Synbiotic yogurt is a type of yogurt obtained by adding probiotics and bioactive prebiotic. probiotics are microorganisms which improves consumer health and gut microbiota when consumed. Prebiotics are non-digestible part of food carbohydrates with health benefits for consumer by selective enhancement of growth of useful bacteria in consumer colon. The aim of this study was production of a synbiotic yogurt as a functional food using Lactobacillus plantarum ( Lp PTCC 1896) and acorn extracted polysaccharide as probiotic bacteria and a prebiotic, respectively. Effect of prebiotic on bacterial growth and survival during cold storage and also its effect on rheological properties of yogurt was investigated. Acorn polysaccharide (AP) was extracted in a few steps including lipid extraction, water extraction and ethanol precipitation. In the next part AP was added (0/25 % and 0/125 % w / v) to a glucose free MRS medium to study its in-vitro effects on Lp PTCC 1896. The results showed that survival of bacteria has increased significantly (p 0.05) compare to that of negative control, and glucose free MRS containing 0.125% glucose and inulin after 17 days. It was also shown that prebiotic activities of AP to be better than that of inulin and due to its suitable WHC could be properly used for production of synbiotic yogurt as a functional food. Therefore, In the third part of this study AP was actually added to a synbiotic yogurt and the microbial and rheological properties of the yoghurt was studied. for this purpose, 0.125 % w/v of AP was added to yogurt containing 6.8 log cfu/g ( Lp PTCC 1896). Results of microbial analysis showed that acorn polysaccharide increases growth of probiotics. Acidity of samples containing prebiotic was less than the other samples. The AP (0.125 % w/v) reduced water holding capacity of samples. The results showed, AP (0.125 %w/v) reduced white color of yogurt (L *). According to the results of this study synbiotic yogurt containing prebiotic can enhance the growth and survival of Lactobacillus plantarum PTCC 1896. Keywords : Synbiotic yogurt, Acorn, Prebiotic, Polysaccharide, Bacterial survival.
