Shrivel development in kiwifruit

• The relationship between fruit water loss, softening and shrivel has been examined.
• Shrivel is not determined simply by an absolute amount of water loss.
• After prolonged storage, soft fruit shrivelled with relatively little water loss.
• Shrivel is influenced by softening and the outer pericarp (OP) water status.
• The OP of Gold9 fruit had lower water mobility than that of Gold3 or ‘Hort16A’ fruit.

Shrivel is a potential storage quality problem for kiwifruit. ‘Zesy003’ (commonly called Gold9) is a newly released, yellow-fleshed Actinidia chinensis cultivar that tends to shrivel more than other commercialised cultivars. Water loss and shrivel in Gold9 fruit were investigated during storage at 1 °C for up to 14 weeks and shelf-life at 20 °C. In addition, the water status of ripe fruit was quantified by magnetic resonance imaging and the capacity of a crude outer pericarp cell wall extract to swell. Shrivelled Gold9 fruit had 1–6% weight loss, although 6% weight loss did not always result in shrivel. Three weeks of storage resulted in fruit taking longer to shrivel during shelf-life, with a concomitant higher weight loss by the time the fruit was shrivelled. In contrast, 14 weeks of storage resulted in fruit that shrivelled more rapidly in shelf-life at a lower weight loss. At any given time after harvest, fruit with more severe shrivel tended to be softer than less shrivelled fruit. Shrivel therefore appears associated with fruit softening. Outer pericarp tissue from ripe Gold9 fruit had lower water mobility and a greater capacity to swell than pericarp from other kiwifruit cultivars. It is concluded that shrivel is not determined simply by an absolute amount of water loss. The development and ease of expression of shrivel in Gold9, and possibly other kiwifruit, is influenced by softening and the water characteristics of the fruit outer pericarp when soft.