Measuring method of glass transition temperature using aroma sensor

Abstract

Glass transition temperature (Tg) is very important to control the flavor release rate and the stability of functional compounds in spray-dried powder. Usually, Tg of wall material is measured by differential scanning calorimetry (DSC). However, it is very difficult to measure Tgs since the heat capacity changes of several compounds such as maltodextrin (MD) are so small. In this study, the simple method to measure Tg was proposed using aroma sensor. Spray dried powders of emulsified hexanol in middle chain triglyceride oil and hexanol containing other four flavors were formed with three kinds of wall materials, MD (dextrose equivalent=19), and two mixtures of MD and Fructose (Fr) (20wt% Fr and 80wt% MD, and 40wt% Fr and 60wt% MD). The release rate of hexanol from spray-dried powder was measured at the linear programmed temperature (ramping method) using an aroma sensor. The release rates of hexanol from spray-dried powder increased rapidly above the specific temperatures, which were the intercept temperatures of tangent line of hexanol release rates as the apparent glass transition temperatures for the wall materials. The apparent glass transition temperatures were similar values by the calculated temperature using Couchmann and Karasz equation. These results indicated the glass transition temperature could be estimated with flavor release measurement using aroma sensor at the linear programmed temperature.