Preservation of Raw

Research background: Oysters have high nutritional value; however, their short shelf life limits their commercialisation to areas close to production sites. Affordable and accessible processing techniques that extend shelf life could expand both market reach and consumer access to oysters. This study evaluates the physicochemical, microbiological and sensory properties of raw Experimental approach: Aliquots of (100±2) g of raw oyster meat were placed into plastic containers containing different solutions: sterile deionised water only (negative control treatment, labelled W), base solution (NaCl, 5 % Results and conclusions: Incorporating weak acids into the marination solutions effectively inhibited the growth of mesophilic and psychrotrophic bacteria in semi-preserved oysters during 16 days of refrigerated storage. In contrast, water and NaCl treatments exceeded the recommended limit of 5 log CFU/g for seafood after 3 and 11 days, respectively. By day 16, total volatile basic nitrogen (TVB-N) values indicated early spoilage in water ((30.0±1.1) mg/100 g), satisfactory freshness in NaCl ((24.5±2.6) mg/100 g) and CA ((18.3±1.1) mg/100 g), and excellent freshness in LA ((14.7±0.0) mg/100 g) and AA ((15.0±1.8) mg/100 g). Thiobarbituric acid reactive substances (TBARS) assay values, expressed as malondialdehyde (MDA), remained below 3 mg/kg in all treatments, indicating good oxidative stability. Among the acids, AA maintained higher pH values (3.78 on day 16) than CA (3.26) and LA (3.14) and showed the lowest microbial loads; however, it received the highest scores for acid odour (median=5.35) and the lowest for characteristic oyster odour. CA and LA produced sensory profiles more similar to fresh oysters, with higher characteristic odour scores and lower acid odour scores, but slightly higher spoiled odour scores (still low in absolute terms). Overall, AA was the most effective for microbiological and physicochemical preservation, while CA and LA offered better sensory acceptance. These results highlight the potential of weak organic acids, particularly AA, as a low-cost method to extend the shelf life of raw oysters to at least 16 days under refrigeration. Novelty and scientific contribution: This study evaluates the effects of marination with weak acids on the physicochemical, microbiological, and sensory properties of raw oyster meat. The wide range of parameters analysed highlights not only its suitability for consumption but also consumer preferences based on sensory aspects such as colour and odour. The combined findings can assist the industry in selecting the most appropriate acid for developing different oyster-based products.