[Simultaneous determination of volatile substances in intact apples and apple juice using gas chromatographic head-space analysis].

Relations between the rate of the generation of volatiles by intact apples during their ripening and the contents of the volatiles in the juice pressed out of the apples were investigated with the aid of two different techniques of headspace gas analysis. The juice was analyzed by the technique of stripping and trapping in a closed circuit, which made it possible to determine the violatiles in concentrations of several tens of micrograms/1 of juice. The volatiles generated by intact apples were determined by analysis the gas percolating through a layer of fruits by a sample-enrichment technique, the sensitivity of analysis being some hundredths of micrograms/1. The resistance of the apple matrix against the transfer of volatiles generated by apples to their surrounding does not vary substantially during the ripening of apples on tree. The permeability constant of the apple matrix ranges from some tenths to units of m1/(kg . h) with all the volatiles and apple species studied.