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Čerstvost a trvanlivost rybích produktů
HAO, Ruoyi
Fish plays an important role in the human diet and health as a source of easily digestible and highly nutritious animal protein and high value n-3 polyunsaturated fatty acids (n-3 PUFA). However, with high moisture, low amount of connective tissues, and neutral pH value, fish muscle is more perishable than other food muscles. Fish freshness depends on physical, chemical, biochemical, and microbiological changes during the post-mortem, which is crucial to fish quality. Generally, fish muscle deterioration depends on three mechanisms: enzymatic autolysis, lipid or protein oxidation, and microbial growth. The deterioration of fish quality is a complex process affected by the nutrient profile of muscles, microorganisms, storage conditions. Nowadays, a farming culture system of omega-3 carp, enabling the increase of healthy n-3 PUFA in common carp muscle, was developed in the Czech Republic. The benefits of this carp on human health have been proven. However, the knowledge of the potential intervention by the innovative culture system on the nutrients pattern, spoilage process, and freshness of carp is not available yet. Nowadays, chill-stored fish is turning into popular fish food with the encouragement of available cold-chains and promoting healthy consumption concepts of fresh food. Nevertheless, fish quality still deteriorates severely during chilled storage, leading to freshness and shelf-life reduction. The rapid growth and metabolism of microorganisms naturally present or from contamination drive this process. However, recent studies did not comprehensively investigate the microorganisms' role in the freshness reduction of chilled stored fish. Moreover, driven by 'green consumerism', foods with few synthetic additives but more natural ingredients are popular, promoting essential oils (EOs) attracting much attention for fish preservation in recent years. However, the preserving effects of these EOs on fish are inconsistent. Thus, how to establish a good preservation strategy for using EOs-based preservation methods to manipulate microbial spoilage and maintain the freshness of chill-stored fish. This thesis is devoted to filling these knowledge gaps. 1) The patented farming system was found a slight increase in storage stability and shelf-life of carp via the investigation on the differences in the potential nutrients, post-mortem freshness, and shelf life between traditionally cultured common carp and omega-3 carp. 2) The relationships among typical freshness indicators and several dominant spoilage microorganisms and the manipulation of spoilage microorganisms by EOs-based preserving method in chill-stored fish were exposed. 3) A sensory acceptable EOs-based antibacterial coating was developed for the preservation of chill stored fish fillets. 4) Intelligent strategies for maintaining fish gel food freshness and properties via phenolic compounds and ultrasound treatment by enhancing protein cross-linking were established.
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