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ARS Home » Pacific West Area » Wapato, Washington » Temperate Tree Fruit and Vegetable Research » Research » Publications at this Location » Publication #101828
Title: EFFECTS OF THE RATE OF HEATING ON APPLE AND PEAR FRUIT QUALITY

Author
item Neven, Lisa
item Drake, Stephen
item Ferguson, Holly

Submitted to: Journal of Food Quality
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 8/27/1999
Publication Date: 7/20/2000
Citation: Neven, L.G., Drake, S.R., Ferguson, H.J. 2000. Effects of the rate of heating on apple and pear fruit quality. Journal of Food Quality. 23:317-326.

Interpretive Summary: Methyl bromide is used to kill insects that may be present in apples before they are shipped to countries which impose a quarantine against these insects. This chemical has been identified as an ozone depleter and is scheduled for phase-out by January 1, 2005 in accordance with the Clean Air Act and the Montreal Protocol. There is an exemption for quarantine uses, but the availability and cost may be prohibitive. The loss or limited availability of this chemical may impact the export of apples. In an effort to maintain current export markets, alternative quarantine treatments are being developed. There is evidence that the rate of heating to meet quarantine security impacts insect mortality as well as fruit quality. A study was conducted to describe fruit quality responses to the rate of heating. Linear heating rates of 4, 6, 8, 10, and 12 deg C/h to treatment temperatures of 44 and 46 deg C were used to treat 8 varieties of apples and two varieties of winter pear. Storage scald was controlled, firmness was higher in heat treated fruit, ripening was delayed but uniform in pears, decay was suppressed, red fruit became redder and green fruit remained green, the fruit sweetness was either unchanged or increased. Heat treatments show great promise as alternative quarantine treatments for apples and pears.

Technical Abstract: There is evidence that the rate of heating to meet quarantine security impacts insect mortality as well as fruit quality. A study was conducted to describe fruit quality responses to the rate of heating. Linear heating rates of 4, 6, 8, 10, and 12 deg C/h to treatment temperatures of 44 and 46 deg C were used to treat 8 cultivars of apples ('Delicious', 'Golden Delicious', 'Granny Smith', 'Fuji', 'Gala', 'Jonagold', 'Braeburn', and 'Cameo') and two cultivars of winter pear ('d'Anjou' and 'Bosc'). Fruits were stored for 90 days in controlled atmospheres, ripened for 7 days, and tested for various quality parameters such as external and internal colors, firmness, soluble solids, titratable acidity, scald, internal break down, and decay. Scald was controlled, firmness was higher in heat treated fruit, ripening was delayed but uniform in pears, decay organisms were suppressed, red fruit became redder and green fruit remained green, the Brix-acid ratio (SS/TA) was either unchanged ('Granny Smith') or increased. Physiological disorders such as bitter pit were exacerbated by the heat treatment and culled after treatment but before the fruit went into storage.