EFFECT OF LOW TEMPERATURE ON PHYSIOLOGICAL AND BIOCHEMICAL CHANGES IN JAVA APPLE 'THABTHIMCHAN'

Abstract

Java apple (Syzygium samarangenese [Blume] Merrill & L.M. Perry ‘Thabthimchan’) fruit bruise easily, and are highly susceptible to weight loss after harvest. The objective of this research was to study the effect of low temperature on quality and biochemical changes of Java apple fruit. Java apple fruit were stored at 6 or 18°C (90-92%RH) for 14 days. Fruit were evaluated for chilling injury index (pitting), weight loss, firmness, soluble solids content (SSC), titratable acidity (TA), peel color, ion leakage, vitamin C content, anthocyanin content, respiration rate, ethylene production, total antioxidant capacity (TAC), and lipoxygenase (LOX) and superoxide dismutase (SOD) activities every 2 days. The results indicated that in 6°C stored Java apple fruit skin pitting (chilling injury: CI symptom) occurred and these fruit had higher ion leakage than those fruit stored at 18°C. Fruit stored at 6°C showed surface pitting on day 4 of storage, coinciding with an increase in ion leakage. Java apple fruit stored at 18°C did not show any CI symptoms. Fruit firmness, SSC, TA, peel color and anthocyanin content did not change during fruit storage at 6 or 18°C. Respiration rate, ethylene production, weight loss and vitamin C content and TAC of fruit stored at 6°C were lower than those in fruit stored at 18°C. LOX activity of fruit stored at 18°C remained constant throughout the storage period. On the other hand, fruit stored at 6°C showed high LOX activity on day 2 of storage, while SOD activity of fruit stored at 6 or 18°C increased during storage. The results suggested that CI of Java apple fruit is closely correlated with ion leakage in fruit skin, vitamin C content and TAC.