Assessment of betaine content in commercial cow and goat milk

Abstract

Betaine is a cytoplasmic osmolyte and a methyl group donor in many biochemical pathways. It exhibits numerous beneficial biological effects and has shown health benefits against some common chronic metabolic and degenerative diseases. In humans, it is obtained mostly from the diet, but it can also be endogenously synthesised by choline oxidation. Although betaine is a valuable human nutrient, information concerning its concentration in milk is still limited. Therefore, the aim of the present work was to quantify and compare the betaine content in commercial cow and goat milk. The betaine content was estimated using a simple isocratic HPLC-UV method following derivatisation with 4-bromophenacyl bromide. The sample pre-treatment included deproteinisation with 0.3% trifluoroacetic acid in acetonitrile. Betaine concentrations in cow milk ranged from 5.56 mg/L in milk with 0.5% fat, to 8.14 mg/L in milk with 2.8% fat. A positive but not significant relationship between fat and the betaine content in milk (r = 0.43) was observed. The average betaine concentration in commercial cow milk (7.21 mg/L) was in line with the results of previous studies. On the other hand, the average level of betaine in commercial goat milk was three times greater (22.82 mg/L). As far as the authors are aware, there are no published results of the betaine content in goat milk, and the present work is the first in this field. The present work demonstrated that the application of a simple and efficient sample pre-treatment and the HPLC-UV method for betaine determination allows for its successful quantification in milk.