Effects of Thawing Methods on Chemical, Biochemical, and Microbial Quality of Frozen Whole Rainbow Trout (Oncorhynchus mykiss)

Effect of magnetic field-assisted thawing on the quality and microstructure of Portunus trituberculatus meat

The objective of this study was to examine the impact of magnetic field-assisted thawing (MFT) on the quality and microstructure of Portunus trituberculatus meat, in comparison to other thawing methods (Air thawing, AT; Hydrostatic thawing, HT; Microwave thawing, MT). A comprehensive comparative analysis was conducted on different physicochemical and flavor properties of crab meat. MFT significantly reduced thawing loss by 18.9-20.0 % and TBARS levels by 40 % compared to the other methods, demonstrating its ability to minimize lipid oxidation. Microstructure analysis showed that MFT preserved muscle fiber integrity, leading to a denser and more organized structure with reduced protein denaturation. This performance was attributed to MFT's ability to reduce protein denaturation, which effectively minimizes water loss and inhibits lipid oxidation during thawing. Moreover, MFT improved the retention of key flavor compounds, increasing nonanal and 2-undecanone levels by 31.4 % and 69 %, respectively, contributing to a fresher aroma. MFT group also retained more umami (Glu + 40.8 %) and sweet amino acids (Gly, Ala + about 19.8 %), and nucleotides (AMP + 0.8 %, IMP + 9.4 %), while less bitter amino acids (Lys -68.2 %, Met -51.9 %). In conclusion, MFT had good ability of keeping quality of crabs meat, providing noval thawing method for P. trituberculatus.

Evaluating biogenic amines and pH levels in farmed rainbow trout (Oncorhynchus mykiss) for freshness assessment during storage

This study examined the production of eight key biogenic amines (methylamine, tryptamine, putrescine, cadaverine, histamine, tyramine, spermidine, and spermine) in 120 samples of farmed rainbow trout during various storage conditions, and determined any accompanying variations in pH. The main objective of this study was to identify which of the eight biogenic amines could be used as chemical markers to evaluate the quality of farmed rainbow trout. Histamine and tryptamine were not present in any of the samples, and the levels of cadaverine were inconsistent. The levels of putrescine significantly increased at 0 °C (by day 9), 2 °C (by day 8), and 4 °C (by day 4). Tyramine, spermidine, and spermine levels exhibited fluctuations but had a significant positive correlation with the levels of putrescine. The pH levels slightly increased from their initial values across all storage temperatures, with no significant variations observed. Based on the results, it can be concluded that putrescine may serve as an effective marker of the freshness of farmed rainbow trout during storage.

A comprehensive review of the principles, key factors, application, and assessment of thawing technologies for muscle foods

For years, various thawing technologies based on pressure, ultrasound, electromagnetic energy, and electric field energy have been actively investigated to minimize the amount of drip and reduce the quality deterioration of muscle foods during thawing. However, existing thawing technologies have limitations in practical applications due to their high costs and technical defects. Therefore, key factors of thawing technologies must be comprehensively analyzed, and their effects must be systematically evaluated by the quality indexes of muscle foods. In this review, the principles and key factors of thawing techniques are discussed, with an emphasis on combinations of thawing technologies. Furthermore, the application effects of thawing technologies in muscle foods are systematically evaluated from the viewpoints of eating quality and microbial and chemical stability. Finally, the disadvantages of the existing thawing technologies and the development prospects of tempering technologies are highlighted. This review can be highly instrumental in achieving more ideal thawing goals.

The Comparison of Microwave Thawing and Ultra-High-Pressure Thawing on the Quality Characteristics of Frozen Mango

As one of the popular tropical fruits, mango has a relatively short shelf life due to its perishability. Therefore, post-harvest losses are always a topic of concern. Currently, freezing is a common approach to extending mango shelf life. In relation, it is also critical to select a proper thawing process to maintain its original quality attributes. In this study, microwave thawing, and ultra-high-pressure thawing were investigated, and traditional thawing methods (air thawing and water thawing) were compared as references. The thawing time, quality attributes, and sensory scores of frozen mangoes were evaluated. Compared to traditional methods, innovative thawing methods can extensively shorten thawing time. These things considered, the thawing time was further decreased with the increase in microwave power. Additionally, microwave thawing enhanced the quality of mangoes in terms of less color change and drip loss and reduced loss of firmness and vitamin C content. Microwave thawing at 300 W is recommended as the best condition for thawing mangoes, with the highest sensory score. Current work provides more data and information for selecting suitable thawing methods and optimum conditions for frozen mango to minimize losses.

Effect of different thawing methods on the quality of mackerel (Pneumatophorus japonicus)

Five thawing methods such as flow water thawing, ultrasonic flowing water thawing, air thawing, microwave thawing and low temperature thawing were used, and the physical, chemical properties and structure of mackerels after thawing were assessed. The results showed that the low temperature thawing had the best water retention, lower protein and fat oxidation. The microwave thawing had the shortest thawing time, but uneven heating leads to partial maturation. Air thawing prolonged exposure to air leads to high levels of protein and fat oxidation. The flow water thawing had better water retention than that of the ultrasonic flowing water thawing, only the thawing time was slightly longer than that of the ultrasonic flowing water thawing. In general, the low temperature thawing performed well after thawing. The flow water thawing used only 1/43 of the low temperature thawing's elapsed time after sacrificing some acceptable qualities. Thus, flow water thawing is more suitable for thawing frozen mackerel.

Effects of freezing on length and mass measurements of Atlantic cod Gadus morhua in the Baltic Sea

An aggregated sample of 925 Atlantic cod Gadus morhua collected by four countries in different regions of the Baltic Sea during different seasons were measured (total length, L_T = 161-890 mm and weighed (mass, M = 45-6900 g) both before freezing and after defrosting. The cod were found to decrease significantly in both L_T and M following death and frozen storage. There was an average (±SD) change in L_T of -2.91% (±0.05%) following freezing, independent of starting L_T . Total M changed by -2.65% (±0.14%), independent of starting mass. Shrinkage of L_T and M did not differ significantly between 1 and 4 months frozen storage, though L_T shrinkage was significantly greater after 1 or 4 months in the freezer compared with after 5 days. There was significant variation in L_T and M shrinkage between regions of capture. A significant negative relationship between condition of cod and L_T or M change was also observed. Equations to back-calculate fresh L_T and M from thawed L_T , M and standard length (L_S ), gutted L_T , gutted L_S and gutted M are provided.