Effect of hydrolysed sunflower lecithin on the heat-induced coagulation of recombined concentrated milk emulsions

In an attempt to decrease the degree of heat-induced intermolecular protein interactions in recombined concentrated milk, the effect of sunflower lecithin, a natural source of phospholipids, was examined. The obtained results proved that lecithin supplemented milk emulsions demonstrated a less pronounced increase in viscosity as well as particle size, upon severe heating. Additionally, enzymatic hydrolysis was performed using a phospholipase A1. Phosphorus nuclear magnetic resonance and high performance liquid chromatography revealed that the lysophospholipid content reached a maximum after 20 min of hydrolysis and gradually declined as the hydrolysis reaction duration was extended. This work showed that sunflower lecithin largely improves the heat stability of whey protein containing solutions and emulsions due to its high phospholipid content. As the phospholipid molecular structure is important, it follows that the heat stability of whey protein containing products may be optimised by appropriate processing, such as enzymatic hydrolysis of intact lecithins.