Study On The Degradation Of Anthocyanins In The Process Of Mulberry Drying

In this study,quick-frozen mulberry was used as raw material,microwave power 500 W,microwave power 550 W,ultrasonic thawing,refrigeration thawing and room temperature thawing were performed on quick-frozen mulberry.The thawed mulberry will be dried,the vacuum-instant controlled decompression drying to do the contrast,drying technology of mulberry fruit pulp with hot air thin layer drying and short and medium wave infrared thin layer drying,study on the quality of mulberry,including physical and chemical,nutrition and other quality.The effects of foam drying on the drying characteristics of mulberry,the physicochemical and nutritional quality of mulberry powder were studied by using the new drying method to study the drying of mulberry fruit pulp.Mulberry is rich in anthocyanins,anthocyanins are extremely unstable and degradation occurs after heating,affect the nutritional quality of mulberry products.In this paper,the kinetics and thermodynamics of anthocyanin degradation in hot air drying and vacuum drying of mulberry were analyzed and to study the degradation of anthocyanins by PPO enzyme activity.For mulberry thawing,milling technology and anthocyanins thermal degradation mechanism provide theoretical basis.Draw the following main conclusions.1.The results showed that the time of microwave thawing was the shortest,which were 0.58 min and 0.35 min,respectively at power 500 W and 550 W,while the time of refrigeration thawing was the longest,which was 305 min.Significant differences were presented in drip loss between different thawing methods.Significant differences were presented in drip loss between different thawing methods.The drip loss after microwave thawing at power 500 W was the lowest with the ratio of 1.34%,and the drip loss after ultrasonic thawing was the highest with the ratio of 9.24%.The content of total phenols(151.66 mg/100 g)and anthocyanin(cyanidin-3-glucoside 2.27mg/g,cyanidin-3-rutinoside 0.69mg/g and pelargonidin-3-glucoside 0.047 mg/g)of mulberry after microwave thawing at power 500 W were the highest.which was accompanied by the highest antioxidant activities,including 2,2'-Azinobis-(3-ethylbenzthiazoline-6-sulphonate(ABTS)free radical scavenging(21.87 Trolox ?mol/g),1,1-diphenyl-2-picrylhydrazyl radical 2,2-diphenyl-l-(2,4,6-trinitrophenyl)hydrazyl(DPPH)free radical scavenging(35.70 Trolox?mol/g)and ferric reducing antioxidant power(FRAP)free radical scavenging(27.85 Trolox?mol/g).Considering,screening out the microwave power 500 W thawing thawing time was short,the effect was high,mulberry quality was better.2.Thawing mulberry using vacuum-pulsating pressure difference flash drying combined dry,hot air thin layer drying,short and medium wave infrared thin layer drying technology.There were significant differences in the quality of mulberry powder prepared by different drying methods.The water content of the mulberry powder prepared by vacuum-pulsating differential pressure flashover was lower,but the content of C3G and C3R was the lowest.Hot air thin layer drying and short and medium wave infrared thin layer drying at a drying temperature of 50?,because the drying temperature is low,the retention of two anthocyanins was higher.However,to the late dry moisture was not easy to decline,drying time was longer.The short drying time of short and medium wave infrared 60?,the drying time was 240 min,the retention of anthocyanins was high,mulberry powder moisture content and water activity is relatively low,the glass transition temperature was relatively high,suitable for thawing mulberry pulp dry.3.Foam drying is a new type of drying method,in this paper,thawed mulberry for hot air foam drying and short and medium wave infrared foam drying.Study on foam drying characteristics of thawled mulberry,the moisture content,water activity,glass transition temperature,particle size,scanning electron microscopy,color and anthocyanin content of mulberry powder.The study found,the drying time of the mulberry powder was 180 min,the drying rate was fast,the moisture content and water activity of the mulberry powder were lower,the glass transition temperature was higher,the storage of the mulberry powder and the storage condition of the mulberry powder could guarantee the quality stability.4.In this paper,quick-frozen mulberry drying and vacuum drying,study on the thermal degradation of mulberry anthocyanins.Study on thermal degradation of anthocyanins in mulberry by kinetics and thermodynamic analysis in drying process.And the activity of PPO in mulberry was studied,and the degradation mechanism of mulberry was studied.The results were drawn,degradation of anthocyanins during mulberry drying was a second order kinetic reaction,which was an endothermic reaction,oxygen accelerates anthocyanin degradation,and may be considered as a catalyst for the reaction.Therefore,the anthocyanin-rich raw material can be isolated from oxygen.