Improvement of Injera Shelf Life and Staling Through Vacuum and Non-Vacuum Polyethylene Packaging: Their Synergistic Effect With Chemical Preservative

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Date

2019-03-05

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Addis Ababa University

Abstract

Injera is naturally-leavened fermented sourdough-risen flatbread, indigenous to Ethiopia. It is commonly made from tef (Eragrostis tef). Injera has nutritional merits, mainly gluten free protein and high calcium and iron content. Unfortunately, injera has a short shelf life of 3-4 days basically due to mould spoilage. Its traditional storage condition favors mold spoilage and quality loss. Use of critical preservation techniques like packaging is ideal for retardation of mold growth. The application of vacuum packaging (VP) and non-vacuum 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+ (non-vacuum packaging with preservative) treatments. Among these, VP+ had least microbial load (5.3*101 & 9.0*101 bacterial & yeast and mold colony forming unit (cfu)/g respectively). But it was least effective regarding staling as it had least average scoring of MC, pH and L value (60.96%, 3.33 & 45.92 respectively) and sensory acceptability, basically due to crumbling effect of the packaging method used. Beside, NP+ had lower microbial load (7.5*101 bacterial cfu/g and 9.0*101 yeast and mold cfu/g). Despite VP and VP+, NP+ was relatively effective method regarding sensory acceptability and staling as it had 62.73%, 3.32 & 48.70 average MC, pH and L value respectively. Generally, packaging methods and preservative used 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.

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Keywords

Improvement of Injera, Shelf Life, Staling Through Vacuum, Non-Vacuum, Polyethylene Packaging, Synergistic Effect, Chemical Preservative

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