Effect of postharvest hot water treatment on papaya.
Kodikara, N.; Adikaram, N. K. B.; Karunaratne, A. M.;
Proceedings of the Australasian postharvest horticulture conference 'Science and technology for the fresh food revolution', Melbourne, Australia, 18-22 September, 1995. Year: 1996 Pages: 417-422 Ref: 11 ref.
1996
บทคัดย่อ
Storage diseases of papaya (Carica papaya)[pawpaws] in Sri Lanka are due to fungal pathogens, with Colletotrichum gloeosporioides [Glomerella cingulata], C. capsici (anthracnose), Phomopsis caricae-papayae, Botryodiplodia theobromae and Cladosporium cladosporioides (stem-end rot) dominating. A hot water double dip treatment (42 deg C for 30 min. followed within 3 min by 48 deg for 20 min) was assessed for its ability to control disease. Changes in pH, the total titratable acidity (TA), total and reducing sugars (TS and RS, respectively) and total soluble solids (TSS) in peel and pulp tissues, were determined at 3 ripening stages 1, 3 and 5 days after treatment, corresponding to the 'colour break' (CBS), 'half fruit yellow' (HFY) and 'entire fruit yellow' (EFY) stages. Peroxidase isoenzyme pattern (by PAGE) and electrolyte leakage (using a conductivity meter) of the peel were determined. A total disease reduction of 55% was observed, with anthracnose, stem end rot, wet rot, Cladosporium rot and o
ther diseases being reduced by 32, 54, 55, 34 and 100%, respectively, 6 days after treatment. Shelf life was increased by c. 3 days. With ripening, no change in TA was observed, although a significant (P=0.05) reduction in pH of pulp occurred; TS and RS in pulp and peel and TSS in the peel increased. Treatment did not change TA or TSS significantly, but the pH of treated pulp at CBS and treated peel at EFY were significantly higher. Ripening was slightly accelerated, but there was no significant weight loss. An increase in TS, which was significant only at CBS of pulp and HFY of peel and a slight increase in RS was seen due to treatment. Electrolyte leakage was significantly reduced; electrophoresis with ionically bound peroxidase extracts, indicated an extra band in treated peel. It is suggested that this may be evidence of peel strengthening and adaptation to stress. Hot water treatment appeared to be a simple, safe and effective method of replacing fungicides as it did not significantly alter the physical
and biochemical attributes of the fruit tested in the edible portion of the fruit (i.e. pulp of EFY).