| چکیده انگلیسی مقاله |
Introduction: Synbiotic foods refers to food ingredients or dietary supplements includes probiotics and prebiotics in a form of synergism; therefore, synbiotics are mixtures of probiotics and prebiotics that beneficially affect the host by improving the survival and implantation of live microbial dietary supplements in the gastrointestinal tract, by selectively stimulating the growth and/or by activating the metabolism of one or a limited number of health-promoting bacteria, thus improving host welfare (Kelly et al., 2008). Prebiotic compounds are substrates that are not metabolized by host enzymes, but by its microbiota, which provide many health benefits related to the gastrointestinal tract, cardiac metabolism, mental and bone health. Among these are the xilooligosaccharides (XOS), which are emerging prebiotics derived from arabinoxylans, polysaccharides present in cereals such as wheat bran, oats bran, buckwheat bran, rice bran, barley bran (Suman and Sreeja, 2019). These compounds are promising bioactive ingredients for the development of new functional ingredients/ products for food and feed industries. As described by previous studies, prebiotics are non-digestible food compounds stimulate the growth and metabolic activity of probiotic bacteria, in food and in the body and exert positive effects on the survival and activity of probiotic bacteria as well as the health of the consumer (Wilson & Whelan, 2017). The use of cereal bran as agroindustrial waste represents a great sustainable way to minimize the impact caused by its accumulation in the environment, as well as explore its beneficial health properties.Considering the important role of prebiotics in the functionality of the probiotic bacteria and the availability of valuable prebiotic sources in agricultural waste such as cereal bran, the purpose of this study was to investigate the effect of oat, rice, and barley bran on the proliferation and activity of probiotic bacteria, Lactobacillus casei and Bifidobacterium bifidum in milk. Material and methods: In this study, barley (Hordeum vulgare L.) Iranian Nusrat variety, oat (Avena sativa) and rice (Oryza sativa) Iranian Khazar variety (under genetic modification) were prepared from the institute of plant breeding research. Barley, oats, and rice seeds were cleaned, brushed, and then milled using a laboratory mill to obtain white flour, fine bran particles, and coarse bran particles. Then, these three components were separated into coarse bran particles, fine bran particles and white flour using a set of sieves with different meshes. Fine bran particles were used for the experiments. To carry out the fermentation process, the inoculation volume of 10 ml (cell population 1012 cfu/ml) of each bacterial culture was mixed with 90 ml of high-fat milk at room temperature. Then, different percentages of oat, rice, and barley bran powder (2.5, 5 and 7% w/w) were added to the milk medium. Control samples were prepared according to a similar method without using bran. All the prepared samples were placed in an incubator at a temperature of 37 degrees Celsius and the pH was measured at one-hour intervals and fermentation was stopped when the pH reached 4.6. After primary fermentation, all the samples were kept at 4 ºC and the cell survival rate, pH, acidity, amount of vitamins B1, B2, B5, B6, B12 and inulin were determined after 1, 7, 14, 21, and 28 days of storage. All tests were performed in three repetitions and the data obtained in the study were presented as mean ± standard deviation. Data analysis was performed using two-way analysis of variance (ANOVA) and Tukey HSD supplementary test (for pairwise comparisons). Results and discussion: The highest survival rate of Lactobacillus casei and Bifidobacterium bifidum was observed in the samples containing 7.5% oat bran, rice and barley during the entire storage period in the refrigerator, and Lactobacillus casei had a higher potential for survival than Bifidobacterium bifidum. Barley bran showed more prebiotic activity in stimulating the growth and survival of studied probiotic bacteria, followed by barley bran and rice bran. The highest value titratable acidity was obtained in the samples treated with 5 and 7.5% of the brans, which contained higher bacterial populations than the control and other samples. The content of group B vitamins was significantly higher in the samples containing rice bran, followed by the samples containing barley and oat bran. The amount of inulin showed the highest amount in the treatments containing barley bran and barley bran during the entire storage period. According to the results of this study, the synbiotic milk medium containing Lactobacillus casei and Bifidobacterium bifidum and rice, barley, and oat bran has a positive prebiotic effect on the metabolic activity and survival of the examined probiotic bacteria during the 28-day storage period in the refrigerator compared to the control samples and has caused an increase in the rate of bacteria reproduction, a rapid decrease in pH and an increase in acidity. The content of vitamins B1 and B2 increased more than 2 times, and the amount of vitamin B5 increased by about 1.5 times, and a slight increase in the amount of vitamins B6 and B12 was observed. Conclusion: According to the results of this study, rice, barley, and oats bran have prebiotic activity and stimulate the growth of probiotic bacteria. |