| Summary: | 碩士 === 國立中興大學 === 食品暨應用生物科技學系所 === 103 === New distilled kaoliang spirit must undergo aging process in order to reduce the pungent taste after drinking ,remove the off-flavor and make the aroma more attractive to consumers. Esters are the key com-pound of alcohol beverages aroma because their low threshold and distinctive flavor. Not only the esters in alchol beverages increase their content via esterifition ,esters and other compounds also reach equi-librium state during the aging process.
Aging process is a time and space-consuming operation. Reducing the aging time via other treatment means lowering the production cost. Microwave irradiation has been utilized in many organic synthesis reac-tion because it can accelerate the reaction rate in short time by inducing compounds to vibrate. The aim of this master thesis is to shorten the aging process time in order to reduce the production cost. Kaoliang spirit is the sample in this experiment because it is one of the most character-istic alcohol beverages and the concentration changes ofethyl acetate -the main aromatic compound in kaoliang spirit is the indicator of the effect of microwave treatment.
The results of batch-microwave treatment shows that microwave treatment can accelerate the esterification reaction rate about 3.35 times without containing ethyl acetate at the beginning. However, because micro- wave improve the forward and reverse reaction rate simul-tane-ously ,the esterification rate gets slower while the ethyl acetate concen-tration accumulated. It is reasonable to doubt that the way to affect the concentration of ethyl acetate and acetic acid is not mainly via esterifi-cation because of the unequal change between ethyl acetate and acetic acid in the continuous experiment. Therefore, the forward and reverse reaction rate are raised while applying continuous operation system and microwave treatment to new distilled kaoliang spirit ,causing the dif-ferent concentration change between ethyl acetate and acetic acid. But the equilibrium constant of reaction turned down from 4.57 to 3.43 after microwave treatment. It reveals that microwave treatment can urge the reaction to equilibrium.
In conclusion, although that the continuous operation system used in this experiment can help the reaction reach equilibrium quickly but is not an appropriate operation way to increase the ethyl acetate concen-tration. However, the flavor quality of aged Chinese spirit would be a harmonization of many compounds, could not just rely on the concen-tration of a particular compound. Hence, a sensory experiment is needed in order to check the effect of continuous microwave treatment on kao-liang spirit in the future.
|
|---|
