Research On The Quality Changes Of Different Onions After Storage&Identification Of A Certain Disease

Through measuring four quality indicators--contents of dry matter, contents of soluble sugar,contents of vitamin C and contents of pyruvic acid in onion, this test conducts comparison among12Chinese and4Japanese onion varieties, to clarify the quality difference and quality change trend of onionvarieties at different storage stages under the same storage condition. This experiment also carries outseparation, purification and preliminary evaluation towards a kind of pathogenic microorganism offrequently-occurring disease in storage period. The results are as follows.1. Each quality indicator value of onion changes with the length of storage period. There are nosignificant difference in the content values of dry matter after one month storing. However, onionsubstance constantly consumes due to the post-picking metabolism and dry matters contents of mostvarieties all appear to a declining trend. Because soluble sugar participates all sorts of metabolicregulation, its consumption appears to be notable and its contents becomes lower when the storage periodis longer. Soluble sugar of16varieties all decrease to some extent after three-month storing. Onioncontains ascorbic acid enzymes which destroy vitamin, thus the longer the storing period, the morevitamins destroyed and consumed. This point is once again proved by comparing the contents of vitaminC at different stages. As pyruvic acid is the product of carbohydrate metabolism, saccharidescontinuously metabolize with the extending of storing period and contents of pyruvic acid shows acontinued increasing trend. The pyruvic acid contents in all varieties increase remarkably throughthree-month storage.2. By comparing indicators of varieties in each storage stage, the storing capacity of twoearly-maturing varieties E-2is superior to E-1, but other indicators of E-1are better. Within the tenmiddle--maturing varieties, M-3and M-10have high nutrition, good storing capacity and light pungenttaste; M-1, M-9and Japanese variety M-5show good storing capacity but contents of soluble sugar andvitamin C decrease rate is high; every indicator of M-2, M-4, M-6and M-8varieties performs the worstwith poor storing capacity, low nutrition content and strong pungent taste. Although L-1in fourlate-maturing varieties is not the highest in vitamin content, its storing capacity is good and pungent tasteis mild; the L-4variety is good storing capacity and high-nutrition content, but the pungenct taste isstrong; storing capacity and vitamin C content of L-2variety are inferior to L-1, but the pungent taste islight; L-3variety is poor storing capacity, nutrition content is not high and shows strong pungent taste.3. By observing infected onion by the pathogenic microorganism in storage period, the separation and purification, growing process and growing stage of pathogenic microorganism, this disease wasidentified as onion black aspergillosis disease, which belongs to fungal pathogen. And the causative agentis Aspergillus niger van Tiegh which is called black aspergillosis belonging to deuteromycota．...