Maintenance of green color in harvested vegetables and ultrastructural changes of their chloroplasts.

1998 Fiscal Year Final Research Report Summary

• Project/Area Number: 09660026
• 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: KOBE UNIVERSITY
• Principal Investigator: TERAI Hirofumi Kobe University Faculty of Agriculture, Associate professor, 農学部, 助教授 (30110802)
• Project Period (FY): 1997 – 1998
• Keywords: Broccoli / Green color / Chloroplast / Ethanol treatment / Blanching

Research Abstract

1) Effect of ethanol vapor treatment for fresh broccoli florets.
Broccoli florets were exposed to ethanol vapor, for 24 hours or continuous 6 days at 20。C.Ethanol vapor was generated by babbling 0 (distilled water), 10, 25, 50 and 100% ethanol solution. Hue angles in 24-hours treatment with vapor of 25 to 100% ethanol decreased slowly compared with treatment with vapor of 0 to 10% ethanol during storage, and florets with vapor of 50 to 100% ethanol became gradually dull green color. Continuous treatment with ethanol vapor afforded the off-flavor and disorder in chloroplast of the florets. These results showed that 24-hours treatment with vapor of 25% ethanol is suitable for maintenance of green color. In the additional experiment, "solid alcohol" cubes that volatilize ethanol vapor were placed in perforated polyethylene bags with broccoli florets. The "solid alcohol" cube treatment maintained the green color of the florets and was expected as a convenient treatment.
2) Effects of tempera ture and lighting for blanched broccoli florets during display.
This study was conducted to elucidate the effects of temperature and lighting on the maintenance of green color in blanched broccoli florets being an item of vegetable salads. Fresh florets were blanched for 1 minute in boiling water. The blanched florets placed on small trays were wrapped with plastic film and stored at 5。C or 10。C under lighting (2,000 lux) or darkness. Chlorophyll contents in florets decreased more quickly under lighting than under darkness, and at 10。C than at 5。C.The observation of chloroplast with light microscope and scanning electron microscope with freeze fracture technique showed that the shape of chloroplast was kept in spite of blanching but considerable change was seen in grana and stroma thylakoid. Degradation of chloroplast seemed to be slightly faster at 10。C than at 5。C, but the influence of lighting on the degradation of chloroplast was not clear. These results suggest that managements of weaker lighting and lower temperature are necessary to maintain the quality of blanched broccoli florets during display.