Recipient Organization
LEAFPRO, LLC
4744 POTATO HOUSE CT
WILSON,NC 27893
Performing Department
(N/A)
Non Technical Summary
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.
Animal Health Component
10%
Research Effort Categories
Basic
0%
Applied
10%
Developmental
90%
Goals / Objectives
A biorefinery approach to the use of sweetpotato leaves, currently wasted in the harvest of the sweetpotato roots, would yield a highly nutritious and functional food ingredient for processed food formulators. Simultaneously the biorefinery can also yield coproducts of similar high value for the food and food supplement industries, such as antioxidant and colorant compounds. The value increase to growers would be tremendous, and the food industry would benefit from the availability of leaf protein concentrates and/or isolates that can meet all the expressed needs of today's food consumer. Specific tasks in the project include:a. Control interaction of polyphenols with proteins, with respect to effects on protein yield and functionality, and maximize extraction of these two classes of components as separate entities for commercialization. To be answered:Can ethanol extraction of leaf material prior to aqueous extraction insure amore functional and pure protein fraction downstream?Does the ethanol extract from whole leaf or extracted leaf biomass evidence sufficient bioactive properties of interest for production of commercially viable co-products?What are the ideal parameters (process, ingredients) to promote maximum extraction of proteins from sweetpotato leaves? (i.e. with minimal interference by polyphenols)b. Control of possible proteolysis that may occur upon tissue disruption of leaves. To be answered:Does proteolysis of key proteins such as rubisco appear to occur during maceration of leaves and aqueous extraction? If so, does this in any way diminish the functional properties or affect downstream processing or yield/purity of the proteins, and can this be mitigated by manipulation of pH?c. Explore various pretreatment, centrifugation, and depth filtration remedies to minimize interference during ultrafiltration of various cell constituents and simultaneously increase protein purity in the fractions retained by ultrafiltration.
Project Methods
According to the goals of the project:a. Control interaction of polyphenols with proteins, with respect to effects on protein yield and functionality, and maximize extraction of these two classes of components as separate entities for commercialization.Two main approaches are taken to mitigate interation of polyphenols with proteins that could hinder recovery and properties of the latter:Addition of inhibitors to the binding reaction, such as metabisulfitePrior extraction of polyphenols with ethanol, to also create a new product stream of possible commercial valueb. Control of possible proteolysis that may occur upon tissue disruption of leaves.Mitigation will be attempted by adjustment of pH to neutralize proteolytic activity that might interfere with protein recovery or final functionalityc. Explore various pretreatment, centrifugation, and depth filtration remedies to minimize interference during ultrafiltration of various cell constituents and simultaneously increase protein purity in the fractions retained by ultrafiltration.A heat pretreatment can ostensibly remove components (during subsequent centrifugation) that likely would obstruct efficient downstream filtration. Depth filtration, which can involve various combinations of filtrants and absorbants, is a known method of capturing fine particles that hinder downstream ultrafiltration, but optimizing high speed centrifugation and prior heat treatment may obviate the need for this more cumbersome step. Microfiltration can also sometimes be substituted for, or used in conjunction with, depth filtration to assure smooth downstream ultrafiltration. Additionally, there are known techniques for optimizing ultrafiltration which can minimize pore clogging and maximize flux.