Ka. Johnston et al., EFFECT OF VARIOUS CUTTING AND STIRRING CONDITIONS ON CURD PARTICLE-SIZE AND LOSSES OF FAT TO THE WHEY DURING CHEDDAR CHEESE MANUFACTURE IN OST VATS, International dairy journal, 8(4), 1998, pp. 281-288
Nine combinations of speed and duration of cutting the coagulum were v
aried during the commercial manufacture of Cheddar cheese in 27 Ost IV
cheese vats. The effects of cut speed ramp-up rate, vat overfilling a
nd stirring rate after cutting were also evaluated. The effects of the
variations were assessed by determining the curd particle size distri
bution and fat losses to the whey at draining. The results of varying
the speed and duration of cutting were compared with the results of a
similar investigation carried out using vertical, double O, Damrow vat
s. Although the results showed similar trends, compared with the Damro
w vat at the same speed the Ost vat's cutting system reduces curd part
icles to a constant size more rapidly, thereby avoiding excessive curd
shattering and high whey fat losses during subsequent stirring. Based
on these results and comparisons with the results from the Damrow tri
al, a model is proposed. It explains how variation in speed and durati
on of continuous cutting, followed by a constant stirring speed, deter
mines curd particle size distribution in an Ost IV cheese vat. The mod
el can be used to maximise moisture retention and minimise whey fat lo
sses. Reducing the cut speed ramp-up rate and the stirring speed signi
ficantly increased the curd particle size. Overfilling Ost IV vats sig
nificantly increased curd the particle size but had no significant eff
ect on whey fat losses. (C) 1998 Elsevier Science Ltd. All rights rese
rved.