Preparation method of instant flexible-packaging purple sweet potato pieces

The invention relates to a preparation method of instant flexible-packaging purple sweet potato pieces. The preparation method comprises the following steps of: selecting purple sweet potatoes with full appearances and without decomposition, and cleaning the surfaces of the purple sweet potatoes; peeling the cleaned purple sweet potatoes; cutting the peeled purple sweet potatoes into purple sweet potato pieces with the length, width and thickness ranging from 3cm to 5cm; putting the purple sweet potato pieces in a sealed tank, adding a taste immersion liquid in the tank, extracting gas in the tank to allow vacuum pressure to reach 0.05 to 0.09 MPa and the temperature to reach 20 to 50 DEG C, fully infiltrating the taste immersion liquid in the pieces for 3 to 10 minutes to flavor; pre-steaming the flavored purple sweet potato pieces, and cooling the pre-steamed purple sweet potato pieces to 20 to 25 DEG C; putting the cooled purple sweet potato pieces in packaging bags and sterilizing the cooled purple sweet potato pieces; and filling nitrogen in the packaging bags of the sterilized purple sweet potato pieces, and sealing the packaging bags. As no chemical addition agent is added in the instant flexible-packaging purple sweet potato pieces, the instant flexible-packaging purple sweet potato pieces are ensured to be nutrient and healthy and are pure green food, more comprehensive in nutrition, rich in flavor and tasty in taste.