Deirdre M. Holcroft

Controlled atmosphere-induced changes in pH and organic acid metabolism may affect color of stored strawberry fruit

Skin and flesh of ‘Selva’ strawberries (Fragaria x ananassa Duch.) stored at 5°C in air or 2 kPa O2 became darker red and accumulated anthocyanin levels, but these changes were reduced in fruit stored in air 20 kPa CO2, 2 kPa O220 kPa CO2, 0.5 kPa O2,, and 0.5 kPa O220 kPa CO2 (balance N2 in all CA treatments). Increasing pH and decreasing titratable acidity in tissues during storage, especially in the internal tissues, were more marked in fruit stored in high CO2 atmospheres. Since pH affects color expression of the anthocyanin pigment, these changes may contribute to the observed changes in color. Combined citric and malic acid concentrations were higher in the external tissues (10.6 mg g 1 ) than internal tissues (5.5 mg g 1 ), and decreases in concentration of both acids were greater in fruit kept in high CO2 atmospheres. Succinic acid in fruit tissues was present in low concentrations, but usually increased in high CO2 atmospheres.

Postharvest physiology and handling of litchi (Litchi chinensis Sonn.)

Abstract The litchi is a stone fruit with a rough indehiscent pericarp surrounding the succulent, edible aril. During development and ripening the fruit exhibits a sigmoidal growth curve and a nonclimacteric respiratory pattern. Maturity is indicated by size and color, but a more accurate measure is the sugar:acid ratio. The major factors reducing the storage life and marketability of litchi are pathological decay and pericarp browning. Low temperature storage has been used to reduce pathological decay but has a limited role in reducing pericarp browning. Pericarp browning is induced by desiccation, and consequently methods to reduce desiccation help retain red color. Sulfur dioxide fumigation has been used to reduce pericarp browning, but there is increasing consumer and regulatory resistance to the use of this chemical. Insect disinfestation has become increasingly important with the expanding export market. Recent research has focussed on reducing these major postharvest problems to produce highly colored fruit free of disease and insects.