Effects of High Hydrostatic Pressure on the Physical, Microbial, and Chemical Attributes of Oysters (Crassostrea virginica)

Abstract

The change in the quality attributes (physical, microbial, and chemical) of oysters (Crassostrea virginica) after high hydrostatic pressure (HHP) treatment at 300 MPa at room temperature (RT, 25 °C) 300, 450, and 500 MPa at 0 °C for 2 min and control oysters without treatment were evaluated over 3 wk. The texture and tissue yield percentages of oysters HHP treated at 300 MPa, RT increased significantly (P < 0.05) compared to control. Aerobic and psychrotrophic bacteria in control oysters reached the spoilage point of 7 log CFU/g after 15 d. Coliform counts (log MPN/g) were low during storage with total and fecal coliforms less than 3.5 and 1.0. High pressure treated oysters at 500 MPa at 0 °C were significantly higher (P < 0.05) than oysters HHP treated at 300 MPa at 0 °C in lipid oxidation values. The highest pressure (500 MPa) treatment in this study, significantly (P < 0.05) decreased unsaturated fatty acid percentage compared to control. The glycogen content of control oysters at 3 wk was significantly higher (P < 0.05) when compared to HHP treated oysters [300 MPa, (RT); 450 MPa (0 °C); and 500 MPa (0 °C)]. HHP treatments of oysters were not significantly different in pH, percent salt extractable protein (SEP), and total lipid values compared to control. Based on our results, HHP prolongs the physical, microbial, and chemical quality of oysters.

Shellfish: Nutritive Value, Health Benefits, and Consumer Safety

“…Growth of C. botulinum type E can be controlled by maintaining the temperature below 3.3 °C (Jay and others ). HHP treatment at 500 MPa for 2 min at 0 °C significantly reduced nonspore‐forming pathogenic microorganisms from oysters (Lingham and others ). Exposure to ionizing radiations (gamma rays, machine‐generated electron beams, or X‐rays) provides an effective safeguard against most microbial and parasitic hazards.…”

Recent developments in non‐thermal processing for seafood and seafood products: cold plasma, pulsed electric field and high hydrostatic pressure

“…Increase in lipid oxidation was due to release of free metal ions and decrease in oxidative enzymes was also observed due to HHP (Cropotova et al, 2020). Lipid oxidation was found to increase in oysters (Crassostrea virginica) treated with increasing HPP from 300 to 500 MPa (Lingham et al, 2016).…”

“…HPP was found to inhibit total aerobic count, total psychrotrophic bacteria, total coliforms and faecal coliforms count in oysters (Crassostrea virginica) with increase in pressure from 300 to 500 MPa. However, further extended levels of inhibition were observed when treatment was carried at 0 °C (Lingham et al, 2016). The inhibition levels were found to be impacted significantly by increase in pressure levels and lowered temperature conditions.…”

“…Total non-essential free amino acids and total free amino acids were found to be reduced at 600 MPa. HPP is known to alter structure of proteins by rupturing weak bonds and forming secondary bonds causing aggregation with increase in pressure (Lingham et al, 2016;Cropotova et al, 2020) indicating denaturation. Significant increase in carbonyl content of sarcoplasmic and myofibrillar protein was observed in haddock and mackerel mince suggesting negative impacts of HPP on proteins.…”

“…Significant loss of moisture was observed in squids (Todarodes pacificus) treated with HPP, increasing pressure caused migration of internal moisture (Zhang et al, 2015). Increase in HPP strength was found to improve cutting strength in oysters (Lingham et al, 2016). The increase could be due to protein denaturation and loss of moisture from matrix because of HHP.…”