The Effect Of Drying Processing On Hami Jujube Quality

Fresh Hami jujube was used in the experiment to study the effect of different dried temperatures onthe relative enzymes and substrates of softening and browning. Also the changes of the relative enzymesand substrates of softening and browning of jujube, which was treated with anaerobic respiration first andthen dried in the hot air of45℃were studied. The results showed that:The activities of PG and CX were both increasing first and then decreasing under different dryingtemperatures. The activities of PG and CX were large and lasting longer when the temperature were35℃、40℃、45℃, the results were opposite when the temperature were50℃、55℃, while the enzymes wereinhibited. The activity of PME were declining all the time and lasting shorter. During drying processing thecontents of protopectin and cellulose were declining, while soluble pectin content was increasing duringthe drying time.The activities of POD were all increasing first and then decreasing under different drying temperatures,when the temperature was45℃the activity of POD was the largest. The tendency of total polyphenolchanges were also all increasing first and then decreasing under different drying temperatures. When thetemperature was35℃and45℃, the largest polyphenol content was2.36OD280/FW, which was the largestamong all the treatments; When the temperature was55℃the largest polyphenol content was1.96OD280/FW, which was the smallest among all the treatments.The activities of PG and CX were both increasing first and then decreasing when the treated time ofCO2was from6h to36h, the longer the treated time, the sooner the largest activity came; When the treatedtime was from42h to72h the activities of the two enzymes were declining all the time; The activity ofPME was declining during the whole process, the longer the treated time, the smaller the activity of PME.The contents of protopectin and cellulose of anaerobic respiration treated jujube were decreasing duringdrying process, the longer the treated time, the smaller contents of them, while the tendency of solublepectin were opposite.The activity of POD was increasing first and then decreasing when the treated time of CO2was from6h to36h, when the treated time was from42h to72h the activities was declining all the time; when thetreated time were12h，18h，24h the peak values were similar and largest among all the treatments.When the treated time of CO2was from6h to48h, the total polyphenol content was increasing firstand then decreasing, when the treated time was from54h to72h the content tendency was nearly stable;When the treated time were24h，42h，48h the peak values were2.6OD280/FW，2.77D280/FW，2.74D280/FW,were the largest among all the treatments.