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Kefir is one of the fermented milk products that plays a major role in nutrition and human health. The aim of this study was to investigate the effect of adding asparagus extract and green tea extract on survival of probiotic bacteria, antioxidant activity and sensory properties of kefir. Different concentrations (0.5, 1 and 1.5%) of asparagus extract and green tea extract were used in kefir and the samples were stored at 4˚C for two weeks.The results showed that addition of herbal extracts decreased pH and increased acidity and antioxidant activity of the samples (p≤0.05). The highest antioxidant activity was related to the sample containing 1.5% green tea extract. During storage time, pH of the samples decreased, but acidity increased significantly (p≤0.05). There was no significant difference between samples in terms of viability of Bifidobacterium lactis and Lactobacillus acidophilus (p>0.05). The viability of probiotic bacteria decreased significantly (p≤0.05) during storage but in all samples, the number of bacteria was more than 10⁸ CFU/ml until the end of the storage period. The sample containing 1.5% asparagus extract had the highest score of overall acceptance. Therefore, this sample was selected as the best treatment.

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Determining the mechanical properties of various agricultural products is necessary to analyze their behavior during transport, processing and precision design of machines to minimize waste. Therefore, in this study, the effect of mass at the levels of m> 500 and m≤ 500 g as well as the loading speed at the levels of 4.5, 7.5 and 10.5 mm/min on some mechanical properties of sugar beet such as rupture force, deformation at rupture point and rupture energy were examined. Then, for data analysis, factorial experiment based on a completely randomized design was used and the comparison of means was performed by Duncanchr('39')s multiple range test at α=1%. According to the results, the effect of loading speed on all mechanical properties was significant, but except for the rupture force, different mass levels did not have a significant effect on the deformation at rupture point and rupture energy. In this regard, the highest rupture force (72.3 N) in samples with mass of m>500 g and in the loading speed of 4.5 mm/min, but the lowest amount (42.4 N) in samples with mass of m≤500 g  and in the loading speed of 10.5 mm/min was measured. In this regard, the highest deformation at the rupture point (25.28 mm) in samples with mass of m > 500 g and in loading speed 4.5 mm/min and the lowest amount (16.4 mm) in samples with mass  m≤500 g  and in speed ‌Load 10.5 mm/ min was obtained. Also, the highest (82.1 mJ) and lowest (26.48 mJ) values of rupture energy were determined in samples with mass of m > 500 g and loading speeds of 4.5 and 10.5 mm/min, respectively. 
 

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Food processing is one of the most important industries, and it has undergone many changes due to the increasing demand for high-quality food. Attention to preserving nutrients and not changing the texture and color of products indicates the need to use technologies with lower temperatures because older technologies usually use high temperatures. Today, the health effects of food are among the most important factors in the acceptability of a product. In newer processes, it is possible to preserve all kinds of vitamins and the quality and color of the final product with less heat. Among these processes, we can mention membrane filtration, bacteriocins, microencapsulation, ultrasound, extrusion cooking, and irradiation. In addition to maintaining the quality and nutrients of the product, the above methods are also cost-effective and environmentally friendly, which clearly shows the need to pay more attention to them to maintain health, along with economic and environmental issues. Encapsulating nutrients also preserves the substances in ecological conditions and the digestive tract, which has led to this method receiving more attention from specialists today. In this article, various types of modern processing methods in the food industry have been investigated.

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The aim of this study was to measure the physicochemical, microbial and sensory properties of synbiotic stirred yogurt containing lemon fiber and probiotic bacterium Lactobacillus acidophilus during 20 days of storage. Sensory characteristics on days 0, 10 and 20 were evaluated by 5 trained panelists with 5 treatments (0.25, 0.5, 0.75 and 1 percentage of lemon fiber) The observed data were analyzed by SPSS.21 software. All experiments were performed in triplicate and Duncan multiple range tests with a confidence interval of 95% was used to compare the means. Excel software was used to draw the charts. According to the results, the effect of sample type and storage time on acidity, pH, synersis, dry matter, viscosity, bacterial viability and sensory indices (except for the effect of storage time on the overall acceptance) was significant (p≤0.05). Physicochemical, microbial and sensory results showed that with increasing lemon fiber content, pH, synersis and sensory indices decreased and acidity, dry matter, viscosity, and survival of probiotic bacteria increased. Also, with increasing storage time, pH, viscosity, probiotic bacterial viability and sensory indices decreased and acidity, synersis and dry matter content increased. The fat content of all treatments within all storage periods was 0.5%. According to the results of sensory evaluation and also considering probiotic bacterial viability, the treatment containing 0.25% lemon fiber was introduced as the superior treatment.