摘要：Freezing conditions affect fish muscle protein functionality due to its denaturation/aggregation.
However, jumbo squid (Dosidicus gigas) muscle protein functionality remains stable
even after freezing, probably due to the presence of low-molecular-mass compounds
(LMMC) as cryoprotectants. Thus, water-soluble LMMC (<1 kDa) fraction obtained from jumbo
squid muscle was evaluated by Fourier transform infrared spectrometry. From its spectra,
total carbohydrates, free monosaccharides, free amino acids and ammonium chloride were
determined. Cryoprotectant capacity and protein cryostability conferred by LMMC were
investigated by differential scanning calorimetry. Fraction partial characterization showed
that the main components are free amino acids (18.84 mg/g), carbohydrates (67.1 µg/mg)
such as monosaccharides (51.1 µg/mg of glucose, fucose and arabinose in total) and ammonium
chloride (220.4 µg/mg). Arginine, sarcosine and taurine were the main amino acids in
the fraction. LMMC, at the mass fraction present in jumbo squid muscle, lowered the water
freezing point to –1.2 °C, inhibiting recrystallization at 0.66 °C. Significant myofibrillar protein
stabilization by LMMC was observed after a freeze-thaw cycle compared to control (muscle
after extraction of LMMC), proving the effectiveness on jumbo squid protein muscle cryostability.
Osmolytes in LMMC fraction inhibited protein denaturation/aggregation and ice
recrystallization, maintaining the muscle structure stable under freezing conditions. LMMC
conferred protein cryostability even at the very low mass fraction in the muscle.
