The Development Of The Purple Potato Probiotic Yogurt

In this paper,a new type of purple sweet potato probiotic yoghurt with bright color and rich nutrition was developed by using purple potato and milk as raw materials,and using mixed probiotics such as Lactobacillus bulgaricus,Bifidobacterium and Streptococcus thermophilus.1.Through the determination of total sugar and anthocyanin in purple sweet potato,the quality of sweet potato varieties was screened for the development of sweet potato probiotic yogurt.On the basis of classical DNS colorimetric method,the method of rapid determination of total sugar content of sweet potato standardization of the three common varieties in the market,"Japanese black potato","Ji potato NO.18","Xinyin NO.1 purple potato" total sugar was determined.The contents of purple sweet potato anthocyanins from three varieties of "Japanese black potato","Ji potato NO.18" and "Xinyin NO.1 purple potato" were determined by using pH differential method.2.The effects of adding amount of sweet potato,adding amount of white sugar,fermentation time and adding amount of galactooligosaccharides on the yogurt quality of probiotics such as Bifidobacterium,lactic acid bacteria and other probiotics were studied,the pH,viable cell number,rheological properties and sensory evaluation were used as evaluation indexes to study the fermentation conditions of yoghurt.On this basis,the main factors affecting the fermented yogurt were determined,purple potatoes were optimized by the orthogonal experiment of probiotic yogurt fermentation conditions.3.Study compared purple potato probiotic yogurt and plain probiotic yogurt at 4 ?refrigerated storage 25 d on the number of living bacterium,pH value and the change of rheological properties.Through the above test to get the final conclusion: Firstly,the results showed that the total sugar content of the three cultivars of "Japanese black potato","Ji potato NO.18","Xinyin NO.1 purple potato" were 44.470%,40.521%,46.571%,respectively,and determine the content of the anthocyanins of the three varieties were 0.802mg/mL,0.376mg/mL,0.978mg/mL.The final comparison showed that the anthocyanin and sugar content of "purple potato new lead 1" were the highest,determined as the best variety.Secondly,determine the optimal fermentation conditions: the ratio of purple sweet potato and pure milk is 1:9,fermentation time 6h,the amount of sugar is 6%,and the amount of the oligosaccharide is 6%.Finally,the best eating quality of sweet potato yoghurt and plain yoghurt was determined from 5d to 10 d,and its shelf life was 25 d at 4?.