PHYSICAL AND CHEMICAL-QUALITY CHARACTERISTICS OF STRAWBERRIES AFTER STORAGE ARE REDUCED BY A SHORT DELAY TO COOLING

'Chandler', 'Oso Grande' and 'Sweet Charlie' strawberries were forced-air precooled after delays of 0 or 6 h at 30 degrees C to study the effect of delaying precooling on physical and chemical quality characteristics of strawberry fruit. Fruit pulp temperatures were equilibrated to 30 degrees C prior to the start of each experiment to minimise water loss differences between treatments. Evaluations were made after storage for one week at 1 degrees C plus one day at 20 degrees C. Delaying the start of precooling resulted in about 50% greater water loss than in control fruit, which was evident as increases in superficial shrivelling. Tissue firmness values were also 14-22% lower in fruit from the delayed treatment. Fruits were darker (lower L* value), less bright (lower chroma) and apparently less red (lower a* value) with the cooling delay, although hue angle was also lower, which may reflect the occurrence of browning. No significant differences in pH were observed in these experiments, but titratable acidity was slightly lower with the delay to cooling. Delaying precooling also caused increased losses of ascorbic acid, soluble solids, fructose, glucose and sucrose compared to controls. In spite of differences related to harvest time and the variability among cultivars, the general responses were quite similar and illustrate the importance of rapid precooling and subsequent storage at low temperature for maintenance of acceptable appearance, texture and nutritive value of strawberries.