Total lipase and protease activity in goat’s milk : detection methods and preliminary study on variability sources

Two colorimetric methods were used to quantify total lipase activity (TLA) and protease activity (TPA) in goat milk. The methods, previously developed for the analysis of bovine milk, were optimized and standardized for quantifying TLA and TPA in goat milk. Moreover, preliminary results on the variation of TPA and TLA in individual goat milk samples are presented. A total of 24 milk samples from Camosciata primiparous goats were collected in an experimental flock. The TPA and TLA mean values were 6.17 mU mL'1 and 27.82 pmol L'1, respectively. Preliminary correlations were estimated between TLA, TPA, and daily milk yield, protein, fat, and lactose percent, somatic cell count (SCC), days in milk, as,-CN genotype and expression level, and percent distribution of the different milk protein fractions. Goat TPA was positively correlated with protein percent and aSi-casein expression, whereas TLA was positively related to somatic cell count. The methods are easily applicable tools for routine tests on bulk or individual milk samples.