Improvement of Injera Shelf Life and Staling through Vacuum and Nonvacuum Polyethylene Packaging: Their Synergistic Effect with Chemical Preservative

Abstract

The application of vacuum packaging (VP) and nonvacuum packaging (NP) of injera, with or without preservative added (sodium benzoate), has been studied for 15 days with the aim of determining their effect on the shelf-life and staling of injera. Samples were tested for microbial load analysis, moisture content (MC), pH, and color “L” value (lightness) determination, visible mold sign inspection, and sensory quality evaluation. Oxygen exclusion of the packaging methods and antimicrobial activities of preservative used, prolong the storage duration of injera without visible mold growth to more than 15 days; with VP (vacuum packaging), VP+ (vacuum packaging with preservative), and NP+ (nonvacuum packaging with preservative) treatments. Among these, VP+ had the least microbial load ( $5.3\ast {10}^1$ & $9.0\ast {10}^1$ bacterial & yeast and mold colony forming unit (cfu)/g, respectively). But it was least effective regarding staling as it had the least average scoring of MC, pH, and L value (60.96%, 3.33, and 45.92, respectively) and sensory acceptability, basically due to the crumbling effect of the packaging method used. Besides, NP + had a lower microbial load ( $7.5\ast {10}^1$ bacterial cfu/g and $9.0\ast {10}^1$ yeast and mold cfu/g). Despite VP and VP+, NP+ was a relatively effective method regarding sensory acceptability and staling as it had 62.73%, 3.32, and 48.70 average MC, pH, and L value, respectively. Generally, packaging methods and preservative used were found to have a significant effect ( $P<0.05$ ) on microbial load, physico-chemical properties, and sensory attributes of injera. Moreover, it was proved that NP+ was the most effective method to improve the shelf life and staling of injera.