F. Bangerth, J. Streif
A restricted capacity of aroma volatile production of apple fruits is often observed if fruits are harvested prior to maturity or stored for an extended period of time at low O2- and/or high CO2- concentration in the storage atmosphere. It appears that in both cases similar if not identical physiological events are responsible for this failure. When fed with different volatile precursors such as alcohols, aldehydes, low to medium size fatty acids, and ketons, these fruit immediately start to produce high amounts of aroma volatiles. This indicates that the enzymes needed for volatile production are present, while precursors are lacking. The analysis of various lipid fractions yielded a good correlation between some unsaturated free fatty acids - in particular oleic- and linoleic acid - and volatile production. This and further experiments employing e.g. inhibitors of fatty acid biosynthesis or desaturation suggests that these substances are limiting under the above conditions.

A too low respiration, as a result of a disturbed ethylene sensitivity and with the consequence of low concentrations of ATP, NADPH etc. (required for fatty acid biosynthesis and desaturation), is proposed as the reason for for failure in aroma production under the conditions mentioned above.

For a more detailed overview on the various mechanisms affecting volatile aroma production discussed during the course of this talk, the reader is referred to our recent publications:

Bangerth, F. and Streif, J. (1998). FACTORS AFFECTING THE AROMA QUALITY OF APPLE FRUITS. Acta Hortic. 466, 29-30
DOI: 10.17660/ActaHortic.1998.466.4
Malus domestica Borkh., harvest, respiration, storage

Acta Horticulturae