The invention discloses purple-sweet-potato
probiotic sour-milk and a preparation method thereof. The preparation method of the purple-sweet-potato
probiotic sour-milk comprises the following steps: (1), preparing purple sweet potato paste; (2), pouring white granulated
sugar, white granulated
sugar, galacto-oligosaccharides and the purple sweet potato paste into
fresh milk, wherein the ratio of the white granulated
sugar to the galacto-oligosaccharides to the purple sweet potato paste to the
fresh milk is 0.5-0.7kg: 0.5-0.7kg: 0.8-1.2kg: 8-10kg, carrying out preheating until the temperature of the mixture is 60-70 DEG C, homogenizing the heated mixture, sterilizing the homogenized mixture at 90-100 DEG C for 3-7 minutes, and cooling the sterilized mixture to 40-45 DEG C; (3), adding mixed probiotics into the cooled mixture; and (4), fermenting the mixture in a constant-temperature
incubator at 40-45 DEG C; and the purple-sweet-potato
probiotic sour-milk is prepared after
fermentation. The invention has the following beneficial effects: the purple sweet potatoes and the
fresh milk are utilized as raw materials, and the mixed probiotics composed of
bacillus bifidus,
lactobacillus bulgaricus,
streptococcus thermophilus,
lactobacillus acidophilus,
lactobacillus casei and the like are used for carrying out
fermentation, so that the prepared purple-sweet-potato probiotic sour-milk with novel
flavor is bright in color, good in taste and rich in
nutrition, and has very good health-care functions.