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Physical characterization of thermally induced networks of lupin protein isolates prepared by isoelectric precipitation and dialysis
Author(s) -
Kiosseoglou Antonios,
Doxastakis Georgios,
Alevisopoulos Stefan,
Kasapis Stefan
Publication year - 1999
Publication title -
international journal of food science and technology
Language(s) - English
Resource type - Journals
SCImago Journal Rank - 0.831
H-Index - 96
eISSN - 1365-2621
pISSN - 0950-5423
DOI - 10.1046/j.1365-2621.1999.00260.x
Subject(s) - isoelectric point , urea , chemistry , denaturation (fissile materials) , isoelectric focusing , chromatography , sodium , precipitation , legume , salt (chemistry) , lupinus , protein isolate , dialysis , food science , biochemistry , botany , biology , nuclear chemistry , organic chemistry , medicine , physics , meteorology , enzyme
Summary Protein isolates of Lupinus albus were obtained from full fat and defatted lupin flour using isoelectric precipitation or dialysis. Calorimetric tests demonstrated that the main protein fractions of the isolates denature well below 100 °C. Mechanical spectra of isolate dispersions obtained at 80 °C indicated the formation of a ‘pseudogel’ whose cohesion increased during cooling to 10 °C. Subsequent heating to 90 °C encouraged extensive formation of disulphide bonds as it produced gels that were insoluble in sodium dodecyl sulphate and urea solutions. Dialysis produced isolates of lower gelling concentrations, which also formed networks of a stronger relative elastic character. The presence of NaCl at concentrations up to 0.5 m had a reinforcing effect on networks. Protein over‐aggregation caused the opposite effect at higher salt levels. Finally, a comparison with results in the literature on soybean protein gelation suggested similar denaturation temperatures and a common pattern of structure formation for the two legume proteins.