A comparative study on the functional properties of mealworm (Tenebrio molitor) larvae and soybean protein isolates and hydrolysates

Abstract

The present work aimed to compare the functional and antioxidant properties of mealworm larvae and soybean proteins at different processing steps. The mealworm larvae protein isolate (MPI) was hydrolysed with 2% alcalase at pH 8 and 60°C for 3 h to produce mealworm protein hydrolysate (MPH). The content of amino acids were higher in MPI than in soybean protein isolates (SPI), except for those of threonine, arginine, glutamic acid, and serine. MPI contained a higher amount of hydrophobic amino acids (941.4 µmol/L) than hydrophilic amino acids (697.1 µmol/L). The emulsifying activity, stability, and fat absorption capacity of MPI were higher than those of SPI, whereas their water absorption and holding capacities were similar. Alcalase hydrolysis increased MPI solubility. MPI showed lower solubility at pH 3 - 9 than that of SPI, whereas MPH had higher solubility than that of soy protein hydrolysate (SPH). The foam expansion capacity and foam stability of MPI were lower than those of SPI, but hydrolysis improved those of MPI. MPI formed a gel at pH 5, 7, and 9 at 15% concentration or at pH 7 and 9 at 10% concentration. However, MPH showed no gel formation under any conditions. The total phenolic content and antioxidant capacity of MPI were higher than those of SPI. The DPPH activity of MPH (70%) was higher than that of MPI (18%), SPI (12%), or SPH (34%). MPI can be used as an alternative to SPI. Alcalase hydrolysis can increase the antioxidant effect, digestibility, and functionality of MPI as a sustainable ingredient in high value-added products.