IDENTIFICATION OF THE KEY ODORANTS IN RAW FRENCH BEANS AND CHANGES DURING COOKING

By application of aroma extract dilution analysis (AEDA) to an extract prepared from raw French beans, 25 odour-active compounds with flavou r dilution (FD) factors in the range 4-2048 were detected and subseque ntly identified. Among them, (Z)-3-hexenal (green, leaf-like), 1-octen e-3-one (mushroom like), 3-isobutyl-2-methoxypyrazine (earthy, beany) and (E,Z)-2,6-nonadienal (cucumber-like) showed the highest FD factors . In an extract prepared from the same amount of cooked beans, 3-isobu tyl-2-methoxypyrazine was identified as the most potent odorant, follo wed by 1,5-(Z)-octadiene-3-one (geranium-like), 3-isopropyl-3-methoxyp yrazine (earthy, beany), 3-(methylthio)propanal (methional; cooked pot ato), 4,5-epoxy-(E)-2-decenal (metallic) and an unknown compound (FD 2 56) with a smell of geranium leaves. A decrease in (Z)-3-hexenal and 1 -pentene-3-one (etheral, pungent) and an increase in methional during cooking were shown to be mainly responsible for the flavour changes in duced by cooking the beans.