Study On Preservation Technologies And Control Of Pathogens During Baby Ginger Storage Period

Wilt and rot occur readily during storage of baby ginger because of its tender skin and high moisture content. This article was focused on preservation technology and control of pathogen infectionduring baby ginger storage. The results were listed as follows:1. The critical temperature of chilling injury was confirmed by testing corruption, weight loss, firmness, chromatism, and PPO activity of baby ginger. The results showed that chilling injury would not happened when baby ginger was stored at 10℃. Less volatile values of firmness, chromatism, and PPO activity were found at this temperature. Serious injury were observed on baby ginger which is stored at 5 and 0℃.2. The measures for reducing chilling caused by low temperature were evaluated by testing MDA content, relative electrolytic leakage, firmness, and CAT activity. The results showed that chilling injury on baby ginger stored at 5℃ was significantly reduced by using heat shock treatment (45℃min) and gradient cooling treatment (10℃ 6h-5℃) in combination. After this combinatory treatment, MDA content, relative electrolytic leakage, CAT activity, and firmness of baby ginger were about 59.5,67.5, 246, and 175 percent of ginger without any treatment respectively.3. Based on the results above, storage mediums consisted of varying proportions of sand, super absorbent polymer, and water were evaluated by testing firmness and weight loss. The results showed medium consisted of 20% initial moisture content and 3.75% SAP had positive effects on baby ginger storage at 5℃. The rate of moisture content change in the medium was less than 5%. The weight loss and firmness decline of ginger stored in the medium were 4.3 and 21.2 percent of control group respectively.4. Based on the results above, soaking treatments with calcium chloride and calcium lactate were evaluated by testing the firmness of baby ginger stored at 5℃. The results showed calcium lactate treatment at a concentration of 0.05% was more efficient for preserving the firmness of ginger at 5℃. Based on the results above, soaking treatment with disodium stannous citrate, citric acid, D-Isoascorbic acid, and D-sodium erythorbate wereevaluated by testing PPO activity and chromatism. The results of disodium stannous citrate treatment at a concentration of 0.05% showed a good effect on preserving color. After the treatment, value of PPO activity and chromatism were 46.7 and 64.3 percent of control group respectively.5. The pathogens isolated from rotting ginger were identified as Penicillium sp. (KC833482.1), Fusarium sp. (KC833483.1), and Mortierella sp. (KC833484.1). The 18S rDNA sequences were submitted to NCBI.6. Antifungal effect of essential oils extracted from Thymus vulgaris, Syzygium aromaticum, Cinnamomum zeylanicum, Litsea cubeba, Ocimum basilicum, Melaleuca alternifolia, Elicium verum, Herba Menthae, Herba Menthae, and Cymbopogon citratus on pathogens were investigated in vitro. Essential oils extracted from Cinnamomum zeylanicum (cinnamon) and Thymus vulgaris (thyme) completely inhibited the growth of all of the above pathogens at a concentration of 2000μl/L.7. The sensitivities of pathogens to Cinnamon, thyme, basil, and clove oil were investigated in vitro. Cinnamon oil showed higher antifungal activity in the drug sensitivity test with minimal fungicidal concentration (<500 ppm against all pathogens).8. Effect of fumigation and soaking treatment with cinnamon oil on pathogens were investigated in vivo. The concentration was 125,250,500μl/L respectively. The results showed both treatments at a concentration of 500μl/L were efficient for control of pathogen infection. But, soaking treatment would cause browning.9. Ultrastructure of pathogen mycelia was observed using TEM. After essential oil treatment, the mycelia of Penicillium sp. and Fusarium sp. showed membrane and cell wall collapse, and the membrane and cell wall of Mortierella sp. was normal.10. GC-MS analysis showed that cinnamon oil used in this work was consisted of trans-cinnamaldehyde (95.7%), copaene (0.52%), benzaldehyde (0.98), a-guaiene (0.35), and limonene (1.18%).11. The main compositions of hydrolyzed tween-80 were linoleic acid and oleic acid. The resistance of Mortierella sp. to cinnamon oil would be enhanced by adding 1% tween-80 to the culture medium. Tween-80 could not enhance the resistance of Penicillium sp. and Fusarium sp.. Absorption capacity of Mortierella sp. for exogenous linoleic acid is stronger than that of Penicillium sp. and Fusarium sp.. Mortierella sp. could translate oleic acid to linoleic acid. Exogenous linoleic acid and oleic acid could enhance the resistance of Mortierella sp. to cinnamon oil.The optimal method of baby ginger preservation was as follow:(1) Soaking the rhizomes for 5min in solution of DSC and calcium lactate with temperature of 45℃. (2) Fumigating rhizomes for 4 h by cinnamon oil after air-dry. (3) Putting the rhizomes into sand-based medium after pre-cooling. (4) Storing rhizomes in the environment of 5℃ and 90% RH. In the case of treating rhizomes by the measure above, the commodity rate of baby ginger could reach 95% and 80% after 24d and 30d, respectively.