Search

Ready-to-eat products have become popular with most of the busy people in modern cities. Heat processing combined with vacuum-packaging is one of the most common methods to make ready-to-eat products with an extended shelf-life. In this study, the influence of heat processing [80 °C (LT) and 98 °C (HT) in water bath] on the quality of salted and vacuum-packaged silver carp ( Hypophthalmichthys molitrix ) fillets, stored at 20 ± 1 °C, was investigated by sensory analysis, biochemical analysis, and microbial diversity. SPME-GC/MS indicated the presence of 27 volatile organic compounds (VOCs) in fillets, and major VOCs were aldehydes and alcohols. Acids tended to increase during storage and caused a fetid odor at the end of storage. Culture-dependent method indicated that Bacillus dominated the spoiled LT and HT samples. In addition, Bacillus was identified as the main spoiler of deteriorated heated fillets by high-throughput sequencing. Sphingomonas and Brevibacillus dominated the indigenous bacteria of fresh raw fillets. After heat processing, LT samples exhibited higher organoleptic quality than HT samples on day 0. HT samples showed extended shelf-life at 20 °C storage compared to LT samples. [ABSTRACT FROM AUTHOR]

The effects of dry-curing with low concentrations of salt and sugar on the quality of rainbow trout (Oncorhynchus mykiss) fillets were studied over a 16-day storage period at 4°C. Physicochemical characteristics (total volatile base nitrogen (TVB-N), biogenic amines (BAs), ATP-related compounds and K value), microbial populations (total aerobic counts (TAC), H2S-producing bacteria, Pseudomonas, Aeromonas, and lactic acid bacteria) and sensory (SA) indicators were analyzed. Fish samples were subjected to the following treatments: untreated (control), dry-cured with 1.3% salt (T1), and dry-cured with 1.3% salt that also contained 0.9% sugar (T2). SA indicated that the sensory quality of the control, T1, and T2 was unacceptable after 8, 12, and 12 days of storage, respectively. Moreover, the cadaverine concentration of treated samples was significantly lower (P < 0.05) than the control after storing for 8 days. T1 and T2 were significantly higher (P < 0.05) than the control in inosine 5-monophosphate (IMP) content from the 2th to 10th day. Cadaverine, putrescine, hypoxanthine, and TAC were correlated significantly (P < 0.01) with SA, and these seemed to be reliable indicators of fish quality. The results indicated that curing treatments extended the shelf life of rainbow trout fillets, which could be exploited by processors. [ABSTRACT FROM AUTHOR]

This study aimed to identify the dominant microbiota of crucian carp fillets during partial freezing (−3°C) and chilled (4°C) storage, and to correlate microbial changes with sensory scores and biogenic amines (BAs). The microbial communities of stored crucian carp fillets were identified by the high-throughput sequencing (HTS) technique of the V4 regions of the 16S ribosomal RNA gene. A total of 217,377 effective sequences and 690 different operational taxonomic units (OTUs) were identified and used in the analysis of microbial diversity. Culture-independent methods showed that thePseudomonaswere the predominant bacterial species of crucian carp fillets at the end of the storage. In addition, microbial enumeration also indicated relatively higher counts ofPseudomonas. Compared to chilled samples, partial freezing inhibited the growth of spoilage microorganisms during storage and extended the shelf-life of crucian carp fillets by 28 days based on the sensory analysis. However, there was no significant change in the composition of dominant species at the end of the shelf-life of crucian carp fillets. Chemical compounds studied in this article: Tryptamine (PubChem CID: 150); Phenethylamine (PubChem CID: 1001); Putrescine (PubChem CID: 1045); Cadaverine (PubChem CID: 273); Histamine (PubChem CID: 774); Tyramine (PubChem CID: 5610); Spermidine (PubChem CID: 1102); Spermine (PubChem CID: 1103) [ABSTRACT FROM AUTHOR]

Effects of oregano essential oil (EO) and nisin on the shelf life and microbial community of grass carp fillets packed under modified atmosphere were investigated. The shelf life of fish samples was evaluated based on sensory attributes and spoilage indicators, including color, odor, texture, overall acceptability, total volatile basic nitrogen, and biogenic amines. The addition of oregano EO, nisin, and oregano EO combined with nisin significantly extended the shelf life of fish fillets from 16 d to 20, 20, and 28 d, respectively. In addition, changes in microbial composition of fish fillets were measured by using Illumina-MiSeq high-throughput sequencing and classical microbiological analysis. Adding oregano EO and nisin significantly inhibited the microbial growth of fish fillets, especially lactic acid bacteria which were the dominant spoilage bacteria in fish fillets. While the use of oregano EO and/or nisin did not change the dominant bacteria of fish samples, they significantly lowered total viable counts. Treating fish fillets with nisin lowered the tyramine level and increased the pH value, due to the inhibitory effect on Gram-positive bacteria. The results suggest that oregano EO combined with nisin have great potential to be used as natural antimicrobials to extend the shelf life of grass carp. • Lactococcus were the dominant bacteria in all spoiled grass carp fillets. • LAB counts were significantly reduced after the addition of nisin. • The combination of oregano EO and nisin achieved the longest shelf life. [ABSTRACT FROM AUTHOR]