New Zealand Journal of Crop and Horticultural Science abstracts
Review: Factors affecting apple aroma/flavour volatile concentration: a review
JONATHAN DIXON
ERROL W. HEWETT
Institute of Natural Resources
College of Sciences
Massey University
Private Bag 11 222
Palmerston North, New Zealand
email: E.W.Hewett@massey.ac.nz
Abstract Typical apple (
Malus domestica Borkh.)
flavour develops during ripening. Maximum endogenous volatile concentration
occurs at the climacteric peak but it is not known whether the volatile
biosynthetic enzymes are constitutive or induced during the climacteric.
Exposing apples to hypoxic conditions induces accumulation of high
concentrations of acetaldehyde and ethanol; after return to air ethyl esters
are enhanced and non-ethyl esters decrease. There are differences in degree of
ethyl ester enhancement among cultivars. These may be because of: differential
activity or synthesis of alcohol acyl CoA transferase (AAT) or alcohol
dehydrogenase (ADH); separate iso-forms of AAT and ADH each with their own
substrate specificity; variation in alcohol precursors in different cultivars;
or a combination of all three. Volatile production is greater at higher
temperatures in the range from 0 to 30deg.C but exposure to low temperatures
(<3deg.C) for more than 3 months decreases production. Temperature
influences the production of specific volatiles with some compounds only being
produced at certain temperatures. It is not known how temperature will affect
volatile production after exposure to hypoxia. It is suggested that the
enhanced volatile production that occurs in apples following an hypoxic
treatment might overcome or reverse the decreases that are induced by low
temperatures and controlled atmosphere (CA) storage. The use of hypoxia to
enhance volatile concentrations may be a beneficial side effect when such
treatments are used for disinfestation purposes. It is possible that given
equal efficacy, hypoxia could be either preferred or used as an adjunct to heat
treatments to eradicate insects. In addition hypoxic treatment of fresh fruit
could induce significant increases in volatile concentrations that could be
used in production of high quality essences from apple juice.
Keywords Malus domestica Borkh.; hypoxia; temperature;
maturity; volatile biosynthesis; ethyl esters; flavour enhancement;
disinfestation; storage; fruit quality; apple juice
H00004
Received 11 February 2000; accepted 6 August 2000
PDF file of entire paper: medium quality (1648K); (scanned from paper original: notes about this process)
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