The role of ethylene on volatile formation associated with ripening was investigated on melon hybrids transformed with an aminocyclopropane-1-carboxylic acid oxidase antisense gene. The headspace of four antisense hybrid fruits was analyzed by GC/MS and compared to that of nontransformed hybrid fruit. The major volatiles extracted from nontransformed hybrids were esters, mostly acetates. However, the most potent odorants were ethyl esters, such as ethyl butanoate, and branched-chain esters, such as ethyl 2-methylpropanoate and ethyl 2-methylbutanoate. In antisense hybrids, the total volatiles were 60-85% lower than that of the nontransformed hybrids. Volatiles with low odor values, such as ethyl, 2-methylpropyl and 2-methylbutyl acetates, were half to a fifth lower than in nontransformed hybrids, whereas potent odorants, such as ethyl 2-methylpropanoate and ethyl 2-methylbutanoate, were <3% that of nontransformed hybrids. Examination of the biosynthetic pathways of volatile esters derived from amino acids demonstrates that ethylene stimulated preferentially the synthesis of the most potent odorants.

Acrylamide levels in cooked/processed food can be reduced by treatment with citric acid or glycine. In a potato model system cooked at 180 degrees C for 10-60 min, these treatments affected the volatile profiles. Strecker aldehydes and alkylpyrazines, key flavor compounds of cooked potato, were monitored. Citric acid limited the generation of volatiles, particularly the alkylpyrazines. Glycine increased the total volatile yield by promoting the formation of certain alkylpyrazines, namely, 2,3-dimethylpyrazine, trimethylpyrazine, 2-ethyl-3,5-dimethylpyrazine, tetramethylpyrazine, and 2,5-diethyl-3-methylpyrazine. However, the formation of other pyrazines and Strecker aldehydes was suppressed. It was proposed that the opposing effects of these treatments on total volatile yield may be used to best advantage by employing a combined treatment at lower concentrations, especially as both treatments were found to have an additive effect in reducing acrylamide. This would minimize the impact on flavor but still achieve the desired reduction in acrylamide levels.