Abstract
This study investigated the effects of yoghurt on the chemical (titratable acidity and pH), microbiological (L. delbrueckii subsp.
bulgaricus, S. thermophilus, mould and yeast counts) and sensory properties of yoghurt that was prepared with fruit
(strawberry, apricot, banana, peach) (at a ratio of 20%) during the incubation (checked at 0, 90 and 210 minutes) and storage
(checked at 1, 3 and 7 days) periods. When compared to plain yoghurt, the values of the traits analysed during this study were
found to be significantly different about both the different fruits and the time intervals. The average acidity counts at the end
of the storage period were found to be highest in strawberry yoghurt (0.665 LA), while apricot yoghurt was found to have the
lowest pH rate (-0.390 pH). The average count of L. delbrueckii subsp. bulgaricus at the end of the storage period was found
to be highest in strawberry yoghurt (2.983 log10 cfu/ml), while peach yoghurt was found to have the lowest rate of L. delbrueckii
subsp. bulgaricus (1.568 log10 cfu/ml). The highest rate of S. thermophilus was found in peach yoghurt (2.648 log10 cfu/ml),
while the lowest rate was in banana yoghurt (1.301 log10 cfu/ml). The highest yeast count was found in plain yoghurt (3.264
log10 cfu/ml) and the lowest mould count was in banana yoghurt (2.246 log10 cfu/ml). Sensory analysis of the fruit yoghurts
revealed that, while the type of fruit had no statistically significant effect on the sensory characteristics, the most popular were
banana and strawberry yoghurts. The results confirmed that the varieties of added fruit affected the pH and acidity rates of the
yoghurt and influenced the development of microflora, so we concluded that these factors could consequently affect the
product’s shelf life.
