Minimizing protein insolubilization during thermal inactivation of lipoxygenase in soybean cotyledons

• Published in: Journal of the American Oil Chemists' Society Vol. 59; no. 2; pp. 88 - 92
• Main Authors: Brown, B.D, Wei, L.S, Steinberg, M.P
• Format: Journal Article
• Language: English
• Published: Berlin/Heidelberg Springer-Verlag 01.02.1982
• ISSN: 0003-021X; 1558-9331
• DOI: 10.1007/BF02678719

ABSTRACT The objective was to develop a procedure for inactivating lipoxy‐genase in soybean cotyledons without losing protein solubility. The approach was to moisten cotyledons to one of 2 levels in soft water or carbonate buffers, steam for a short time, hold for a definite period at a known temperature, cool and analyze for enzyme activity and protein solubility. Temperature dependence of both inactivation and insolubilization kinetics was determined. Increasing temperature of steaming and holding favored our objective. At 16.3% moisture, the pH 9.8 buffer was beneficial but the pH 10.8 buffer was not. The holding period was not beneficial compared to steaming alone. Recommended conditions were adjustment of cotyledon moisture to 16.3% with pH 9.8 buffer and then heating in steam for about 10 sec; at temperatures of 91 C and above, 99% of the lipoxygenase could be inactivated with retention of over 70% protein solubility. The effect of buffers on kinetics of heat inactivation and insolubilization appeared to be related to the states of hydration water, i.e., the presence of solute water at the higher moisture content.