Combination of controlled enzymatic hydrolysis and ultrafiltration as the technique for bioactive peptide production intended for the food industry

Abstract

Hypertension is the main risk factor for cardiovascular disease and one of the most common diseases worldwide. Long-term use of antihypertension drugs causes potentially adverse effects. The ACE-inhibitory peptides from natural sources are a safer therapeutic alternative without side effects. This work investigates obtaining bioactive peptides from whey proteins by combining controlled enzymatic hydrolysis and ultrafiltration. Hydrolysis of whey protein with three enzymes showed a significant increase in antioxidant and ACE-inhibitory capacity compared to the non-hydrolyzed sample. The hydrolysate obtained by proteinase k, trypsin, and thermolysin shows 60, 33, and 24 times higher ACE-inhibitory activity than the non-hydrolyzed sample. Hydrolysis with trypsin increases the amount of peptides with molecular weight lower than 3 kDa from 0.2 to 31, thermolysin to 52 and proteinase k to 62 %. Since large differences in the bioactivities of the peptide fractions of the hydrolysate were shown, ultrafiltration as a step after hydrolysis proved to be a good option for increasing the overall bioactivity of the sample after hydrolysis. Thermolysin showed the highest need for single-stage ultrafiltration after hydrolysis, while proteinase k showed no need for ultrafiltration. Hydrolysis of whey proteins by proteinase k creates the largest amount of peptides with a molecular weight below 3 kDa, and the highest antioxidant and ACE-inhibitory activity which can be used as pharmaceuticals or additives to functional food specially created for people with hypertension. The confectionery filling enriched with bioactive peptides didn't change the sensory properties but significantly increased antioxidant and ACE-inhibitory activity and stayed stable during storage.