Sweet potato is a major root crop utilized widely for diverse food applications. Processing enables the usability of sweet potato in various forms for longer durations. Post-harvest processing of sweet potato involves grading and sorting, cleaning, peeling, drying or secondary processing and storage. Commercial utility of sweet potato is comprised of conventional and composite ingredient-based foods, starch, and industrial products.
Many parts of the sweet potato plant are edible, including the root, leaves, and shoots.
Sweetpotato vines also provide the basis for a high-protein animal feed.
Sweetpotato use has diversified considerably over the last four decades. With high starch content, it is well suited to processing and has become an important source of raw material for starch and starch-derived industrial products.
Added value for farmers comes from a variety of products and ingredients made from sweetpotato root including flour, dried chips, juice, bread, noodles, candy, and pectin.
New products include liquors and a growing interest in the use of the anthocyanin pigments in the purple varieties for food colorings and use in the cosmetics industry.
Processing and Utilization
Sweet potato roots and other plant parts are used as human food, animal feed, and processing industry. For industrial processing, starch, sugars, and natural colorants are the major inter-mediate products that can be used in both food and non food processing industry. Sweet potato varieties with high levels of dry matter (35–41%), total starch (25–27%), and extractable starch (20–23%) are available for starch processing. There are many small and medium factories. The process for manufacturing sweet potato starch is basically similar to the starch extraction from other sources. The roots are ground in limewater (pH 8.6–9.2) to prevent browning due to polyphenol oxidase, to dissolve pigments, and to flocculate the impurities. The extracted starch is separated from the pulp by thoroughly washing over a series of screens, bleaching with sodium hypochlorite, and then settling by gravity or centrifugation. In small‐scale establishments, starch is stored wet in concrete tanks or sun‐dried to a moisture con-tent of about 12%, pulverized and screened. Centrifugation and mechanical drying, such as flash dryer, are commonly used for medium‐scale factories. Sweet potato starch is used in the production of traditional noodles, vermicelli, thickening agents, or converted into sugar syrups, which are used in many processed food products. The sweet potato starch and sugars are also utilized in the production of fuel alcohol, monosodium glutamate, microbial enzymes, citric acid, lactic acid, and other chemicals.