Submitted to: Meeting Abstract
Publication Type: Abstract Only
Publication Acceptance Date: March 10, 2004
Publication Date: May 9, 2004
Citation: Sessa, D.J., Hojillaevangelist, M.P., Mohamed, A. 2004. Protein concentrates and isolates by ultrafiltration/diafiltration of fatted and defatted soy and lupin meals [abstract]. American Oil Chemists Society. p.116. Technical Abstract: High PDI soy flour and milled lupin (Lupinus albus L.2043N) meal were used to investigate two different processing methodologies to generate protein concentrates and isolates. Common to the two processes, undefatted flour and meal were each aqueous extracted using a Ross HSM-100LC mixer-emulsifier equipped with a disintegrator head. Those extracts were clarified by centrifugation and filtration. Processing method #1: the protein dispersions were subjected to ultrafiltration/discontinuous diafiltration with a Pall Centramate tangential-flow system with a 5kDa molecular weight cut-off polyether sulfone membrane. Freeze-dried retentates yielded protein concentrates (i.e. greater than 70% protein) based on a Dumas nitrogen x 6.25. For processing method #2: the aqueous extracts were each subjected to acid, pH 4.5, to precipitate the proteins. The dispersions were centrifuged to collect the precipitated proteins. Those proteins were redissolved by neutralization and then dialyzed with 1000 MWCO casing to remove the salts. Retentates from each process were freeze-dried to yield fractions with protein contents of 74.9% for soy and 71.5% for lupin with process #1 and 92.1% for soy and 92.4 for lupin with process #2. At least six replicates were performed for each flour and meal using process #1, yet, only a concentrate could be made from undefatted starting materials. Soy and lupin samples, defatted with diethyl ether, when subjected to process #1 increased in protein contents to about 84% for each, whereas, with process #2, the acid precipitation method, protein contents increased to greater than 98%. Based on our findings only concentrates could be generated from either soy or lupin by the use of ultrafiltration/-diafiltration. Protein concentrates and isolates were subjected to sodium dodecylsulfate polyacrylamide gel electrophoresis (SDS-PAGE), stained with Coomassie blue to compare protein contents with known standards. Visualization of the stained gels showed evidence for aggregated proteins that remained at the top of the running gel for 3-12% gradient gels. Both processing methodologies generated some aggregate formation. The polyether sulfone membranes worked well for both undefatted and defatted samples with no evidence for fouling and protein rejections for either soy or lupin proteins were greater than 98%.