The postharvest handling of zucchini fruit includes low-temperature storage, making cold stress unavoidable. We have investigated the changes of soluble
carbohydrates under this stress and its relation with
weight loss and chilling injury in zucchini fruit during postharvest storage at 4 °C and 20 °C for up to 14 days. Two varieties with different degrees of chilling tolerance were compared: Natura, the more tolerant variety, and Sinatra, the variety that suffered more severe chilling-injury symptoms and
weight loss. In both varieties, total soluble
carbohydrates, reducing soluble
carbohydrates and polyols content was generally higher during storage at 4 °C than at 20 °C, thus these parameters are related to the physiological response of zucchini fruit to cold stress. However, the
raffinose content increased in Natura and Sinatra fruits during storage at 4 °C and 20 °C, although at 20 °C the increase in
raffinose was more remarkable than at 4 °C in both varieties, so that the role of
raffinose could be more likely related to
dehydration than to chilling susceptibility of zucchini fruit.
Glucose,
fructose,
pinitol, and
acid invertase activity registered opposite trends in both varieties against chilling, increasing in Natura and decreasing in Sinatra. The increase in
acid invertase activity in Natura fruit during cold storage could contribute in part to the increase of these reducing
sugars, whose metabolism could be involved in the adaptation to postharvest cold storage.