Comparison between mechanical and near-infrared methods for assessing coagulation properties of bovine milk

Abstract

The aim of the present study was to compare milk coagulation properties measured through a traditional mechanical device, the Formagraph (FRM; Foss Electric A/S, Hillerød, Denmark), and a near-infrared optical device, the Optigraph (OPT; Ysebaert SA, Frépillon, France). Individual milk samples of 913 Brown Swiss cows from 63 herds located in Trento Province (Italy) were analyzed for rennet coagulation time (RCT, min), curd-firming time (k(20), min), and 2 measures of curd firmness (a(30) and a(45),mm) using the 2 instruments and under identical conditions. The trial was performed in the same laboratory, by the same technician, and following the same procedures. Extending the analysis by either instrument to 90 min permitted RCT and k(20) values to be obtained even for late-coagulating milk samples. Milk coagulation properties measured using the OPT differed considerably from those obtained using the FRM. The average k(20) values varied greatly (8.16 vs. 5.36 min for the OPT and the FRM, respectively), as did the a(45) figures (41.49 vs. 33.66 mm for the OPT and the FRM, respectively). The proportion of noncoagulating samples for which k(20) could be estimated differed between instruments, being less for the OPT. The between-instrument correlation coefficients were either moderate (0.48 for a(30)) or low (0.24 and 0.17 for k(20) and a(45), respectively) when the same traits were compared. The correlations between k(20) and a(45), and milk yield varied among instruments, as did the correlations between k(20), a(30), and a(45) and milk composition, and the correlations between a(45) and pH. The relative influence of days in milk on k(20) and a(45) varied, as did the effect of parity on a(45) and that of the measuring unit of coagulation meter on k(20) and a(30). The RCT estimated by the OPT was the only milk coagulation property to show good agreement with the FRM-derived value, although this was not true for the data from late-coagulating samples.

Phenotypic factors affecting coagulation properties of milk from Sarda ewes

“…Similar results have been obtained for dairy cows (Ikonen et al, 2004;Tyrisevä et al, 2004;Cipolat-Gotet et al, 2012) and confirmed the low reproducibility of amplitude measurements of the different pendulums. As a result, position of the pendulums should be considered when MCP data are statistically analyzed.…”

Genetic variation and effects of candidate-gene polymorphisms on coagulation properties, curd firmness modeling and acidity in milk from Brown Swiss cows

“…A comprehensive discussion of the phenotypic variations among MCP traits was previously published by Cipolat-Gotet et al (2012). In the present work, the average values for RCT and k 20 were 19.95 and 5.36 min, respectively, whereas the average value for a 30 was 30.09 mm.…”

“…The present study is part of the Cowplus Project described by Cipolat-Gotet et al (2012). Briefly, a total of 1271 Brown Swiss cows from 85 herds located in Trento Province (Italy) were sampled once.…”

“…MCPs were obtained using two mechanical lactodynamographs (Formagraph; Foss Electric A/S, Hillerød, Denmark) according to the procedure described by Cipolat-Gotet et al (2012). Each individual milk sample (10 ml) was heated to 35°C and mixed with 200 μl of a 1.2% (w/v) rennet solution (Hansen Standard 215 with 80 ± 5% chymosin and 20 ± 5% pepsin; Pacovis Amrein AG, Bern, Switzerland) diluted in distilled water to yield 0.051 IMCU × ml −1 .…”

Milk coagulation properties and methods of detection

“…The detected signal is amplified and registered, then generating diagrams shaped as "bells" or "champagne flutes" called lactodinamogram expressed in gel firmness versus clotting time (O'CALLAGHAN et al, 2002). The Formagraph ® equipment includes devices that record the width (mm) of the graph during testing, every 15 seconds (CIPOLAT et al, 2012); however, the new equipment, Lattodinamografo V2 ® , is more efficient registering a signal every 7.5 seconds. As can be seen in Figure 1a, three parameters are considered (ANNIBALDI et al, 1977): r (rennet coagulation time) -represents the time for the beginning of enzymatic coagulation in minutes and concerning the time interval between rennet addition and the onset of clotting (the instrument detects a change in viscosity); k20 -time required in minutes for the gel to Beux et al reach a consistency with an amplitude of 20mm.…”