Nafiseh Karimi; Rezvan Pourahmad; Salman Taheri; Orang Eyvazzadeh
Abstract
Introduction: Yogurt contains valuable compounds, some of which enter yogurt whey and if discarded, remains unused. Yogurt whey has a high nutritional value due to its high quality biological proteins which can be a good source of bioactive peptides. Bioactive peptides are food-derived peptides that ...
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Introduction: Yogurt contains valuable compounds, some of which enter yogurt whey and if discarded, remains unused. Yogurt whey has a high nutritional value due to its high quality biological proteins which can be a good source of bioactive peptides. Bioactive peptides are food-derived peptides that are small in size and usually consist of 3- 20 amino acids. These peptides are considered as functional ingredients. Bioactive
peptides have antioxidants and antimicrobial properties. The aim of this study was to investigate the effect of adding bioactive peptide derived from enzymatic hydrolysis of yogurt whey on physicochemical, sensory and microbial properties of doogh during storage.
Materials and Methods: In this study, peptide derived from tryptic hydrolysis of yogurt whey protein fractionated by RP- HPLC was used. Minimum inhibitory concentration (MIC) and Minimum bactericidal concentration (MBC) of this peptide were determined against Staphylococcus aureus and Escherichia coli. This peptide was incorporated to heated doogh at concentrations of 12, 20, 24, 40, 48, and 80 mg/mL. Moreover, doogh samples were inoculated with 106 CFU/mL Staphylococcus aureus and Escherichia coli. Doogh samples were stored for two months. During 60 days storage, bacterial count, pH, acidity, ABTS radical cation inhibitory activity and sensory properties (taste, odor, texture, color and overall acceptance) of doogh samples were studied.
Results and Discussion: The MIC of yogurt whey peptide against Staphylococcus aureus and Escherichia coli was 12.2 and 24.4 mg/mL, respectively. Moreover, the MBC of yogurt whey peptide against Staphylococcus aureus and Escherichia coli was 12.2 and 48.8 mg/mL, respectively. Addition of this peptide to doogh showed that during storage period, the Staphylococcus aureus and Escherichia coli counts, pH and ABTS cation radical inhibitory activity of the samples were significantly decreased, but acidity was increased (p<0.05). The peptide of yogurt whey showed good antioxidant and antibacterial activities in doogh samples. By increasing the level of peptide in samples, the ABTS cation radical inhibitory activity was significantly increased (p<0.05). During storage, the control sample (without bioactive peptide) showed the highest reduction in antioxidant activity and the lowest reduction was related to the sample containing 48.8 mg/mL bioactive peptide. The ABTS cation radical inhibitory activity of the control sample and sample containing 48.8 mg/mL bioactive peptide was 9.72 and 3.66 Unit/mL, respectively on the 60th day. By increasing the levels of bioactive peptide, pathogenic bacteria counts were decreased (p<0.05). The sample containing the highest level of peptide (48.8 mg/mL) was free of Staphylococcus aureus and E. coli on the 20th day of storage. The control sample and samples containing 12.2 and 24.4 mg/mL bioactive peptide were free of these pathogenic bacteria on the 60th and 40th days, respectively. The highest rate of acidity and pH changes was related to the control sample and sample containing 48.8 mg/mL bioactive peptide had the lowest changes during storage. The acidity of control sample and sample containing 48.8 mg/mL bioactive peptide was 0.68 and 0.56% lactic acid, respectively on the 60th day.The results of sensory evaluation showed that in the control sample and sample containing the lowest level of peptide (12.2 mg/mL), the score of sensory characteristics decreased during the storage period, however, the use of the highest level of yogurt whey peptide (48.8 mg/mL) in the doogh formulation was able to reduce the rate of loss of sensory properties and maintain product quality over time. The sample containing 48.8 mg/mL bioactive peptide had the highest score of overall acceptability. Finally, the concentration of 48.8 ppm peptide can be considered as the best level to enrich the doogh in terms of physicochemical, microbial and sensory properties. Therefore, it is concluded that bioactive peptide derived from yogurt whey can be used as a natural antioxidant and antimicrobial agent in fermented dairy products like doogh.
Zohreh Bor bor moradi; Leila Nateghi; Orang Eivaz zadeh
Abstract
Introduction: Flour products are one of the most widely used food products in all over the world. Various types of pastry products derived from wheat flour are including the varieties of soup, plumura, and cane produced by traditional and semi-industrial methods. They are categorized in the bread and ...
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Introduction: Flour products are one of the most widely used food products in all over the world. Various types of pastry products derived from wheat flour are including the varieties of soup, plumura, and cane produced by traditional and semi-industrial methods. They are categorized in the bread and cereal group. The place of wheat- flour dough products, including Ashi noodle in the food basket of Iranian households, is gradually being consolidated. This product is a mixture of wheat flour, water and salt after the treatment process by the machine before being dried. The high consumption of salt in the Ashi noodle leads to the development and progression of hypertension in addition to increasing the risk of cardiovascular disease and, on the other hand, reducing salt leads to problems such as loosening and loss of Ashi noodle drying, as well as the degradation of the strand when boiling. Hydrocolloids or gums are compounds creating consistency and texture and increasing stability, acting as emulsifiers, forming gels, and improving oral sensation. Materials and methods: The general objective of this study was to investigate the effects of adding Farsi gum extract at concentrations of 0.2, 0.4, 0.6, 0.8, 1 and 1.2% based on the weight of flour instead of the salt used in the control group of the Ashi noodle (4.5%) on the rheological properties of Ashi noodle, as well as the evaluating physicochemical, texture, colorimetric, qualitative and sensory properties of low salt Ashi noodle one day after production. Zedo gum is a clear gum leaked from mountain almond trees. Zedo gum is found in white, light yellow, yellow vegetable, orange yellow, red and brown, in various sizes and forms. This gum is also composed of Arabinose and Galactose units. It is also known as Shirazi gum. Therefore, seven treatment groups and a control group were designed according to a completely randomized design. In order to analyze the data, Duncan’s method was used at 95% significance level in mini-fever software. Results and discussion: The results of rheological tests of dough with aloe vera revealed that salt reduction and increased gum significantly (p≤0.05). Those rheological properties of the aqueous pulp which were influenced were including mean curve height, mean curve length, inflation index, and mean surface under the curve, configuration test, and elasticity. The physicochemical results showed that by adding gum and reducing salt content. The amount of moisture was increased and the amount of ash and salt decreased significantly. The results of texture test were determined by texture analysis analyzer. By reducing salt, increasing the concentration of gum, and the hardness of the treatments, the decreasing trend and adhesion rate increased, with the highest adhesion ratio for gum samples 1 and 2. There was no statistically significant difference in the level of adhesion, elasticity and gumminess. The results of colorimetric tests with Hunter lab showed that there was no statistically significant difference in the color components a*, b⃰ and L* between all treatments with the control sample. In evaluating the qualitative characteristics of Ashi noodle, it was shown that by reducing the amount of salt to 3.90% and adding gum to the concentration of 0.6% of the weight of the heterogeneous strands, the weight of the broken and degraded strands showed a decreasing trend compared to the control; and in the concentrations higher than 0.6% gum, these incremental changes showed a statistically significant difference between the samples with 1.2% gum and the other treatments. Moreover, the results of sensory evaluation indicated that there was no significant difference compared to the control sample by reducing the amount of salt to 3.90% and adding 0.6% gum to smell, color, texture and overall acceptance of treatments. The taste score of all treatments did not differ significantly from the control sample. The results of this study showed that the amount of Ashi noodle salinity could be reduced to 0.6%, and instead, gum can be added to it with no effect on the qualitative, textural and sensory properties of the Ashi noodle compared to the control sample.
