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Effects of two thermal treatments (sterilization at 118°C and pasteurization at 90°C) and acidification on the color, texture, chemical composition, and microstructure of high‐moisture laver were investigated. Results showed that the reddish‐purple of laver faded to varying degrees after heating due to rapid degradation of phycoerythrin. With increasing heating time, the a* value gradually decreased accompanied by the increase in b* value, and the color changed to yellow‐green. Besides, the hardness and toughness gradually decreased, while the adhesiveness increased. Microstructure and soluble sugar results indicated that the cell tissue of the laver was destroyed after intensive heating. Compared to sterilization, laver subjected to pasteurization at 90°C exhibited better texture and color. Intensive thermal processing accelerated quality deterioration as evidenced by pigment degradation, cell rupture, and increase in soluble substances. The combination of acidification (pH < 4.6) with mild heat treatment contributed to better quality retention of ready‐to‐eat lavers with higher moisture. Practical applications: Since most of the existing laver products in the market are dry, the development of high‐quality wet laver products has attracted attention. However, due to the extremely thin leaves and soft texture, the color and texture of laver are prone to deterioration during the heat sterilization process. Understanding the quality changes of laver under typical sterilization conditions is conducive for exploring solutions. The present study clarifies the effects of heat treatment and acidification on the characteristics of high‐moisture laver, which serves as a foundation for the future development of instant wet laver products that can meet both safety and palatability, and provides theoretical guidance for the seaweed processing industry. [ABSTRACT FROM AUTHOR]

In order to clarify the action of a seasoning mixture of salt and Chinese liquor in maintaining the hygienic and quality characteristics of refrigerated grass carp, the changes in physicochemical properties, biogenic amines, and microbial growth in grass carp fillets during storage at 4°C for 30 days were investigated. Results showed that fillets lightly salted with Chinese liquor had lower values of total volatile basic nitrogen, drip loss, biogenic amines contents, and higher hardness as well as stable pH during storage, compared to the untreated or individual salted groups. The increase in total viable counts and total psychrophile counts were significantly inhibited by combined adding salt and Chinese liquor. Additionally, Illumina sequencing analysis showed Enterobacteriaceae and Carnobacteriaceae were the major spoilage bacteria species in untreated samples at the end of storage, but they were highly inhibited by adding salt and Chinese liquor. Practical applications: Refrigerated storage can better maintain the fresh quality of fish because it is stored under nonfrozen conditions, but the shelf life is limited due to the action of microorganisms and endogenous enzymes. Food seasoning ingredients have the characteristics of high safety, low cost, and convenient application. The combination of salt with other ingredients in fish curing to develop low‐salt preservation techniques has attached increasing interest. The present study showed that curing of grass carp using salt combined with Chinese liquor can largely delay chemical changes, lower the accumulation of putrescine and cadaverine, and inhibit the growth of spoilage microorganisms in refrigerated fish fillets compared to the untreated group. This study provided a promising cost‐efficient and simple preservation technique of fish. [ABSTRACT FROM AUTHOR]

The effect of mixed starter cultures isolated from Suanyu on flavor compounds development has been researched. Microorganism, pH, TA, sugars, nonvolatile organic acids and volatile compounds were analyzed in Suanyu with or without starters. In inoculated samples, a higher growth of lactic acid bacteria (LAB) and a declining rate of pH were determined when compared with the controlled samples. Besides, higher levels of volatile compounds were detected in inoculated Suanyu (19342.47, 19852.74 × 106 area units for PS) than those in controlled samples. During the process, aldehydes, acids, alcohols, esters and ketones were formed and increased continuously. Especially in Suanyu with PS, higher levels of ethanol (6973.8, 6549.9 × 106 area units) and acetic acid (2116.8, 2471.1 × 106 area units) were detected, which could produce unique wine flavor and moderate acid taste. Furthermore, high content of hexanal was generated through the addition of PS, which could contribute to a green grass odor. Practical Applications In this study, microorganism, pH, TA, sugars, nonvolatile organic acids and volatile compounds were analyzed in Suanyu with autochthonous starter cultures. The results showed that the generative stability of Suanyu can be assured and the product quality can be advanced by adding autochthonous starter cultures compared with that of noninoculated samples. There is a need to add modern processing technology such as microbial fermentation of the fermentation process to achieve effective control to ensure product flavor and product quality stability. In this study, autochthonous starter cultures isolated from Suanyu, which were propitious to the demand of industrialization. Besides, once the research is applied in the industrialized production, and considerable social and economic benefits can be obtained. Therefore, this study has a good prospect in application. [ABSTRACT FROM AUTHOR]

The hydrolysis of sarcoplasmic proteins during the growth of Lactobacillus plantarum 120 originally isolated from Suanyu, a traditional Chinese low salt fermented fish, was evaluated. Fermentation was carried out in a fish meat model system at 30C for 96 h. Proteolytic activity of this strain on fish muscle sarcoplasmic protein was determined by proteins, peptides and free amino acids analyses. There was a pronounced hydrolysis of almost all protein bands in electrophoretic pattern by L. plantarum 120. It also resulted in the generation of new peptides and disappearance of original peaks. In addition, the studied strain generated greater amounts of free amino acids than the control, especially for alanine, glutamic acid, phenylalanine, valine, methionine, aspartic acid, isoleucine and leucine. In general, proteolysis of fish sarcoplasmic proteins by L. plantarum 120 occurred during fermentation, resulting in increase in peptides and free amino acids, which may contribute to the taste and aroma of Suanyu. Practical Applications Suanyu is one of the Chinese traditional fermented fish products in South China. According to its characteristic flavor and high nutrition value, Suanyu has been accepted around China in recent year. However, Suanyu is still manufactured on a small scale by spontaneous fermentation. It is difficult to guarantee product quality and increase the efficiency. Lactic acid bacteria is one of the essential agents of the meat fermentation process that contribute to the hygienic and sensory qualities of meat products. Lactobacillus plantarum 120, isolated from Suanyu, exhibited optimal properties as a potential starter in our previous work. Once L. plantarum 120 is used as an industrial starter, it will promote fish muscle proteolysis, shorten the fermentation period and then improve product quality assurance activity. [ABSTRACT FROM AUTHOR]

This study examined the inhibitory effects of catechin, tea polyphenols, gallic acid and Na-citrate on the collagenase activity, collagen degradation and texture change of grass carp (Ctenopharyngodon idella) fillets over a period of 21 days under superchilling (−1.5C ± 0.2C) and ice storage (0.2C ± 0.1C) conditions. The results showed that catechin was the most effective inhibitor of collagenase activity, followed by tea polyphenol and gallic acid. Na-citrate exhibited the lowest inhibitory effect on collagenase activity. All additives were able to suppress the softening of chilled fillets to varying degrees. Catechin effectively retarded the softening of grass carp fillets under both conditions. The firmness of chilled fillets treated with catechin were 72.6 (superchilling storage) and 75.8% (ice storage) higher than of the firmness of control fillets after 3 days of storage, respectively. However, treatments with Na-citrate showed no obvious inhibitory effect on textural deterioration. Practical Applications The texture of fillets when stored in chilled conditions inevitably deteriorated, represented by gapping and decreases in hardness. Recent studies have found that muscle softening is highly associated with collagen degradation induced by collagenase. Thus, the inhibition of collagenase and the stabilization of collagen are of great importance for controlling the autolytic degradation of fish muscle, thus alleviating the texture deterioration of chilled fillets. The inhibitory effect of four selected edible additives on the collagenase activity and texture deterioration of chilled grass carp fillets was investigated. Catechin effectively retarded the softening of chilled grass carp fillets. The present study provides a promising method for maintaining the texture quality of chilled fillet and extending the post-mortem shelf-life. [ABSTRACT FROM AUTHOR]

The effects of three autochthonous starter cultures (Lactobacillus plantarum 120, Saccharomyces cerevisiae 2018 and Staphylococcus xylosus 135) on biogenic amines (BAs) accumulation in Chinese traditional fermented freshwater fish products (CTFPs) were studied. Some quality parameters of CTFPs, namely microbiological characteristics, α‐amino nitrogen, trichloroacetic acid (TCA)‐soluble peptides, protease activity, and free amino acids (FFAs) were also detected. No histamine accumulation was observed in each fermentation group. Putrescine and tyramine were the dominating BAs in CTFPs. Putrescine accumulation was significantly (p < 0.05) suppressed by inoculated with L. plantarum 120 and S. xylosus 135, and lowest tyramine content (363.15 mg/kg) was observed in sample inoculated with mixed starter cultures. Low levels of cadaverine (8.22–20.03 mg/kg), spermidine (6.60–8.11 mg/kg) and spermine (7.94–9.62 mg/kg) were observed in all groups at the end of the fermentation. Additionally, total BAs contents showed a significant (p < 0.05) correlation with protease activities and α‐amino nitrogen contents. Practical applications: The present study demonstrated the changes in some quality parameters and BAs contents of CTFPs influenced by different starter cultures. Results showed that lactic acid bacteria (LAB) and yeast were gradually increased, severe hydrolysis of proteins was occurred during CTFPs fermentation process, histamine accumulation was inhibited completely in all fermentation groups, putrescine was significantly (p < 0.05) suppressed by inoculated with L. plantarum 120 and S. xylosus 135, and significant (p < 0.05) inhibition of tyramine was observed in sample inoculated with mixed starter culture. To date, CTFPs were usually produced by spontaneous fermentation, and the quality was unsteady. Therefore, to improve the quality and avoid the unacceptable levels of BAs accumulation, inoculation of proper autochthonous starter cultures is advisable. [ABSTRACT FROM AUTHOR]