Induction of apple scald by anaerobiosis has similar characteristics to naturally occurring superficial scald in `Granny Smith' apple fruit
Anne D. Bauchot, Suzanne J. Reid, Gavin S. Ross and Douglas M. Burmeister
Postharvest Biology and Technology Vol: 16 Issue: 1 Pages: 9-14
1999
บทคัดย่อ
Scald, which can be induced by anaerobiosis (N2-induced), may
involve similar physiological and biochemical mechanisms to those which
contribute to naturally occurring superficial scald. To investigate this
hypothesis, Granny Smith apples were harvested weekly from four orchards and
stored in air for 16 weeks at 0°C, before being ventilated
with N2 for up to 4 days, or held in air at 20°C.
Following N2 treatment, scald developed within a few minutes of
transfer to air and its severity was positively correlated with duration of N2
treatment. Susceptibility to induction of scald with N2 decreased
through the harvest season and increased with length of refrigerated storage.
Following N2 treatment, the levels of -farnesene,
conjugated triene (CTH) and OD200 (Abs200) were
significantly lower than in fruit held continuously in air. This effect was
more apparent in the early than late harvest fruit. RNA gel blot analysis of
polyphenol oxidase (PPO) was conducted on selected samples. Expression of PPO
was very low while fruit were held in N2, suggesting that the
regulation of PPO gene expression is dependent on oxygen. Once fruit were
removed to air, browning occurred almost immediately, too rapidly for the
initial development of browning symptoms in scald to be attributed to increased
PPO gene expression. We conclude that anaerobically induced scald development
has similar characteristics of naturally occurring superficial scald and in
both cases elevated PPO gene expression may not be associated with the initial
development of symptoms.