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The aim of this research was to study the effects of whey protein concentrate (WPC) and casein hydrolysate (CH) on chemical (pH and titratable acidity), physical (consistency and syneresis) and sensory properties of yogurt containing probiotic bacteria. Reconstituted skim milk at 10% total solids was fortified with 1 and 2% of WPC, CH and blend of them (WPC to CH ratios of 1:1). Reconstituted skim milks were made with 11 and 12% total solids as control. Bioyogurts were prepared with commercial probiotic starter culture (Lactobacillus acidophilus, Bifidobacterium sp., Streptococcus thermophilus and Lactobacillus delbrueckii ssp. bulgaricus). Fermentation was stopped at pH=4.6 and samples stored at 4°C for 21 days. Addition of WPC resulted in the highest pH value and the lowest titratable acidity. Acidity values of supplemented bioyogurt samples increased between 0.12 - 0.19% during 21 days of storage. Mَoreovere syneresis of these yogurts was lower and their consistency was higher than control. Bioyogurts containing WPC had the lowest syneresis and samples containing CH or WPC had the highest consistency. With regards to total acceptability, the best samples were bioyogurts supplemented with WPC and blend of WPC and CH.

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The aim of this research was to study the effects of whey protein concentrate (WPC) and casein hydrolysate (CH) on chemical (pH and titratable acidity), physical (consistency and syneresis) and sensory properties of yogurt. Reconstituted skim milk at 10% total solids was fortified with 1 and 2% of WPC, CH and blend of them (WPC to CH ratios of 1:1). For comparison, reconstituted skim milks were made with 11 and 12% total solids as control. Yogurts were prepared with commercial starter culture (Streptococcus thermophilus and Lactobacillus delbrueckii subsp. bulgaricus) and their fermentation proccess were stopped at pH=4.6 and samples stored at 4°C up to 21 days. The lowest pH value was obtained when milk base was supplemented with WPC. pH values of all yogurt samples did not change significantly during 21 days of storage and ~0.18% increase in titratable acidity was observed during storage period. The lowest syneresis was observed in yogurts containing blend of WPC and CH. Moreover, the syneresis values of these yogurts increased slower than other samples during storage. Consistency of fortified yogurts was higher than control yogurt and the consistency values of these samples reduced slower than control sample during 21 days of storage. With regards to total acceptability, the best samples were yogurts supplemented with blend of WPC and CH.

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Protein hydrolysate (PH) from viscera of cultured Siberian sturgeon (Acipenser baerii) was produced. To optimize the production conditions, Response Surface Method (RSM) was employed to examine the effects of three different operating conditions, including time, pH, and enzymatic concentration (Alcalase) on the degree of hydrolysis.The mathematical model showed acceptable fitness of the experimental data as R2 equaled 0.97, which indicated  that   major part of  the  variability  within  the  range  of  values could  be explained  by  the  model. The results showed that the highest degree of hydrolysis (58.21%) was related to the treatment which happened at the enzymatic concentration of 2%, 60 minutes time, and pH=8. Treatment under hydrolysis condition (i.e., E/S = 2%, Time = 45 min, and pH = 8.5) had the highest protein content (42.37g/l), which was used as an alternative to commercial peptone medium (Triptic soy broth) to assess the growth of Salmonella typhi bacteria from 0 to 48 hours. Although there was an upward trend in growth rate of S. typhi both in control and No. 15 (Alcalase) treatments, the log growth of control treatment was found to be better than that of Alcalase treatment. However, there existed no significant difference between the two treatments.

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The response surface methodology was employed to optimize the effects of pH, temperature (˚C), time (min) and the ratio of enzyme to substrate (% of substrate) on the hydrolysis process of cuttlefish muscle by alcalase. Central composite rotatable design with 5 levels and 4 factors and α=2 was used for the optimization of the process to gain the highest degree of hydrolysis. pH, temperature, time, enzyme concentration, interaction of temperature-enzyme concentration, square of pH, temperature, time and enzyme concentration had significant effects on the process. The R2 = 0.95, lack of fit < 0.05 and adeq-Precision of 14.16 for the model showed that the model could explain the variability within the range of values. The optimum condition for 42.0117 % of degree of hydrolysis was determined by Design Expert as pH 8.19, temperature 50.23, time 129.62 and enzyme2.15%.

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In this study, gelatin was first extracted by alkaline and acidic treatment including 0.19 N NaOH and 0.12 N acetic acid solution by ratio of skin of rainbow trout (Oncorhynchus mykiss (to solution of 1 to 7 and then heat treatment in 50 °C. Then, hydrolysed by alcalase enzyme for 4 hours with the ratio of enzyme to the substrate 1 to 100 and the degree of hydrolysis were measured after 4 hours. DPPH and ABTS free radical scavenging activity, as well as reducing power assay of gelatin hydrolysate were measured. The results showed that the degree of hydrolysis after 4 hours was 46/7%. Also the highest DPPH and ABTS free radical scavenging and reducing power at concentration of 10 mg/ml were 39/8%, 50/7%, and 0/123, respectively. The skin from fish filleting can be a suitable raw material for extraction of peptides with biological activities. The results showed that peptides derived from rainbow trout fish skin gelatin can be considered as a natural antioxidant.

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Optimization of protein hydrolysate from head and arms of cuttlefish (Sepia pharaonis) was examined. For this purpose, response  surface  methodology  (RSM)  was  employed  to  investigate  the effects  of different  operating  conditions  on  hydrolysis  process  of  cuttlefish protein by the application of alcalase enzyme. A Box-Behnken design with three factors at three levels was used for hydrolysis optimization and to check any individual or interaction effects between the experimental factors. In this method, the effects of three independent variables, including temperature, pH and enzyme to substrate ratio, were investigated on hydrolysis rate as a surface response. The mathematical model showed a good fitness with experimental data. Optimum conditions for temperature, pH and enzyme quantity were determined as 54.33 ˚C, 8.49 and 1.97 %,  respectively, which caused nearly 14.5 % hydrolysis degree. Based on the lack of fitness factor which was not significant, it was deduced that the resulted model was capable of prediction at different studied levels of variables. In this study, in order to confirm the conditions that proposed by mathematical equation, the hydrolyzed protein was produced accordingly at which resulted in a 16.8% hydrolysis degree. This finding was according to the aim of present trial by producing a protein hydrolysate with maximum hydrolysis degree. Then the functional properties of protein hydrolysate powder from optimized conditions were measured. Functional properties of this protein powders indicated a good solubility, but weak levels of emulsifying and foaming capacities.

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Aims: Skipjack tuna has the highest level of catch rate among tuna all over the world. Its head contains about 64% protein. Many Protein Hydrolysates and peptides obtained from various marine sources have a high antioxidant power. The aim of this study was to investigate the antioxidant activity of Protein Hydrolysate in Skipjack tuna head.
Materials & Methods: In this experimental study, 30 Skipjack tunas were investigated. At first, the amount of different compounds (protein, fat, ash, and moisture) was evaluated in the raw material; then, the hydrolysis process was performed by Alcalase enzyme and the hydrolysis degree of the protein hydrolysate was evaluated at different times. The antioxidant activity of the protein hydrolysate mixture was measured by DPPH radical scavenging activity, iron revival power, and ABTS radical inhibitory activity. For data analysis, the analytical tests were used.
Findings: The main part of the fish head was protein and it had high levels of ash. The degree of hydrolysis increased with increasing time and was it significant at 15, 60, and 120 minutes (p<0.05), but not significant at 120 and 240 minutes (p<0.05). DPPH radical scavenging activity increased with increasing hydrolysis time and there was a significant difference in all samples obtained from different times (p<0.05). The iron reduction capacity of the protein hydrolysate samples increased with increasing the hydrolysis time, and the highest amount was at 240 minute. The samples obtained from different times had a significant difference in iron reduction capacity (p<0.05). Increasing the concentration of protein hydrolysate increased inhibitory activity (p<0.05).
Conclusion: Protein hydrolysate in Skipjack tuna head has a high antioxidant activity and can be used in food products to increase oxidation stability.

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Aims: the aim of this study was to extract gelatin from the skin of farmed great sturgeon at different temperatures, hydrolysis using Alcalase enzyme, and to measure molecular weight distribution of peptides, amino acid composition and antioxidant activity of hydrolysates.
 
Materials & Methods: After removing pigments and non-collagenous proteins, defatting, and swelling of triple-helix structure, gelatin was extracted at temperatures of 50, 60, 70 and 80 ºC for 6 h and then hydrolysed using Alcalase (E/S ratio of 1:20 w/w) for 3 h. Molecular weight distribution of peptides, amino acid composition and antioxidant activity of hydrolysates were determined.
 
Findings: Degree of hydrolysis reached its maximum within the first 30 min. Hydolysate from extraction temperature of 80 ºC had the highest DH.  No significant differences were found among hydrolysates with regards to amino acid composition and peptide molecular weight distribution. At of 60 ºC, the content of small peptides (< 1 kDa) and amino acids were slightly higher compared to other samples. This could influence antioxidant activity to some degree. At higher extraction temperature of gelatin, the efficacy of hydrolysates in preventing the loss in total sulfhydryl groups content was decreased (P < 0.05) while TBARS and surface hydrophobicity were not influenced (P < 0.05).
 
Conclusion: Extraction temperature of gelatin did not reveal a considerable effect on properties and antioxidant activities of the resulting hydrolysates and gelatin hydrolysates with antioxidant activity and rich in peptides with molecular weight less than 1 kDa could be produced at 50 ºC.

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In this study Response Surface Methodology (RSM) was employed to investigate the effects of different operating conditions on the hydrolysation process of poultry by-products protein by the alcalase. Central Composite Design (CCD) by 5-level and 3-factor was used for the optimization of the hydrolysate production and to evaluate the effects and interactions of process variables: time (minute), temperature (C^◦) and enzyme to substrate ratio on the response. The response was included degree of hydrolysation (%). The mathematical model showed good fit with the experimental data, since the R² of 0.96 indicated that 96% of the variability within the range of values studied could be explained by the model. Furthermore lake of fit of the model was not significant (p<0.05). The optimum conditions for production of poultry by-products protein hydrolysate by 15.24% degree of hydrolysis were established as an enzyme activity to substrate ratio 0.07 AU/g protein; time 127.69 minute, and temperature 52.51°C. According to amino acid analysis and chemical score, methionine and histidine was the limiting amino acids in the hydrolysate. The poultry by-products protein hydrolysate tends to be a potential source in balanced fish diets and functional additive in food industries.

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Aim: In this study, the antioxidant properties of hydrolyzed protein from longtail tuna dark muscle with commercial enzymes (alcalase, alkaline protease, and evatase) were investigated.
Materials & Methods: Protein hydrolysates from tuna dark muscle were prepared by different enzymes Degree of hydrolysis (DH) was performed by TCA technique. The five aliquots at 60, 180, 240, 300, and 360 min were gathered during hydrolysis. The antioxidant activity of aliquots was monitored by in vitro assays (DPPH inhibition ability and Ferric (Fe3+) reducing power).
Findings: The antioxidant activities of protein hydrolysate from tuna dark muscle (TDM) increase with increasing time and DH. Alcalase hydrolyzed protein (AHP) generally showed higher antioxidative activity than evatase hydrolyzed protein (EHP) and alkaline protease hydrolyzed protein (APHP). Among the samples (concentration 3 mg.ml^-1), AHP at 360 min significantly exhibited the highest ability to scavenge DPPH radical (72.6 %). Furthermore, AHP and APHP significantly showed a minimum IC50 value of 1.1 mg.ml^-1 at 240 and 360 min hydrolysis. APHP significantly exhibited the highest ferric reducing power of 0.83 at 300 min and 0.76 at 240 min. AHP and APHP significantly showed the highest ferric reducing power of 0.74 at 360 min (p < 0.05).
Conclusion: This study confirmed that protein hydrolysate from TDM could be a good source of antioxidant peptides. In addition, the antioxidant activity of hydrolyzed protein relay on protease type and hydrolysis condition.
 

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In recent years, there has been an increased consumer interest and demand for low fat food products. Chocolate is a product with high fat and energy, therefor calorie reduction and partial replacement of cocoa butter is one of the efficient solution in this way. This study investigates the effect of collagen hydrolysate (Instant Gel Schoko) as a partial replacement of cocoa butter on the rheological and sensory properties of milk chocolate. Chocolate samples prepared with collagen hydrolysate having replacement levels of 15, 20, 25, 30% investigated and compared to control (contaning cocoa butter) group. The result showed that moisture content increased with increasing replacement levels, but water activity didn’t show significant difference with control group. The values of hardness, tixotropy, plastic viscosity and apparent viscosity increased with increasing the percentage of replacement, as a result, samples by least replacement levels (15, 20%) had less diffrence with control group. The amounts of yield value had increasing trend with enhancing of replacement percentage as the least yield value was related to M15. In spite of reducing total acceptance with increasing the levels of replacement in sensory evaluation, there was no significant difference with control group and in five levels hedonic test the most acceptance alloted to M20. In conclusion, according to results of rheological and sensory evaluations, in most cases, samples up to 15, 20% replacement had the least difference with control group and can be counted as optimum level for cocoa butter replacement.    

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In the present study Protein hydrolysate was prepared from the sheep visceral (stomach and intestine) using Alcalase 2.4 L. The effect of temperature (40, 45, 50 and 55 °C), time ( in six levels) and enzyme/substrate ratio (30, 60 and 90 Anson unit), on degree of hydrolysis and antioxidant activity were investigated using factorial experiment. The highest degree of hydrolysis was observed at 45 °C, after 180 min and enzyme/substrate ratio of 90 Anson unit/ Kg substrate (p< 0.05). Under these conditions, degree of hydrolysis was 36/92%. To study the antioxidant activity of protein hydrolysate, DPPH radical scavenging activity, ferric reducing power and effect of protein hydrolysate on stability of soybean oil were measured. All antioxidant activity experiments were performed at constant temperature (45°C). The highest DPPH radical scavenging activity and ferric reducing power were achieved after 150 min at enzyme/substrate ratio of 90 Anson unit/ Kg substrate (p< 0.05) and after 180 min at 90 Anson unit/ Kg substrate (p< 0.05), respectively. Results show that protein hydrolysate can be used as a natural antioxidant source instead of synthetic antioxidants.    

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This study aimed to evaluate the effect of squid protein hydrolysate prepared from protamex (P1, P2, P3) and alcalase (A1, A2, A3) enzymes respectively, at 0.5%, 1% and 1.5% concentration and also control sample (0%), on some physicochemical and organoleptic properties of low-fat set style yoghurt such as viscosity, synersis percentage, water holding capacity, acidity, pH, odor, taste, texture and color. Results showed that the lowest viscosity (416/66) was for control sample. Protein hydrolysates of both of enzymes increased viscosity while the highest amount was for P3 and A3. The highest pH and lowest acidity were for the control sample and protein hydrolysate in yogurt formulation decreased pH and increased acidity of samples. Maximum synersis obtained with control sample (4.47); protein hydrolysate decreased synersis while 1% protein hydrolysate with alcalase had the lowest synersis (0.33). Results of organoleptic tests showed that alcalase samples, especially in higher concentrations, modified odor and taste of low-fat yoghurt but these changes were not clear in texture and color. Generally, squid protein hydrolysate with alcalase and protamex in yoghurt formulation improved functional properties of low-fat yoghurt and it was more efficient in alcalase treatments in comparison with protamex.

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Abstract
Bioactive peptides are considered specific protein fragments that are inactive within the sequence of the parent protein. After they are released by enzymatic hydrolysis, they may exert various physiological functions. In the present study, response surface methodology was used to optimize hydrolysis conditions for preparing protein hydrolysate from whey protein, using Alcalase 2.4L enzyme. The investigated factors were temperature, time and enzyme/substrate ratio which were selected in the range 43-52°C, 65-175 min and 45-90 AU/Kg protein, respectively to achieve maximum degree of hydrolysis. Experiments were designed according to the central composite design. Each of the studied variables had significant effect on degree of hydrolysis (p<0/05). The optimum conditions to achieve the highest degree of hydrolysis were temperature 49.02°C , time 174.28 min, and enzyme / substrate ratio 90AU/Kg protein. Under these conditions, hydrolysis degree was 41.57 %. Regression coefficient for, chariot models (Quadratic type) was, 0.95. The values indicated the high accuracy of the model to predict the reaction conditions for different variables.

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Tomato waste can be used as a new protein source for the production of hydrolyzed protein. Free radicals are among the most important factors in the development of cancer and genetic mutations, which have become one of the greatest threats for human health in recent centuries. In this research, hydrolysis condition of tomato seed protein (temperature, time and amount of alcalase enzyme) to achieve maximum antioxidant activity and nitric oxide reducing power were investigated. The values were evaluated using Design Expert software and analyzed by the response surface methodology. Results showed that with the optimimizing hydrolysis conditions using the alcalase enzyme, it is possible to achieve a products with significant DPPH radical scavenging activity and nitric oxide reducing power. The results indicate that optimum conditions for achieving the maximum DPPH free radical inhibition activity and nitric oxide reducing power is temperature of 50 ° C, hydrolysis time 210 min, and the amount of enzyme 1.85%. Under these condition the amount of DPPH free radical inhibition activity and nitric oxide reducing power was 85.53 and 61.17, respectively. The results showed that the hydrolyzed protein produced from tomato seed could be used as a natural additive in the foods formulation and pharmaceutical uses with high antioxidants and nitric oxide reducing activity.

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The waste from food processing involves high-quality nutrients that can be widely used in food formulations. About 8100 tons of tomato pomace is produced annually by factories, which are often discarded without taking into account their potential use in the supply chain. Seeds isolated from tomato pomace are rich in protein and essential amino acids. In this research, chemical composition (protein, fat, moisture and ash) and functional properties (water absorption, oil absorption, foaming property and emulsion activity), in different fractions of tomato seed (defatted meal, protein concentrate and hydrolysate) and soy isolate (as the control sample) was determined and the effect of different concentrations of salt and pH on these characteristics was also investigated. The results showed that the tomato protein hydrolysate contained 79.37% of protein. There was a significant difference between the samples in terms of functional characteristics (water absorption, oil absorption, foaming and emulsification properties) ​​between the de-oiled and concentrate samples (P <0.05). In conclusion, it can be said that the protein hydrolysate derived from tomato seeds protein showed the best functional properties and therefore could be used as substitute for animal based proteins in the diet as well as active ingredients in food formulations.

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In this research, enzymatic hydrolysis of casein was performed using alcalase and pancreatin enzymes under optimal conditions. Then, the effect of type and combination of maltodextrin and gum Arabic carriers on physicochemical properties (moisture content, water activity, bulk density, tapped density, solubility, hygroscopicity), maintaining antioxidant activity (ABTS, DPPH and hydroxyl radical scavenging activities, reducing power, Fe²⁺ and Cu²⁺ chelating activity), morphology and mean particle size of spray-dried casein hydrolysates was evaluated. The results showed that moisture content, water activity, bulk density, tapped density and solubility as equally were affected by type and combination of carrier (P< 0.05). The hygroscopicity value of casein hydrolysates decreased significantly after the microencapsulation process. The antioxidant activity of the hydrolysates varies depending on type of enzyme. For example, ABTS and hydroxyl radical scavenging activities of pancreatin hydrolysates were higher than alcalase types (P< 0.05). The combination of maltodextrin and gum Arabic showed the best effect in maintaining of ABTS radical scavenging activity (92.72-94.93%), DPPH (98.47-98.94%), hydroxyl radical scavenging activity (88.59-94.95%), reducing power (98.94-99.65%), Fe²⁺ chelating activity (98.38-98.61%) and Cu²⁺ chelating activity (82.86-98.12%). The images of the electron microscope showed the presence of particles with different size distribution and wrinkles. In addition, the samples produced with gum Arabic had a larger particle size than maltodextrin. Finally, the results of this study showed the effectiveness of spray-drying process on the production of microencapsulated hydrolysates with desired physical, stability and antioxidant properties.