Annona Species Monograph.pdf - Crops for the Future

Chapter 11. Harvest & Processing
and Paull (1998) suggested mechanical harvesting in larger soursop orchards.
Cherimoya fruits are hand harvested by cutting the peduncle and by using net
bags to hold or catch the fruit (Accorsi and Manica, 1994; Agustín and
Angel, 1997).
11.3 Postharvest handling
11.3.1 Physiological changes
Annona fruits have a respiration peak and an increase in ethylene
concentration after fruit harvest; this is typical of climacteric species.
Cherimoya, soursop and sugar apple fruits present two successive rises in
respiration rate, whereas the custard apple presents only one (Brown et al.,
1988). The ripening process occurs during climacteric respiration, with some
modifications in the chemical composition leading to remarkable changes in
flavour and a decrease in pulp firmness (Mosca et al., 1997 a). Knowledge
about this process is very important for post-harvest handling, because
ripening occurs very quickly after harvest (Torres and Sánchez, 1992).
Cherimoya presents a climacteric peak 5 days after the harvest point and a
second one after 10 days, when the fruits soften, and the flavour and aroma
development are completed (Kosiyachinda and Young, 1975). In the cultivar
‘Fino de Jete’, Martinez et al. (1993) demonstrated a temporal coincidence
between ethylene production and physical-chemical alterations. During the
ripening process at 20°C, the pH dropped to 4.8, total titratable acids
increased to 0.36 g citric acid/100 g fresh weight, starch content declined to
20.7 g/100 g fresh weight and Brix increased to 18.7°.
In soursop fruits, the climacteric peak corresponds to an increase in soluble
solids content, the pH value decreases and titratable acids rise about 10 fold,
due to increases in malic and citric acid concentrations (Paull et al., 1983).
Maximum production of volatile compounds and ethylene diffusion occurs 5
days after the harvest point. At this time, the highest concentrations of sugars
and acids are attained; this is the moment of best quality for consumption.
Fructose and glucose reach their peaks 5 days after the harvest point, while
sucrose content rises to a maximum concentration 3 days after harvest point
and then declines. Fructose exceeds sucrose concentration and contributes to
the sweetness of the fruit (Paull et al., 1983). Starch breakdown by amylases,
polygalacturonase and cellulase activities increase during ripening 2 days
after the harvest point (Paull et al., 1983). These changes are ethylene
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