Preparation and thermo-reversible gelling properties of protein isolate from defatted Antarctic krill (Euphausia superba) byproducts

Protein isolate was prepared from defatted Antarctic krill (Euphausia superba) byproducts by 0.1 M NaOH extraction. Maximum yield of krill protein isolate reached 28.66% by precipitation at pH 4.6. Krill protein isolate demonstrated its excellent nutritional values through amino acid composition and in vitro digestibility. Thermal transition of krill protein isolate was determined by differential scanning calorimetry measurement. Extrapolated values of glass transition temperature (Tg) and denaturation temperature (Td) of krill protein isolate were 33.8 °C and 80.3 °C when the heating rate was 2 °C/min. Dispersions of krill protein isolate generated self-supported gels at concentrations above 100 g/L without the addition of salt or other additives. A noticeable enhancement of gel strength was induced through cooling. Gels with krill protein isolate displayed a thermo-reversible behavior under repeating heating/cooling cycles, which was primarily due to the formation and disruption of hydrogen bonds. Network strength of protein gels was strongly dependent on protein concentrations.