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 SDS–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 (10⁶–10⁷ 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.