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Ester biosynthesis in "Rome" apples subjected to low-oxygen atmospheres.

Fellman, J. K.; Mattinson, D. S.; Bostick, B. C.; Mattheis, J. P.; Patterson, M. E.;

Postharvest Biology and Technology Year: 1993 Vol: 3 Issue: 3 Pages: 201-214 Ref: 27 ref.

1993

บทคัดย่อ

Ester biosynthesis in "Rome" apples subjected to low-oxygen atmospheres.

The relationship was investigated between acetate ester-forming activity of acetyl CoA alcohol transferase (ACAT), non-ethylene volatile emission, and flesh volatile content of apple fruits (cv. Rome) after removal from 9 months' storage in low O2 environments. Fruits held at 0-1 deg C in refrigerated air (RA) or controlled atmosphere (CA) storage (1.0 or 0.5% O2/1% CO2) were removed and placed in ambient laboratory conditions. Every 3 days, fruit flesh and headspace were analysed for volatile compounds using capillary gas chromatography. Acetate ester forming activity was assayed spectrophotometrically on partially-purified extracts of cortical tissue. Patterns of acetate ester formation depended upon storage environment and alcohol moiety precursor. Ethyl acetate content was always higher in the headspace and flesh of RA fruits, regardless of time after storage. Propyl acetate concentrations were higher in CA-stored fruit flesh than in RA-stored fruit flesh until post-storage Day 9. Headspace

propyl acetate levels were higher in RA fruits until Days 9-15 after which more propyl acetate emanated from CA fruits. Butyl acetate concentrations were lower in flesh and headspace of CA fruits until Day 15, at which time RA fruit headspace levels decreased. Headspace and flesh concentrations of 2-methyl-1-butyl acetate were generally higher in CA fruits than in RA fruits. Acetate ester-forming activity was detectable at Day 0 in fruits stored in 1.0% O2 but not in fruits stored in 0.5% O2. By post-storage Day 9, ACAT activity in CA fruits reached maximum levels, only to decrease by Day 15. RA-stored fruits had more ACAT activity at Day 0, but did not substantially increase in activity after removal from storage. It is not known whether the ACAT protein is reactivated by exposure to ambient O2 or synthesized de novo.