Title: Effect of packaging methods on the storage stability of dried capelin in the temperature and humidity conditions of Uganda.

Type:
Final project
Year of publication:
2015
Publisher:
UNU-FTP
Place of publication:
Reykjavík
Number of pages:
43

Abstract

Commercially dried capelin (Mallotus villosus) was packaged using conventional air packaging (AP), vacuum packaging (VP), modified atmosphere packaging (MAP, 99.9% N2) and hessian bags (HB) before storage in simulated temperature and humidity conditions of Uganda (Relative Humidity ≈ 54% and 83%; Temperature ≈ 30 °C and 17 °C respectively) for 8 weeks. Physicochemical, lipid and microbiological stability of the dried capelin was assessed during this period and varied with packaging method. Water content and water activity increased significantly for HB packed capelin (12.7 – 17.6% and 0.62 - 0.74 respectively). pH and colour were generally stable for all methods within a narrow range. Lipid content decreased significantly towards the end of storage in HB packed dried capelin. Primary lipid oxidation as measured by peroxide value (PV) was lowest in vacuum packed dried capelin (31.46 – 53.49 μmol/kg) over the 8 weeks. Secondary lipid oxidation indicated by thiobarbituric reactive substances (TBARS) content decreased significantly with storage time in modified atmosphere packed dried capelin (250.33 – 152.85 μmol MDA/kg). Free fatty acid (FFA) content of dried capelin increased throughout storage irrespective of packaging method. Total microbial count (TC) decreased significantly in vacuum packed dried capelin (4.81 – 3.55 Log cfu/g) while mould counts increased significantly in HB packed dried capelin (1 – 2.97 Log cfu/g). Yeasts initially proliferated in the air packed dried capelin however, the counts were generally low over the 8 weeks. Preliminary high coefficients of determination for independent validation (R 2cv) values (0.92 - 0.96) indicate that near infrared spectroscopy (NIR) can potentially be used to estimate changes in water content, water activity and pH of dried capelin with a good degree of accuracy. Overall, the present study showed that storage stability of dried capelin was dependent on packaging method. Nevertheless, the good quality of dried capelin raw material ensured that most quality indicators remained within acceptable specification limits for human consumption by the end of the storage period.

 

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