11.5.1 Ripening indicators  Printer-friendly version   Figure
11.12 Ethylene production, total volatiles (including flavour
compounds) and tissue firmness are interrelated in ripening
kiwifruit. Production of ethylene (a) is highest from soft
fruit, with firmness of around 0.45 kgf. Fruit is considered
soft and ripe enough to eat once firmness falls below 0.7 kgf.
As fruit soften, production of specific aroma compunds
(volatiles in (b)) rises dramatically as fruit pass through
their climacteric. Ethylene production and aroma production are
biochemically linked.  (Based on Paterson et al. 1991)  Several
major changes can take place as fruits ripen. Not all occur in
every type of fruit, but taken collectively they charac-terise
ripening processes. They include:  1. a rise in respiration
rate;  2. production of ethylene;  3. flesh softening;  4.
appearance of colour;  5. formation of volatiles with associated
development of flavour (Figure 11.12).  One prime objective of a
postharvest physiologist is to ensure t