Title: EFFECT OF MOIST HOT AIR TREATMENT ON POSTHARVEST QUALITY OF STRAWBEERIES
Submitted to: Advances in Strawberry Research
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: December 21, 1998
Publication Date: N/A
Interpretive Summary: Strawberries are highly perishable with a short postharvest life. They are susceptible to decay, mechanical injury, and physiological deterioration. A major problem with strawberry storage is the development of decay caused by a variety of fungi. These diseases can be reduced with the application of certain fungicides. However, increasing public concern has been raised over the possible harmful health effects of the use of agricultural chemicals. We have found that moist hot air treatment can reduce the decay of strawberry fruit caused by fungi. This nonchemical method has the potential of being used as an alternative to fungicide application. We have found that heat treatment at certain temperatures and durations can also help maintain postharvest quality and extend storage and shelf life of strawberries. This research is therefore beneficial to the strawberry industry and consumers.
'Northeaster' strawberries were heated with moist hot air at 36, 39, 42, 45, 50, or 55 C for durations of 0, 20, 40, 60, 80, or 100 min. Fruit were injured when exposed to temperatures 50 C or higher, or durations of 60 min or longer at 45 C. Treatment at 45 C for 40 min or at 42 C for 60-100 min resulted in the least decay incidence after 5 days at 0 C, 3 days at 10 C, and 1 day at 20 C. No significant differences in pH of strawberry juice was detected among all the treatments. However, heated strawberries in general had lower titratable acidity, higher soluble solids content and higher levels of fructose, glucose, and sucrose than nonheated samples. Heated fruit also had a higher soluble solids/acid ratio, but lower citric acid and malic acid content. The lightness measurements, L, and chroma values, C, were decreased by moist hot air treatment and the fruit were duller and less bright in appearance after heat treatment. However, no consistent patterns were detected in other color readings, a, b and h. Strawberries heated with 39 C or lower temperatures had no discernable differences from nontreated fruit in quality attributes measured. However, fruit treated with 45 C for 40 min or 42 C for 60-100 min maintained better postharvest quality than other treatments because of less decay, higher sugars, lower acidity, and greater soluble solids/acid ratios.