Study On Drying Characteristics,Mathematical Model And Quality Change Of Taro

Last few years,the thin layer tunnel drying gradually becomes the focus of attention because of no pollution,and the dried sample is excellent in traits of low cost compared with freeze-drying.So explore the subject of impact on different thin layer tunnel drying conditions on the material is now in full swing.Taro is a common raw material in daily life of rich nutrient and have good biological activity,but not easy to store.So it s dry products have great prospects for development.In this paper,the drying characteristics and the establishment of dynamic model of taro,effects of drying conditions on physical and chemical properties and antioxidant activities will be research.The main contents and results of this paper are as follows:(1)The taro slice thickness,hot air temperature,hot air volume,and hot air direction will be compared as influencing factors.The experimental data were processed using SAS 8.0 software,and the mathematic model of drying process was established based on the drying characteristic curve and drying rate curve of taro.The results showed that taro slice thickness,hot air temperature,air volume and air direction had an effect on the drying rate.The statistics show that,Page model can best describe dry kinetics.The mathematical model is Ln [-ln(MR)] = Ln(-0.00969 + 0.00020337 T + 0.00014736 V-0.0019 P + 0.00002162X)+(1.19495-0.000845 T + 0.0006885V-0.00285 P + 0.00077346X)Lnt.(2)The effects of three different air volumes(90 m3/h,100 m3/h,110 m3/h)and three different temperatures(60?,70?,80?)on the physical properties of dried taro slices were studied and compared.The results show,temperature and air volume on the dry taro color,rehydration ratio,recovery rate,shrinkage ratio,hardness and brittleness have a certain impact,and the impact on each indicator is different.In summary,temperature 70?,air volume 100m3/h when the physical properties are better.(3)The effects of temperature and air volume on dried taro nutrient composition were compared.The results shows,two factors on the dried taro in the seven common nutrients have a certain role.Comparison of protein content,free amino acid content and brass content by the temperature greater impact,70? treatment of the sample protein and free amino acid content is high,the content of flavonoids in dry samples treated at 60? was higher.Non-enzymatic browning index,the content of soluble solids and the content of polyphenols were mainly affected by the air volume,but the overall difference in the sample is not significant.The nutrient content of all dried samples,are not as good as the original taro.(4)The effects of different drying conditions on the antioxidant capacity of ried taro were discussed.Determination of DPPH free radical scavenging capacity,determination of ABTS free radical capability,determination of iron ion reduction ability(FRAP method),determination of total reduction capacity(potassium ferricyanide method),the effects of different temperature and air volume on the antioxidant activity of dry samples were observed.from the experimental results we can see,the removal rate of DPPH and ABTS in dry samples is mainly determined by the temperature,by comparing IC50 values,the samples treated with 60? and 70? had strong antioxidant capacity.Simultaneously,from the iron ion reduction method and the total reduction ability of the determination results can be seen,the FRAP value is mainly affected by temperature,70 ? dry sample antioxidant capacity is better than 60?,60? is better than 80?,Ability to restore are mainly affected by air flow,100m3/h after treatment of the sample reduction ability better,have more antioxidant capacity.These results together illustrate the antioxidant capacity of dried taro tablets,physical and chemical properties,at the same time in the dry conditions by the impact of air flow and temperature changes.However,whether the traits of dried taro slices are affected by other drying conditions requires further study.