Preservation of chilled Asian sea bass (Lates calcarifer) steak by whey protein isolate coating containing polyphenol extract from ginger, lemongrass, or green tea

The effects of whey protein isolate (WPI)-polyphenol coating on the microbial counts, physico-chemical properties, and sensory qualities of Asian sea bass (Lates calcarifer) steak during chilled storage were systematically investigated. Crude phenolic extracts (200 ppm) from ginger, lemongrass, and green tea were comparatively tested. WPI with crude plant extracts, especially ginger extract, can retard microbial growth by maintaining the total microbial quality below the acceptable limit of 7 log CFU/g for 15 days, whereas the shelf-life for the control was found to be 8 days. WPI-phenolic extract coating markedly retarded lipid and protein oxidation, heme protein degradation, metmyoglobin formation, discoloration, muscle softening, and drip loss of chilled sea bass steak. Lowered TVB-N, TMA, and propanal contents with a superior odor likeness score were found in the coated samples, suggesting the preventive effect against off-flavor development. Therefore, coating with WPIphenolic extracts, particularly ginger extract, can be an effective method for the preservation of chilled Asian sea bass steak.