Post‐harvest application of diphenylamine and ethoxyquin for the control of superficial scald on Bramley's seedling apples

Abstract

Recent changes in the antioxidant regulations in the UK and the need to evaluate the effectiveness of scald control chemicals in the presence of other post-harvest chemicals led to a comparative study of the effects of diphenylamine (DPA) and ethoxyquin on scald development in Bramley's Seedling apples. A range of concentrations (1000-4000 mg litre-l a.i.) of DPA completely controlled scald on Bramley apples kept in controlled atmosphere storage for 241 days; ethoxyquin at equivalent rates was less effective. Only partial control of scald was achieved with 500 mg litre-' a.i. DPA. None of the treatments injured the fruit. Control of scald by 2000 mg litre-' a.i. DPA or ethoxyquin was not impaired by adding thiophanate-methyl (I g litre-l a.i.) or calcium chloride (10 g litre-l) although the measure of control was reduced when both fungicide and calcium chloride were added. Calcium chloride caused lenticel injury which was aggravated by adding ethoxyquin but reduced by incorporating DPA. The concentrations of ethoxyquin and DPA residues on the fruit immediately after treatment were within the limits required by UK legislation (see reference I ) of 3 mg kg-1 and 10 mg kg-*, respectively, even where 4000 mg litre-l had been applied. An initial residue concentration of 2.3 mg kg-1 DPA was associated with complete control of scald. Residue levels, particularly of DPA, declined rapidly during the first month of storage.

Land Spreading of Wastewaters from the Fruit-Packaging Industry and Potential Effects on Soil Microbes: Effects of the Antioxidant Ethoxyquin and Its Metabolites on Ammonia Oxidizers

“…Their chemical structures, along with those of the pesticides studied, are shown in Assessment of the effects of pesticides on the soil microbial community (soil microcosm experiment I). The study was carried out in a soil collected from a noncultivated plot in the farm of the Aristotle University of Thessaloniki, Greece, characterized as clay (50% sand, 9% silt, 41% clay) with 1.04% organic C content, an N-NO 3 Ϫ content of 37 mg kg (dry weight) soil Ϫ1 , and pH 7.85. Soil samples were taken from 5 selected points of the top soil (up to 10 cm depth) by following the W nonsystematic pattern of sampling, according to ISO 10381-1 and -2 guidelines (22,23).…”

Control of Superficial Scald of Apples by Low-oxygen Atmospheres

“…Diphenylamine inhibits electron transport in plant mitochondria (Baker (1963). Superficial scald of 'd'Anjou' pears (Chen et al, 1990) and apples (Johnson et al, 1980) is controlled by ethoxyquin, an antioxidant commonly used to control oxidative rancidity in poultry feeds. The antioxidants BHT and BHA also reduce scald; BHA and BHT are widely used in food packaging to prevent lipid oxidation.…”

Deciduous Tree Fruit

“…Barden and Bramlage (1994), working in the eastern U.S., were able to predict the relative susceptibility of apple fruit to scald based on the accumulated time at temperatures <10°C during the maturation period. Smock (1957) pioneered the use of diphenylamine (DPA) treatments to control storage scald of apples, and ethoxyquin (6-ethoxy-1,3-dehydro-2,2,4-trimethyl quinoline) was subsequently found to be effective (Johnson et al, 1980). The EPA recently restricted use of these chemicals; ethoxyquin can be used only on pears, and alternatives that do not require chemical treatment are being sought.…”