Abstract

The effects of pasteurisation on the survival patterns of the microflora as well as vitamin C retention in kunun-zaki fortified with vitamin C was syudied. A laboratory sorghum based kunun–zaki was fortified with 90 mg/l of vitamin C. The content was subjected to pasteurisation at 70^oC for different time intervals ranging from 0 - 30 min.  Samples of the beverage were then taken at 5 min intervals during pasteurisation and were analysed for microbial load and residual vitamin C content by 2,6-dichloroindophenol titration method. The results showed that there was a gradual decline in vitamin C retention and steep decline in the microbial load reduction during pasteurisation. The result also showed that at the 20^th min of pasteurisation, 80% of microbial isolates had been eliminated leaving only Bacillus Subtilis and Saccharomyces cerevisiae as the surviving organisms. The D₇₀ -value of the most heat resistant organism B. subtilis was found to be 6.5 min.

Key words: Kunun-zaki, pasteurisation, D-value, vitamin C, Bacillus subtilis.