Measurement of fat in the ovine milk: comparative study of the results acquired by official methodology and by electr onic equipments

Abstract

The aim of this work was to perform a comparative study between the official method recommended by Brazilian laws and the electronic equipment of photometric measurement and ultrasound spectroscopy equipment for the quantification of total lipids of the ovine milk in order to check which equipment establishes the lipids level better. The experiment took place at Technology of Food Department in Santa Maria Federal University together with School Plant of Dairy products and Ovine culture Section of Zoo Technical Department. It was used twelve sheeps half Lacaune Lait blood, milked individually from the first to the tenth week of lactation. The milking was performed manually and the analyses took place after the refrigeration of the samples. Before executing the analyses, the samples were homogenized and soon after evaluated in terms of fat amount by three distinct methodologies: official Brazilian methodology through Gerber’s butyrometer (GB), electronic equipment of photometric measurement Milko-Tester® (MT) and ultrasound spectroscopic equipment Lactoscan 90® (LS), which all analyses were performed in triple. The reproducibility of LS equipment was 100% for the analyzed samples, while MT equipment showed variability in most of the analyzed samples obtaining reproducibility of the results in just 22,5% of the samples. For the others samples the latter equipment obtained 50% of overrated values and 27,5% underrated values. Therefore, the results of this study let us to settle that the analysis of ovine Milk by ultrasound spectroscopy is efficient for the fat parameter when compared to the official Brazilian methodology.