The effect of pasteurization of milk and use of a native starter culture on the volatile components and sensory characteristics of a Spanish ewe's-milk cheese were examined. Three cheese batches were made, one from raw milk, another from pasteurized milk, and a third from pasteurized milk with an added native starter culture in addition to the commercial starter. Cheeses were analyzed at 1, 120, and 240 d of ripening. Analysis of the volatile components was by purge and trap connected to a gas chromatograph with a mass spectrometer and disclosed a total of 76 components belonging to the following chemical families: hydrocarbons, fatty acids, esters, sulfur and carbonyl compounds, and, in particular, alcohols. Pasteurization lowered the levels of certain volatile components, especially alcohols, aldehydes, and ketones. The cheeses made from pasteurized milk showed lower scores for attributes of characteristic taste and aftertaste, as well as a characteristic aroma at 240 d of ripening. These results suggest that the components present in higher concentrations in the cheeses made from the raw milk were necessary for development of characteristic Roncal cheese aroma. The new native starter culture tested did not exert a significant effect on any of the parameters considered, with the exception of certain isolated components, for which higher or lower quantities were recorded in the cheeses made with that starter culture, although the differences did not have a definite effect on the sensory characteristics of the cheeses.

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Free amino acids (FAAs) and volatile components were analysed in commercial samples of yoghurt and Actimel® drink as well as laboratory‐made kefir. The lysine and cysteine were the principal amino acids and accounted for about 70% of the total FAAs in all the samples. However, the amino acid profiles in the different fermented milk products differed: on the whole values for most of the amino acids were observed to be significantly higher in the Actimel® samples. A total of 50 volatile components were identified. The largest number of volatiles were found in the kefir. Ethanol, 2,3‐ butanodione and 3‐hidroxybutan‐2‐one were the most prevalent volatile components, with ethanol significantly higher in the kefir samples.

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