บทคัดย่องานวิจัย

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Storage-temperature-dependent time separation of softening and chlorophyll loss from the autocatalytic ethylene pathway and other ripening events of 'Anjou' pears.

Gerasopoulos, D.; Richardson, D. G.;

Journal of the American Society for Horticultural Science Year: 1997 Vol: 122 Issue: 5 Pages: 680-685 Ref: 30 ref.

1997

บทคัดย่อ

Storage-temperature-dependent time separation of softening and chlorophyll loss from the autocatalytic ethylene pathway and other ripening events of 'Anjou' pears.

Mature Anjou [Beurre d'Anjou] pears continuously stored at 20 deg C or stored at -1 deg then transferred to 20 deg exhibited differences in the sequence of ripening events up to 100 days. Pears continuously held at 20 deg showed little change in ripening characteristics (chlorophyll, firmness, titratable acidity) for 14-28 days, then these characteristics decreased at a daily rate of 1.4% thereafter. A 40% increase in soluble polyuronides paralleled firmness loss, while ACC concentration did not exceed 0.5 nmol/g until the 84th day, and internal ethylene did not exceed 0.2 micro l/litre until after 90 days, whereas ACC oxidase activity (and total protein) peaked after 63 days. Fruits stored at -1 deg showed no changes in chlorophyll, firmness, protein or total polyuronides for at least 84 days. Despite essentially no change in firmness during storage at -1 deg , there was a slow but steady increase (approx equal to 15%) in soluble polyuronides. ACC oxidase activity, expressed as ethylene product

ion, rose to 71 nl g-1 h-1 and ACC content increased to almost 1.0 nmol/g by the 84th day. Internal ethylene concentration slowly increased and levelled to 1 micro l/litre by the 56th day. Satisfaction of a chilling requirement thus appears to favour the development of ethylene synthesis capacity, which on transfer from cold storage to higher temperatures results in enough internal ethylene to rapidly drive the associated ripening mechanisms. Fruits for which the chilling requirement (<more or equal>70 days at -1 deg ) was met softened in response to accelerated internal ethylene production on transfer to 20 deg for 7 days. However, fruits that were not chilled or partially chilled did not sustain the increased ACC levels or ACC oxidase activity.