Effect of packaging methods on the storage stability of dried capelin under simulated temperature and humidity conditions
Small pelagic fish have grown in importance for the food and nutrition security of people in developing countries. The goal of this study was to improve the storage stability of dried small pelagic fish (Capelin - Mallotus villosus) using appropriate packaging methods. Commercially dried capelin was packaged using conventional air packaging (AP), vacuum packaging (VP), modified atmosphere packaging (MAP, 99.9% N2) and hessian bags (HB) before storage at simulated temperature and humidity conditions of Uganda (relative humidity H” 54 and 83%; temperature H” 30 and 17 °C, respectively) for 8 weeks. Chemical and microbiological stability of the dried capelin was assessed with respect to packaging methods. Water content and water activity increased significantly (p<0.05) for the HB packed capelin (12.7 – 17.6% and 0.6 - 0.7, respectively). Lipid content decreased significantly (p<0.05) towards the end of storage in the HB packed dried capelin. Primary lipid oxidation (peroxide value) was lowest in the vacuum packed dried capelin (31.5 – 53.5 ìmol kg-1). Secondary lipid oxidation (TBARS) decreased significantly (p<0.05) with storage time in the modified atmosphere packed dried capelin (250.3 – 152.9 ìmol MDA kg-1). Free fatty acid content of dried capelin increased throughout storage irrespective of the packaging method. Total microbial count decreased significantly (p<0.05) in the vacuum packed dried capelin (4.8 – 3.6 log cfu g-1); while mould counts increased significantly (p<0.05) in the HB packed dried capelin (1.0 – 3.0 log cfu g-1). VP and MAP enhanced the storage stability of dried Capelin.
Key words: Lipid oxidation, Mallotus villosus, vacuum packaging