Extraction Of Tremella Polysaccharide And Flavonoids Compounds From Flos Sophorae And Its Application In Yogurt

Low-fat yoghurt is popular because of its health benefits and high nutritional quality with unique flavor and taste.However,the omission of fat results in a number of quality issues including poor textural properties,syneresis and terrible taste.Tremella and Flos Sophorae are both edible and medicinal plants with rich nutrition and health benefits.In this experiment,Tremella polysaccharides and active ingredients of Flos Sophorae were extracted and added into low-fat emulsion to develop three kinds of low-fat yogurt with unique taste,good quality and health improvement.The main conclusions are as follows:1.The determination of extraction method of Tremella polysaccharides: the extraction yield of Tremella polysaccharides can reach 18.98% when it is bathed for 4.5 hours at 100? with 100-mesh Tremella powder.2.The effect of Tremella polysaccharide on yoghurt: in this experiment,different concentrations(0.37,0.74,1.11,1.48 and 1.85mg/mL)of Tremella polysaccharide were added to make low-fat yoghurts,and the texture,microbial quantity and fermentation time of low-fat yoghurt were measured to investigate the effect of Tremella polysaccharide.The result showed that the fermentation time of yoghurt was shortened as the number of Lactobacillus bulgaricus and Streptococcus thermophilus increased with the increment of polysaccharide concentration.Sensory testing showed that the addition of 0.37 and 0.74mg/mL Tremella polysaccharide improved the sensory acceptability and score of product compared to the control(p<0.05).Moreover,the water holding capacity,hardness and frangibility of yogurts were increased(p<0.05)when the concentration of Tremella polysaccharides was 0.37mg/mL.These results indicated that the proper addition of Tremella Polysaccharide(0.37mg/mL)can improve the sensory quality,water holding capacity and texture of low-fat yoghurt,and increase the number of fermentation bacteria and shorten its fermentation time.3.The effect of Flos Sophorae extract on yoghurt: Flos Sophorae extract was prepared by "boiling + ultrasound" after crushing Flos Sophorae.Different proportions of Flos Sophorae extract(12%,24%,36%,48% and 60%)was added to investigate the effect of Flos Sophorae extract on the quality of low-fat yoghurt,by measuring its microbial quantity,texture and fermentation time of the yoghurt.The result showed that the antioxidant capacity of yoghurt increased with increasing Flos Sophorae extract.Low concentration of Flos Sophorae(12-24%)significantly improved the amount of Streptococcus thermophilus and sensory score including the appearance and state.Moreover,its fermentation time was significantly shortened compared to the control group(p<0.05).Adding 24% Flos Sophorae extract increased,significantly(p<0.05)the water holding capacity and antioxidant capacity of yoghurt,while reduced the hardness and viscosity.According to all indexes,the sensory quality,water holding capacity and antioxidant capacity of low-fat yoghurt could be improved by adding appropriately the extract of Flos Sophorae(24%).4.Combinatorial supplementation of Flos Sophorae extract and polysaccharide affected on quality of yoghurt: based on the optimum concentration of Flos Sophorae extract(24%),different concentrations of Tremella polysaccharide(0.20,0.40,0.60 and 0.80mg/mL)were added to investigate the effects on the rheological and textural profiles,microbial quantity and fermentation time of yoghurt.The results showed that the fermentation time of yoghurt was shortened,and the DPPH scavenging ability was gradually increased with increasing polysaccharide concentration.Supplementation of appropriate Tremella polysaccharide(0.20-0.60mg/mL)improved the rheological properties,and textural properties,the water holding capacity and sensory score were increased(p<0.05)when 0.40mg/mL polysaccharide was added.Thus,appropriate amount of Tremella polysaccharide(0.40mg/mL)and Flos Sophorae extract can improve sensory quality,antioxidant ability,the water holding capacity,textural and rheological properties,and shorten the fermentation time.