Volatile components in microwave- and conventionally-heated milk

Raw milk was microwave-heated in two different modes: at 120°C using closed vessels, and at 70–90°C using a continuous flow device. Conventional heatings were carried out at the same temperatures, using a glycerol bath or a water bath instead of the microwave oven. Samples were analyzed following a dynamic headspace method; the volatile components were quantified by GC and identified by GC–MS. Volatile composition was similar using both heating systems, although when milk was heated in closed vessels some quantitative differences were found between microwave and conventional heating. The latter results were attributed to the unevenness of microwave heating inside the vessels, whereas the continuous flow device seemed to allow a very uniform heating. ©