Roberts, D.D. and Pollien, P.
Analysis of aroma release during microwave heating,
A device to measure aroma compounds released during microwave heating was developed which allows time profiles of release to be determined. During microwave heating of food in an enclosed glass vessel, gas is displaced from the vessel due to water in the food turning to vapour. The released aroma compounds are trapped by a series of cold traps, all designed with serpentine flow to maximize surface and time contacts. The first cold trap uses liquid nitrogen to trap the aroma compounds released prior to the food attaining 100 degree C. The second trap is a modified condenser and traps the aroma compounds released with the water, i.e., at 100 degree C. Multiple fractions over time are collected. Aroma compounds in each water fraction are quantified by solid phase microextraction (SPME) and GC-FID. The sample analysed was frozen spaghetti with added aroma compounds. Total losses of aroma compounds during heating were between 30 and 50%. The aroma compounds eluted at different times, and their air-water partition coeff. predicted this order.