A comparison of the Formagraph and low amplitude strain oscillation rheometry as methods for assessing the rennet coagulation properties of bovine milk

Citation
M. Auldist et al., A comparison of the Formagraph and low amplitude strain oscillation rheometry as methods for assessing the rennet coagulation properties of bovine milk, MILCHWISSEN, 56(2), 2001, pp. 89-92
Citations number
10
Categorie Soggetti
Food Science/Nutrition
Journal title
MILCHWISSENSCHAFT-MILK SCIENCE INTERNATIONAL
ISSN journal
00263788 → ACNP
Volume
56
Issue
2
Year of publication
2001
Pages
89 - 92
Database
ISI
SICI code
0026-3788(2001)56:2<89:ACOTFA>2.0.ZU;2-K
Abstract
Rennet coagulation properties of milk can be used as indicators of subseque nt cheese composition, recoveries of milk solids, and cheese quality. The t ransformation of milk during coagulation involves a number of physicochemic al changes, the detection of which form the bases of methods for measuring aspects of rennet coagulation. The objective of this study was to compare t he rheological changes in rennet-treated milk measured using 2 such methods , i.e. the Formagraph method, and low amplitude oscillation rheometry using a Cari-Med CSL2 Rheometer. These techniques have been used extensively in research, yet there are no published data comparing them. Milk samples from 31 cows were adjusted to pH 6.55 before analyses. Measurements made were: time until onset of gelation (GT, Rheometer, and RCT, Formagraph); curd fir ming rate (CFR and 1/K-20); and curd firmness 1 h after rennet addition (G' (60) and A60) There were significant (p<0.001) positive correlations betwee n GT and RCT (r=0.850), CFR and 1/K20 (r=0.946), and G'(60) and A60 (r=0.78 9). The regression equations defining the relationships were: GT = (1.74 x RCT)-469, CFR = (28.54 x 1/K-20)-0.24, and G'(60) (4.07xA(60))+68. The rang es for GT, CFR and G'(60) were 659 to 2622 s, 0.48 to 8.04 Pa/min and 8.0 t o 192.9 Pa respectively. These strong correlations indicate that the 2 tech niques provide estimates of rennet coagulation parameters that are comparab le. These data will allow continuity of data interpretation in studies wher e either method is used.