Effects of high-hydrostatic-pressure processing on the chemical and microbiological quality of raw ready-to-eat hard clam marinated in soy sauce during cold storage

Abstract

The aim of this study was to determine whether high-pressure processing (HPP) shucking method can replace the conventional frozen shucking method for the preparation of soy sauce-marinated Asian hard clams products, while also inactivating microorganisms. The chemical and microbiological quality of samples marinated in soy sauce and HPP treatments at 300, 400, and 500 MPa for 3 min (marinated HPP clam), and frozen and marinated in soy sauce (frozen marinated clam) were evaluated during storage at 4 °C for 15 days. Surface area, moisture content, aerobic plate count (APC), psychrotrophic bacteria count (PBC), and coliform counts of marinated HPP clams were significantly lower than those of frozen marinated clams. During storage at 4 °C, the APC and PBC of frozen marinated clams increased rapidly, reaching 8.3 log CFU/g and 8.4 log CFU/g at day 15, while the pH of frozen marinated clams decreased rapidly, reaching 3.4 at day 15. In contrast, high-pressure treatment could delay the increase of APC and PBC loads, and the drop of pH. Therefore, the results indicated that HPP conditions of ≥300 MPa for 3 min significantly extended the shelf life of marinated clam during cold storage.