Effects of Single Film, Packaging Methods and Relative Humidity on the Moisture Content and Water Activity of Kilishi during Storage

Abstract

This study was carried out to determine the effect of single film packaging and relative humidity (RH) on the moisture content and water activity of Kilishi during storage. Polypropylene (PP) and high-density polyethylene (HDPE) films were used for the packaging. Kilishi was prepared by trimming off blood vessels, fat and connective tissues from the beef raw material, cutting the beef into strips and mixing with the standard ingredients slurry consisting defatted groundnut cake and array of spices. It was dried in two stages and roasted briefly over charcoal fire, cooled and packaged 50 gram per pack in 40 polypropylene (PP) and 40 high-density polyethylene (HDPE) films. Twenty of each of these were vacuum-sealed with Koch Provac 880 vacuum sealer, while the other twenty of each film were sealed with an impulse sealer. Storage was at ambient temperature 32-34 o C over a 40 week period. Moisture content and water activity were determined at eight week intervals using means of triplicate determinations. The moisture content decreased in the PP packs from 11.9% to 9.5%, while it decreased from 11.9% to 10.4% in the HDPE. The water activity (aw) remained constant at 0.63 for the PP packs, but rose from 0.63 to 0.66 in the HDPE packs. There were significant differences between PP and HDPE films in both moisture content and water activity at the 5 percent alpha level. The RH was measured with the wet and dry bulbs and later converted using adiabatic chart. It increased from 21% to 72% as storage progressed from dry season to wet season.