Decrease of microbial community diversity, biogenic amines formation, and lipid oxidation by phloretin in Atlantic salmon fillets

Abstract

Phloretin is a naturally occurring flavonoid that has antimicrobial and antioxidant activities. The objective of this study is to examine the feasibility of using phloretin as a preservative for salmon fillets. Salmon samples were dipped in phloretin solution (2 mg/mL and 4 mg/mL), stored at 4 °C for three days. The effect of phloretin on the quality of salmon fillets was investigated during storage time. The results showed that phloretin reduced microbial species diversity and the relative abundance of bacterial community composition in genus level in salmon fillets. Specific spoilage organisms (Pseudomonas, Photobacterium, and Shewanella), Acinetobacter, Flavobacterium, and Chryseobacterium were identified as dominant bacteria in salmon fillets during storage time. Besides, phloretin inhibited the growth of test microorganisms, in particular, Gram-positive bacteria including Listeria monocytogenes, Staphylococcus aureus, and Bacillus subtilis. When dipped into 4 mg/mL of phloretin, phloretin showed growth inhibitory effects against Pseudomonas and Photobacterium by 1.6 and 0.7 logarithmic, respectively; and total viable bacteria counts were decreased. Notably, the formation of biogenic amines was retarded by 18.84 times and lipid oxidation measured by thiobarbituric acid-reactive substances (TBARS) was reduced by 3.23 times compared to control samples. Overall, phloretin is promising as a natural preservative to improve seafood safety.