HEAVY COAGULUM FORMATION IN LACTIC CASEIN MANUFACTURE - SOLIDS CONTENT, PH AND GEL STRENGTH VARIATIONS THROUGH SETTING LACTIC COAGULUM

Samples of lactic coagulum were obtained from various depths in a lact ic casein silo. The casein content at the base of the silo was in the range 38-62 g/kg compared with 25-30 g/kg in the bulk of the silo. Thi s layer of higher casein concentration, called heavy coagulum, was up to 1. m deep and appeared long before the bulk milk had fully coagulat ed. It had a lower pH than the bulk, e.g. pH 4.35 when the bulk pH was 5.2. The heavy coagulum layer was removed from the silo last during p ump-out. A laboratory coagulation tube was designed to permit more int ensive study of heavy coagulum formation. Starter bacteria levels in t he heavy coagulum were 10-160 times those in the bulk. Heavy coagulum had a visibly different curd structure (a much more granular gel), pro duced differently shaped extrusion curves, and had a higher gel streng th than coagulum from the bulk. The heavy coagulum phenomenon had many similarities to minor sludge formation in Cottage cheese manufacture.