THE EFFECTS OF CHEMICAL PRESERVATIVES AND PASTEURIZATION ON THE MICROBIAL SPOILAGE AND SHELF‐LIFE OF KUNUN‐ZAKI

“Kunun‐zaki” was produced using pasteurization alone or in combination with chemical preservatives. Diverse microbial genera (Lactobacillus, Bacillus, Aspergillus and Saccharomyces) dominated the untreated control samples but only two microbial genera (Bacillus and Lactobacillus) were isolated from the samples subjected to preservation treatments with Lactobacillus being the predominant genus. The effects of pasteurization alone were comparable to the combined effects of pasteurization and chemical preservative treatments in reducing microbial populations. Of all the treatments, sodium benzoate (0.08% w/v) with pasteurization was most effective, reducing the total viable counts by approximately 4.5 log at the end of the storage period. In contrast, the combination of potassium sorbate (0.06%w/v) with pasteurization was least beneficial, resulting in only 2.6 log reduction. Shelf‐life (based on sensory overall acceptability and microbial quality) of the samples varied with the treatments, but combination of 0.08% w/v sodium benzoate with pasteurization extended the shelf life by approximately 4 days whereas samples pasteurized without preservatives showed marginally enhanced shelf‐life of about 2 days. However, untreated control samples exhibited remarkably high microbial loads and were virtually unacceptable 24h after production. Pasteurization alone would therefore be adequate for small scale production and commercialization.