Common sprats frozen yellowing causes investigation

In accordance with ISS 32744-2014 “Frozen small fish. Technical conditions” shelf life of frozen sprat is no more than 6 months. At the same time, in the process of storing frozen sprat in the terms established by the regulatory document, the presence of surface and subcutaneous yellowing is noted, which significantly reduces the quality and demand for this type of product. The purpose of the work was to identify the causes of yellowing of frozen sprat and to propose ways to prevent their occurrence. It is shown that the common keel caught in the spring contains about 5% fat and retains high quality throughout the shelf life established in ISS 32744-2014 “Small frozen fish. TC”. Common sprats of the autumn fishing period contain an average of 8% fat and retain quality when stored frozen for four months. At the end of this period, a gradually increasing surface trend appears. Sprats of the winter fishing period are characterized by an increased level of fat retention (14%) and retain quality in frozen form for no more than three months. Based on changes in the quality indicators of fat of ice cream sprat during storage, it was found that the formation of surface and subcutaneous yellowing is influenced not only by an increase in the acid number of fat, as previously thought, but also by the aldehyde number. The need for work to increase the shelf life of ice cream sprat was justified, taking into account the season of production (catch), followed by amendments to ISS 32744-2014 “Small frozen fish. TC”.