OPTIMIZATION OF HEATING UNIFORMITY FOR DIARY PRODUCT PASTEURIZATION USING A PASTEURIZER

This study was carried out to optimize the process parameters for the pasteurization of cow milk using microwave heater. To ensure uniformity in heating in the samples, a rotor device was attached to the microwave. Fresh cow milk obtained from Lokpanta, along Umuahia-Enugu express way in sterile 5 litre plastic container placed in a cooler containing ice cubes was used for this study. The cow milk was divided and pasteurized according to the outcome of the design obtained from response surface methodology. Two independent variables (microwave power and pasteurization time) was employed, 4 dependent variables (total bacteria, total Coliform bacteria, total staphylococcus, and total Pseudomonas load count) were selected to test the effect of the dependent variables on the cow milk. The results obtained showed the total bacteria, Coliform bacteria, total staphylococcus, and total Pseudomonas load count of the samples ranged 0 – 29 x104, 0 – 5 x, 0 – 11 x104 and 0 – 5 x 104 cfu/ml respectively. The 3D plot diagram of the microbial load counts confirmed that there was a positive linear effect of microwave power and pasteurization time on the microbial load count. The ANOVA result showed that the quadratic effect of the process parameters on the microbial load counts were positive. The R2 and Adj R2 values obtained for total bacteria, total Coliform bacteria, total staphylococcus, and total Pseudomonas load count; 0.9257 and 0.9046, 0.7119 and 0.6398, 0.8100 and 0.7625 and 0.7789 and 0.7234 respectively were high, thus, significantly explained the variation observed in this experiment. The significance and adequacy of the model was measured in terms of F-value and p-value at 5% significance level (p≤0.05). The measurement of F-value and p-values indicated that the microwave power and pasteurization time had positive significant linear effect on all the responses,