Microwave Irradiation: Impacts On Active Substance Of Red Wine During Production Process

With the consumer’s love for wine,the consumption of wine is increasing year by year.At the same time,the production technology of wine has also attracted people’s attention.The effect of microwave irradiation on the content of active ingredients and the structure of catechol oxidase in grape juice were studied by using a closed magneticstirrer and controlled-temperature cooling microwave irradiation(CMCC-MI).The effects of microwave irradiation on the physical and chemical properties of red wine in the aging stage were also studied.The main results are as follows:Firstly,in the microwave-treated resveratrol and gallic acid system,the signal of hydroxyl radical was captured by electron paramagnetic resonance(EPR).The results of HPLC detection showed that in CMCC-MI system,the stability of gallic acid and resveratrol was affected by the different concentration of ethanol,as well as microwave power,temperature and time.The fragmention peaks of gallic acid and resveratrol after microwave treatment were detected by UPLC-MS,which indicated that microwave irradiation caused partial cracking of gallic acid and resveratrol,thus reducing the content of compounds.The degradation of phenolic compounds was slightly affected by microwave treatment with 500 W,60 ℃,8 min.Secondly,carbon-centered free radicals in the microwave-treated catechol oxidase system were captured and identified by electron paramagnetic resonance(EPR).With the increase of power,temperature and time of microwave treatment,the intensity of free radical signal in catechol oxidase system tends to increase.Compared with the experimental results,free radicals were not only produced after microwave heating,but also a small amount of free radicals in catechol oxidase.In microwave field,the free radical signal increases with the increase of microwave power.With the increase of microwave treatment time,the intensity of free radical signal increases but the growth rate decreases.By measuring the oxidation indexes of carbonyl,sulfhydryl group and surface hydrophobicity,it was found that catechol oxidase was decomposed by heat,the hydrophobic side chains were exposed and some of the peptide chains were broken during microwave treatment.Combining with the formation of free radicals during microwave heating,it can be inferred that the structure of catechol oxidase can be changed greatly by microwave treatment at high power,higher temperature and longer time,thus reducing the browning of grape juice.Finally,different microwave power,time and temperature were used to treat young Cabernet Sauvignon dry red wine.The total phenol content,total monomeric anthocyanin content,titratable acidity and DPPH free radical scavenging activity of red wine decreased significantly,but had no significant effect on pH and electrical conductivity.After microwave treatment,the color density of red wine decreased and the color hue increased,which was consistent with the change of traditional aging process.Principal component analysis(PCA)results showed that microwave treatment changed the physical and chemical properties of red wine,and there were significant differences between the untreated red wine with the treated red wine under different microwave conditions.In the process of red wine aging,microwave technology can be effectively use to shorten the aging time and change the physical and chemical properties of red wine.