The Influence Of Prebiotics Addition On Quality Of Low Fat Fresh Cheese

In recent years,consumers’ dietary habits began to change,people are in favor of more healthy food, functional health food market is expanding rapidly. Fresh cheese is an immature soft cheese,tastes soft and light,in accordance with the tastes of the Chinese people.At the same time,low-fat food meets the trend of food development in recent years. Although fresh cheese has been accepted by consumers,because of the higher water content, lower water-holding,whey precipitatin and water loss has an impact on the quality of fresh cheese,however, low-fat cheese because of reduced fat content,leading to cheese texture dense,hard and brittle.Therefore, research on how to keep the activity of low-fat fresh cheese probiotics and to improve the quality has practical significance and research value.In this study,firstly,the live characteristics of prebiotics were compared.In order to select suitable prebiotics for low-fat fresh cheese.Lactobacillus acidophilus, Lactobacillus casei two kinds of probiotics and FOS,Inulin and GOS three common kinds of prebiotics were selected and used in the research.The concentration and acid production of Lactobacillus acidophilus,Lactobacillus casei and mixed bacteria fermentation liquid were compared.The effect of different carbon sources medium on the growth of probiotics were investigated;different prebiotics added medium enrichment effect were compared,in order to determine the optimal concentration of each prebiotics;Drawed the growth curve of Lactobacillus acidophilus, Lactobacillus casei mixed fermentation of different carbon source medium,calculate the reducing sugar content in the different growth periods of the fermentation broth of each prebiotics utilization.to explore the use of each prebiotics.The results showed that:Inulin and GOS with growth promoting effect to Lactobacillus acidophilus,Lactobacillus casei and mixed bacteria;when bacteria fermentation alone,GOS better enrichment; when mixed bacteria fermentation, inulin enrichment effect is better.The optimum concentration of inulin is 1% inulin,the optimum concentration of GOS is 1.5%, the optimum concentration of FOS is 1%. In the experimental group,the logarithmic phase of FOS fermentation broth was shorter,close to 10h; the logarithmic phase of inulin and GOS were about12h;in the end of the logarithmic phase, inulin, and GOS group broth reducing sugar content was no significant difference(P> 0.05). Based on the results,inluin is the suitable prebiotics add to the low-fat probiotics fresh cheese.The fresh cheese’s water-hold capacity, texture, the amount residual and sensory quality were evaluated, the effect of low-fat probiotic fresh cheese by different inulin addition and the optimum amount of inulin were determined. The results showed that:with the amount of inulin increased,thefresh cheese’s water-hold capacity first increased and then decreased, at the dosage of 1% inulin,fresh cheese water-hold capacity of up to 83%; fresh cheese’s hardness, viscosity, chew proportional to the amount of added inulin,the elastic difference between groups was not significant(P> 0.05). When inulin’s addition is 1%, combined with the quality of the sensory evaluation, the optimization of the texture parameters..Based on the results, the optimal dosage of inulin is 1%.The number of fresh cheese’s viable bacteria and pH during the storage period(0-15d)were determined,in order to discuss the effects of fresh cheese by different probiotics ratio. The results show that the storage of fresh cheese in a ratio of added probiotic Lactobacillus acidophilus:Lactobacillus casei =1:2, the number of viable probiotics was significantly higher than the proportion of other experimental groups(P<0.05). At the end of the storage period(15d) fresh cheese keeps the number of viable cells in 107cfu/g or more, in line with the number of viable cells of probiotic food requirements(>106cfu/g). Determining the addition ratio of probiotic is Lactobacillus acidophilus: Lactobacillus casei = 1:2.The low-fat fresh cheese’s physicochemical index, yield, texture, microstructure, sensory evaluation and assessment of low-fat fresh cheese’s viable count during the storage time were evaluated,in order to research the effect of low-fat probiotic fresh cheese quality by inulin. The results showed that, compared with the low-fat fresh cheese(not added inulin), inulin added to improve the yield of cheese, no significant effect on the physicochemical index of cheese(P>0.05), improve the hardness of low-fat cheese’s large defects, increases the elasticity of fresh cheese, sticky; fresh cheese’s microstructure scanning shows, added inulin made low-fat fresh cheese’s microstructure smooth and orderly close to the full-fat fresh cheese, showed its characteristic fat substitutes;fresh cheese in early storage period,inulin addition could promote the growth of probiotics in cheese and make the end of the storage period remains the number of viable bacteria,higher than control group(without inulin addition).The conclusion of this study is that inulin has the dual characteristics of prebiotics and fat substitutes.In the process of making cheese,adding 1% inulin and probiotics(Lactobacillus acidophilus: Lactobacillus casei = 1:2) can obtain low-fat probiotics fresh cheese with higher activity of probiotics and soft texture.