QUALITY EVALUATION OF PLAIN-STIRRED PROBIOTIC YOGHURT PRODUCED FROM SKIM AND WHOLE MILK POWDER DURING REFRIGERATED STORAGE

Study was carried out to evaluate changes in chemical, microbial and sensory characteristics of plain-stirred probiotic yoghurt produced from skim and whole milk powder during 35days refrigerated storage at 4oC. The pH and total solids (%) decreased while total titratable acidity increased but no change in the fat contents of both types of yoghurt. The decrease in the pH was as a result of acidity developed by the samples under the storage condition. There was no significant decrease in the total plate count for the first 14days, subsequently, a significant decrease was observed. No yeast, mould or coliforms were found in both samples of yoghurt. Colour, consistency, taste and flavour of both types of yoghurt did not change over the storage period. However, despite these changes in the quality attributes of both samples of the plain-stirred probiotic yoghurt, overall, both samples were still acceptable at the end of the storage period.