NEUTRAL VOLATILE COMPOUNDS IN THE RAW MILKS FROM DIFFERENT SPECIES

A comparative study was carried out on the flavour constituents of bov ine, ovine, caprine and water buffalo fresh raw milks. The volatiles w ere isolated from milks by means of vacuum distillation and liquid-liq uid extraction. Eighty neutral volatile compounds were identified usin g high resolution gas chromatography (HRGC) and HRGC-mass spectrometry . About 30 of these components have not been detected previously in mi lk. The volatiles in milk were similar for the four species, although several quantitative differences might explain the different odours. T he volatiles consisted mainly of ethyl esters, especially those derive d from butyric and hexanoic acids. Dimethylsulphone alone comprised ap proximately 25% of the volatile components in bovine, caprine and ovin e milk, but only 4% in buffalo milk. Among the aldehydes, pentanal and nonanal were the most representative. Other aldehydes were present se lectively: 3-methylbutanal was found only in buffalo milk; phenylaceta ldehyde and benzaldehyde were present in large quantities in caprine m ilk. and in trace amounts in the other milks. The content of ketones, mainly 2-methylketones, was higher in buffalo milk than in the other t hree types. Alcohols varied between species, from 1.5% (bovine) to 5% (buffalo). Among these, 1-octen-3-ol and phenylethanol could be partic ularly important for the aroma of milk. The level of 1-octen-3-ol in t he milks was: buffalo > ewe > goat much greater than cow. Phenylethano l was not found in ewes' and goats' milk and its concentration in buff alo milk was 100 times higher than in bovine milk. Finally, indole and 4-methylphenol, interesting because of their odorant properties, were present in higher quantities in buffalo, ewes' and goats' milks than in cows' milk.