This work will optimize extraction of edible proteins from sweetpotato leaves, an agricultural waste stream, and develop them into a nutritious, functional dry protein concentrate for use in production of the high-protein foods in strong demand today. A biorefinery approach allows extraction of coproducts, such as polyphenols and carotenoids, useful in food products for their antioxidant and/or colorant properties, while still maximizing protein yields and purity (goal: >70% protein dry weight). The Phase I research effort will be focused upon optimizing process parameters with respect to plant throughput, protein yield, and protein purity during commercial scale production of a whole-leaf derived protein concentrate that is light in color and pleasant in taste. Sweetpotato leaf protein has advantages over animal proteins with regard to environmental impact and animal rights issues, and advantages over the main competing plant proteins--soybeans may cause hormonal side effects and wheat protein contains gluten, which also faces problems with consumer acceptance. The yield of leaf proteins per acre is higher than from traditional soybean production, and will add value to a presently wasted byproduct, as the leaves are cut just prior to harvest of tubers. Optimizing the process parameters for whole-leaf protein extraction and purification will later (during Phase II work) enable fractionation of a protein extract rich in rubisco, the main protein component of leaves. Rubisco has been shown to successfully replace many of the unique food functional properties (whipping, foaming, gelling) that presently are available by only by use of expensive egg white.
