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  • Author or Editor: Daryl G. Richardson x
  • Journal of the American Society for Horticultural Science x
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Abstract

High performance liquid chromatography of mature ‘Beurre d'Anjou’ and ‘Beurre Bosc’ pear (Pyrus communis L.) fruit flesh showed that the major phenolics at harvest were chlorogenic acid, catechin, and arbutin. Neither cultivar contained epicatechin nor p-coumaroyl quinate. During 160 days at –1°C the chlorogenic acid content of d'Anjou increased significantly. In ‘Bosc’, chlorogenic acid levels decreased during storage. Catechin content increased linearly while arbutin levels remained nearly constant in both cultivars. Coincident with the completion of the cold requirement for initiation of ripening and endogenous ethylene production, i.e., 20 days for ‘Bosc’ and 50 days for ‘d'Anjou’, there was an appearance of low levels of a p-coumaric acid derivative and trace amounts of epicatechin/p-coumaroyl quinate. At 120 days epicatechin/p-coumaroyl quinate increased in ‘d'Anjou’ but not in ‘Bosc’. There is a coincidence, and perhaps relationship, between ethylene production and the quantity as well as the composition of phenolics present during storage. Bruising pear fruit after 120 days of storage caused a 30% increase in chlorogenic acid and a 50% increase in catechin, but no increase in p-coumaric acid derivatives.

Open Access

Abstract

Forty-six days at –1°C were required to stimulate ethylene synthesis in harvested ‘d'Anjou’ pears (Pyrus communis L.). The effect of exogenous ethylene on changes in quality parameters and organoleptic properties, and the effect of cold temperature on the development of ethylene production, were studied during the 46 days at –1°. Pears were held in 10 or 50 ppm exogenous ethylene at 20° after 30 or less days at –1°. Respiration increased from 8 to about 19 mg CO2·kg-1·hr-1 in fruit held in ethylene over a 12-day period, whereas fruit held in air showed only a slight increase. Firmness of fruit held in ethylene decreased from 66 to 12 N over 12 days at 20°. No significant change in firmness occurred in fruit held in air at 20°. The volume of extractable juice was unchanged in fruit held in air, but declined in fruit held in ethylene. The soluble solids content was not affected by ethylene treatment. Taste panel evaluation determined that fruit held 30 days at –1° then held 10 days in ethylene at 20° were ripe, sweet, and juicy, but fruit held in air were comparable to fruit never held at 20°. Pear flesh disks cut from fruit held 21 days at –1° did not convert exogenous 1-aminocyclopropane-1-carboxylic acid (ACC) to ethylene, but did so when cut from fruit held 41 or 50 days at –1°. Only with the onset of ethylene production was endogenous ACC detectable in pear flesh. During the 46 days at –1° required for initiation of ethylene production, the capacity to convert ACC to ethylene developed first, followed by production of ACC and ethylene.

Open Access

Abstract

Internal ethylene of attached fruit of ‘Starkspur Golden Delicious’ apple as influenced by 6 rootstocks: Seedling, Mailing (M1) 1, Mailing Merton 106 (MM 106), M 7, OAR 1, M 26, at 2 levels each of soil-applied K and N were measured during maturation for 2 years (1980 and 1981). Ethylene evolution of detached fruit as a result of these treatments also was measured after 2.5 months of storage at 0°C in 1981. Internal ethylene in the attached fruit was less than 0.1 μl·liter-1 in late September and early October and began to rise between 9 Oct. and 15 Oct. Internal ethylene increased in all treatments, almost at the same time in 1980. In 1981, ethylene in the fruit on OAR 1 began to increase 9 days later than in the other rootstocks. However, levels of ethylene in the fruit were relatively low on OAR 1 and high on M 26 as compared to those on other rootstocks in late October 1980 and 1981 and during poststorage 1981 samplings. Ethylene levels in fruit from other rootstocks were similar. Because of these variable effects of rootstocks, and the effects of a low field temperature in reducing internal ethylene levels, field sampling of internal ethylene levels was an unreliable indicator of the proper harvest time, as measured by other maturity indices. No consistent influence of K or N applications was found in the internal ethylene of the attached fruit; however, high N applications increased ethylene evolution after storage.

Open Access