Microbiological, chemical, and sensory assessment of Pacific oysters (Crassostrea gigas) stored at different temperatures

Abstract

The changes were studied in microbiological, chemical, and sensory properties of Pacific oysters stored at 10°C, 5°C, and 0°C. Pseudomonas (22%) and Vibrionaceae (20%) species were dominant in raw oysters. The dominant bacteria found in the spoiled samples were Pseudomonas regardless of the storage temperature. During storage, rapid increases in aerobic plate count (APC) values of the samples stored at 10°C and 5°C were observed, while no obvious lag phases were detected. With the samples stored at 0°C, a decrease in APC value during the first 4 days and a lag phase of about 6 days were observed. The APC values of the samples stored at 10°C, 5°C, and 0°C reached the level of 10 7 CFu/g on day 6, 10, and 18, respectively. All the tested samples stored at different temperatures revealed a slight decrease in pH and a significant increase of total volatile basic nitrogen (TVB-N) during storage. The average TVB-N concentration of about 22.0 mg N/100 g was observed at the end of the shelf-life as determined by APC. Combined with the sensory assessments, the shelf-life of 6-7, 10-11, and 17-18 days for oysters stored at 10°C, 5°C, and 0°C, respectively, was determined.

Sensory Evaluation of Hatchery-Reared Spotted Babylon (Babylonia areolata) and the Effects of Chilled Storage (4°C) on the Main Sensory Attributes

“…Our results are comparable to Gokoglu (2002) on fresh mussels (Mytilus galloprovincialis) stored at 4°C, which is acceptable up to 4 days, while air packed green mussels (Perna viridis) on polystyrene trays at 4°C were (Masniyom et al, 2011). Cao et al (2009) however reported a higher shelf-life of 10-11 days for Pacific oysters (Crassostrea gigas) stored at 5°C. In this study we found that odour as the most important characteristics associated with fresh B. areolata freshness compared to appearance and colour.…”

Effect of chitosan and acetic acid on the shelf life of sea bass fillets stored at refrigerated temperature

“…In the present study, pH values of all the samples were well within the acceptable limit during the storage period.This might be due to antimicrobial effects of chitosan and inhibitory activity on the endogenous proteases which may have delayed the increase in pH and reduced the changes in the quality of the samples (Fan et al, 2009 et al (2005) reported that a chitosan coating consisting a blend of acetic acid and 1% chitosan exerts an inhibitory effect on the gram-negative flora of fish patties since non-ionized acetic acid penetrates the bacteria cell wall and disrupt the normal physiology of certain types of bacteria that presented as pH-sensitive, meaning that they cannot tolerate a wide internal and external pH gradient. Sensory characteristics: Sensory evaluation is an important tool for assessing the quality of fish and fishery products and thereby their acceptability (Cao et al, 2009).Sensory evaluation of food is defined as the scientific means of quantifying and interpreting the variations in food characteristics (Color, odour, taste, texture, appearance and overall acceptability) by using human senses of sight, smell, taste, touch and hearing. Studies have shown that assessment of food freshness/ characteristics using sensory methods are capable of giving objective and / reliable results when assessments are done under controlled conditions.…”

Sensory Qualities of Oysters Unaltered by a Short Exposure to Combined Elevated pCO2 and Temperature

“…This technique is considered an accurate quality predictor (Reineccius, 1991;Chang et al, 1998), and has been used extensively for oyster quality assessments (Aaraas et al, 2004;Cao et al, 2009;Buzin et al, 2011;Cochet et al, 2015).…”