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Heavy coagulum formation in lactic casein manufacture: solids content, pH and gel strength variations through setting lactic coagulum

Published online by Cambridge University Press:  01 June 2009

Michael G. Weeks
Affiliation:
Department of Food Technology, Massey University, Palmer-ston North, New Zealand
Eileen J. Gosling
Affiliation:
Department of Food Technology, Massey University, Palmer-ston North, New Zealand
Peter A. Munro
Affiliation:
Department of Food Technology, Massey University, Palmer-ston North, New Zealand

Summary

Samples of lactic coagulum were obtained from various depths in a lactic 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. This layer of higher casein concentration, called heavy coagulum, was up to l m deep and appeared long before the bulk milk had fully coagulated. 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 pump-out. A laboratory coagulation tube was designed to permit more intensive study of heavy coagulum formation. Starter bacteria levels in the heavy coagulum were 10–160 times those in the bulk. Heavy coagulum had a visibly different curd structure (a much more granular gel), produced differently shaped extrusion curves, and had a higher gel strength than coagulum from the bulk. The heavy coagulum phenomenon had many similarities to minor sludge formation in Cottage cheese manufacture.

Type
Original Articles
Copyright
Copyright © Proprietors of Journal of Dairy Research 1994

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