OVINE MILK .3. EFFECT OF SEASONAL-VARIATIONS ON PROPERTIES OF SET ANDSTIRRED YOGURTS

Milk from a Scottish, commercial flock of dairy sheep was collected at 7 monthly intervals over an entire lactation. Set and stirred yogurts were manufactured from the milk. Portions of the milk were homogenise d before heat treatment. Satisfactory product was made throughout the entire season although differences in viscosity, the extent of serum s eparation and pH were observed. Product quality was improved by homoge nisation. The extent of serum separation was substantially reduced, es pecially for set product, and the viscosity of set yogurts made from h omogenised milks was higher than for the un-homogenised counterparts. Total solids, fat and protein content of the raw milks were highly cor related. These three compositional factors were related, albeit loosel y, to the extent of serum separation and pH of un-homogenised, set yog urt. Higher solids were associated with reduced serum separation and h igher pH. A trend between the content of soft fat and the viscosity of set product was noted.