Glycation of pea protein isolate with different mannooligosaccharides to improve solubility

Due to the increasing demand for plant based proteins in food products, research is being carried out to improve the functional properties of pea protein. Here, the glycation of pea protein isolate (PPI) with mannooligosaccharides (MOS) was studied, with the aim to increase solubility. Various MOS were released by enzymatic hydrolysis of galactomannans and separated into four fractions according to their degree of polymerization (DP; DP of 2, 3, 7–9 and ≥ 9). MOS reacted with PPI under controlled conditions via the Maillard reaction. Different reaction times were tested for the MOS fractions to vary the extent of glycation and the progress of the Maillard reaction. Thus, the color and the decrease in free amino groups were measured, and gel electrophoresis was performed to observe the change in molecular weight of the proteins. Based on the results, MOS fractions with a DP of 7–9 and ≥ 9 and reactions times of 24–48 h, respectively, were classified as promising due to a moderate decrease in free amino groups and only a slight change in color. Differently, glycation with mannobiose and mannotriose resulted in advanced glycation and was considered unsuitable. The solubility of the glycated proteins was determined at a pH of 3.5 and 7.0. Under neutral conditions, solubility did not change as a result of glycation. However, under acidic conditions, glycation increased the solubility of the pea proteins from 26% to about 46%.