Abstract: This work was undertaken in order to study the combined treatment effects of ultrasound and caffeic acid on the quality of sea bass (Lateolabrax japonicas) during refrigerated storage. Fresh sea bass fillets were arbitrarily allocated into five groups: ultrasonic treatment at 20 kHz and 600 W for 10 min (US), dipping in 2.0 g/L caffeic acid for 10 min (CA), ultrasonic treatment at 20 kHz and 600 W for 5 min followed by dipping in 2.0 g/L caffeic acid for 5 min (US + CA), dipping in sterile water for 10 min (blank control, CK), and dipping in 1% acetic acid for 10 min (AA). After draining off the soaking solution, the samples were packed separately with polyethylene (PE) pouches, and then stored in a refrigerator at 4 ℃. Total viable count (TVC), physicochemical properties such as pH, total volatile basic nitrogen (TVB-N) content, thiobarbituric acid (TBA) value, texture profile analysis (TPA) parameters, and water-holding capacity (WHC), intrinsic fluorescence intensity (IFI) and sensory quality were measured every two days. The results showed that the US and CA treatments retarded the growth of TVC. On the fifth day, the TVC values in the CA and US groups were 18.49% and 15.53% lower than that in the control group, respectively. The increase of pH and TVB-N values in the treatment groups was obviously slower than that in the control group. On the 10th day of storage, the TVB-N content of the control group exceeded the spoilage limit, reaching (33.88 ± 0.56) mg/100 g compared to (16.71 ± 0.41) mg/100 g for the US + CA group. Both the US and CA treatments improved the WHC of fish greatly, while the CA treatment also had a stronger inhibitory effect on lipid oxidation in fish. Among the five groups, the US + CA group had the best overall quality. Compared with the CK group, the US + CA treatment maintained the quality better and extended the shelf-life of sea bass by four days at least.

Key words: ultrasonic; caffeic acid; sea bass; refrigerated storage; quality