Food Biotechnology
Dina Shahrampour; Morteza Khomeiri; Seyed Mohammad Ali Razavi; Mahboobeh Kashiri
Abstract
Introduction
Increasing public awareness of the impact of diet on health has increased the demand for healthy food products, especially probiotics. Probiotics are living and non-pathogenic microorganisms with beneficial effects on the host when consumed on a regular basis and sufficient amounts ...
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Introduction
Increasing public awareness of the impact of diet on health has increased the demand for healthy food products, especially probiotics. Probiotics are living and non-pathogenic microorganisms with beneficial effects on the host when consumed on a regular basis and sufficient amounts (106 cfu/gr or ml). A significant number of probiotics become inactive during various food processes (thermal, mechanical and osmotic stress), storage condition (exposure to oxygen, UV light and low or high temperature) or during interaction with food ingredients. In addition, the breakdown and passage of food through the digestive system can also affect the survival and ability of probiotics to form colony in the intestine. Therefore, it is a challenge for food manufacturers to maintain and deliver live probiotic cells in sufficient quantities via food product. On the other hand, the variety of probiotic food products in the market, especially in Iran, is low and is mainly limited to dairy products, fermented drinks and pickles. Bioactive edible films and coatings are defined as biopolymer-based structures that carry bioactive components such as vitamins, enzymes, peptides, etc, and slowly release them on the food surface during storage. Biopolymers such as polysaccharides, proteins, and lipids are used in the preparation of edible films and coatings. Trapping probiotic bacteria in the structure of edible films and coatings is a new approach that has been proposed to increase the survival of these microorganisms and to develop new probiotic products in the food industry.
Materials and Methods
In this study, an alginate-based probiotic bioactive film containing L. plantarum was fabricated after centrifuging of overnight culture of probiotic bacterium from MRS medium and adding the bacterial cells into film forming solution. The effect of bacterial addition on physical, mechanical and prevention properties of alginate film was evaluated. In addition, the effect of two temperatures 4 °C and 25 °C on the survival of embedded probiotic bacterium in the film structure during one month of storage was also investigated by microbial count assay on MRS agar medium. Then, the model food was covered with probiotic film and the survival of probiotic bacterium during storage at 4 °C was determined.
Results and Discussion
The results showed that the population of probiotic bacterium declined about 4.61% after drying of alginate film solution. Addition of probiotic bacterium to the alginate film increased the thickness, turbidity, and tensile strength of the film, while had no significant effect on solubility, water activity, Elongation (%) and microstructure of alginate film. In addition, the probiotic film containing bacteria had less Lightness (L*), and moisture content than the control film. Also, the incorporation of L. plantarum in alginate film could decrease the water vapor permeability (WVP) from 0.755 to 4.51 (×10-10 g m-1s-1pa-1). The total color difference (ΔE) of alginate film containing probiotic bacteria compared to control film without probiotic bacteria was 1.1. The SEM images were confirmed the proper and uniform distribution of probiotic L. plantarum cells on the surface of alginate film. The survival percentage of L. plantarum in alginate film after one month of storage at 4 °C and 25 °C was 96.84 and 47.29%, respectively. Also, the population of embedded bacteria in the film structure on the food model (sausage) surface after three weeks storage in refrigerator was in desired level of probiotic products (> 106 cfu / gr).
Conclusion
The viability of probiotic bacteria after the application of alginate film containing L. plantarum on the surface of food model (sausage) during cold storage remained at the optimal recommended level for three weeks. Therefore, alginate film is recommended as a suitable carrier for probiotic microorganisms to produce new functional products.
Food Biotechnology
Maryam Moosavi; Mahboobeh Kashiri; Yahya Maghsoudlou; Morteza Khomeiri; Mehran Alami
Abstract
Introduction: Hydrogels are a three-dimensional network of polymeric matrices with the ability to absorb water through chemical or physical cross-linking. Recently, the development of bio-based hydrogel with the aim of reducing the use of fossil fuel is becoming interested. Wheat filter flour (WFF) is ...
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Introduction: Hydrogels are a three-dimensional network of polymeric matrices with the ability to absorb water through chemical or physical cross-linking. Recently, the development of bio-based hydrogel with the aim of reducing the use of fossil fuel is becoming interested. Wheat filter flour (WFF) is a by-product obtained from air-classification in the modern wheat milling industry. It contains a high level of non-endosperm materials with the ability of water absorption and bio-film making capacity. Nevertheless, hydrogel-based films usually display weak water resistance, flexibility problems, and gas barrier properties. Carvacrol as a phenolic component is used to improve the functional properties of film and reduce the growth of pathogenic and spoilage microorganisms. Materials and Methods: Hydrogel based films were prepared by casting technique. Six grams of WFF was added to 100 ml of distilled water, the pH of the solution was adjusted near to 10.7 with NaOH solution (1 N). The dispersion was heated up to 85°C, with gentle stirring at 250 rpm for 30 min.Glycerol (35 g/100g of dry polymer) was then added and stirred for another 15 min. Carvacrol, as an active agent incorporated at two concentrations (5 and 10% (g/100g of dry polymer)) and stirred for another 15 min at 40°C and dried in a forced-air oven at 35± 5°C for 24 h. Physical (density, water-solubility, moisture content), mechanical, barrier and antimicrobial properties of active hydrogel-based film were determined. Antimicrobial properties of active hydrogel-based were evaluated in the vapor phase by using the micro- atmosphere method and liquid medium (immersion in broth) as a food model system. Statistical analyses were performed on a completely randomized design with the analysis of variance procedure using SAS software. Results and Discussion: Increasing the carvacrol concentration in the film making solution led to decreasing the water solubility, moisture content, and hydrophobicity properties of WFF based films. The SEM observations confirmed a porous structure of the active hydrogel-based film. The highest water vapor permeability (1.32×10-10 gm-1s-1Pa-1) and the minimum water solubility (37.01± 0.63%) were observed in hydrogel film with 10% carvacrol. An increase in the concentration of carvacrol produced a greater growth inhibition zone for all microorganisms. The results in vapor phase showed that A.niger exhibited greater sensitivity to carvacrol than other studied bacteria. Hydrogel based films with 5% carvacrol in liquid food model system produced 1.16 and 1.34 log reduction against E. coli and L. monocytogenes, respectively. The greatest antibacterial activity was observed with films containing 10% carvacrol against L. monocytogenes (2.71 log reduction). This work suggested that the WFF hydrogel base film with 10% carvacrol can be used as an active packaging for improving the safety and shelf-life of food products.
Food Technology
Fahimeh Hajinia; Alireza Sadeghi; Alireza Sadeghi Mahoonak; Morteza Khomeiri; Yahya Maghsoudlou; Ali Moayedi
Abstract
Introduction: Bread is the main source of nutrients and it is a cheap staple food in the daily diet of people in many parts of the world. One of the most important ways to improve the quality of bread is to ferment cereals and use fruit resources. Cereal fermentation has a well-known potential to improve ...
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Introduction: Bread is the main source of nutrients and it is a cheap staple food in the daily diet of people in many parts of the world. One of the most important ways to improve the quality of bread is to ferment cereals and use fruit resources. Cereal fermentation has a well-known potential to improve the nutritional properties of the baked goods. It stabilizes the levels of various bioactive compounds, retards starch retrogradation and increases mineral bioavailability. A diet rich in cereal and fruit-based products could improve human health. Oat grain has a high functional potential due to its composition. This grain is known to be an excellent source of dietary fiber, antioxidants and a well-balanced protein fraction. Jujube fruit is also getting popularized due to the high content of vitamins, phenolic, polysaccharides and natural colorant agents. The quality of available commercially jujube depends on the contents of its bioactive compounds and micronutrients. There is no report about simultaneous application of fermented oat and jujube powder in processing of wheat bread. Accordingly, the aims of this study were to produce a supplemented wheat bread containing these ingredients, and evaluate the textural and antioxidant properties of the product. Materials and methods: In the present study, controlled fermented oat containing selected LAB isolated from oat sourdough (as starter culture) was used to produce supplemented wheat bread. Crumb hardness, porosity, specific volume, overall acceptability and antioxidant activity in wheat bread containing fermented oat, jujube powder and their mixture were investigated in comparison with the control (wheat bread). All the experiments were done in triplicates. A complete randomized design with the least significance difference (LSD) post-hock was also used to statistical analysis of the data at p < /em>< 0.05 by SPSS (version 20) software. Results and Discussion: The highest amount of crumb hardness was observed in the sample containing mixture of controlled fermented oat and jujube powder, meanwhile the lowest amount of hardness was belonged to the control sample. The results of specific volume showed an inverse relationship between the values of hardness and specific volume, and the lowest specific volume was observed in sample containing controlled fermented oat along with jujube powder. The highest amount of specific volume was also observed in the control sample. The porosity of all the produced breads was also significantly (p < /em><0.05) higher than the control sample, and the highest porosity was observed in the sample containing controlled fermented oat. The amount of produced gaseous compounds and carbon dioxide during fermentation affect the porosity of the produced bread. Furthermore, water retention capacity is also involved in increase in bread specific volume. Water reduces the stiffness of protein structures and allows better air to enter the dough texture and more specific volume of the product. Wheat breads containing controlled fermented oat + jujube powder and jujube powder (alone) had the highest antioxidant activity, and the control sample had the lowest antioxidant activity. During fermentation, the amount of phenolic compounds or flavonoids increases, and fermentation also causes the synthesis or release of various compounds that have antioxidant properties. Characterization of wheat bread containing the optimal formulation of controlled fermented oat and jujube powder didn’t show significant effect on the overall acceptability of the product. The presence of fiber in fortified breads is likely to increase water uptake, which in turn increases water retention capacity, reduces dough stability and increases overall acceptability. Fruits and whole grains are rich in phytochemicals such as phenolic compounds. Application of phenolic compounds in bread processing, in addition to improve antioxidant properties, affects the physicochemical properties of the dough and the quality characteristics of the produced bread due to various interactions with flour compounds such as gluten and starch. Accordingly, the combined use of plant-rich resources such as jujube powder and fermented oat, which are rich in minerals and micronutrients, can be used to improve the nutritional and quality characteristics of the supplemented wheat bread as a simple and efficient method. Due to the adverse effects of chemical additives and improvers, the importance of providing natural alternatives such as fermented substrates and plant resources in wheat bread processing is quite necessary. The best alternatives for this purpose include sourdough and fiber-rich plant. Wheat bread containing a mixture of controlled fermented oat and jujube powder had the highest crumb hardness and the lowest specific volume. Antioxidant activity in all samples was significantly higher than the control sample and wheat bread containing a controlled fermented oat and jujube powder with 90.52% had the highest amount of antioxidant activity. According to the results, controlled fermented oat and jujube powder, as functional ingredients, may be successfully incorporated into the wheat bread with positively effects on its quality characteristics.
Rahil Rezaei; Morteza Khomeiri; Mahdi Kashani-Nejad; Mostafa Mazaheri Tehrani; Mehran Alami
Abstract
β-d- glucan as a soluble dietary fiber, has many desirable physical and physiological characteristic. In this research the effect of β-d- glucan and aging conditions (Time and Temperature) on some physicochemical and textural properties of frozen soy yogurt was investigated. Three variables ...
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β-d- glucan as a soluble dietary fiber, has many desirable physical and physiological characteristic. In this research the effect of β-d- glucan and aging conditions (Time and Temperature) on some physicochemical and textural properties of frozen soy yogurt was investigated. Three variables including concentration of oat β-d- glucan (0, 1 and 2%), aging time (2, 13 and 24 h) and aging temperature (2, 4 and 6°C) were studied. The results showed that the addition of β-d- glucan to frozen yogurt increased viscosity, overrun, hardness and fat destabilization but the melting resistance and L*value were decreased. In terms of aging conditions, it was revealed that increasing aging time could improve the quality of product whereas higher temperature had an undesirable effect on the quality of frozen soy yogurt. Longer aging time caused an increase in viscosity, hardness, fat destabilization and melting resistance. By increasing aging temperature, fat destabilization, overrun and viscosity were decreased and melting rate was increased. It was concluded that addition of β-d- glucan as a dietary fiber and prolonged aging time at low temperature could adjust textural properties of frozen soy yogurt and improve quality of this frozen dessert.
Sanaz Ghassemi; Seyed Mahdi Jafari; Morteza Khomeiri; Elham Assadpour
Abstract
Orange peel oil,a widely used industrial flavoring, is volatile and chemically unstable in the presence of air, light, moisture and high temperatures. Biopolymer Nano complexes, a bunch of Nano carriers, are produced between groups of charged polysaccharides and proteins with the use of electrostatic ...
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Orange peel oil,a widely used industrial flavoring, is volatile and chemically unstable in the presence of air, light, moisture and high temperatures. Biopolymer Nano complexes, a bunch of Nano carriers, are produced between groups of charged polysaccharides and proteins with the use of electrostatic interactions. The nanoparticles are able to carry, protect, and increase their bioavailability of food-drug materials. Hence, in this study, the Nano complexes of pectin- whey protein concentrate, as a carrier of orange peel oil, were produced and the features of prepared Nano complex solution with various concentrations of whey protein (4, 6 and 8%), pectin (0.5, 0.75 and 1%) and different values of pH (3, 6 and 9) were studied. The Viscosity, stability and color (index L *) of the treated designs, done in a response surface methodology, were examined. The results showed that whey protein 4% and pectin 1%( with a pH of 3 and 9) had the lowest and highest stability respectively. Also this treatment with a pH of 3 showed the highest viscosity as well as the highest L *. The lowest viscosity was achieved by whey protein 6% and pectin 0.75% with a pH of 3, and because of the unbalanced compound, the complex did not form and a phase separation occurred. The lowest L * was obtained by whey protein 4% and pectin 0.5% with a PH of 9. Ultimately, whey protein 4% and pectin 1% with a PH of 3 were selected as the optimum sample because of formation the strong and suitable complex. Particle size and zeta potential measurement of optimum sample, were 160 nm and -0.53 mV respectively.
Ehsan Azadbakht; Yahya Maghsoudlou; Morteza Khomeiri; Mahboobeh Kashiri
Abstract
Introduction: The edible films and coatings had remarkable growth in recent years to increase the shelf life and to enhance food quality, stability, and safety and expected to have an important impact on the food market in the following years. In addition, these matrices can be used as carriers of antimicrobials ...
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Introduction: The edible films and coatings had remarkable growth in recent years to increase the shelf life and to enhance food quality, stability, and safety and expected to have an important impact on the food market in the following years. In addition, these matrices can be used as carriers of antimicrobials to minimize the risk of foodborne contamination by pathogens and inhibit the development of spoiler microbes. Antimicrobial packaging is a type of active packaging that provides the continuous migration of antimicrobial components to the surface of the foods. Chitosan is a linear copolymer of β-1, 4-linked D-glucosamine and N-acetyl-d-glucosamine. It is a cationic polysaccharide for food packaging applications, due to its unique characteristics of films, including excellent oxygen barrier properties, good mechanical properties, nontoxicity and good antimicrobial activity. Eucalyptus is a plant native from Australia and the Myrtasya family that includes about 900 species and sub-species. There is abundant scientific evidence regarding the efficacy of different species Myrtasya as the antibacterial and antifungal compounds used in health products, and food industry. Using natural antimicrobials are interesting strategies for reducing the use of chemical additives in the food industry. Essential oils (EOs) are defined as a mixture of volatile water insoluble substances to be incorporated into the edible films due to exhibit antimicrobial effects. Moreover, evaluation EOs on the physical, optical and structural properties of the resulting film is also important. Therefore, the aims of this work were to determine the effect Eucalyptus globulus essential oil on antibacterial properties (2) to determine the antimicrobial activity of chitosan based films containing Eucalyptus globulus essential oil against S. aureus, B. cereus, E. coli and S. intertidis.
Materials and methods: The foodborne microbial strains were prepared from Persian Type Culture Collection. The essential oil was analyzed by gas chromatography (GC) (Thermoquest 2000, UK). In this study, the antimicrobial activity of Eucalyptus globulus essential oils (EGOs) was evaluated against two gram positive (S. aureus and B. cereus) and two gram negative (E. coli and S. intertidis) bacteria by the agar diffusion technique and microdilution test. The effect of EGO was evaluated in liquid media and vaporous phase too. Chitosan solution were prepared by dissolving 1.5 % (W/V) of chitosan in aqueous solution containing 0.7% (V/V) of acetic acid under a magnetic stirrer at 40°C until chitosan was completely dissolved. Glycerol as plasticizer (10% weight of chitosan powder) was added to the solution and stirred for 10 minutes. The EGO with concentrations of 0.5, 1 and 1.5% v/v was added to the solution and was stirred for 5 minutes. The film forming solutions using a homogenizer (Heidolph, Germany) were homogenized with 12000 rpm for 4 min, then degassed for 5 min and 25 ml were cast on a 10 cm diameter petri dish. After drying the film in the oven at 38°C for 24 h, they were peeled from the plate surface and were evaluated. The antimicrobial activity of the films was evaluated in contact with liquid and vaporous media.
Results and discussion: Minimum inhibition concentration for gram negative (E. coli, S. enteritidis) and gram positive (B. cerus and S. aureus) bacteria showed 3.125 and 1.562 µg/l respectively. The inhibition zone for gram positive bacteria was bigger than gram negatives. The effect of EGO on bacteria based on Log reduction value (LRV) of S. aerus > B. cerus > E. coli> S. enteritidis. Thses results confirmed that gram positive bacteria were more sensitive to inhibition by plant essential oils than the gram-negative bacteria. Our results showed that chitosan film containing 1 and 1.5 % essential oil was able to reduce the density of bacteria. The Log reduction value of chitosan bioactive film was increased by increasing the concentration of E. globulus essential oil than 0.5 to 1.5 % in liquid media. The results of this work had demonstrated that chitosan bioactive film containing 1.5% EGO can be used an effective antimicrobial film for food packaging in direct contact.
Conclusion: Chitosan is a good biopolymer for active food packaging. The result of this study showed that chitosan films containing EGO could be used as active films due to enhanced the antimicrobial properties which are important in food packaging applications. Films containing essential oil had unique properties that are useful for coating of perishable foods such as fish and poultry.
Samira Shakiba; Morteza Khomeiri; Zeid Ahmadi; Soheil Amiri
Abstract
Introduction: Ispharzeh is a plant from genus Plantago whose seeds are used commercially for the production of mucilage. The plant is mainly cultivated in Iran and Middle East. Psyllium is mainly used as a dietary fiber to relieve symptoms of both constipation and mild diarrhea and occasionally as a ...
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Introduction: Ispharzeh is a plant from genus Plantago whose seeds are used commercially for the production of mucilage. The plant is mainly cultivated in Iran and Middle East. Psyllium is mainly used as a dietary fiber to relieve symptoms of both constipation and mild diarrhea and occasionally as a food thickener. Research has also shown benefits in reducing cholesterol levels. Basil seed gum is a novel hydrocolloid extracted from Ocimum basilicum L. seeds. It has shown promising stabilizing and emulsifying properties, which makes it a potential functional ingredient for the food industry. Previous works pointed out that these gums can be used successfully for food industry. However, a detailed study on Ispharzeh hydrocolloids seeds and basil gum has not yet been done. Therefore, the objective of this study was to evaluate the ability of using Ispharzeh hydrocolloids seed and basil gum as replacing with imported gums as well as to evaluate physicochemical, and sensory properties of ketchup sauce contain these gum were evaluated.
Materials and methods: Mixture design was employed to investigate the variation of ketchup properties with respect to operating parameters including xanthan, Ispharzeh seeds and basil gum in the range of 0 to 0.1 % using design expert software. Experiments were randomized in order to minimize the effects of unexplained variability in the observed responses due to extraneous factors. The treatments were selected regarding combination of xanthan, Ispharzeh seeds and basil gum in the range of 0 to 0.1 % using Design expert software. After extraction of gums, ketchup formulation was prepared with the treatments contain Ispharzeh hydrocolloids seeds and basil gum. Control sample contained ketchup formulation without gums. pH, apparent viscosity, syneresis, color and sensory properties of produced ketchup were evaluated.
Results and discussion: The impact of Ispharzeh seeds and basil gum addition on the pH of ketchup showed that all the treatments were in the standard pH range (3.67-3.74) according to the Iran national standard of ketchup. In addition, the results showed that addition of these gum were not significantly effect on pH. The regression coefficients were calculated according to the multiple regression coefficients and a polynomial regression model equation was fitted as quadratic equation. Regarding syneresis, all the treatments were stable with no syneresis except K2 (1% Ispharzeh) and K4 (1% basil gum). Addition of Ispharzeh and basil alone, were not significantly effect on synersis but when they used in combination and with xanthan, prevent syneresis significantly. The highest and the lowest viscosity were related to K4 (1% basil gum) and K10 (0.5 % xanthan+ 0.5% Ispharzeh), respectively. The regression coefficients were calculated according to the multiple regression coefficients and a polynomial regression model equation was fitted as quadratic equation. Hunter Lab colorimeter analyzing L*, a* and b* showed that K2 and K5 (1% xanthan) had the lowest and highest L* index. Variance analysis showed that quadratic model was fitted for L* value and coefficient correlation (0.9943) was satisfactory. In addition of effects of single gums, interaction of gums also had significant effect on lightness of ketchup. According to the results obtained from the sensory analysis, overall acceptability of K4 (1% basil gum) gained the highest scores. K2 (1% Ispharzeh) had the highest firmness so, led to unpleasant mouth feel in panelists. In addition, the presence of impurities in Ispharzeh seeds which not removed in centrifuge may darkening the produced ketchup hence got lower scores by panelists. Optimization evaluation by RSM evaluated the effects and interactions of the Ispharzeh hydrocolloids seeds and basil gum concentration to optimize ketchup properties. Optimized treatments were 0.42% Ispharzeh hydrocolloids seeds gum and 0.58% basil gum. Therefore, the values for stability tests are very close to the experimental values demonstrating that the model are applicable, which showed determination coefficient (R2) of 0.99. The formulation optimization showed that combination of 0.58% Ispharzeh and 0.42% basil gum as stabilizing agents in ketchup sauce, was a suitable replacer for imported commercial gums. Future studies on the Ispharzeh seeds and basil gum in other foods as well as the stabilization of these systems during the digestion process may help to understand the mechanism behind the functionality of these gums in food products.
Abbas Abedfar; Alireza Sadeghi; Mahdi Kashani-Nejad; Morteza Khomeiri; Mehran Alami
Abstract
Introduction: Sourdough is a very complex biological system and an important modern fermentation method of cereal flours and water. Sourdough fermentation is based on lactic acid and alcoholic fermentation depending on the composition of micro flora and fermentation conditions. Commercial sourdough processes ...
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Introduction: Sourdough is a very complex biological system and an important modern fermentation method of cereal flours and water. Sourdough fermentation is based on lactic acid and alcoholic fermentation depending on the composition of micro flora and fermentation conditions. Commercial sourdough processes do not rely on fortuitous flora but on the use of specific starter cultures. There has also been much progress in the development of tools that allow for the selection of key sourdough microorganisms for particular activities such as those concerned with enzymatic, antimicrobial, nutritional and additive replacement aspects. Most of the beneficial properties attributed to sourdough are determined by the acidification activity of dominant Lactobacillus starters. Sourdough fermentation can improve texture and palatability of whole grain fiber-rich, stabilize or increase levels of various bioactive compounds, retard starch retro-gradation and improve mineral bioavailability. The acidification of the sourdough and the partial acidification of the bread dough will impact on structure-forming components like gluten, starch and arabinoxylans. The swelling of gluten in acid is a well-known effect and mild acid hydrolysis of starch in sourdough systems has also been hypothesized for delay bread staling. The objectives of this research were to apply the dominant Lactobacillus starter isolated from traditional sourdough for cup bread production with whole wheat flour and delay it's staling. Materials and methods: In this study, following isolation of dominant Lactobacillus starter from traditional sourdough produced with whole wheat flour, the starter was identified by specific PCR. The single colonies obtained from streak plate of the sourdough culture, were subjected to species specific PCR. Afterwards, the mentioned starter was used for sourdough preparation. For this purpose, the effect of flour components (extraction rate, moisture, protein, ash and falling number), fermentation times (8, 16, 24 h) and sugar contents (0.5, 1, 1.5%) on starter activity were evaluated. pH and total titratable acidity (TTA) of sourdough treatments were measured. After processing of cup breads with sourdough treatments, the staling of these breads were also examined 2, 48 and 96 h after baking, based on crumb firmness (texture analysis) and amount of porosity (Image j method). Finally for statistical analysis a completely randomized design with factorial arrangement and 3 replications was used. To study the relationship between bread hardness and porosity with fermentation conditions, multiple linear regression was used and regression models were exhibited. Results and Discussion: By sequencing of the PCR products (obtained from sourdough culture), dominant Lactobacillus starter was identified as Lactobacillus plantarum. The TTA profile for the sourdoughs was also quite similar (starters interestingly continue to produce acid) and by increasing of TTA, the pH values were decreased. The acid production depends on factors such as fermentation temperature, time and dough yield. In general, a higher temperature, a higher water content of sourdough and the utilization of whole meal flour enhances the production of acids in wheat sourdoughs. The effect of sourdough on softness improvement was partly due to a higher porosity. Among the bread samples, 96 h after baking, lowest crumb firmness was observed in sample produced with sourdough with 24 h fermentation and 0.5%. sugar content. The maximum amount of crumb firmness was observed in sample produced with sourdough after 8 h fermentation and 1.5% sugar content. Furthermore, the maximum amount of porosity was obtained after 24 h sourdough fermentation and 1.5% sugar content, while the lowest amount was obtained after 8 h sourdough fermentation and 0.5% sugar content. After evaluation the results of texture analysis and porosity tests, significant correlation coefficients were established between porosity and softness, and it is reported that volume improvement is the main reason for a better shelf life in sourdough breads. The relationship between factors affecting on sourdough fermentation including fermentation time, sugar content and flour components, were also exhibited as regression models for examination texture characteristics of sourdough breads based on those viscoelastic behavior. By increasing the fermentation time in all of the sourdoughs, crumb hardness was decreased. Acids strongly influence the mixing behavior of doughs. Doughs with lower pH values require a slightly shorter mixing time and have less stability than normal doughs. Fundamental rheological evaluation of acid effect on gluten systems model indicated that both softness and elasticity of gluten were increased. Further to the direct impact of low pH on dough characteristics, secondary effects of acidification and fermentation time including changes in the activity of cereal or bacterial enzymes associated. Wheat flour proteases have optimal activity around pH=4. In addition, proteolytic enzymes with acidic pH optima in vital wheat gluten have been detected. Process requirements for optimum quality were strain-specific and different for textural improvement which should be taken in to account in designing future sourdough baking processes. According to results of this research, the influence of sourdough on bread softness during storage was depended on fermentation conditions and significant effect of sourdough process conditions on bread staling was clarified in comparison to control sample.
Maryam Ebrahimi; Morteza Khomeiri; Yahya Maghsoudlou
Abstract
Introduction:Toxigenic fungi such as A. flavus grow widely in peanut and produce aflatoxins, a group of carcinogenic metabolites. Aflatoxin produced in peanut differed from the genetic variety of plant. The high humidity and moderate temperatures in the subtropical Caspian littoral of northern Iran could ...
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Introduction:Toxigenic fungi such as A. flavus grow widely in peanut and produce aflatoxins, a group of carcinogenic metabolites. Aflatoxin produced in peanut differed from the genetic variety of plant. The high humidity and moderate temperatures in the subtropical Caspian littoral of northern Iran could increase the growth of A. flavus and the production of aflatoxin. The objectives of this study were 1) to determine the chemical composition of peanut cultivars grown in Golestan Province, Iran, 2)to select resistant variety of peanut to aflaoxigenic A. flavus growth and 3) to evaluate relationship between A. flavus growth and changes in oleic and linoleic acid content and peroxide value. Materials and method: Peanut samples were used from four important varieties of peanut, Goli, Mahalli, China and India. those have been harvested from farms in Golestan province, Iran. Fat, protein, ash, moisture, reducing sugar, AFB1 content and peroxide value in each sample were measured by the standard method of AOAC. Fatty acids of the peanut seed oil were analyzed using gas chromatography (GC, Varian CP-3800 model) with a flame ionization detector (FID) and a DB-WAX column (50 m × 0.32 mm ×0.2 µm). To study the effects of A. flavus on peanut varieties, they were sterilized with 0.5% NaClO solution and then one ml of A. flavus spore suspension was added to every 20gr disinfected peanut and was placed in the incubator for eight days at 26°C. After incubation, the number of seeds colonized by fungi, spore production, AFB1 production, the association between colonization rate of hydrolysis of fatty acids and peroxide value were determined.Results and Discussion: The results showed that there were significant differences (P
Mohammad Reza Edalatian Dovom; Masoud Yavarmanesh; Fariba Ghiamati Yazdi; Morteza Khomeiri; Neda Nayyeri
Abstract
Introduction : Lactic acid bacteria (LAB) are a group of gram positive, catalase negative bacteria which possess unique metabolic, physiological and morphological characteristics. In addition, lactic acid bacteria are considered as a valuable source of antimicrobial agents including bacteriocins. Bacteriocins ...
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Introduction : Lactic acid bacteria (LAB) are a group of gram positive, catalase negative bacteria which possess unique metabolic, physiological and morphological characteristics. In addition, lactic acid bacteria are considered as a valuable source of antimicrobial agents including bacteriocins. Bacteriocins are defined as non-toxic peptides produced by LAB. "Maskeh" as an Iranian traditional butter carries indigenous LAB which secrete and harbor bacteriocins. Our objective in this study was to evaluate the influence of antimicrobial compoundsproduced by isolated LAB from Maskeh, a local traditional butter, against some pathogenic bacteria suchas: staphylococcus aureus, Listeria innocoa and E. coli using culture-based methods. In the following step, influence of some technological parameters including different temperatures, pHs and proteinase K were determined on stability of antimicrobial compounds in bacteriocins.Materials and methods: Three samples of milk, yoghurt and local butter known as Maskeh were collected from different regions in the south ofKhorasanRazavi, Gonabadcity.Indicator microorganisms and culture condition: In order to activate the indicators, following the cultivation in corresponding and suitable media, they were incubated for 24 hours in suitable temperatures.Survey of antimicrobial activities: In Agar Spot, Antagonistic activities of isolates were evaluated in solid media. Finally clear zone of inhibition was measured in mm. In Well- Diffusion Assay (WDA), positive isolates from previous step, were selected for this assay. In this method, cell-free supernatant (CFS) of isolates were examined for their antagonistic activities. Finally clear zone of inhibition were evaluated around the wells.Determination of antimicrobial compound nature: Effect of proteinase K on CFS: In order to evaluate the enzyme sensitivity of bacteriocin like compounds produced by LAB, CFS of isolates were subjected to proteinase K (final concentration 0.5 mg/ml). Mixture of enzyme- CFS was incubated in 37C for four hours. Finally, the remaining inhibitory activity was determined using WDA.Influence of different temperatures on CFS: Heat sensitivity of bacteriocin like compounds was evaluated with subjecting the CFS of isolates to various temperatures. Again remaining activity of isolates was evaluated with the help of WDA.Influence of different levels of pH on CFS: CFS of isolates was adjusted at different pHs and their inhibitory effects were determined using WDA.Discussion & Results: Following the sequencing, 51 isolates were identified from different steps of Maskeh production. Results showed that 44 out of 51 isolates were effective at least against one indicator. It was clear that E.coli, Staph.aureus, Listeria. innocoa, Lb.plantarum, Lb.sake, Lac.lactis ssp. lactis,Lac.lactis ssp. cremoris were inhibited by 33, 7,11,12,7,35 and 7 isolates, respectively. Among pathogenic indicator bacteria, E.coli was inhibited maximally and regarding the non-pathogenic indicators, Lac.lactis ssp. Lactis was inhibited by the most of the isolates. Among the isolates, Ent.faecium B161 and Str.thermophilus B258 presented the highest inhibitory effect against Listeria.innocoa.Interestingly both these strains had been isolated from Maskeh, implying that they originated the same source. Formation of clear inhibition zone in agar spot method is related to colony-associated antimicrobial compounds like H2O2, lactic acid and other organic acids. Also, the strongest clear zone of inhibition was against Listeria.innocoa. Lb.plantarum B120 showed inhibitory effect against 6 out of 7 indicator bacteria. This strain has been isolated from Maskeh, and only did not affect on Lac.lactis ssp. lactis.In the next step, in WDA, CFS obtained from isolates were subjected to inhibition activity evaluation. In this assay, 39 isolates showed inhibitory activity against at least one indicator and 12 isolates had no inhibition against indicators. E.coli was inhibited by the most of the isolates (11), followed by Listeria.innocoa by 8 and Staph.aureus by 2 isolates. But noticeable point is that the strongest influence was seen against Listeria. In the last step, influence of technological parameters such as : temperature, pH and enzyme were determined on antimicrobial and inhibitory activity of CFS. In this survey, only those isolates were chosen which showed inhibitory effect against Listeria innocoa. Regarding the temperature, with increasing of this factor, the diameter of clear zone had decreasing trend. This means that bacteriocin- like compounds are sensitive to heat. Among analyzed isolates, CFS of two isolates namely Aerococcusviridans M156 and M141 possess the highest sensitivity. In contrast, the highest resistance was related to Aerococcusviridans M165. Evaluation of antagonistic activity of CFS of isolates at different pHsexperienced, in pH between 3-5, growing trend of inhibitory activity which is due to produced lactic acid. Maximum of antagonistic activity was seen at pH=3 and along with pH increase toward the alkaline condition, it decreased.Aerococcusviridans M165 and M141 showed clear zone of inhibition equal to 6.5 and 6, respectively at pH=7.Proteniase K as a proteolytic enzyme, exhibited decomposing influence on antimicrobial effects of all isolates, except two of them. This phenomenon implies the proteinaceous nature of antimicrobial compound in CFS, because of decomposition as a result of proteolytic enzyme. But regarding two isolates, the clear zone did mot destroyed even after enzyme treatment.Conclusion: Some CFS or their producing isolates can be exploited as bio-preservatives; CFS of Aerococcusviridans M 165 can be applied in foods subjected to high heat treatment. In acidic and low pH food, we can use those isolates which theirCFS remain their activity at low pH.
Amin Rangriz; Seyed Ali Mortazavi; Morteza Khomeiri; Soheil Amiri
Abstract
IntroductionTraditional mayonnaise is probably one of the oldest and most widely used sauces in all over the world. Mayonnaise is a product with particular consistency and is classified as a type of oil in water emulsions. Vegetable oil, acetic acid, and egg yolk are main components of mayonnaise. In ...
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IntroductionTraditional mayonnaise is probably one of the oldest and most widely used sauces in all over the world. Mayonnaise is a product with particular consistency and is classified as a type of oil in water emulsions. Vegetable oil, acetic acid, and egg yolk are main components of mayonnaise. In addition, mayonnaise may contain salt, sweeteners, spices, effective flavor materials, preservatives and stabilizers. It must contain at least 78.5 % of total fat and 6 % pureegg yolk. Due tohigh levels of oil present in mayonnaise, continuous usageof this product may result in diseases such as obesity,arteriosclerosis, hypertension and cardiovascular diseases.Therefore, consumers tend to consume low-fat products.Yoghurt is a very useful fermented milk products in terms of lactic acid bacteria that have beneficial effects on human health and Because of the similarity between this productand mayonnaise in terms of rheological properties, Yoghurt have been selected as a fat mimetic in mayonnaise.Therefore, the objective of present study was to investigate the effects of partial fat substitutionby yoghurt on physicochemical, rheological and sensory properties of low fat mayonnaise.Materials and methodsMayonnaise preparationOne kilogram of each mayonnaise sample was prepared.Different recipes of mayonnaise contained yoghurt asfat mimetic (as % of oil and yoghurt) including (49.5 % & 25%), (33% & 50%), (16.5% & 75%). All formulations contained 13 % Egg yolk, 10 % Vinegar, 1 %Mustard, 1 % common salt ,4 % sugar , sodium benzoate 0.07 % , Xanthan gum 0.2%.Mayonnaise preparation procedure was as follows; firstlyegg and vinegar were mixed together and then all otherIngredients(including Yoghurt for the low fatmayonnaise recipes) except oil were added and mixed well. The oil was finally poured insidethe mixer very slowly and homogenized for 1 min. Subsamples (250 g) of mayonnaise were aseptically transferredto sterile 250 ml, Duran glass bottles withpolypropylenescrew caps and left for one-day at 5 °C.Proximate composition analysisMoisture, protein, and ash contents were determined accordingto AOAC (2005) official methods. Fat content wasmeasured by Bligh and Dyer (1959) method, and totalcarbohydrate content was calculated by difference.Rheological measurementsRheological measurements were performed after 24 hstorage using a Brookfield viscometer Model RVDV-IIwith aspindle no.6 at 5 °C and 25 °C. Shear stress data wereplotted versus shear rate for each mayonnaise sample ata range of spindle speed (10–200 rpm). Plots of Lnshear stress versus Ln shear rate (for each sample) werethen used to calculate values including flow behaviorindex (n) andconsistency coefficient (K).Texture analysisMayonnaise samples were stored in refrigerator for 24 huntil texture analysis. The measurements were carriedout using a Brookfield texture analyzer (BrookfieldLFRA texture analyzer model number 4500 texture prolite) equipped with a 38 mm diameter cylindrical probeat 25 °C.The condition of the analysis was as follows; one cyclewas applied, at a constant crosshead velocity of 1 mm/s to asample depth of 30 mm, and then returned. From the resultingforce-time curve, the values for texture attributes, i.e.firmness, adhesiveness, and consistency were obtained usingtexture pro lit software.pH measurement and stability testpH was determined using AOAC standard method at 25 °C. The samples were assessed for the stabilitytest after 24 h storage at 35 °C. Mayonnaise stability wasdetermined after centrifugation (10 min, 2,500 rpm), andwas expressed as the volume of separated phase to the totalemulsion volume.Color measurementMayonnaise samples were measured for color in the L*, a*,b* system using a Lovibond Colorimeter.Sensory analysisAfter 1 day storage Sensory characteristics including appearance,color, odor, texture, taste, and overall acceptabilitywere evaluated by 14 semi-trained panel on 5-point hedonicscale (1 = the least or the lowest; 5 = the most or thehighest).Statistical analysisAll the tests were performed in triplicate. The data collectedwere analyzed by one-way analysis of variance (ANOVA),and significant differences of means were compared usingDuncan test at 5 % significance level using SAS softwareprogram.Results and Discussion: In present study, physicochemical, texture, sensory and rheological properties were evaluated in mayonnaise formulation with dairy-based. Fat was partially substituted by yoghurt at levels of 25, 50 and 75% which were referred respectively as SM1 (25% fat substitution level), SM2 (50% fat substitution level) and SM3 (75% fat substitution level) and the full fat mayonnaise (S) with 66 % oil was used as control sample. Results indicated that low-fat mayonnaise samples had considerably lower energy content compared with control sample, but higher water content than it. In terms of texture, SM3 had lower hardness compared with control sample. The samples exhibited thixotropic and shear thinning behavior through rheological studies and all samples were classified in the group of solid viscoelastic materials because, in all samples, storage modulus was greater than loss modulus. Also, the loss tangent of low-fat mayonnaise samples were higher than the control sample which reflects the tendency of these samples behavior to pseudo-liquid behavior. Results of sensory evaluation demonstrated that SM2 and SM3samples, were more acceptable. It was concluded that yoghurt can be used as a suitable fat replacer in mayonnaise formulation.
Soheil Amiri; Morteza Khomeiri; Mehran Alami
Abstract
Introduction: Mayonnaise is typical oil in water emulsion prepared from vegetable oil, egg yolk, vinegar, sugar, salt, mustard and a variety of food additives. Among its ingredients, egg yolk is most critical in term of stability of the mayonnaise. Nevertheless, one main problem with egg yolk is its ...
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Introduction: Mayonnaise is typical oil in water emulsion prepared from vegetable oil, egg yolk, vinegar, sugar, salt, mustard and a variety of food additives. Among its ingredients, egg yolk is most critical in term of stability of the mayonnaise. Nevertheless, one main problem with egg yolk is its high cholesterol content; therefore different attempts have been carried out to develop low cholesterol sauces with similar characteristics to the real mayonnaise. Employing another emulsifier in addition to egg yolk, or completely replace this important ingredient, provides several advantages, including a decrease in cholesterol content. Therefore, several protein products such as whey and soy protein have been evaluated as emulsifying agents in oil / water emulsions. On the other hand, to achieve mayonnaise with appropriate emulsion properties and high stability, several investigations have been conducted mostly using proteins with various emulsifiers and gums such as xanthan and guar gums. According to the studies identified, whey powder and Tragacanth gum have considerable emulsification and consistency properties. Therefore, the goal of this research was to investigate of the effect of gum tragacanth and whey powder as an emulsifying agent in mayonnaise. Material and methods:Raw materials characterizationRaw materials wereused in this research in order to production of mayonnaise included vegetable oil (alia GolestanCompany), water, egg, vinegar (varda company), spices, gum tragacanth (herbal local market in gorgan city) and whey powder (Pegah dairy company).pH measurement and stability testpH was determined using AOAC standard method (AOAC 2005) at 25 °C. The samples were assessed for the stability test after 24 h storage at 35 °C. Mayonnaise stability was determined after centrifugation (10 min, 2,500 rpm), and was expressed as the volume of separated phase to the total emulsion volume.Color measurementMayonnaise samples were measured for color in the L*, a*, b* system using a Lovibond Colorimeter (Lovibond CAMSystem500).Sensory analysisAfter 1 day storage Sensory characteristics including appearance, color, odor, texture, taste, and overall acceptability were evaluated by 14 semi-trained panel on 5-point hedonic scale (1 0 the least or the lowest; 5 0 the most or the highest).Viscosity measurementViscosity measurements were performed after 24 h storage using a Brookfield viscometer Model RVDV-II(Engineering Lab Inc., Stoughton, Mass., U.S.A) with a spindle no.7 at 25°C.Texture analysisMayonnaise samples were stored in refrigerator for 24 h until texture analysis. The measurements were carried out using a Brookfield texture analyzer (Brookfield LFRA texture analyzer model number 4500 texture prolite) equipped with a 38 mm diameter cylindrical probe at 25 °C.Statistical analysisIn this study, to evaluate the effect of gum Tragacanth and whey powder on physicochemical and sensory characteristics of low cholesterol mayonnaise, statistical design was used by statistical software minitab (16) which eventually combining multiple of 10 mixed were obtained and also to draw the charts and calculation software Excel 2010 and minitab (16) were used. For this purpose, to show the relationship of each of the dependent variables in the regression model with independent variables, their mixed contour diagram was drawn by the mentioned software from the appropriate equations and also to model data, the coefficient of determination of R2 model was determined.Results and Discussions: The results of physicochemical, rheological and sensory tests of low cholesterol mayonnaise have been illustrated in table 1. In terms of stability, viscosity and textural properties, samples containing whey powder and gum tragacantwere appropriate as an egg substitute. Except M5, M8 and M10 samples, other samples were stable, completely. On the other hand, the maximum and minimum viscosity was observed in M6 and M5, respectively. The highest preference belonged to M9.Table 1 – Experimental results for viscosity, hardness, adhesiveness, cohesiveness, stability and total acceptability for each sample.sample Viscosity(cp) Hardness(g) Adhessivness(mj) Cohesiveness Stability (%) L* acceptabilityM1 8460 213 6.6 0.66 100 81.2 4.28M2 8615 215.6 6.7 0.65 100 77.6 4M3 9390 223.2 7.4 0.63 100 77.3 4.14M4 10910 268.5 9 0.63 100 77.6 3.71M5 4315 100.6 4.9 0.76 54.3 70.2 4.14M6 13998 301.5 18.2 0.63 100 78.4 4.28M7 9925 240 7.7 0.65 100 77.3 4.28M8 5580 125 5.3 0.69 58.5 74.1 4.28M9 9700 226.5 7.6 0.66 100 70.2 4.57M10 5505 111 5.2 0.71 78.7 65.1 4.28The numbers were obtained from 3 replications.Considering optimization of low cholesterol mayonnaise formulation and study of its properties, it was revealed that 2.17 g egg, 5.28 g whey powder and 2.74 g tragacanth was an appropriate mixture in order to substitute egg in mayonnaise and making of low cholesterol product.
Rahil Rezaei; Morteza Khomeiri; Mehran Alami; Mahdi Kashani-Nejad
Abstract
In this study, effects of Guar and Arabic gum on the viability of two common probiotic, Lactobacillus acidophilus and Bifidobacterium lactis, in frozen yogurt during 60 days were investigated. Results of survival evaluation of probiotics showed that although during storage time bacteria counts decreased ...
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In this study, effects of Guar and Arabic gum on the viability of two common probiotic, Lactobacillus acidophilus and Bifidobacterium lactis, in frozen yogurt during 60 days were investigated. Results of survival evaluation of probiotics showed that although during storage time bacteria counts decreased significantly, this product could maintain 107 cfu/gr of probiotic at the end of storage. Maximum death rate of lactobacillus acidophilus was observed in control sample. Best viability of this microorganism was seen in samples containing 0.2% guar gum and 0.1% Arabic gum that these two treatments had no significant difference. The highest loss of bifidobacterium lactis belonged to sample containing 0.3% guar and lowest was seen in samples containing 0.1% Guar and 0.1% Arabic gum.
Somayeh Rezai Erami; Seyed Mahdi Jafari; Morteza Khomeiri; Houman Bayat
Abstract
The aim of this study is extraction of phenolic compounds from walnut leaves of touyserkani variety with two extraction methods (traditional method and with microwave assisted extraction (MAE)) and evaluation of their antioxidant activity. Total Phenolic contents and antioxidant properties of aqueous, ...
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The aim of this study is extraction of phenolic compounds from walnut leaves of touyserkani variety with two extraction methods (traditional method and with microwave assisted extraction (MAE)) and evaluation of their antioxidant activity. Total Phenolic contents and antioxidant properties of aqueous, methanol (80%) and ethanol (50%) extracts in different times was determined. At the next stage, effect of methanol extract on retarding of oxidation of soy oil was assessed. All of extracts showed antioxidant activity in a concentration-dependent way. In MAE, methanol extract had highest total phenol whose content is 89.15 ± 0.25 mg/g. the ethanol extract presented highest activity in radical-scavenging activity (EC50 = 27.90 µg/ml), reducing power assay (EC50 = 93.26 µg/ml) and antioxidant activity assay (EC50=68.23 µg/ml). Also extract at 1000 ppm could control oxidation of soy oil and this extract was effective than all of synthesis antioxidant in retarding oil oxidation Hence we can present walnut leaves as a potential source of phenolic compounds and natural antioxidant.
Zohreh Karami; Habibollah Mirzaee; Zahra Emam-Djomeh; Alireza Sadeghi Mahoonak; Morteza Khomeiri
Abstract
In this research, anti-microbial activity of ethanolic extract of licorice root against food spoilage microorganisms (Lactobacillus delbrueckii, Leuconostocmesenteroides, Candida krusei, Saccharomyces cerevisiae) in an orange flavored carbonated soft drink was investigated. The MIC and MBC of extract ...
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In this research, anti-microbial activity of ethanolic extract of licorice root against food spoilage microorganisms (Lactobacillus delbrueckii, Leuconostocmesenteroides, Candida krusei, Saccharomyces cerevisiae) in an orange flavored carbonated soft drink was investigated. The MIC and MBC of extract against Lactobacillus delbrueckii was 0.7 mg/ml and 0.8 mg/ml respectively, and against Leuconostoc mesenteroides MIC and MBC were 0.9 mg/ml. Also, MIC and MBC against Candida krusei and Saccharomyces cerevisiae using microdillution method was equal to 0.8mg/ml. In this research an orange flavored beverage preserved with natural licorice root extract was formulated and parameters such as phenolic contents, changes in population of aerobic mesophilic bacteria, yeast and acid-resistant micro-organisms during storage time were evaluated. Concentrations of 1000, 1500 and 2000 ppm of licorice root extract and samples containing 1000, 1500 and 2000 ppm of licorice root + 50% benzoate was used to control growth of food spoilage microorganisms in the beverage. Samples enriched with licorice root and a blank sample (commercial sample) were kept at room temperature and microbial counts were monitored during 1, 10, 20, 30, 40, 50, 60, 70, 80 and 90 days. Results of microbial examinations showed that the use of licorice root extract preserved the orange flavor carbonated soft drink during 90 days storage. Also, phenolic compounds showed good stability during 90 days storage time.
Seyedeh Mahsa Dadpour; Morteza Khomeiri; Hamidreza Sadeghi Pour; Shiva Rofigari Haghighat; Mehran Alami
Abstract
Fermentation is an important process for black tea production. During this process, by exposure of substrate to enzymes and the underlying oxidation reactions, quality determining factors of tea is produced. It is known that the exogenous application of cell-wall degrading enzymes leads to the increased ...
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Fermentation is an important process for black tea production. During this process, by exposure of substrate to enzymes and the underlying oxidation reactions, quality determining factors of tea is produced. It is known that the exogenous application of cell-wall degrading enzymes leads to the increased production of these compounds through enhancement of enzyme-substrate interactions. Pectinases in an important enzyme in this regard which is produced by microorganisms like genera of Aspergillus. In the present study, pectin lyase was isolated and partially purified through three- phase partitioning method from Aspergillus niger. The enzyme was purified by 16.65- fold from Aspergillus niger. The yield of purification was 52%. To assay the effects of purified enzymes on some qualitative characteristics of tea, Crude and purified enzyme were sprayed in the fermentation stage of tea. Molecular weight, optimum pH and optimum temperature of enzyme were 12KDa, 8 and 40°C, respectively. Results showed the effect of crude enzyme preparation on qualitative characteristics of tea is more than purified enzyme.
Keywords: Pectin lyase enzyme, Aspergillus niger, Three phase partitioning, Black tea
Maryam Ghaderi; Alireza Sadeghi Mahoonak; Mehran Alami; Morteza Khomeiri; Rahil Rezaei
Abstract
In this study, total phenolics and flavonoids content, antiradical and antimicrobial activity of methanolic extract of two Iranian acorn varieties, namely Quercus.castaneifolia var castaneifolia and Quercus.branti var persica were evaluated. Total phenolic and flavonoid content and extraction yield of ...
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In this study, total phenolics and flavonoids content, antiradical and antimicrobial activity of methanolic extract of two Iranian acorn varieties, namely Quercus.castaneifolia var castaneifolia and Quercus.branti var persica were evaluated. Total phenolic and flavonoid content and extraction yield of methanolic extract of castaneifolia variety (MC) were significantly higher than that of the extract of persica variety (MP). Extracts were also tested for their antioxidant activities using scavenging activity of 2, 2-diphenyl-1-picrylhydrazyl and compared with synthetic antioxidant namely BHA and BHT. EC50 values for MC, MP, BHA and BHT were 42.84, 70.40, 89.46 and 41.73 mg/ml, respectively. The extracts also showed good antimicrobial activity against all of tested microorganisms and the tested gram-negative bacteria was more resistant to the inhibitory effect of extracts. The ranges of minimum inhibitory concentration (MIC) of the extracts were 0.312-5 and 1.25-5 mg/ml for MC and MP, respectively. There was no difference between the MIC of MC and MB extract against Salmonella typhi and Shigella dysenteriae but MC extract showed the strongest activity on Escherichia coli and Yersinia entrocolitica at lower concentration. MP extract at concentration of 5mg/ml had bactericidal effect on all of gram negative bacteria (except Citrobacter). The most efficient bactericidal activity of MC extract was against Bacillus cereus, with MBC = 0.312 mg/ml while Shigella dysenteriae had the highest MBC (10mg/ml). A high-performance liquid chromatography was used for determination of phenolic acids of extracts. gallic, caffeic, p-coumaric and cholorogenic acid were found in MC and Gallic, caffeic, cholorogenic and sirinjic acid were detected in MP extract.
Keywords: Acorn fruit, Antimicrobial activity, Gallic acid, Methanolic extract, Phenolic Compounds
Morteza Khomeiri; Mahdi Kashani-Nejad; Mehran Alami
Abstract
Gums are the most important stabilizers that are used in ice cream and other frozen dairy dessert industries. In this study, effect of different levels of guar gum (0, 0.1, 0.2 and 0.3%) and Arabic gum (0, 0.1, 0.3 and 0.5%) on rheological behavior of frozen yogurt was investigated. The rheological behavior ...
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Gums are the most important stabilizers that are used in ice cream and other frozen dairy dessert industries. In this study, effect of different levels of guar gum (0, 0.1, 0.2 and 0.3%) and Arabic gum (0, 0.1, 0.3 and 0.5%) on rheological behavior of frozen yogurt was investigated. The rheological behavior of samples showed that all samples exhibit shear thinning behavior and power law model found to be the best model to predict flow behavior of samples. Sensory evaluation also showed that addition of gums could improve total acceptance of samples compare to control.
Keywords: Guar gum, Arabic gum, Frozen yogurt, Rheology
Seyed Mahdi Jafari; Morteza Khomeiri; Mehran Alami
Abstract
The aim of this study was to extract phenolic compounds from olive leaves of Cronaiky, Roghani and Mishen varieties by maceration and Microwave-assisted extraction (MAE) methods. Our result revealed that effect of extraction method and variety was statistically significant (p
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The aim of this study was to extract phenolic compounds from olive leaves of Cronaiky, Roghani and Mishen varieties by maceration and Microwave-assisted extraction (MAE) methods. Our result revealed that effect of extraction method and variety was statistically significant (p
