Aroma characteristics of lupin and soybean after germination and effect of fermentation on lupin aroma

- Lupin and soybean flavor profiles were influenced by germination and fermentation.
- Beany odor volatiles were significantly higher in soybean compared to lupin.
- Sweet and meaty characteristics increased after germination.
- Methoxypyrazines were important odor-impact volatiles in lupin and soybean.

Greater human consumption of Australian sweet lupin (Lupinus angustifolius) and other legume products such as soybean (Glycine max) is often limited due to undesirable beany flavor. The impacts of germination of lupin and soybean seeds and fermentation of lupin flour on aroma profiles were compared by gas chromatography olfactometry using trained sensory assessors. Untreated soybean compared to untreated lupin had significantly higher concentrations of volatiles commonly associated with beany flavor in legumes; (E)-2-hexanal, (E)-2-octenal, 1-octen-3-one, 1-hexanol and 1-heptanol. After germination of lupin and soybean, 2-methylbutanal was the most abundant volatile, increasing meaty and brothy odor characteristics. Germination of lupin and soybean also increased sweet, woody, mushroom and baked aroma notes. Fermentation of lupin increased mushroom, soil, green and nutty aroma characteristics, however beany odor did not decrease. Germination and to a lesser extent fermentation, may be successful strategies to increase the acceptability of legume flavor.