Prolonged observation and modelling of milk coagulation, curd firming, and syneresis

The aim of the present work was to evaluate the prolonging of the lactodynamographs observation period from 30 to 90 min, and to model curd firmness as a function of time (CFt, mm) using a fourparameter asymptotic function. The model tested was: CFt ¼ CFP ð1 ekCFðtRCTÞÞ ekSRðtRCTÞ, where RCT (min1) is the rennet coagulation time, CFP (mm) is the potential asymptotical CF at an infinite time, kCF (min1) the curd-firming rate constant, and kSR (min1) the curd syneresis rate constant. The CFt model was applied to data from milk of 105 Brown Swiss cows. The model appears promising as the four novel parameters are less interdependent than are the traditional measures and it gives also an insight on the syneresis. The repeatability of parameters of the CFt equation, estimated using information obtained from 50 samples (two bulk milks 5 consecutive days 5 replicates each) gave better results than traditional parameters.