Effects of Natural Cryoprotectants on Preserving the Protein-Lipid Complex of Round Goby (Neogobius melanostomus) during Freezing and subsequent Storage

Abstract

The research aims to establish the effectiveness of natural cryoprotectants in stabilizing the protein-lipid complex of round goby (Neogobius melanostomus) muscle tissue during freezing and long-term storage at low temperatures. Three types of natural cryoprotectant compositions were used in the study: glucose (2%) + inulin (1.5%); pectin (1%) + rosemary extract (0.3%); honey (3%) + sea salt (1%). Samples were frozen at –35°C and stored for 1, 3, and 6 months at –18°C. The results confirmed pronounced protective effects of all natural cryoprotectants studied, but the pectin-rosemary extract combination proved to be the most effective. The water-binding capacity of the fresh fillet was 79%, while in the control variant, it decreased to 60.8% after 6 months of storage. In samples treated with cryoprotectants, this indicator remained significantly higher – 68.4% (glucose + inulin), 68.9% (honey + salt), and 71.2% in the variant with pectin and rosemary. A similar pattern was observed for freezer weight loss: the control sample showed a gradual increase from 1.8% to 7.9%, while in the variants treated with cryoprotectants, the values were 5.6, 5.0, and 4.2%, respectively. Additional indicators, such as pH, peroxide value, and TBA-active substances, also confirmed a decrease in the intensity of protein and lipid degradation in the treated samples. Thus, natural cryoprotectants, especially the pectinrosemary extract composition, significantly reduce dehydration, slow protein denaturation, and lipid oxidation, preserving the structural and functional properties of round goby during long-term frozen storage. Research findings can be used to develop new environmentally safe technologies for the biopreservation of fish raw materials without the application of synthetic stabilizers.