2002 Fiscal Year Final Research Report Summary
Study on the mechanism of preservation and alteration of green color in vegetables
| Project/Area Number |
13660030
|
|---|
| Research Category |
Grant-in-Aid for Scientific Research (C)
|
| Allocation Type | Single-year Grants |
|---|
| Section | 一般 |
|---|
| Research Field |
園芸・造園学
|
|---|
| Research Institution | Faculty of Agriculture, Kobe University |
|---|
Principal Investigator |
TERAI Hirofumi Kobe University, Faculty of Agriculture Professor, 農学部, 教授 (30110802)
|
|---|
| Co-Investigator(Kenkyū-buntansha) |
SUZUKI Yasuo Kobe University, Faculty of Agriculture Assistant Professor, 農学部, 助手 (30335426)
PARK Pyoyun Kobe University, Graduate School of Science and Technology Professor, 自然科学研究科, 教授 (20147094)
|
|---|
| Project Period (FY) |
2001 – 2002
|
| Keywords | Postharvest / Senescence / Ripening / Broccoli / Sweet pepper / Chloroplast / Electron microscope / Ethanol treatment |
|---|
| Research Abstract |
1) Broccoli (Brassica oleracea L.var. Italicd) senesces rapidly and the florets turn yellow at room temperature after harvest. As a result, this vegetable has a short shelf life. A simple and cost-effective ethanol vapor treatment with powdery alcohol was conducted to inhibit the senescence in harvested broccoli and to clarify the mechanism involved in the preservation of the green color in stored broccoli florets. Some branchlets of the broccoli were stored in a perforated polyethylene bag together with 0, 3, 6, or 12 g powdery alcohol at 20℃ in the dark. Results showed that ethanol vapor treatment with 3 g powdery alcohol was very effective in delaying the yellowing of broccoli florets. However, higher concentration of ethanol vapor with 12 g powdery alcohol produced off-odor and softened the florets, and darkened the green color of florets. Results also indicated that ethylene production increased rapidly after 2 to 3 days in storage and simultaneously, ACC oxidase activity increase
… More
d in untreated broccoli florets but not in broccoli samples treated with powdery alcohol during storage. These results revealed that powdery alcohol treatment was simple and cost-effective method for prolonging the shelf life of broccoli since it suppresses ethylene production by inhibiting ACC oxidase activity.
2) Further study was conducted using transmission electron microscope (TEM) to elucidate the mechanism involved in the occurrence of these anomalous phenomena with higher concentration of ethanol vapor. The structural changes in the cells and chloroplasts in the sepal tissues of broccoli florets during storage were examined. We found that the treatment with adequate concentration of ethanol vapor evaporated from 3 g powdery alcohol did not induce the structural changes of broccoli sepal cells but retarded the conversion of chloroplasts to chromoplasts. On the contrary, higher concentration of ethanol vapor induced 'false' plasmolysis, plasma membrane breaks and modified plastids, resulting in production of off-odor and the appearance of darkened green color in the florets.
3) Red-colored sweet peppers are well-ripened fruit, which have been recently sold in the market. This study was investigated to improve the quality of pepper fruit harvested at mature green stage during storage at room temperature. In this experiment, the ultrastructural changes of plastids were examined to elucidate the transfomation mechanism of chloroplasts to chromoplasts during ripening in sweet peppers by using scanning electron microscope (SEM) and TEM. Based on SEM observation, disorganization of grana and stroma thylakoids appeared as the ripening progresses. At the developed stage of ripening, a large number of tubules with nods occupied in the plastids, which were probably derived from the thylakoid membranes. Based on TEM observation at the same stage, the greater parts of the plastids were filled with aggregated tubules. At fully-ripened stage, the appearances of fibril structures were observed. The morphometrical analysis showed that the ratios of grana thylakoids and stroma thylakoids to plastids decreased with ripening whereas the ratios of single thylakoids, vesicles, oil droplets, tubular structures, and fibril structures increased. The results of morphometrical analysis confirmed the quantitative changes of sub-organelles during ripening. Less
|
Research Products
(2 results)
