Effect of products of Fucus alga processing on structure formation and oxidation of lipids in fish muscle tissue

An increase in the nutritional value and improvement of technological parameters of semi-finished products and final fish products correspond to the modern trends of healthy nutrition and ensure the rational use of raw materials. The labile structure of components of fish raw materials and especially their lipid constituents facilitates negative changes linked to oxidative processes during processing and storage. Dietary fiber with proven antioxidant activity can inhibit peroxidation of lipids in biological systems and food raw materials exerting at the same time the stabilizing effect on rheological properties of products. The aim of the work was to study an effect of products of processing of brown alga Fucus evanescens (namely gels with sulfated fucoidan and the extract of water-soluble polyphenols) on the oxidative stability of lipids and structure formation in fish muscle tissue by the example of humpback salmon minced meat. Processing of fucoidan gels with ultrasound allowed obtaining a product with the high antioxidant activity (AOA) and increased viscosity. The AOA of gels and extracts was 45 and 91% per 1 mg of dry matter, respectively. Introduction of gels into the composition of minced meat mixtures from muscle tissue of humpback salmon ensured a decrease in their viscoelastic characteristics (strength, adhesiveness and elasticity), which exerted a positive effect on the consistency of semi-finished products and final products. Addition of dry extracts of polyphenols into humpback salmon minced meat led to the loss of its shaping ability linked to a decrease in the water holding capacity of proteins. Cooking losses in minced meat with addition of gel were two times lower than those in the control samples and remained stable during frozen storage. The study of the dynamics of accumulation of primary and secondary products of lipid oxidation, Schiff bases and malondialdehyde during frozen storage showed that the initial oxidative changes in the humpback salmon minced meat affected phospholipids, and then they were spread to triglycerides. After five months of frozen storage, accumulation of malondialdehyde up to the values of 1.27 and 1.60 mg/kg minced meat was observed in the control samples and the samples with the addition of the extract. When adding fucoidan gels, the content of malondialdehyde was 0.16 mg/kg minced meat by the end of the indicated storage period. The results obtained make it possible to recommend fucoidan gels with increased AOA to stabilize the structure of fish muscle tissue and antioxidant protection of its components.