Development Of Texture System Of Low-Fat And Low-Sugar Dietary Fiber Normal Temperature Yoghurt

In order to construct the low-fat and low-sugar dietary fiber yogurt system,the fermentation characteristics of stabilizer,dietary fiber,sweetener and flavor strains were studied,and the formula and fermentation conditions of low-fat and low-sugar dietary fiber normal temperature yogurt were explored.The fermentation characteristics of yogurt were evaluated by stability kinetic index,water holding capacity and acidity,and the stability index during storage was evaluated by rheology,texture and flavor.Different stabilizers have different effects on the stability of yogurt.The optimal addition of agar is 0.08%,hydroxypropyl disaccharide phosphate is 1.0%,and pectin is0.1%.Through the optimization of response surface curve,the best formula of compound stabilizer is 0.09% agar,0.52% hydroxypropyl starch phosphate and 0.05% pectin.Dietary fiber will destroy the stability system of yogurt.Polydextrose is a water-soluble dietary fiber.Compared with other dietary fibers,polydextrose has the least damage to the stability of yogurt and has a high overall acceptability.Through the single factor experiment,the optimal addition of polydextrose is 4%,inulin is 0.8%,resistant dextrin is 15% and citrus fiber is 0.9%.The contribution of glucose to flavor was the smallest and the sensory damage was the smallest.The polydextrose content of high fiber yoghurt was determined to be 4%.The construction of low sugar system is to analyze the sweetness intensity of each sweetener through the sweetness curve.Adding various sweeteners to the sugar free formula to obtain the optimum monomer ratio.According to the results of orthogonal test,the best formula of compound sweetener is: sucralose 0.005%,stevioside 0.005%,erythritol 4.5%,xylitol 2.0%.The single factor optimization experiment of Lactobacillus casei: Lactobacillus rhamnosus determined that the optimum conditions for mixed fermentation were 3% of inoculation amount,1:2 of mixed bacteria ratio(Lactobacillus casei: Lactobacillus rhamnosus),35 ℃ of fermentation temperature and 6 hours of fermentation time.Different storage temperature and storage time have different damage to the stability of yogurt system,and the stability at 25 ℃ is the best.High temperature will destroy the stability of yogurt.At the storage temperature of 47 ℃,the stability of the sample decreased significantly on the 7th day,the water holding capacity decreased,and the problems of whey precipitation and protein precipitation were serious.The sensory evaluation results showed that high temperature would aggravate the sour taste and reduce the fermentation flavor of acetaldehyde and diacetyl.