45C-21 |
Measurement of volatile release from an amorphous carbohydrate matrix as a function of relative humidity using dynamic vapor sorption technology |
D. M. BOHN, K. R. Cadwallader, and S. J. Schmidt. Dept. of Food Science & Human Nutrition, Univ. of Illinois, Urbana-Champaign, 905 S. Goodwin Ave., Urbana, IL 61801-3896 Incorporating volatile compounds into amorphous matrices is a common practice within the food industry due to the ability of the amorphous matrix to retain a high percentage of the volatile. However, the amorphous structure can be disrupted when exposed to an increase in relative humidity and/or temperature that results in the ambient temperature to be above the glass transition temperature (Tg). This structural disruption, in turn, results in volatile release. Dynamic Vapor Sorption (DVS) is a fully automated system that can expose a food matrix to select relative humidity (ranging from 0 to 98%) and temperature (ranging from 5ºC to 85°C) conditions as specified by the researcher. Using DVS technology for humidification and temperature regulation, the impact of the depression of Tg on volatile retention by a model amorphous encapsulating matrix (Durarome, Firmenich) was studied. Initial moisture content of the sample was determined by Karl Fischer. Water activities were measured using an AquaLab Series 3 TE Aw Meter. Approximately 10mg of sample were placed in the DVS 2000 and exposed to relative humidities between 40% and 90% for varying lengths of time at 25°C. The purge air containing the volatile component was expelled from the DVS, and the extent of volatile release was measured using purge and trap gas chromatography-flame ionization detection technology connected to the DVS. The Tg's of the humidified samples were determined using a TA Instruments Differential Scanning Calorimeter model 2920. Results showed that as moisture was sorbed and Tg depressed below ambient temperatures, volatile release occurred rapidly and in large quantities. The initial moisture content (db) was 4.67% and the initial Tg was approximately 28.37ºC. At all relative humidities, sorption of merely 0.70% caused the Tg to drop below ambient temperature (25°C) to 10.26ºC; simultaneously, a burst of volatiles was released from the amorphous matrix.
Session 45C, Food Chemistry: Flavor and aroma chemistry
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