EFFECT OF GINGER EXTRACT ON THE VIABILITY OF LACTIC ACID BACTERIA AND SENSORY CHARACTERISTICS OF DAIRY YOGHURT AND SOY YOGHURT

Yoghurt is usually produced from cow milk which is unsuitable for vegetarian diet. Chemical preservative used for its preservation may have adverse effect on the lactic acid bacteria. This research was designed to evaluate the effect of ginger extract on the viability of lactic acid bacteria, physico-chemical property and sensory attributes of bio preserved functional yoghurt produced from dairy milk and soy milk during storage at refrigerated temperature. The result obtained showed that yoghurt produced from soy milk (5.67 – 7.52 CFU/ml) had higher lactic acid bacteria count than yoghurt from dairy milk (4.71 – 7.31 CFU/ml) throughout the period of storage. Ginger extract was more active against fungi in dairy yoghurt than (0 - 5.09 CFU/ml) soy yoghurt (0 – 5.29 CFU/ml). The pH was generally lower in dairy yoghurt (4.29 - 4.67) than soy yoghurt (4.69 – 5.14) while the titratable acidity was higher in dairy yoghurt (1.30 – 2-01%) than soy yoghurt (0.7 – 1.54%). Addition of ginger extract improved the texture and flavour of soy yoghurt. It is therefore suggested that functional yoghurt with good sensory attributes can be produced from soy milk and dairy milk using ginger extract as bio-preservative.