Effect of κ-carrageenan on gelation and gel characteristics of Antarctic krill (Euphausia superba) protein isolated with isoelectric solubilization/precipitation

Isoelectric solubilization/precipitation (ISP) was used to extract krill protein isolate (KPI). Due to krill endogenous proteases ISP-KPI barely forms gel which is a major hurdle in wide application of this tremendous protein source for direct human consumption. The objective was to improve gelation and elucidate interaction mechanism between kappa-carrageenan and KPI kappa-Carrageenan was added to KPI at 0.00, 0.75, 1.50, 2.25, and 3.00 g/150 g and heated at 90 degrees C for 15 min. Added' kappa-carrageenan improved texture of KPI gels. However, the level of addition had minimal effect. SDS-PAGE revealed severe proteolysis of KPI even during heating. Total and free sulfhydryl were not different, while surface hydrophobicity and water-holding-capacity slightly decreased and increased, respectively with added kappa-carrageenan. Fourier-transform-infrared-spectroscopy showed none-tominimal shift of beta-sheet and alpha-helical protein structure; while C-C and C-O stretching as well as C-H bending of kappa-carrageenan showed the greatest shift, indicating that kappa-carrageenan was mainly responsible for gel formation.