Effects of Ohmic Heating on Denaturation of Whey Proteins Solutions: Influence on Whey-Derived Products

Ohmic heating is one of the earliest applications of electricity in thermal processing of food and is receiving increased attention because of its uniform heating of liquids with faster heating rates, which presumably enables obtaining products of a superior quality to those processed by conventional heating technologies. Given the biochemical structure of proteins, it is expectable that ohmic heating and its moderate electric fields will influence their properties and hence their behavior. The aim of this work was to evaluate the effects of moderate electric fields on denaturation and aggregation of whey proteins and its subsequent effects in whey-derived products. Results presented here show that ohmic heating led to lower whey protein denaturation at the early stages of heating, kinetically traduced by lower values of n and k, when compared to those from conventional heating (p < 0.05) under equivalent heating rate and holding times. Furthermore, whey protein aggregation (measured by dynamic light scattering in terms of aggregate size) was found to decrease with the presence of moderate electric fields applied during ohmic heating at 85 oC, up to 30 min. Edible films prepared from ohmic heated film forming solutions present a decrease of water vapor permeability of 10%, when compared with films produced through conventional heating.