarded as the most critical genera in fruit juice spoilage.The main objective ofthis study was the evaluation of anti-yeast activity of Lactobacillus plantarum isolates from different stages of Lighvan production against Rodotorulamucilaginosa as fruit juice spoilage indicator. In the next step, technological parameters effects were analyzed on antimicrobial potential of cell-free supernatant of these isolates. Finally, we aimed at finding the most effective isolate on aforementioned yeast.Materials and methods: NineteenLb.plantarumisolates, which were identified previously, were subjected to antifungal assay. For this purpose, RodotorulamucilaginosaPTCC 5257 was selected. Agar spot and Well Diffusion Assay (WDA) were applied for antifungal assay in solid and liquid media, respectively.Determination of yeast colony: Following the cultivation of yeasts in Potato Dextrose Broth, it was determined using Spectrophotometer.Preparation of Lb.plantarum cell-free supernatant (CFS) was carried out. In agar spot method, clear zones of inhibition around the spotted colonies were evaluated after 24-48h incubation. In WDA, CFS of Lb.plantarum isolates were poured in wells and clear zones were evaluated around each well after 24-48 h incubation.Technological properties: The influence of different levels of pH (2, 3, 4, 5, 6, and 7) was analyzed on CFS of Lb.plantarum isolates. This assay was done according to Wang et al., 2011. Finally, results were reported using the measurement of clear zone diameter in mm. All experiments were performed in duplicates.The effects of various temperatures were applied on CFS and remaining the antifungal activity was evaluated according to Rouse et al., 2008. Finally, all CFS of Lb.plantarum isolates were subjected to Proteniase K and antifungal properties of CFS were assayed by WDA according to Ghrairi et al., 2005.Results and discussion:Agar spot results showed the highest and lowest clear zone of inhibition related to C28 and LF49 with 16 and 6 mm diameter, respectively. In this method, 11 out of 19 isolates (60%) presented anti-yeast activity with clear zone formation. In comparison between two incubation temperatures (25 and 30◦C), all isolates stronger clear zone in 30◦C than in 25◦C. This was due to enhancement of yeast growth in 25C rather than in 30C. Also, with respect to the mesophilic nature of Lb.plantarum isolates, the possibility of metabolite production are more likely in 30C. It was reported that antifungal activity of LAB is mostly due to synergistic effect of lactic acid and acetic acid. In agar spot, some colony-associated antimicrobial compounds are responsible for antifungal activity. In WDA, 8 out of 19 isolates (42%) were positive for their inhibitory effects. The highest anti-yeast activity was seen at pH=2. It seems that antimicrobial compounds are likely more stable at acidic conditions than at alkaline ones. Among isolates, C28 presented the highest stability at alkaline conditions. With pH increase, the antifungal activity decreased so that no anti-yeast activity was seen at pH=7. Regarding the different temperatures, we should mention that thermal resistance of isolates' CFSwitnessed declining trend with increasing of temperature. This fact implies the presence of low- molecular weight compounds in CFS. Finally, all isolates' CFS was subjected to proteinase K. All isolates have lost their anti-yeast activity after enzyme treatment showing their proteinaceous nature.Conclusion: In WDA, the number of positive isolates showing anti-yeast activity declined in comparison with agar spot. Since some isolates retain their inhibitory activity toward food spoilage yeast at low pH, their CFS can be applied in acidic foods like fruit juice. Also, some isolates showed their antifungal activity at high temperatures (80C and 100C) which are applied for fruit juice pasteurization, so they can be applied in fruit juices as a bio-preservative.
Research Article
Babak Ghanbarzadeh; Sahra Bashiri; Hamed Hamishekar; Jalal Dehghan nia
Abstract
Introduction : The encapsulation of nutraceuticals in lipid based carriers, such as liposomes, can lead to increasing of bio-active ingredients bioavailability and controlled release, maintaining their stability in different environmental conditions and increasing solubility of hydrophobic active ingredients ...
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Introduction : The encapsulation of nutraceuticals in lipid based carriers, such as liposomes, can lead to increasing of bio-active ingredients bioavailability and controlled release, maintaining their stability in different environmental conditions and increasing solubility of hydrophobic active ingredients in aqueous conditions. Food grade liposomes are being increasingly used in food industry to delivery hydrophilic and hydrophobic components such as vitamin E and vitamin C, ascorbic asid, nutraceuticals, essential omega 3 fatty medium chain fatty acids-vitamine C, nisine, cartenoides, oleic acids, polyphenols include catechine, synamic acids.One of the hydrophobic nutrients with antioxidant and beneficial pro-vitamine property is beta-carotene, which its high hydrophobicity and sensitivity in different environmental conditions has limited using of it for foodstuff enrichment. In order to improve the characteristics of the lipid bilayer, cholesterol traditionally has been included in the lipid membrane. It is important in decreasing permeability and strengthening the membrane. People suffering from hyper-cholesterolaemia are encouraged to avoid foods containing cholesterol. Since the plant sterols are natural compounds found in plant cell membranes which help maintain the membrane integrity. Such as Gama oryzanol is combination of different of plant sterols that is used in the formulation of nanoliposomes in this study to improve the stability of bilayers. The principal aim of this study was to prepare beta-caroten encapsulated nano- liposome formulations as a mean to improve its aqueous dispensability and to study the effect of lecithin-phytosterol concentrations on the partical size, encapsulation efficiency (EE), zeta potential, turbibility of beta carotene loaded nano-liposomes to get the optimized formulation. Materials and methods: Preparing liposomes is being carried out using different methods one of which is a novel technique called is “Mozafari method” (based on heating method). This method is characterized by the absence of organic solvent for the solving of lipids.Non-toxicity of produced liposomes; rapid production and scalability are some of the advantages of Mozafari method over other methods of liposome production. In this study, the liposomal ingredients were added to a preheated (60 0C, 5 min) water, mixeture of beta-carotene, gamma oryzanol solution and glycerol (final concentration 3% v/v) were added. The mixtures volume increased by adding warm water until 50ml, the mixture was further heated 60 while stirring 1200 rpm for 50-60 min under nitrogen atmosphere.Results and discussion: Effect of different concentration of lecithin (20, 40, 75, 100, 150, 200 mg) on particle size and zeta potential of nano-liposomes with constant amount of beta carotene (4 mg) and gamma-oryzanol for different concentration of lecithin with ratio 1:14 w/w were evaluated. The Particle size of nano liposomes with different concentration of lecithin was obtained below 500nm andthe optimal concentration of lecithin was 100 mg that particle size was minimum (64-88 nm).The gamma-oryzanol is a natural phytostrol which is as stabilizer for liposome membrance and promoting agent of hardness of vesicles wall however, the particle size of liposomes were reduced especially in low concentration of lecithin. The using phytosterols (gamma oryzanol) for maintaining the stability of liposomal membranesystems caused to reducing of particle size from 88nm to 64nm in 200 mg concentration of lecithin.The entrapment efficiency increased by increasing concentration of lecithin for nano-liposomes. It is because increasing the lecithin concentration, more vesicles were produced which in turn increased the loading capacity of nano-liposomes. In the liposome structure, the aqueous core and bilayer are the hydrophilic and hydrophobic parts, respectively. Therefore, the phospholipid bilayers place for beta carotene, and other hydrophobic substances. The entrapment efficiency in different concentration of lecithin was between 27-98%. The entrapment efficiency of liposomes containing beta carotene that used gamma oryzanol was less than liposomes without gamma oryzanol probably because the position of capsulation of gamma oryzanol and beta carotene is same in the bilayer of liposome that’s hydrophobic source of liposomes. But Gamma oryzanol was not effective on encapsulation efficiency of beta-carotene.The zeta potential, the electric potential in the interface or particle surface charge, is used to predict the stability of colloidal systems. In general, higher zeta potential values, regardless of their positive or negativity, indicate a higher and longer-term stability of the particles. Zeta potential of liposomes, which is a measure for the electrostatic repulsion and stability, was -29 and -35 milivolt for samples with and with not containing gamma oryzanol, respectively.For turbidity of liposomes, encapsulation of bioactive compounds can change the optical appearance due to the fact that the refractive index at the interface between solvent and internal phase changes and the size of liposomes may be altered. Increasing significantly of turbidity of liposomes (16% -80%), the wave length increase from 0.116 to 0.585 cm-1 high concentration of lecithin maybe due to increasing visuals and hydrophobic interactions.
Research Article
Hamideh Separdar; Ebrahim Rahimi; Iman Shahabi; Behzad Aghabarari
Abstract
Introduction : One of the most important problems of synthetic packaging of materials had been the time consuming process of their decomposition. Therefore, they have the potential to contaminate the environment. During the recent years, the above-mentioned problem has paved the way for developing biodegradable ...
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Introduction : One of the most important problems of synthetic packaging of materials had been the time consuming process of their decomposition. Therefore, they have the potential to contaminate the environment. During the recent years, the above-mentioned problem has paved the way for developing biodegradable biopolymers. One group of these polymers is films and edible coatings. Soy protein isolate is the purest type of soy protein which is available commercially and amount of its protein is more than 90% (based dry weight). These films have better nutritional value. In addition, they have better mechanical features and permeability than films made of carbohydrates and fats. Tragacanth gum is composed of two main ingredients under the name of Tragacantic acid or Basorin and Tragacantin. Basorin is in 60-70% of whole gum and is insoluble in the water. It can swell and make gel. Also, another ingredient or Tragacantin solves in the water and leads to make colloid solution. Hence, the main purpose of this work is studying effect of tragacanth gum as a supplementary and firmness-making material on physical and mechanical features of soy protein isolate film and are determining the best level of tragacanth gum and optimal film for using in food packaging.Materials and methods: A specified amount of soy protein isolate was solved in distilled water. Then, pH of solution was set on 10 by NaoH (0.1N). Solution of soy protein isolate was heated by bain-marie to 70˚c. Afterwards, solution of tragacanth gum with suitable amount of treatment which was solved separately in the water was added to solution of soy protein isolate slowly during agitating by magnetic mixer. Then, glycerol was added to the final solution as plasticizer. Final solution was agitated by magnetic mixer about 15 minutes to become smooth and pure. After degassing, the film forming solutions were casted by pouring the mixture onto polystyrene plate (10 cm diameter) and dried at 25±5˚c for 48 h in a laboratory oven and room relative humidity. Finally, the dried films were peeled off the casting surface. Film solutions were prepared from soy protein isolate with ratio of 0.5:4.5(A), 0.3:4.7(B) and 0.1:4.9(C), tragacanth gum: soy protein isolate and plasticizer of glycerol were prepared in 100gr water with ratio of 90% (w/w) dry weight. According to plasticizer effect of water, to uniform moisture before performing each test, all the films were conditioned inside desiccators containing saturated magnesium- nitrate solution to ensure a relative humidity 0f 50-55% at 25˚c ± 1 for 48 h.Tensile strength (TS) and elongation at break (EB) were conducted by using tensile evaluation machine (7010, Gotec of Taiwan) according to ASTM standard method D882-10 (ASTM, 2010).Films were cut in the dimension of 2×2 cm2 and dried to reach constant weight at 100 ˚C in a laboratory oven. Dried samples weighed to determine the initial dry weight (m1) and placed inside beaker including 50 ml of distilled water with periodic stirring for 24 h at 25˚C. Afterwards, the remained pieces of films were taken out and dried at 100˚C to reach constant weight (m2).After the films reached in moisture balance at 25˚C and a proportional humidity at %55. Their moisture was determined by measuring the loss amount of film weight during drying in a laboratory oven at 105˚c unti constant weight.The specimens of films was provided at 2×2cm2 dimensions and prepared by dried calcium chloride until reached to constant weight (m1). After the initial weight, they were conditioned in a desiccator containing saturated magnesium nitrate solution at 25˚c to provide reaching a relative humidity of %50-55. Then, the specimens were weighed in regular intervals until the equilibrium state was reached (m2).Water vapor permeability tests of films were performed according to ASTM- E95-96 standard (ASTM, 1995).The color of films was evaluated using a colorimeter device (LabscanXE, Hunterlab, USA). Statistical analysis was conducted in a completely randomized design with variance analysis (ANOVA) using SPSS software (Version 21; SPSS Inc., USA). Also, comparing the difference among mean values of film specimens was performed using Duncan,s multiple range tests at the confidence level of 95%.Results and Discussion:The obtained results indicated that tensile test (TS) of film was increased by increasing tragacanth gum and decreasing soy protein isolate but elongation to break (ETB) decreased. This result was agreed with the results of Fazel et al (2013), Tian et al (2011), Chen and Lai (2008). The amount of film moisture increased by increasing tragacanth gum, while amount of solubility in water, water absorption decreased by increasing tragacanth gum. The highest of wvp was observed in SPI:TG (4.9:0.1) but the lowest value was related to the sample SPI:TG (4.7:0.3). In general, the amount of wvp decreased by increasing tragacanth gum. The free space between chains decreases by forming transversal connections between protein filaments. Also, filaments mobility decreases, while penetration and spread of vapor molecules from polymer will decrease and its prevention becomes more in the water. The highest L, a, and whiteness index was observed in SPI:TG (4.5:0.5). In contrary, the highest b, total color difference (ΔE), and yellowness index was observed in SPI:TG (4.9:0.1). Optical properties of films used in food packaging are very important for their effects on acceptance and food quality. Results of Sarmadizadeh et al. (2014) showed that increasing protein has changed films color. Therefore, adding tragacanth gum caused to improve the structure and to improve physicochemical properties of the samples. It could be concluded biodegradable film of SPI+TG has desirable characteristics for the application in food packaging.
Research Article
Ainaz Khodanazary; Sara Golgolipour; Kamal Ghanemi
Abstract
Introduction: Grass carp (Ctenopharyngodonidella, family Cyprinidae) is one of the main fresh water fish species and highly demanded aquaculture species in Iran. Among the cultivated fish, grass carp, also called farmed white fish, has received great attention because of its similarity to Caspian white ...
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Introduction: Grass carp (Ctenopharyngodonidella, family Cyprinidae) is one of the main fresh water fish species and highly demanded aquaculture species in Iran. Among the cultivated fish, grass carp, also called farmed white fish, has received great attention because of its similarity to Caspian white fish in Iran. The muscle of fish contains important levels of nutrients which are beneficial to health. Most research has been done and published on raw flesh. Cooking can lead to a loss of the nutritional value of foods. In this case the preservation of the maximum nutritive value can be ensured by using correct methods of cooking. The aim of this research was the influence of five cooking methods (poaching, boiling, microwave pan- frying and deep- frying) on changes of free fatty acids, thiobarbitoric acid, heavy metal (Ni, Cr, Co, Cd, Pb) and sensory properties of grass carp (Ctenopharyngodonidella)fillets was evaluated.Materials and method: Grass carpsamples were purchased from a local market in Khorramshahr city, Khuzestan province, Iran. The fish were kept alive and transported to thelaboratory. On arrival,tsamples were washed and eviscerated. The samples were filleted and cut into slices (100 g each). The fish samples were cooked using AOAC 976.16 procedure (method for cooking seafood). Five common cooking procedures were selected: poaching in stainless steel pot of boiling water for 30 min and 30 s, steaming in stainless steel steamer for 5 min and 30 s, microwaving in microwave for 40 s, pan-frying (without oil) in frying pan for 6 min at 180 ºC and deep-frying in olive oil in a deep fryer for 5 min at 180 ºC. After the cooking process, the samples were cooled to room temperature and the skin and backbone of the samples were removed. All fish in each lot were homogenized using a kitchen blender and analyzed to determine free fatty acid, thiobarbitoric acid, heavy metal and sensory properties. All sample homogenates were assayed in triplicate.Results and discussion: The results indicated that the cooking methods of pouching, microwave and deep-frying increased thiobarbitoric acid (TBA), while cooking methods of boiling and pan- frying did not change TBA. The free fatty acid (FFA) content of the fillets was significantly reduced by the different cooking methods. The Ni in the cooking methods of boiling, pan- frying and deep- frying was not detected. The Cr in the cooking method of deep-fried samples was significantly decreased. The Co concentrations were below limits of detection in all samples. The Cd was only detected in microwave samples. The Pb content increased during cooking of fillets. The results of sensory properties were showed that the texture, odour, flavor, colour and overall likeness properties improve likeness score to some extent in deep-frying method and there were not significantly different between boiling, poaching and pan-frying.
Research Article
Setareh Hosseinzadeh; Aram Bostan; Mohammad Hossein Hadad Khodaparast; Mohebbat Mohebbi
Abstract
Introduction : Flavors play an important role in consumer satisfaction and influence further consumption of foods. Most available aroma compounds are produced via chemical synthesis or extraction. Foodstuffs containing synthetic flavor in many cases are avoided, because the consumers suspect that these ...
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Introduction : Flavors play an important role in consumer satisfaction and influence further consumption of foods. Most available aroma compounds are produced via chemical synthesis or extraction. Foodstuffs containing synthetic flavor in many cases are avoided, because the consumers suspect that these compounds are toxic or harmful to their health. Recently, the market of flavors is focused in using aromatic materials arriving from natural sources to replace the use of synthetic flavors gradually (Badee, et al., 2012).Flavorsare indispensable ingredients of food preparations, and usually they are in liquid form that makes their handling and incorporating into food more difficult. Furthemore, many flavorcomponents exhibit considerable sensitivity to oxygen, light, and heat. In response to these difficulties, dried flavors have been developed. The objective of this work was to study the influence of different wall material concentration on the emulsion and spray dried flavor powder characteristics.Materials&methods: Spearmint oil was obtained by clevenger distillation method and modified starch was obtained from National Starch&Chemical Limited company (England).Different concentration of modified starch solutions (10, 20 & 30% w/w) were prepared by dispersing the solids in deionized water and heating at 40 ⁰C over a steam bath to facilitate solubilization. Thesolutions were allowed to cool to room temperature before storing at 4°C overnight. The spearmint oil (2.5 % w/w) was added to the solution and was homogenized vigorously (15000 rpm for 10 min.) with an Ultra Turrax homogenizer (T25, IKA, Germany) at ambient temperature. The emulsions were then further emulsified using Ultrasounds (20kHz, 1 min) (Jafari, et al., 2007).The obtained emulsion was spray dried in a BUCHI 190 Spray Dryer (Swiss) with an evaporation rate of 600 lit/1 hour, equipped with a pressurized nozzle operating at 4bar pressure. Feed ismetered into the dryer by a peristaltic pump. Powder was collected at the bottom of dryer cyclone and kept inair tight containers at -18⁰C until analyzed.The particle size of emulsion droplets and spray dried powder were determined using dynamic laser light scattering (Analysette22, Fritsch company, Germany).Encapsulation Efficiency was defined as the percentage of Menthol ad d-limonene thatwere entrapped inside the microcapsules to the total loaded to the emulsion. . Theequations was as follows:Encapsulation Efficiency=(Menthol or Limonene in Microcapsul(ppm))/(Menthol or Limonene in Emulsion(ppm))×100%The powders were attached to SEM stubs using double adhesivetape, coated with 3–5 mA gold/palladium under vacuum,and examined with a scanning electron microscope (S360 model, Oxford , England).Results&disscussion: Emulsion particle size were found to be in the range of 1.8 to 3.3 μm and wall material concentration had significant effect on it ( p
Research Article
Mahmood Reza Golzarian; Mansoureh Shamili; Omid Doosti Irani; Peyman Azarkish
Abstract
Introduction: Machine vision, which uses image processing techniques, is a branch of artificial intelligence that simulates human vision. These systems can be used for quality control, sorting and grading of agricultural products. Unlike engineering materials, agricultural fruits are living tissues that ...
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Introduction: Machine vision, which uses image processing techniques, is a branch of artificial intelligence that simulates human vision. These systems can be used for quality control, sorting and grading of agricultural products. Unlike engineering materials, agricultural fruits are living tissues that continue living even after they are harvested from trees or bushes. Therefore, the post-harvest process such as handling and packaging need to be done such that they make the least damage to these products (Barchi et al., 2002). Combination of suitable techniques and post-harvest management is required to bring down the waste loss in this supply chain. Fruits are susceptible to receive mechanical damages during harvesting (either manually or mechanized), or in transport or at the time of initial packaging. These damages may cause damage to the internal tissue of the fruit that subsequently causes the internal substances of the damaged cell leave spread out. While eradicating the fruit, the surrounding fruits are also affected negatively.Mangos are sensitive to mechanical and thermal sudden change (Xing & Baerdemaker, 2005). Today, surface defect detection and grading of many fruits including mangos are still performed in many cases with the help of trained workers which is time consuming and cost effective.. Image processing has been successfully used for measurement and calibration of products; it shows also a good potential to be used for assessing the quality of products (Mata et al, 2012). There has been no or very little research on the quality assessment of mangos based on the dark spots on the skin surface of mango fruits.The aim of this study was to detect and identify surface damage in mangoes of Kelk-e Sorkh cultivar using digital image processing as it has higher accuracy and processing speed as opposed to manual detection.Materials and methods:Mango fruits were picked from a garden in Minab in Hormozgan province, in Iran. Sixty samples were selected for imaging. These samples had black spots on the skin surface due to mechanical damages received during harvesting and handling. The imaging was performed in a homogenously controlled lighting condition(in an imaging box)against a blue sheet as background and at 24°C and 22% RH. The images were taken in visible range with a Nikon Coolpix P510 digital camera (Nikon Inc, Japan) of 4928 x 3264 dimensions (16.1 MP resolution). Considering the camera lens’s focal length, the samples were placed 20 cm under the camera’s lens to be in camera’s field of view. The taken images were read and analyzed in Matlab (Ver 2011a, Mathworks Inc, US). The quality of segmentation process, which is an important step in image processing project, affects the quality of information extracted from the objects or regions of interest (ROIs) in the next steps. The images of mangos were segmented from the background using thresholding of the high contrast images of red and blue difference. The optimum threshold value was obtained to be 0.3. Then, the affected and healthy regions of mangos were specified manually in each image. Then, the color features in two L*a*b* and RGB and HSI color models were extracted from each region on the sample surface.Results and discussion: The statistical analysis of these features showed that the accuracies for detecting the surface defects on mangos were 90% and 91.6% using the color factor of G and 0.16*G/0.5R in RGB color space, respectively. However, from the a* data, only 56 samples were correctly classified as damaged. This showed the classification accuracy of 93.33% using this color parameter. The accuracy reached to 100% when the two color parameters of a* and L* was used as an integrated color parameter of 0.16*L-a*. In L*a*b* color space, the influence of ambient light on the color of samples is trivial and much less than that on RGB. This can be the reason for higher classification error when R, G and B color components, which might be due to non-uniform lighting and the existence of highly bright or highly dark points on the surface of samples. According to USDA standard, the ratio of the size of defect region to the size of whole fruit can be used as an indicator for grading mangos (USDA, 2006). In this research, the k-means clustering was used to group the mangos based on their defect region size. The results showed that the mangos could be classified into three categories of grade 1, with the defect size of less than 5% of the total area, grade 2: when the defect region size was between 5 and 15% and grade 3: when the defect area size was more than 15% and less than 25%. By K-means clustering, the samples were grouped in two clusters. The cut-off point between two clusters was found from the ROC curve to be 3.11. The parameter of ROC area was equal to unity, which indicated the high discrimination capability of the clustering model. Conclusion: In this research, after assessing several color factors and their combinations, four color components of a*, green (G), 2G/R and L*-0.16a* were selected and used for classifying mechanically defected mangos and the results were promising. The results of this research and similar ones can provide helpful recommendations in grading mangos considering the higher capability of Hormozgan province in Iran for producing mangos for fresh consumption, being used in high-quality domestic market, being exported to global markets.
Research Article
Leila Monjazeb Marvdashti; Masoud Yavarmanesh; Arash Koocheki
Abstract
Introduction:Packaging is an important factor in food industry and is dominated by petroleum-derived polymers. Therefore, the amount of research involving the production and characterization of biodegradable films has increased substantially, mainly due to interest in minimizing the ecological impact ...
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Introduction:Packaging is an important factor in food industry and is dominated by petroleum-derived polymers. Therefore, the amount of research involving the production and characterization of biodegradable films has increased substantially, mainly due to interest in minimizing the ecological impact caused by the use of synthetic packaging materials. Several biopolymers have been exploited to develop eco-friendly food packaging materials. Usually, films based on biopolymers are highly sensitive to environmental conditions and generally present low mechanical resistance. As a result, several researchers have developed films based on mixtures of biopolymers and synthetic polymers. In order to increase the workability and flexibility of biodegradable films, various plasticizers, usually poly-ols, have been widely used, glycerol being one of the most preferred and most studied. Plasticizers reduce intermolecular forces, increase the mobility of the biopolymer chains and thereby improve the mechanical properties of the films. Therefore, the aim of the present study were to investigate the effect of different proportions (20e100% w/w) of plasticizer (glycerol) on physicochemical, mechanical, permeability, surface and thermal properties of biodegradable PVA-AHSG blend films.Polymer blending is one of the most effective methods to have new material with desired properties. Films formed by blending of polymers usually results in modified physical and mechanical properties compared to films made of individual components. Since synthetic polymers are easily obtained and have low production cost, blending of natural and synthetic polymers improves the cost performance ratio of the resulting films. Since Alyssum homolocarpumseed gum (AHSG) is environmentally friendly due to its biodegradability and has good film forming properties, it is considered as a very promising biopolymer. Some synthetic polymers from non-renewable sources are also biodegradable, such as polyvinyl alcohol (PVA). PVA is a synthetic, water soluble polymer with excellent film forming, emulsifying, and adhesive properties. It also imparts good tensile strength (TS) and biodegradability and hence has been used in many biomaterial applications. PVA has also been approved for use in packaging meat and poultry products by the USDA (DeMerlis&Schonek, 2003). AHSG contains free hydroxyl and amine groups, and is therefore miscible with PVA due to the formation of hydrogen bonds.Materials and methods: The aim of this study was to investigate the possibility of producing a novel biodegradable blend film from PVA-AHSG with glycerol as plasticizer in the different concentrations. Films were prepared by the casting method using PVA and AHSG (60:40 ratio). Glycerol was used ac plasticizer because it is compatible with PVA-AHSG blend improving film flexibility, facilitating its handling and preventing cracks. The PVA–AHSG blend film was prepared with different glycerol concentration (20–70%, w/w).The optical properties such as opacity and color were measured. Water vapor permeability, moisture content, water solubility and density of the films were also investigated. Films were evaluated for mechanical and antitoxin properties. The PVA–AHSG blend films were characterized using DSC, FTIR and scanning electron microscopy.Results and Discussion: The results of this study showed that blend of PVA and AHSG could be used as a new film-forming material. However, it was not possible to make PVA-AHSG blend films without addition of glycerol as a plasticizer to the formula. Glycerols in 20-70% (w/w) concentration were used to prepare the blend films. At the level of 20% (W/W) of glycerol, PVA-AHSG blend films had the lowest thickness (0.065 mm), moisture sorption (118.76%), water vapor permeability (WVP) values (4.9 g mm m-2 kPa−1 d-1), elongation at break (EB)(2.1%), moisture content (22.5%) and water solubility (16.6%) and the highest values for tensile strength (TS)(64.6 MPa), young modulus (YM) (892 MPa),density (0.109 g cm-3),opacity (0.069 A/mm) and water contact angle (74.52◦). Increasing of glycerol concentration in PVA-AHSG blend films resulted in increase in water vapor permeability and percent of elongation while, decreased tensile strength and surface hydrophobicity. Increasing the glycerol concentration significantly (p < 0.05) diminished initial water contact angle of films from 74.52◦ to 37.80◦. It has been shown that the addition of plasticizers diminished the films’ water contact angle, which in turn, decreased hydrophobicity of the films. The higher hydro-philicity of the samples is attributable to the hygro-scopicity (water-binding capacity) of the plasticizer. Plasticizer can diminish interactions between biopolymer molecules and increase solubility due to its hydrophilic nature, giving the polymer molecules higher affinity to attract water. The moisture content increased significantly from 22.5% to 40.9% as the plasticizer content increased (p < 0.05). Because of glycerol acts as a water-holding agent, with the higher number of water molecules in glycerol-plasticized films increasing plasticizing activity.WVP increases as plasticizer content of the film increases due to its hydrophilic nature. WVP can be directly related to the quantity of OH group on the molecule. Also, environmental conditions can significantly affect the WVP. Increasing plasticizer concentration decreased the intermolecular forces between polymer chains and increased free volume and segmental motions, allowing water molecules to diffuse more easily and giving a higher WVP. Mechanical strength of films decreases due to plasticizer addition resulting in decreased tensile strength and increased elongation. The measurement of color values showed that by the increasing of the glycerol concentration in polymers blend matrix, the b and L values increased while a value decreased. Furthermore, the addition of glycerol promoted the interactions among PVA, AHSG and glycerol through hydrogen bonding as reflected on the shifting of main peaks of the glycerol-free film to higher wavenumbers as shown by FTIR spectra. Microscopic views indicated smooth and uniform surface morphology without obvious cracks, breaks, or openings on the surfaces after the incorporation of glycerol as a plasticizer. Scanning electron microscopy showed that the microstructure of PVA-AHSG blend films have a critical effect on their physical and mechanical properties that is important in food packaging applications.
Research Article
Seyed Amir Oleyaei; Babak Ghanbarzadeh; Ali Akbar Moayedi; Farhang Abbasi
Abstract
Introduction: Biodegradable films for food packaging applications have attracted an increasing amount of consideration over the last two decades, predominantly due to environmental pollution and the realization that our petroleum resources are not infinite. Starch, which is one of the natural biopolymers, ...
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Introduction: Biodegradable films for food packaging applications have attracted an increasing amount of consideration over the last two decades, predominantly due to environmental pollution and the realization that our petroleum resources are not infinite. Starch, which is one of the natural biopolymers, has been considered as one of the best candidates primarily because of its processbility, availability and price. The main disadvantages of starch films are their pronounced hydrophilic character therefore; they are permeable to water vapor and have usually poor mechanical properties. However, these features can be significantly improved by blending with nanodimension materials such as Montmorillonite (MMT) and Titanium dioxide (TiO2). The main reason for this improvement in comparison with conventional composites is the large surface area which results in high interactions between the nanofillers and polymer when these nano-materials are well dispersed. The behavior of nanocomposite films has been depended to the dispersion of the nanoparticles in the polymer matrix. MMT as a one-dimensional (1D) material is the most commonly used layered silicates. TiO2 as three-dimensional (3D) nanoparticle has been investigated most widely because it is inert, inexpensive and, has a high refractive index with UV shielding potential. The study on films with different dimensions of nanofillers simultaneously is rarely reported. MMT and TiO2 as two inorganic nanofillers have different shapes and structures, so the combination of TiO2 and MMT apparently had a synergistic effect on the starch film properties. The aim of this study was to control particle agglomeration and investigate the synergistic effect of combination of TiO2 nanoparticles and MMT layers and on the surface topography, color, and thermal properties of plasticized starch-MMT-TiO2 nanocomposites.Materials and methods:.First, 100 ml of potato starch solution with a concentration of 4% (w/v) was prepared by dispersion of the starch in distilled water and was gelatinized at 80ºC for 15 min. Different levels of MMT (3 and 5% w/w starch) and TiO2 (0.5, 1 and 2% w/w starch) were dissolved in distilled water and were added to the gelatinized starch after treatment with ultrasound for 30 min. Glycerol, as a plasticizer, with concentrations of 50% (w/w starch) were added to the filmogenic solution. The plasticized starch (PS) based filmogenic solutions were dried in an oven at 45 °C for 15 hours. The surface roughness and topography and thermal properties of the films were determined through atomic force microscopy (AFM) and differential scanning calorimetry (DSC) analysis, respectively. Fourier transforms infrared (FTIR) spectroscopy in the range of 4000 to 400 cm-1. UV-Vis spectroscopy was employed to evaluate the absorbance and opacity behavior of the PS-MMT-TiO2 nanocomposite films in the wavelength range of 200-800 nm. The color parameters of films were measured by a portable colorimeter. Statistical analysis was performed on a completely randomized design with the analysis of variance (ANOVA) and Duncan’s multiple range tests was used to detect differences among the mean values of the films propertiesResults and discussion: Atomic force microscopy’s images demonstrated an obviously uniform dispersion of MMT and TiO2 nanomaterials in the PS-3%MMT-TiO2matrix with smoother surfaces and a lower roughness parameters than that for the corresponding binary PS-MMT nanocomposites with the MMT filler content (3 wt%). Surface roughness of starch films was changed depending on the MMT and TiO2 content. The results of the roughness parameters and topographic images were confirmed by the high frequency distribution curves. In the PS-3 and 5% MMT films, most parts have height of about 400 and 600 nm, respectively; While the height of the PS-MMT-1% TiO2 bionanocomposites film were 200 and 800 nm. FTIR revealed the hydrogen bonds and electrostatic interactions between nanofillers with starch and themselves by the peaks associated with bond C-O-H at 1142 cm-1 and 990 cm-1 and wide and high intensity IR absorption in the 500-800 cm-1.Evanescence of 3626 and 3452 cm-1 peaks assigned to OH groups of MMT in the PS-3MMT spectrum affirmed the interaction between starch and MMT.Shift in melting temperature and glass transition (Tg) towards higher temperature respectively from 295.1C to 306.3 C and from 199.1 C to 207.6 C were illustrated by DSCresults due to addition of TiO2 in the PS-3%MMT matrix.Improvement of thermal stability might be attributed much jammed and conjugated 3D MMT-TiO2 network combined together, or powerful interaction between PS and nanofillers could also slowdown the polymer chains motion and melting point during heating. These results showed a significant effect of combination of 1D MMT layers and 3D TiO2 nanoparticles on the thermal properties of PS nanobiocomposite starch based films. Montmorillonite did not affect color of nanocomposite. The transparency of a nanobiocomposite film is not significantly varied when the clay layers with about one nm thick are excellent dispersed through the polymer matrix, since such MMT platelets are less than the of visible light wavelength and do not block lights transmission. Transmittance, redness and yellowness of new ternary films decreased when TiO2 was added to PS-3%MMT matrix at 1%. In this case, color difference (ΔE) and whiteness index (WI) are increased 86.6% and 76% respectively.Starch and PS-MMT films were colorless. The presence of TiO2 imparted whiteness to the nanocomposites due to its inherent whiteness. This phenomenon can be enucleated as the large specific surface area and high refractive index of nanosized TiO2 particles were accounted or diffuse reflection of light from the interface of the materials, and consequently, transparency loss of the composite films. UV-Vis spectroscopy was employed to evaluate the absorbance and opacity behavior of the PS-MMT-TiO2 nanocomposite films in the wavelength range of 200-800 nm. Incorporation of TiO2 nanoparticles into the starch film solution caused a significant decrease of transmittance in visible, UV-A (360 nm), UV-B (300 nm), and UVC (240 nm) regions. The results of UV-Vis spectroscopy showed that this type of films could be used as a packaging material to shield against UV and visible light.
Research Article
Sara Rrahbaran; Aazam Aarabi
Abstract
Introduction: The consumption of dietary fiber plays an important role in the prevention of illnesses such as diabetes type 2, hypercholesterolemia. Dietary fibers are not only desirable for their nutritional properties but also for their functional and technological properties. This study was undertaken ...
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Introduction: The consumption of dietary fiber plays an important role in the prevention of illnesses such as diabetes type 2, hypercholesterolemia. Dietary fibers are not only desirable for their nutritional properties but also for their functional and technological properties. This study was undertaken to investigate the possibility of alkaline hydrolysis to remove fiber from rice bran. Material and methods: In this study, the extraction of fiber from rice bran was carried out in the presence of sodium hydroxide as an alkaline media and under autoclave condition. The Response Surface methodology was evaluated by the central composite design (CCD) to build a model based on three variables including the time (X1), temperature (X2) and the concentration of Hydrogen Peroxide (X3) for the extraction of fiber, and water binding and fat binding capacity of produced fiber.Results and Discussion: Results showed that the optimum conditions for the maximum production of extracted fiber were 35min, 99.6 °C and 13.47% for time, temperature and the concentration of hydrogen peroxide, respectively. Results indicated that temperature was the most significant factor influencing considerably on fiber extraction and fiber fat binding capacity and none of the parameters had significant effect in the level of (0.05) on the water binding capacity of fiber
Short Article
Fatemeh Heidari Dalfard; Masoud Taghizadeh; Seyed Mohammad Ali Razavi
Abstract
Introduction: Malt extract is one of the malt products obtainedfrom concentrations of water soluble extract of grains such as barley and is a proper alternative to white sugar. It has a high diastasis properties andcontainshigh amount of different vitamins specially the group of vitamin B as well as ...
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Introduction: Malt extract is one of the malt products obtainedfrom concentrations of water soluble extract of grains such as barley and is a proper alternative to white sugar. It has a high diastasis properties andcontainshigh amount of different vitamins specially the group of vitamin B as well as high amount of fermentable sugars. Therefore, malt extract has high nutritional value and is recommended by nutritionist for children and people who are having growth problems. In addition, it has a high potential to be used as sweetening agent in different food products such as cookies, biscuits, ice cream, chocolates etc. Knowledge on the thermo-physical properties of malt extract such as density, specific heat, thermal conductivity as well as thermal diffusivity is highly necessary for the designing of processing equipments, formulation of derived products, heating and chilling processes, and other unit operations such as pasteurization, concentration, dehydration as well as final safety and quality of formulated products. Since, no research work has been reported on thermo-physical properties of malt extract, the aim of this study was to determine different thermal properties of malt extract as well as investigation of the effect of temperature and soluble solid contents (SSC) of the studied properties.Materials and methods: Barley malt was purchased from local market. 150 gr of malt was first grounded and added to 600ml water at 46°C and stored for 30 minutes. Then, its temperature was increased using a heater to reach 70°C. 300 ml water was then added to the mixture and stored at 70°C for 60 minutes. Then, the mixture was cooled at room temperature and filtered to gain a sweet solution. The obtained solution was concentrated to 60, 70 and 80 degree of Brix for further experiments.Specific heat and thermal conductivity of samples were determined using a differential scanning calorimeter (DSC). DSC is a powerful tool which is able to spontaneously measure different thermal propertiesof samples such as specific heat, thermal conductivity, glass transition temperature, melting point, crystallization point etc. as a function of time and temperature at the desired temperature levels. Density of samples was also measured using a 50ccvolumetric pycnometer. 25 grams of samples were first solved in hot water and then were placed in an isothermal bath to measure the density. Thermal diffusivity of samples was determined using the following equation:∝=k/〖pC〗_p Results and discussion: The obtained results on specific heat measurement showed that decreasing SSC from 80 to 60% and increasing the temperature from 25 to 90°C would increase cp from 2.074 to 3.063 kJ/kg°C in a linear manner. Following equations were obtained to predict specific heat as a function of temperature:C_p=2.756+0.004T R^2=0.893 ، X_s=60C_p =2.245 +0.005T 〖 R〗^2=0.868، X_s=70C_p=2.066 +0.001T R^2=0.75، X_s =80Thermal conductivity measurements were also showed that decreasing SSC from 80 to 60% and increasing temperature from 25 to 90°C would increase the K values from 0.1196 to 0.347 W/m°C in a linear manner. Increasing temperature would increase molecular movements and therefore it elevates the heat transfer velocity and K increases. Following equations were obtained to predict thermal conductivity as a function of temperature:K=0.152 +0.003T R^2=0.761، X_s=60K =0.097+0.002T R^2=0.851، X_s=70K=0.114+0.001T R^2=0.706،X_s =80In order to develop a model to predict thermal conductivity of malt extract based on its soluble solid content and temperature, multiple regressions was used. The obtained model was a two-parameter linear model with R2 of 0.858. The results showed that 1% increase in soluble solid content percentage would cause an increase of 6% in K, while 1% increase in temperature would cause only 49% increase in thermal conductivity value.Density measurements were also showed that increasing density from 60 to 80% and temperature from 25 to 90°C would increase density of malt extract. Following equations were obtained to predict density as a function of temperature:P=1328.699-0.402T R^2=0.999، X_s=60 P=1375.451-0.290T R^2=0.999، X_s=70 P=1426.201-0.286T R^2=0.998،X_s =80Thermal diffusivity of samples was also determined using indirect method for soluble solid content of 60 to 80 and in the temperature range of 25 to 90°C. It was found that thermal diffusivity would increase linearly by decreasing soluble solid content and increasing temperature. Following equations were obtained to predict thermal diffusivity as a function of temperature:∝=5.176〖×10〗^(-8)+0.049×〖10〗^(-8) T R^2=0.783، X_s=60∝=2.993×〖10〗^(-8)+0.050×〖10〗^(-8) T R^2=0.929، X_s=70∝=3.125×〖10〗^(-8)+0.036×〖10〗^(-8) T R^2=0.94،X_s =80The results of the present work were in agreement with the results reported by other researchers confirming that both SSC and temperature have significant effect on thermo-physical properties of malt extract.
