Immature and mature durian (Durio zibethinus Murr.) fruit dehiscence was studied. Fruit were stored at 27C and 65% or 95% relative humidity, with or without 24-hour exposure to 100 ppm ethylene. Low relative humidity and ethylene increased fruit dehiscence. Spraying fruit with 100 ppm GA3 delayed dehiscence but allowed pulp ripening to continue. The plant-growth regulators IBA; 2,4-D; 2,4,5-T; BAP; daminozide; and mepiquat chloride had no consistent effects on fruit dehiscence. Various coating materials delayed dehiscence and ripening; a sucrose fatty acid ester at 1% concentration gave the best result. All coating materials reduced weight loss 7% to 14% below that of the control fruit. Fruit coated with the sucrose fatty acid ester and 100% apple wax had higher internal CO2 levels than fruit coated with any other coating. Ethylene is more important in durian fruit dehiscence than weight loss. Chemical names used: 3-indolebutyric acid (IBA); 2,4-dichlorophenoxyacetic acid (2,4-D); 2,4,5-trichlorophenoxyacetic acid (2,4,5-T); 6-benzylaminopurine (BAP); succinic acid-2,2-dimethyl hydrazide (daminozide); 1,1-dimethyl-piperidinium chloride (mepiquat chloride); gibberellic acid (GA3).
Siriphun Sriyook, Somboon Siriatiwat and Jingtair Siriphanich
Chien Wang, Korakot Chanjirakul, Shiow Wang and Jingtair Siriphanich
The effect of naturally occurring volatile compounds on decay and antioxidant activities in fresh-cut papayas (Carica papaya L.) was studied. Exposure to methyl jasmonate (MJ), methyl salicylate (MS) or allyl isothiocyanate (AITC) substantially delayed the onset and reduced the severity of decay during and after storage at 5 °C. Treatment with tea tree oil (TTO) or ethanol (ETOH) was also effective in retarding decay, but to a lesser extent. No beneficial effect was obtained with the use of vinegar vapor. MJ and MS increased oxygen radical absorbance capacity and elevated the activities of several antioxidant enzymes, including glutathione reductase, glutathione peroxidase, guaiacol peroxidase, ascorbate peroxidase, monodehydroascorbate reductase, dehydroascorbate reductase, and superoxide dismutase. The nonenzyme components in the ascorbate-glutathione cycle were also increased by MJ and MS treatments, including ascorbate and glutathione. It is possible that MJ and MS treatments enhanced the antioxidant system and increased the resistance of tissue to decay. However, while AITC also suppressed the development of decay in papaya slices, it had little effect on antioxidant levels and antioxidant enzyme activities. Apparently, AITC exerted its effect through different mechanisms. Studies are in progress to determine if AITC inhibits decay directly via its antimicrobial properties.