PRODUCTION OF PROTEIN ISOLATES AND CONCENTRATES FROM OILSEED FLOUR EXTRACTS USING INDUSTRIAL ULTRAFILTRATION AND REVERSE OSMOSIS SYSTEMS

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Abstract
The consumption of protein isolates from oilseed flours is expected to continue its upward trend as meat analogs from vegetable proteins are more widely marketed. However, conventional protein isolation procedures are lengthy and somewhat expensive. These processes also result in whey‐like liquid by‐products which constitute a water pollution threat unless properly processed. Preparation of protein isolates and concentrates from glandless cottonseed and soy flours by extracting the protein and ultrafiltering the solubilized protein directly from the liquid extract was investigated. In the process devised, proteins normally precipitated to produce isolates were recovered together with the conventional whey protein by ultrafiltration (UF). The UF permeate was further processed with a reverse osmosis (RO) membrane. Different industrial UF and RO systems were utilized in 22–60 lb extractions. UF membranes were found which gave desirably high permeation rates and satisfactory constituent separations, especially with cottonseed storage protein (SP) extract. With SP extract, initial LJF permeate flux achieved was in excess of 1.50 gal of permeate per square foot of membrane area per day (gfd). The flux declined to 96 gfd over a period of 8 hr while the volume of original extract in the feed solution was being reduced by a ratio of 12.5 to 1 in the final UF concentrate. As expected, nonstorage protein (NSP) and SP extracts from cottonseed were found to require membranes having different molecular weight cutoff points. Noncellulose‐based membranes performed better for this application because of their broader pH and temperature operating ranges.