The application of ice glazing containing D-sodium erythorbate combined with vacuum packaging to maintain the physicochemical quality and sweet/umami non-volatile flavor compounds of frozen stored large yellow croaker (Pseudosciaena crocea)

Ice glazing containing 0.3 % D-sodium erythorbate (DSE), combined with vacuum packaging, was used as a method to maintain the quality of large yellow croaker during frozen storage. This study aimed to assess various aspects, including water properties (water holding capacity and moisture distribution), protein-related characteristics (secondary and tertiary structure of myofibrillar protein), freshness indicators (K value and total volatile base nitrogen (TVB-N)), and non-volatile flavor compounds (free amino acids (FAAs) and nucleotides) in samples stored for 300 days at -23 °C. The results showed that vacuum packaging had a significant inhibitory effect on the growth of ice crystal. Notably, it successfully maintained the cross-sectional area of nearly all ice crystals below 20,000 μm2, effectively curtailing water loss. Simultaneously, the combination of vacuum packaging with the complex ice glaze effectively mitigated the degradation of IMP and free amino acids, maintaining low levels of K value (12.85 %) and TVB-N (11.28 mg N/100 g) throughout the 300-day frozen storage, retaining first-class freshness. Among the various treatment modalities assessed, the combined application of vacuum packaging and 0.3 % DSE-infused ice glazing emerged as the most effective in terms of preservation outcomes. This efficacious combination shows promising potential for the frozen storage of aquatic products and is therefore recommended for practical implementation.

Effects of temperature fluctuations on non-volatile taste compounds in tilapia fillets (Oreochromis niloticus)

In this study, the effect of temperature fluctuations on the taste quality of tilapia fillets during frozen storage was investigated. Major temperature-responsive factors included free amino acids (FAAs) and flavor nucleotides in fish fillets, which were identified using multidimensional infrared spectroscopy (MM-IR). The main FAA in tilapia fillets is a sweet amino acid (glycine). Compared with the control group, the umami FAAs and sweetness FAAs were significantly increased, and the total FAAs content increased to 1.30 times after the ninth fluctuation, reaching the highest level (611.16 ± 73.60 mg/100 g). Considering the equivalent umami intensity values, adenosine monophosphate and inosine monophosphate were retained during the first and second temperature fluctuations. In addition, the content of Na⁺, K⁺, and Ca²⁺ decreased (P < 0.05). Therefore, MM-IR is an effective method to identify taste components. With regard to taste quality, temperature fluctuations in the twofold range have an umami-enhancing effect.

Optimization of a novel vacuum sublimation-rehydration thawing process

To better guarantee the quality of the thawed meat, maximize the thawing rate, and minimize the system energy consumption, the multiparameter and multi-objective coupling optimizations for the newly proposed vacuum sublimation-rehydration thawing (VSRT) process was conducted. The polynomial nonlinear regression equations of single and comprehensive objectives were established by the central composite rotatable design, and the corresponding test of fitting degree and the analysis of influencing factors order were carried out. Furthermore, the interaction effects of influencing factors were investigated through the response surface methodology and were experimentally validated to obtain the optimal process parameters. The results showed that the established regression equations were in good agreement with the experimental values. For the different objectives, there were great differences in the influence order and interaction of factors. In the sublimation and rehydration stages, there existed an optimal region in the response surface to achieve a better value for the single and comprehensive objectives. When the sublimation time was 19 min, the heating plate temperature was 26°C, the rehydration water volume was 1634 ml, the rehydration water temperature was 29°C, the thawing time was relatively short (1.00 h), and the thawing loss (1.19%), the total color difference (1.02), and the system-specific energy consumption (0.026 kW h/kg) were relatively low. The comprehensive performance of the VSRT system reached the best state. PRACTICAL APPLICATION: The purpose of this work is to make the novel vacuum sublimation-rehydration thawing method not only better guarantee the quality of thawed meat but also maximize the thawing rate and minimize the energy consumption of the system, which can provide a new idea and reference for the development of new high-efficiency thawing equipment.