Influence of Heat Treatment on Microbial Quality of Tiger Nut-Soy Milk Blends

Abstract

The aim of this study was to evaluate the effect of pasteurisation on the microbial property of tiger nut-soy milk blend. Twenty-six different formulations (F1 – F26) were prepared from tiger nut and soy milk and packaged in plastic bottles for pasteurisation. The process treatments employed were; pasteurisation temperature, pasteurisation duration and mixing duration which varied from 60 - 800C, 5 - 20 secs and 5 - 15 mins respectively. Microbial analysis was carried out on all the twenty-six samples. The method of total coliform bacteria count was adopted in assessing the microbiological quality of the milk. The results showed that all the counts for the microbiological quality of the twenty-six blends were below the maximum acceptable limit of 1.0 x 106 (cfu/ml) for consumption. Formulation eighteen was found to be the safest with total coliform bacteria count of 1.0 x 103 (cfu/ml). Pasteurised tiger nut-soy milk is safe for drinking. Microbiological examination showed that the total coliform count decreased with increase in pasteurisation temperature.