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Summary: The alkaline ionised water (AIW) could inactivate food‐borne microorganisms, ensuring the vegetables and fruits security. However, the application of AIW in preserving fish is still unknown. Therefore, the present study aimed to explore the effects of AIW on grass carp fillets during storage at 4 °C for 12 days. The results of total volatile basic nitrogen (TVB‐N), thiobarbituric acid reactive substances (TBARS), colour and the sensory attributes showed that the AIW‐treated grass carp fillets exhibited better shelf life. As for the microbial composition, AIW treatment for 5 min significantly inhibited the growth of the predominant bacteria, such as Staphylococcus and Pseudomonas. According to the result from microstructure, the neat and even structure of myofibrillar proteins (MPs) was conducive maintained the fish quality. Overall, the results demonstrated that AIW treatment exerted a protective effect of inactivating spoilage microorganisms and preserving the quality of grass carp fillets. [ABSTRACT FROM AUTHOR]

Abstract: Ultrasound treatment was used for accelerating drying process and shortening drying time of salted‐dried grass carp, in parallel with evaluation of physicochemical properties and microstructure. The grass carp blocks were salted with ultrasound‐assisted treatment at 0–480 W, 40 kHz for 120 min, then put into heat pump dryer for drying at 50% humidity, 30 °C for 50 hr. The moisture content results showed that ultrasound treatment could significantly promote water loss rate. As the ultrasound power increased, the hardness, the relative content of monounsaturated fatty acid and polyunsaturated fatty acid and total content of free amino acid decreased while the saturated fatty acid and sensory scores increased, respectively. Furthermore, microstructure of the dried‐salted grass carp was studied using paraffin sections and the scanning electron microscope to understand the change of microstructure. In general, ultrasound‐assisted salting significantly increased drying rate, and improved the quality of salted‐dried grass carp. This study shows the potential application of ultrasound in food drying process. Practical applications: The ultrasound was applied in order to facilitate the traditional process to produce salted‐dried grass carp. And physicochemical properties and microstructure of salted‐dried fish were measured. The results showed that the application of ultrasound could significantly promote the mass transfer of water and improved the product's appeal for customers. The outcome of this study demonstrated a method for producing better quality dried‐salted fish products with a fast speed in the future and showed a great potential of ultrasound in food drying process. [ABSTRACT FROM AUTHOR]

The main monomer compounds from spoiled Grass carp ( Ctenopharyngodon Idellus) were analyzed and deduced using high-performance liquid chromatography coupled with quadrupole time-of-flight mass spectrometry (HPLC-Q-TOF-MS). Forty-six kinds of monomer compounds were determined in spoiled Grass carp, including 3 kinds of non-nitrogenous compounds and 43 nitrogenous compounds. Forty-three nitrogenous compounds including 6 kinds of amino acids (2 kinds of α-amino acids), 10 kinds of amines, 12 kinds of amide compounds, 2 kinds of nitro compounds, 12 kinds of heterocyclic nitrogenous compounds, and 1 kind of nitriles compound. The results indicated that the quantity and chemical structure of main monomer compounds of Grass carp were significantly changed during the spoiled process. Practical applications Structure of monomer compounds in fresh and perishable materials can be inferred and identificated by HPLC-Q-TOF-MS. They can be used to increase efficiency in identification and analysis of chemical component. It will be benefit for identification, evolution, and deduction of active ingredients and new compounds of fresh material in preservation. [ABSTRACT FROM AUTHOR]

The impacts of pre-frozen with −80 °C liquid nitrogen spray freezer (LNF), −80 °C refrigerator freezer (RF), and −30 °C micro-freezer (MF) on the freezing rate, physical and chemical properties and microscopic structures of freshwater fish (grass carp, tilapia and bighead carp) stored at −18 °C (14 days) were evaluated. LNF and MF were effective in shortening the entire freezing period and their muscle tissue microscopic structures were more homogeneous and thicker than the RF group, also with smaller and more regular ice crystal. Additionally, the LNF-treated samples had good water holding capacity and textural characteristics and significantly delayed changes in immobilized water content, effectively suppressing the increase in L* values in grass carp samples (p < 0.05). However, MF was not as effective as LNF and RF in inhibiting the formation of TBARS and TVBN. In conclusion, LNF played a more positive role in quality retention of freshwater fish. • Different freezing techniques have significant differences in the quality of three types of freshwater fish. • 80 °C LNF reduced thawing loss and maintained some water-holding capacity. • 80 °C LNF reduced water migration during frozen storage. [ABSTRACT FROM AUTHOR]