Effects of Modified Atmospheric Packaging Conditions on the Quality Changes of Pasteurized Oyster (Crassostrea belcheri) Meat during Chilled Storage

Effects of anhydrous low-temperature storage on the post-capture survival, bacterial counts and meat quality of Hong Kong oyster Crassostrea hongkongensis

This study comprehensively evaluated the freshness and quality changes of Hong Kong oyster (Crassostrea hongkongensis) during anhydrous low-temperature storage through a multi-indicator method. The results revealed that TVB-N and MDA levels showed significant increase after nine days of storage, while pH and surface color remained stable. The counts of Escherichia coli, Vibrio parahaemolyticus, and V. vulnificus peaked on day three before declining, contrasting with the continuous proliferation of anaerobic lactic acid bacteria. The crude protein, total lipid, phospholipid and fatty acid contents decreased significantly with prolonged storage, while glycogen content exhibited a biphasic trend, and triglyceride levels consistently increased. Most non-volatile compounds peaked at three to six days of storage, whereas lactic acid levels progressively increased. Among volatile compounds, aldehydes were the most abundant, with hexanal levels remaining stable and 2,4-heptadienal significantly increasing by day six. In conclusion, the optimal shelf life for Hong Kong oysters under anhydrous low-temperature storage conditions should be not exceed six days.

Ready-to-Cook Foods: Technological Developments and Future Trends-A Systematic Review

Ready-to-cook (RTC) foods can significantly improve the cooking experience of busy or unskillful consumers, based on production involving technical combinations of food processing and packaging. Initialized by a market survey of 172 products in Beijing, this systematic review analyzes RTC foods' development status according to ingredients, packaging, and storage conditions to further clarify the scope of RTC foods. The working principles and efficacy of various food processing techniques, such as washing, cutting, marinating, and frying, and packaging design or innovations such as modified atmosphere packaging (MAP) were both summarized in detail, with attention to their ability to extend shelf life, reduce safety risks, and maximize production efficiency in RTC food production. The cutting-edge technologies that may potentially apply in the RTC food processing or packaging sector were compared with current approaches to visualize the direction of future developments. In conclusion, we have observed the specific pattern of RTC food varieties and packaging formats in the Beijing market and revealed the advancements in RTC food technologies that will continue playing a critical role in shaping this growing market, while challenges in scalability, cost-efficiency, and sustainability remain key areas for future research. The data and perspectives presented will articulate the conceptions and existing challenges of RTC food, foster consumer perception and recognition of similar products, and deliver useful guidance for stakeholders interested in such products.

Intelligent Evaluation and Dynamic Prediction of Oysters Freshness with Electronic Nose Non-Destructive Monitoring and Machine Learning

Physiological and environmental fluctuations in the oyster cold chain can lead to quality deterioration, highlighting the importance of monitoring and evaluating oyster freshness. In this study, an electronic nose was developed using ten partially selective metal oxide-based gas sensors for rapid freshness assessment. Simultaneous analyses, including GC-MS, TVBN, microorganism, texture, and sensory evaluations, were conducted to assess the quality status of oysters. Real-time electronic nose measurements were taken at various storage temperatures (4 °C, 12 °C, 20 °C, 28 °C) to thoroughly investigate quality changes under different storage conditions. Principal component analysis was utilized to reduce the 10-dimensional vectors to 3-dimensional vectors, enabling the clustering of samples into fresh, sub-fresh, and decayed categories. A GA-BP neural network model based on these three classes achieved a test data accuracy rate exceeding 93%. Expert input was solicited for performance analysis and optimization suggestions enhanced the efficiency and applicability of the established prediction system. The results demonstrate that combining an electronic nose with quality indices is an effective approach for diagnosing oyster spoilage and mitigating quality and safety risks in the oyster industry.

Lactiplantibacillus plantarum 299V-fermented soy whey improved the safety and shelf life of Pacific oysters (Magallana gigas)

This study developed a postbiotic fermentation solution for fresh oyster preservation with the use of food waste soy whey. Lactiplantibacillus plantarum 299V was able to proliferate in soy whey within 24 h without any supplementation. Pacific oysters (Magallana gigas) were immersed in the postbiotic fermentation solution and stored at 4 °C for 12 days. Pathogenic bacteria Vibrio parahaemolyticus and Salmonella enterica introduced by bioaccumulation were suppressed to levels below the detection limit (<2 log CFU/g) within 4 days. The spoilage-related microbial parameters and chemical parameters were maintained at low levels across the 12 days. Sensory evaluation revealed that the product had a positive effect on most of the participants (>60%). Overall, the postbiotic fermentation solution reported in this study enhanced the shelf life and safety of oysters in a sustainable way and could also be recognized as an innovative probiotic vehicle with potential implications for human health promotion.

Effects of Modified Atmosphere Packaging, Storage Temperature, and Absorbent Pads on the Quality of Fresh Cape Hake Fish Fillets

This study investigated the effects of modified atmosphere packaging (MAP), storage temperature, and the use of absorbent pads (PAD) on the quality attributes of Cape hake (Merluccius capensis) fish fillets. Fresh Cape hake fillets were packaged under active-MA (40% CO2 + 30% O2 + 30% N2) or passive-MA (0.039% CO2 + 20.95% O2 + 78% N2), with and without PAD, and stored at 0 °C, 4 °C, and 8 °C (to mimic abuse temperature). The control fresh fillets were stored under passive-MAP without PAD at 0 °C, 4 °C, and 8 °C. Headspace O2 gas composition continuously decreased below critical limits under passive-MAP, with an increase in storage temperature. Similarly, O2 levels decreased under active-MAP but did not reach critical levels, with the lowest being 9.5% at 0 °C. The interaction of storage temperature and modified atmosphere had a significant effect on quality attributes of Cape hake fillets. Drip loss was higher in active-MAP packaged fillets without PAD (0.64%) than passive-MAP packaged fillets without PAD (0.27%). Drip loss was significantly reduced when using absorbent pads (p < 0.05). Firmness, color, and pH were better maintained under active-MAP at the lowest temperature of 0 °C. Firmness (work of shear) of active-MA packaged fillets on day 12 at 0 °C and 4 °C was 527 N/s and 506 N/s, respectively. Fillets packaged under active-MAP at 0 °C had longer shelf-life than control passive-MAP fillets.