Development of a protein concentrate for human consumption by direct enzymatic hydrolysis of antarctic krill (Euphausia superba)

Krill protein concentrates could be part of human diets as high-quality food ingredients. We have focused on food-grade enzyme hydrolysis of Antarctic krill Euphausia superba, aiming at the production of well-defined protein, phospholipid, and shell fractions. Different enzyme combinations, concentrations, and reaction times of three commercial proteases have been tested for effects on protein yield and lipid content in the soluble protein fraction. The highest protein yield (10.1 g/100 g of the initial wet weight) was obtained in the highest enzyme concentration and longest reaction time treatment, however, associated with lower cost benefits.

The lipid content in the protein fractions was not statistically different among treatments, ranging within 9.2–15.8 g/100 g wet weight. The protein fractions were screened for antioxidative capacity by ORAC and minimum stable astaxanthin content. Two of the protein concentrates were fractionated by size exclusion chromatography, to define their peptide profiles. 91% of the total peptides for the single enzyme treatment and 95% after combined enzyme treatment had predominant molecular weights below 1 kDa. The detection of crustacean tropomyosin was strongly reduced after enzymatic hydrolysis in all samples. As part of food safety assessment, all hydrolysates were well tolerated by human monocytes, having no impairing effect on their viability.