Impact of Fluoridation of Milk on Manufacturing and Properties of Yoghurt

Fluoridation ( F ) of yoghurt milk ( YM ) was done by adding sodium fluoride to YM before ( treatment A ) and after ( treatment B ) the heat treatment applied on cow's milk . Activity of yoghurt starter culture (YSC) was followed during fermentation by measuring acidity and pH at different intervals up to the complete coagulation. The resultant control (C) and treated yoghurt were analysed when fresh and after 10 days of cold storage (5 ± 1 ⁰C).The attained results revealed that F had no pronounced impact on YSC, while the differences in acidity, pH, TS, fat and protein contents of the resultant yoghurt due to the applied treatments were slight. Curd syneresis (CS) of C kept for 10 and 30 min at room temperature (30 ± 1 ⁰C) was higher than the corresponding treated samples, while after 60 and 90 min the differences in CS were slight in fresh samples. The stored samples showed opposite trend of results. F of YM had no obvious impact on hardness, springiness and gumminess of yoghurt. Adhesiveness was higher in C, while the opposite was noticed for cohesiveness.Organoleptically, the fresh treated yoghurt ranked less scores for appearance and firmness while some improvement was recorded during storage of all samples. No adverse impact of F was noticed on flavour attributes.