Soheyl Reyhani Poul; Seyed Ali Jafarpour
Abstract
Introduction: Following extensive research on antibacterial and antioxidant properties of chitosan and hydrolyzed proteins and their satisfactory results, the use of these compounds as natural preservatives and good alternative to antibacterials and synthetic antioxidants in various nutrients is essential. ...
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Introduction: Following extensive research on antibacterial and antioxidant properties of chitosan and hydrolyzed proteins and their satisfactory results, the use of these compounds as natural preservatives and good alternative to antibacterials and synthetic antioxidants in various nutrients is essential. The aim of the present study was to investigate the properties of chitosan coating containing FPH in the preservation of rainbow trout (Oncorhynchus mykiss) fillets at refrigerated temperatures. Materials and methods: The hydrolyzed protein powder (FPH) used in this study was produced by enzymatic hydrolysis of frame (skeleton with the meat attached to it) of common carp (Cyprinus carpio) with flavourzyme enzyme. Accordingly, this powder was added to the chitosan coating (2% w/v chitosan + 2% w/v FPH). In order to investigate antibacterial and antioxidant properties of chitosan coating containing FPH, rainbow trout fillets were coated with chitosan (treatment 2) and chitosan containing FPH (treatment 3). Then, these sample treatments and control (treatment 1) were subjected to chemical (PV, TVN-B, TBA, FFA and pH) and microbial (count of aerobic mesophilic and psychrophilic bacteria) tests on days 0, 4, 8, 12, 16 and 20 in refrigerated storage. This study was implemented in form of completely randomized design and data were analyzed by one-way ANOVA and significant differences between the means were tested by Duncan's test at 95 confidence level. Results and discussion: According to the chemical tests, TBA, TVN-B and FFA indices showed an increasing value during the refrigeration period significantly (P<0.05) while their trend was lower in treatment 3 compared to the treatments 1 and 2. TBA index for treatments 1, 2 and 3 in day 0 was 0.017, 0.015 and 0.014 mg MDA/kg fillet respectively that this amounts reached to 1.49, 0.99 and 0.52 mg MDA/kg in day 20. At the beginning of the preservation period, TVN-B index was calculated 13.36, 13.18 and 12.46 mgN/100gr fillet for treatments 1, 2 and 3, respectively. But these values changed to 43.36, 30.19 and 22.11 mgN/100gr fillet for mentioned treatments at the end of preservation period. FFA index was 0.16, 0.14 and 0.12 percentage of oleic acid for treatments 1, 2 and 3 in day 0 whereas after 20 days of storage, this index increased to 2.55, 1.76 and 0.98 percentage of oleic acid for mentioned treatments respectively. The PV index was significantly less in treatment 3 compared to the treatments 1 and 2 in days 12, 16 and 20 (2.72, 4.42 and 4.12 meq o2/kg lipid respectively) but continuous incremental trend was not recorded in this index with increasing preservation time, even the end of the experimental period (day 20), the index decreased in all of treatments compared to the 16th day. The results of pH changes showed the stability of this index in treatment 3 during the preservation period (pH~6.30). Meanwhile, in day 12, 16 and 20, the pH of treatment 3 was significantly less than treatments 1 and 2 (p<0.05). The bacterial load count of aerobic mesophilic and psychrophilic bacteria in treatments (while having an increasing trend during the preservation period) showed that in day 8, 12, 16 and 20, the bacterial levels of treatment 3 were significantly less than treatments 1 and 2 (p<0.05). In this study, adding FPH produced from common carp fish (with degree of hydrolysis 15.9%) to chitosan resulted in enhanced antioxidant and antibacterial properties of chitosan coating. So that, the film obtained from the combination of chitosan and FPH was much stronger barrier against lipids oxidation and bacterial proliferation in rainbow trout fillets (at refrigerated temperatures) than pure chitosan film.
Zahra Eskandari; Seyed Ali Jafarpour
Abstract
Introduction: Gelatin is a water-soluble protein mixture that is obtained by partial hydrolysis of collagen, which forms the major protein in bones, cartilage, and skin. Gelatin is made from collagen fibers, which is low in protein, cholesterol, fat and carbohydrates, with a special positive effect on ...
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Introduction: Gelatin is a water-soluble protein mixture that is obtained by partial hydrolysis of collagen, which forms the major protein in bones, cartilage, and skin. Gelatin is made from collagen fibers, which is low in protein, cholesterol, fat and carbohydrates, with a special positive effect on human health. Gelatin is one of the most notable natural biopolymers, the most important source of this hydrocolloid is pig. Trying to find suitable gelatin supplements for food products is increasing. Fish gelatin is one of the most suitable mammalian gelatinous substitutes and is accepted as a Halal (Kosher) food item. The purpose of this study was to extract gelatin from sturgeon Beluga skin using pepsin enzyme and then investigate the effect of the enzyme on the improvement of physiochemical and its functional properties in comparison to the gelatin extracted by chemical method. Material and Methods: Pre-treatment and extraction of gelatin and application of factorsSkin Preparation was performed according to Feng et al. (2013) with slight changes in pre-treatment steps. A solution of 3.5% NaCl was used to remove non-collagenic proteins and 0.5% sodium carbonate solution (Na2CO3) to remove lipid from the skin. The initial pretreatment was carried out with a solution of 3.5% sodium chloride at a rate of 1:10 w / v at a speed of 180 rpm for 6 hours which was replaced every 3 hours with the water. Extraction by was carried out following Tong et al. (2013) method. Gelatin was obtained from pre-treated skin in distilled water at temperature of 30, 40 and 50 degrees Celsius and a percentage of enzymes (0.01, 0.055 and 0.1) at different pH (2, 3 and 4) for 6 hours and 45 minutes in hot water bath. Then, the mixture was kept in the boiling water bath, for 5 minutes to inactivate the enzyme. The solution was passed through a cleaning cloth and then centrifuged at 3500 rpm for 20 min and finally was lyophilized in a freeze-drier. In this research, the Response surface methodology response (RSM) method was used to optimize the experimental treatments. The central composite rotatable design was used to optimize the gelatin enzyme extraction process. Results and Discussion: The α chains were clearly visible in the sample extracted by the enzyme, with molecular weight of 130 kDa (treatment 5), while the α2 chain is much weaker in the extracted gelatin by chemical method. By decreasing enzyme ratios, chains with molecular weights of less than 130 kDa disappeared gradually in chemical samples as well as in an enzyme-extracted sample (treatment 19). The gelatin extracted by the enzymatic method contains α1 and α2 chains. In the average amount of enzyme (treatment 17), the α2 chains were relatively weaker than the maximum value of the enzyme (treatment 5), and these chains almost disappeared in the minimum amount of enzyme (treatment 19). These chains are weaker in the chemical extracted gelatin than that of treatment 5. Moreover, it can be seen that in the gelatin extracted by the enzymatic method, the ratio of the α2 / α1 chain is about 2 (the intrinsic ratio in collagen I), which shows that the inherent structure of gelatin is preserved.The highest and lowest amidic wavelength A was obtained for treatment 17 and treatment 19, the highest and lowest wavelength amide I for treatment 5 and treatment 19, the highest and lowest amid II wavelengths for chemical extracted treatments and treatment 17, The highest and lowest ratio of amide III to amide 1454 is related to treatments 5 and 19, and the highest and lowest amount of amide B is related to treatment 19 and 5.The behavior of the viscoelastic modulus of the treatments extracted with the pepsin enzyme (treatment 5, 17 and 19) and the chemically prepared sample showed that at temperatures lower than 20 ° C the storage or elastic modulus (G ') and the loss or viscous modulus (G') decreased with increasing temperature and the elastic modulus was larger than the loss modulus (G' >G'' ) indicating that the samples are still jelly-like (with the exception of treatment 19 that had the weakest gel strength).In all gelatin samples extracted using pepsin and chemical method, first, a relaxation stress index (viscosity increase at the beginning of the graph), and then a thinning non-Newtonian behavior (pseudo-plastic) was obvious during the shear rate. In fact, in the behavior of pseudo-plastic, the viscosity of the fluid is related to the shear rate and has decreased with increasing shear rate. Non-Newtonian viscosity of treatments prepared by the enzymatic method (except treatment 19) was higher than that of the chemically prepared sample at different applied shear rate.
Narjes Badfar; Seyed Ali Jafarpour; Mehdi Abdollahi
Abstract
Introduction: There is an expanding market for surimi in the world, and much interest in surimi throughout the seafood and food industry by the rapid growth in popularity of surimi-based products. This interest justifies an investigation into the applicability of freshwater fish species such as Silver ...
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Introduction: There is an expanding market for surimi in the world, and much interest in surimi throughout the seafood and food industry by the rapid growth in popularity of surimi-based products. This interest justifies an investigation into the applicability of freshwater fish species such as Silver carp, as an alternative fish resource, for surimi and surimi based products. Rheology concerns the flow and deformation of substances and, in particular, to their behavior in the transient area between solids and fluids. Moreover, rheology attempts to define a relationship between the stress acting on a given material and the resulting deformation and/or flow that takes place. Rheological properties are determined by measuring force and deformation as a function of time. Rheological evaluation is a useful technique for gathering information on the textural characteristics of surimi and kamaboko. It describes the surimi dynamic characteristics in the form of storage modulus (G′), loss modulus (G″), and phase angle (δ). Materials and methods: Whole Silver carp fish were gutted and the head removed, Fillets were minced by a meat mincer with a mesh size of 3 mm, then mince washed one, two and three times at ratio of 1:3 and 1:2 (mince: water) and dewatered. The mince was turned into surimi in a food processor operated for 2 min. salt (2%) was sprinkled over the mince. Ice water was also sprinkled over the mince to adjust the moisture content of the paste to 80 mL/ 100 g.Dynamic tests using a rheometer (MCR-301, Anton Paar- Germany) were carried out on the surimi gel after setting. The region of linear viscoelasticity of the surimi paste was determined by both stress and frequency sweep tests. The thermorheological behavior of Silver carp surimi was evaluated using a temperature sweep test and reported using sol-gel transition thermographs. The stress of 100 Pa was considered as the stress and the frequency of 1 Hz was considered as the frequency in the frequency sweep test, then Temperature sweep test involved heating the surimi samples from 10 to 90°C. Also Crip-recovery test was performed on the surimi in 300 seconds. Results & discussion: Rheological tests: Frequency sweep, Stress sweep and Temperature sweep graphs were relatively similar and in all samples affected by H2O2 and the control sample, the lowest value of G' was recorded between 50 and 52°C. Then, with increasing temperature from 52 to 62°C, the curve G' increased and the curve was stable at temperatures up to 80°C. Changes in the G' graphs can be attributed to the process of forming the gel by heating. Changes in the G" graph showed a similar trend with G’. In the creep-recovery test, the lowest and most strain were belonged to the control and sample 5 (1% H2O2, 1: 2, twice washing). Studying the figure of Creep-recovery test showed the samples affected by H2O2 had more resistance against applied stress in compression with control sample which expressed the effect of H2O2 on creating more and effective covalence cross-linking resulting more stable and constant gel network. During Surimi's heating, there are several reactions that involve various mechanisms, such as protein gelation. About Surimi, the observed macroscopic changes are related to the effect of temperature on proteins. The presence of H2O2 during the washing process did not have a significant negative effect on rheological properties of Surimi.
Soheyl Reyhani Poul; Seyed Ali Jafapour; Reza Safari
Abstract
Introduction: With the growing population and following the efforts of food production industries, more waste is produced which can be recovered by adding value and brought them back into the cycle of production and consumption. The reason behind is firstly the reduction of waste and secondly the economic ...
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Introduction: With the growing population and following the efforts of food production industries, more waste is produced which can be recovered by adding value and brought them back into the cycle of production and consumption. The reason behind is firstly the reduction of waste and secondly the economic importance of value added resultant products. Aquaculture sector produces large volume of wastes including the head, tail, fins, spine, and most importantly their viscera. If the waste managed properly, valuable materials such as hydrolyzed protein powder (the resulting waste hydrolysis using proteases enzymes) and fish oil (byproduct of enzymatic hydrolysis) can be produced. In this study rainbow trout waste was chosen, due to its large volume production in the country. The functional properties and antioxidant activity of hydrolysates as well as the oil fatty acid profile are the main factors to be considered. This study was aimed to investigate the hydrolysis of rainbow trout viscera (oncorhynchus mykiss) by protamex and neutrase enzymes individually and compare the functional properties and antioxidants activity of protein hydrolysate as well as analyze the fatty acid profile of fish oil obtained as by-product of enzymatic hydrolysis process.
Materials and methods: Rainbow trout viscera (Oncorhynchus mykiss) were obtained from the fish market in Sari and transported in ice containers to the laboratory. Protamex and neutrase enzymes were purchased from Novozymes Company and protein hydrolysates prepared enzymatically according to the method of Guerard et al. (2002). Proximate analysis was carried out according to the procedures outlined by the AOAC (1995). Degree of hydrolysis determined as described by Hoyle and Merritt (1994). Peptide chain length (PCL) was measured using the method of Adler-Nissen and Olsen (1979). Protein recovery (PR) determined using the method used by Ovissipour et al (2009). Protein solubility for hydrolysates was determined using the method of Robinson and Hodgen (1940). Foam stability index was measured according to the method described by Sathe and Salunkhe (1981). Water holding capacity (WHC) was determined using the method of Rodriguez-Ambriz et al. (2005). DPPH radical-scavenging activity was measured using the method of Yen and Wu (1999). Reducing power was determined by the method of Oyaiza (1986).The chelating activity on Fe2+ was determined, using the method of Decker and Welch (1990).
Results & Discussion: Protamex leads to the production of protein powder with higher degree of hydrolysis (34.76 ± 2.92%) and protein recovery (68/16 ± 1.98%) compared to neutrase (p0.05) despite the difference in L* value. The viscera oil contains 34% monounsaturated, 34.49% polyunsaturated and 31.4% saturated fatty acid. Apart from pH 4 (isoelectric point), the solubility of both protein powders in water was remarkable (more than 90%). The foam activity and stability index of hydrolyzate produced by protamex were more desirable than hydrolyzate produced by neutrase, whereas at pH 6, these indices reached to their maximum values of 200.13± 9.31% and 135.6 ± 5.64 %, respectively. Furthermore, water holding capacity of both hydrolyzates was measured as approximately 4.5 ml/g protein (p>0.05). Protamex leads to the production of protein powder with the higher DPPH radical scavenging activity compared to hydrolyzate produced by neutrase. Conversely, the reducing power of hydrolyzate produced by neutrase was higher than that of protamex (p0.05).
Keivan Ali Asgari; Sakineh Yeganeh; Seyed Ali Jafarpour; Reza Safari
Abstract
Introduction: Nowadays, use of new processing method is important for converting by-products into more marketable and acceptable forms to achieve a better utilization. Sea food processing generate protein rich by-products that their quantity depends on processing method. One of the methods for effective ...
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Introduction: Nowadays, use of new processing method is important for converting by-products into more marketable and acceptable forms to achieve a better utilization. Sea food processing generate protein rich by-products that their quantity depends on processing method. One of the methods for effective protein recovery from this protein rich by-product is preparation of protein hydrolysate through enzymatic, autolytic and chemical hydrolysis. Enzymatic hydrolysis is widely employed to improve the functional and nutritional properties of the fish byproducts. Hydrolysis may be conducted as a method of separating soluble nitrogenous compounds from insoluble particles and fish oil, and offers good predictability of the products. So nitrogen recovery assay can determine enzyme efficiency in separation of soluble protein from insoluble protein. Different factors (Enzyme level, temperature, pH, enzyme to substrate ratio) can effect on the hydrolysis degree, nitrogen recovery and functional properties of protein hydrolysate, so optimization method is used for obtaining the best condition. RSM is a statistical model frequently used for the optimization of complex systems and uses quantitative data from an appropriate experimental design to determine and simultaneously solve multivariate problems. Based on the experimental data, RSM could tell us the optimum conditions to obtain the desired responses, as well as the mathematical model in explaining the relationship between the experimental variables and its responses. Alcalase has great ability to solubilize fish protein and is nonspecific, with an optimum temperature that ranged from 50 to 70°C. It has optimal pH range at the value of 8 to 10 that could reduce the risk of microbial contaminations. Moreover, it has been reported that produced protein hydrolysate by Alcalase had less bitter principles compared to those prepared with papain. Furthermore Alcalase has been documented to be a better candidate for hydrolyzing fish proteins based on enzyme cost per activity.
The Cuttlefish (Sepia offıcinalis) can be found in the south water of Iran including Persian Gulf and Oman Sea and their catch has been recorded about 5102 t according to FAO Statistic. This species has been considered for exporting to other country. During Cuttlefish processing, 30-35 % byproducts including head, arms and viscera are generated that can be invaluable products and environmental pollution while it is protein rich source. The objective of this study was to optimize nitrogen recovery in the enzymatic hydrolysis of head and arms of cuttlefish (Sepia pharaonis) using Alcalase.
Materials and methods: Response surface methodology (RSM) based on Box-Behnken was employed to investigate the effects of different operating conditions including temperature (45, 50 and 55˚C), pH (7.5, 8 and 8.5) and alcalase enzyme to substrate ratio (1, 1.5 and 2) on the nitrogen recovery as a surface response. Referring to the R2 of 0.96 for nitrogen recovery, the mathematical model showed acceptable fitness with the experimental data, which indicated that major part of the variability within the range of values studied could be explained by the model.After obtaining optimum condition for nitrogen recovery, freeze dried protein powder was produced by optimized condition and analyzed for amino acid composition, chemical score of cuttlefish protein hydrolysate and protein efficiency ratio.
Results & Discussion: The obtained results showed the interactive effect of temperature and enzyme to substrate ratio was not significant (P> 0.05) but the interaction effect of enzyme to substrate ratio and pH and the interaction effect of temperature and pH was significant (P
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.
Seyed Ali Jafarpour; Elizabet Gorczyca; Berayan Leonard
Abstract
The preferred colour for surimi is white, but surimi prepared from light fillets of common carp (Cyprinus carpio) is slightly pink. Hydrogen peroxide (H2O2; 1-3% v/v) with and without sodium tri-polyphosphate (STP; 1-2% w/v) was added to a sodium carbonate bath (pH 7.0-11.5) resulting in a final pH range ...
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The preferred colour for surimi is white, but surimi prepared from light fillets of common carp (Cyprinus carpio) is slightly pink. Hydrogen peroxide (H2O2; 1-3% v/v) with and without sodium tri-polyphosphate (STP; 1-2% w/v) was added to a sodium carbonate bath (pH 7.0-11.5) resulting in a final pH range of 4.4 to 10.1 which was injected into carp fillets. After soaking and tumbling for 30 min at 4-10ºC, the fillets were evaluated for colour and water holding capacity (WHC). Fillets tumbled with treatment solution at different pH levels (7.0-11.5) without H2O2, had improved colour with significantly (P < 0.05) higher L* compared with untreated fillets as the control. However, the colour improvement [(L* and colour deviation (ΔE)] was not significantly different (P > 0.05) within the pH levels (7.0-11.5) trialled. With increasing H2O2 levels (1-3%), fillets became lighter and ΔE increased significantly (P < 0.05), especially with a 3% H2O2 treatment at pH of 10.5. The whiteness (L*-3b*) of surimi produced from treated (3% H2O2, pH 10.5) common carp fillets was compatible with that of Alaska Pollock and significantly (P < 0.05) higher than that of surimi from threadfin bream. On the contrary, WHC of treated fillets and its resultant kamabok gel significantly decreased in comparision with other samples. This was investigated by scanning electorn microscopy (SEM) technique. It was concluded that application of 3% H2O2 has possibly denatured the myofibrillar proteins which caused lower number of polygonal structure at the gel matrix of kamaboko prepared from treated fillets. It is recommended to improve the colour of common carp surimi while keeping the myofibrillar proteins intact by application of lower concentration of H2O2 on either chopped fillets or mince.
Keywords: Hydrogen Peroxide, Surimi, Colour, Water holding capacity, Microstructure
