Inactivation of microbial loads and retardation of quality loss in Asian hard clam (Meretrix lusoria) using high-hydrostatic-pressure processing during refrigerated storage

Authors: LIN, C-S - Yuan-Pei University Of Medical Technology; LEE, Y-C - National Kaohsiung University Of Science And Technology; KUNG, H-F - Tajen University; CHENG, Q-L - National Kaohsiung University Of Science And Technology; QU, T-Y - National Kaohsiung University Of Science And Technology; CHANG, SAM - Mississippi State University; TSAI, Y-H - National Kaohsiung University Of Science And Technology

Submitted to: Food Control
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 9/28/2021
Publication Date: 9/30/2021
Citation: Lin, C., Lee, Y., Kung, H., Cheng, Q., Qu, T., Chang, S.K., Tsai, Y. 2021. Inactivation of microbial loads and retardation of quality loss in Asian hard clam (Meretrix lusoria) using high-hydrostatic-pressure processing during refrigerated storage. Food Control. 133(Part A):108583. https://doi.org/10.1016/j.foodcont.2021.108583.
DOI: https://doi.org/10.1016/j.foodcont.2021.108583

Interpretive Summary: Bivalve shellfish such as clam and oyster are filter-feeding organisms and have been known to accumulate pathogens and virus that can cause diseases. Vibrio parahemolyticus and coliforms are commonly seen undesirable organisms in shellfish. In addition, shellfish and other seafood are susceptible to spoilage by contaminated microorganisms. High hydrostatic pressure (HPP) is an emerging non-thermal postharvest processing technology and its effect on improving food safety, meat yield and quality of Asian hard clam has not been characterized. Our objective was to define what HPP experimental conditions would eliminate Vibrio parahemolyticus and eliminate total bacteria counts during the cold storage of clam in hope to extend the shelf-life and to enhance food safety. The results showed that pressurizing at about 58,000 pound per square inch force for 3 minutes increased meat yield by 60% and eliminated all coliforms and Vibrio parahemolyticus to a non-detectable level. In addition, high pressure also significantly extended shelf-life of clam meat due to inactivation of total bacteria and reduction of nitrogenous odor compounds. Our results provided fundamental data which can be used as a good reference for enhancing safety and extending storage life of other bivalve shellfish such as oysters.

Technical Abstract: The effects of high pressure processing (HPP) at 200, 300, 400, 500, and 600 MPa for 3 min on physicochemical quality and inactivation of microbial loads of Asian hard clam were evaluated. In addition, the retardation effects in microbial growth and quality loss of pressurized hard clams stored at 4 °C were investigated. Results showed that the expanding rate, moisture content, shucking ratio, pH, L * (lightness), and W (whiteness) of clam meat increased significantly with the increase in pressure, but a* (redness) and b* (yellowness) values decreased. With the increase in pressure, the levels of aerobic plate count (APC), psychrotrophic bacteria count (PBC), coliform, and Vibrio parahaemolyticus in clam meat significantly decreased. Furthermore, HPP with a pressure of equal to or greater than 400 MPa on clam samples significantly delayed the increase in APC (delayed by 6-9 days) and PBC during storage at 4 °C. However, the samples pressurized more than 300 MPa had significantly lower levels of total volatile basic nitrogen (TVBN) than control samples during storage. Overall, the results indicated that pressurization at least 400 MPa for 3 min on Asian hard clam was able to reach the highest expanding rate and moisture content, and 100 % shucking, while it can reduce the coliform, and V. parahaemolyticus to a non-detectable level. In addition, HPP conditions of >400 MPa for 3 min significantly extended the shelf-life of hard clam during refrigerated storage. Therefore, HPP is a useful technique to preserve Asian hard clam meats due to its ability to reduce bacterial load and retard TVBN production.