THE EFFECT OF BOILING ON THE PH, ELECTRICAL CONDUCTIVITY AND LACTOSE CONTENT OF COW MILK PUBLISHED

Mihaela OSTAN, I. GOGOAŞĂ, Olga-Alina RADA, B. BAUL, Mihaela FERICEAN, Mihaela CAZACU, Mihaela PETCU, Iuliana CREŢESCU
The most important milk components are proteins, lactose, fat and minerals. Electrical conductivity is a biophysical parameter that can be used for assessing the quality of milk. The aim of the present paper is to study the effect of boiling on the pH, electrical conductivity and lactose content, as well as to evaluate the correlations among these parameters. For this reason, 5 samples of fresh milk were taken from healthy cows, and then subjected toheat treatment by boiling. The pH was determined by a digital pH meter OP-211/2, connected with a combined electrode of the type OP-0808P; electrical conductivity was measured with an OK 112conductometer, and lactose was determined with a MilkoScan S54B. The results were processed statistically with ANOVA and are presented as averages ± SD (standard deviation). The results reveal a decrease of the pH from 6.58±0.0841 to 6.54±0.0735, as an effect of boiling, and an increase of the lactose content from 5.07±0.1551 to 5.30±0.2927. It is also worth noting that negative correlation was found between the lactose content and electrical conductivity (r = -0. 6400) in fresh milk and (r= -0.4215) in boiled milk.
cow milk, boiling, pH, lactose
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