Effects of deamidation on aggregation and emulsifying properties of barley glutelin

The structure, solubility and emulsifying properties of the deamidated barley glutelin were investigated. The SOS-PAGE, size exclusion chromatography combined with a laser photometer (SEC-LP) and Fourier transform infrared spectroscopy (FTIR) results revealed that glutelin underwent a rapid hydrolysis and unfolding even at the initial stage of deamidation, leading to remarkably improved glutelin solubility at both acidic and neutral pHs. The deamidated glutelin demonstrated a strong tendency to form soluble aggregates of very large molecular weight (10(6)-10(7) g/mol) probably due to disulphide-crosslinking and hydrophobic interactions. These aggregates played a major role in stabilising the emulsions at a broad range of deamidation levels (2.2-5.6% to 43%). In this way, undesirable property changes which result from excessive deamidation can be avoided, leading to wider applications of deamidated barley glutelin as an emulsifying ingredient in food and non-food applications. (C) 2011 Elsevier Ltd. All rights reserved.