# Aroma Compound Release from Starches of Different Origins: A Physicochemical Study
## 6 Conclusions  
In this study, the mass transfer coefficients and activation energies needed for the evaporation of diacetyl and dl-limonene from both bulk liquids and starch granules of different botanical origins were investigated. It was found that the mass transfer coefficient \(k_{\rm c}\) increased with temperature for both compounds. Diacetyl, a polar compound, exhibited a significantly higher activation energy requirement for evaporation from wheat starch (98.65 kJ/mol), indicating strong chemical sorption. This could be due to interactions with amino groups in proteins or hydrogen bonding with starch hydroxyl groups. In contrast, the non-polar compound dl-limonene showed a much lower activation energy requirement for evaporation from wheat starch (9.03 kJ/mol), suggesting weaker interactions with the starch matrix.  
The results also showed that the activation energies required for diacetyl's release from rice, corn, and potato starches ranged between 19 and 26 kJ/mol, which aligns with previously reported values for similar interactions between ethanol and starch. The activation energies needed for dl-limonene's evaporation from these starches were between 16 and 49 kJ/mol, values which are comparable to the enthalpy of adsorption for hydrocarbons like heptane and octane on cellulose, further confirming the different sorption mechanisms of polar and non-polar aroma compounds on starchy substrates. These findings underscore the roles of chemical structure and starch composition in influencing the evaporation behavior of aroma compounds.  
The usage of RF-GC with the appropriate mathematical approaches to the experimental results can lead to the determination of various physicochemical and kinetic parameters concerning the interaction of volatile or semi-volatile compounds with food ingredients.  
The results from this and other similar studies have important implications for the food industry, particularly for new product development. Understanding the mechanism of the release of aroma compounds from the food matrix by calculating the mass transfer coefficients and activation energies needed for the release of aroma compounds from one of the main food components, such as starch, allows the food industry to optimize the sensory properties of foods. The reversed-flow gas chromatography (RF-GC) technique can also be used to study the release of aroma compounds from other substrates as well as from mixtures of these substrates in different proportions. This knowledge can lead to improved product quality, better taste stability during storage, and more controlled release of flavorings during food consumption.  
Conceptualization, J.K. and A.K.; methodology, J.K. and A.K.; validation, J.K., A.K., and L.F.; formal analysis, J.K.; investigation, M.-M.E., A.S., and P.K.; resources, J.K. and A.K.; data curation, J.K.; writing--original draft preparation, M.-M.E., A.S., and P.K.; writing--review and editing, J.K., A.K., and L.F.; visualization, M.-M.E., A.S., and P.K.; supervision, J.K., A.K., and L.F.; project administration, J.K. and A.K. All authors have read and agreed to the published version of the manuscript.  
This research received no external funding.  
Not applicable.  
The data presented in this study are available on request from the corresponding author.  
The authors declare no conflicts of interest.