Using multivariate analysis to explore the relationships between color, composition, hygienic quality, and coagulation of milk from Manchega sheep

摘要

This study explores the relationships between composition,hygienic quality, and color values of milk toevaluate whether colorimetry could be used as a validpredictor of the quality of raw milk and its coagulation.For this purpose, we performed analyses in 1,200individual samples of Manchega sheep milk from 4flocks from the region of Castilla–La Mancha, Spain.Based on the measured variables, we determined thedifferences and similarities between coagulating andnoncoagulating samples using discriminant analysistechniques. The variables with a higher discriminantability were lactose content, somatic cell score, pH, andthe color values lightness (L*) and red/green value (a*).The model based on color values showed a predictiveability similar to that found in the model based on milkcomposition and hygienic quality. Canonical correlationanalysis allowed us to explore the relationships betweenboth sets of variables. Canonical correlations for thefirst and second pair of canonical values were 0.794 and0.438, respectively. Both values were significant andrepresented 92.82% of the observed variability. The correlationstructure showed that color values had a strongcorrelation with fat and protein content and with totalsolids, and they had a weak correlation with lactosecontent and somatic cell score. The 2 first combinationsof standardized canonical variability could be considereda predictable measure of the composition and, toa lesser extent, the hygiene of milk. Measurement ofcolor values could be a rapid and effective means ofsupplementing standard analyses when determining thecoagulation ability of Manchega sheep milk.