EFFECTS OF DIFFERENT POSTHARVEST TREATMENTS ON THE RESPIRATION PATTERNS OF GUAVA (PSIDIUM GUAJAVA L.)

In Malaysia, guava (Psidium guajava L.) has been exploited commercially, using introduced cultivars such as ‘Kampuchea’, ‘Vietnam’ and ‘Taiwan’ which yield big fruit with thick flesh.
Storage life of guava is about 3 days at room temperature (27 – 33°C), one week at 20°C and about 2 weeks at 0 – 10°C (Gupta et al., 1979; Wills et al., 1983). One of the methods employed to extend the storage life of the fresh fruit is to retard the metabolic processes which occur during ripening and storage, by subjecting the fruit to different postharvest treatments.
Thus, the objective of the present study is to determine the effects of different postharvest treatments on the respiration patterns, rate of ethylene evolution and several other physico-chemical changes of guava cv. ‘Kampuchea’. Fruits of commercial maturity which were free from injury were used in this study.
Fruit were subjected to six different postharvest treatments; namely control (storage at ambient temperature; 27 ± 1°C; 60–80% RH), storage at optimum conditions (10 ± 1°C; 85–90% RH), coating with paraffin (10%), hydrocooling prior to storage (0 – 3°C), or exposure to chilling injury (3 ± 1°C; 65– 85% RH) and mechanical injury (fruits dropped from a height of 1.5 m to a rough but flat cement surface). All the fruit except the control were then kept at optimum storage conditions.
CO₂ and C₂H₄ concentrations were measured using a gas chromatograph.
All determinations were made on day 0 (start of experiment) and at every 2 day interval until the fruits had rotted: the physico-chemical parameters measured included fruit firmness, percentage weight loss, pH, total soluble solids, titratable acidity, and ascorbic acid content

In general, rate of respiration was influenced by storage temperature and the different postharvest treatments.
Fruits stored at higher temperature exhibited a higher rate of respiration than fruits stored at lower temperature.
Storage life of fruits stored at ambient temperature was only one week, through appearance of mould growth which led to fruit softening and rot.
Even though there was no significant difference in the CO₂ production between all treated fruits except for control, there was a general trend observed.
Mechanically-injured fruits exhibited a higher rate of respiration compared to the chilling- injured fruits, with a storage life limited to 2 weeks due to onset of mould growth.
Chilling- injured fruits failed to ripen satisfactorily.
The rate of C₂H₄ evolution showed a similar trend to CO₂ production between fruits from all treatments.
Except for percentage weight loss and total soluble solids content, there was no significant difference in the physico-chemical characteristics between all the treated fruits.

Based on the general trends in all the parameters studied, shelf life of guava cultivar ‘Kampuchea’ could be extended when stored at the optimum conditions.
Percentage weight loss could be further reduced with 10% paraffin coating.

International Postharvest Science Conference Postharvest 96

A. Osman, M.N.A. Ayub

https://doi.org/10.17660/ActaHortic.1998.464.94