Synergistic effect of tannic acid and modified atmospheric packaging on the prevention of lipid oxidation and quality losses of refrigerated striped catfish slices

Chemical, microbiological and sensorial changes of striped catfish (Pangasius hypophthalmus) slices treated without and with tannic acid (100 and 200 mg/kg) were determined during 15 days of storage at 4 °C in air and under modified atmospheric packaging (MAP, 60% N2/35% CO2/5% O2). The slices consisted of 9.2 g lipid/100 g and the lipid contained 64.55% unsaturated fatty acids and 33.87% saturated fatty acids. During the storage, the sample treated with 200 mg/kg tannic acid and stored under MAP (M2) had the lowest peroxide value (PV) and thiobarbituric acid-reactive substances (TBARS) with the coincidental lowest non-haem iron content, indicating the retarded lipid oxidation. Fourier transform infrared (FTIR) spectra indicated the formation of primary oxidation products and free fatty acids in M2 sample after 15 days. Conversely, these compounds were found at lower contents in the control samples kept in air without tannic acid treatment (A0), suggesting that the deterioration was more advanced. Myosin heavy chain of A0 was degraded by 17.85% after 15 days of storage, whereas no change was noticeable in M2, compared with the fresh sample (F). Based on microbiological acceptability limit (107 cfu/g), the shelf-life of A0 and M2 was estimated to be 3 and 15 days, respectively. M2 had the acceptable scores for all sensory attributes up to 15 days, while A0 was acceptable when stored for 9 days. Therefore, tannic acid exhibited a synergistic effect with MAP on retarding lipid oxidation and microbial growth, thereby increasing the shelf-life of striped catfish slices during refrigerated storage.