Ethanol, in combination with carbon
dioxide, gives kefir its stimulating and subtly effervescent
characteristics. Soymilk revealed lower ethanol concentrations,
however, Liu and Lin (2000) have demonstrated that
addition of 1% glucose or lactose to soymilk enhances the
production of ethanol. The milk and soymilk kefirs generally
revealed increased levels of acetaldehyde and diacetyl, with a
lower n-hexanal level for soymilk kefir than soymilk. Produced
from the breakdown of polyunsaturated fatty acids
catalyzed by a lipoxygenase, n-hexanal exists naturally in
soymilk and is deemed responsible for the unpleasant,
spoiled flavor of soymilk (Murti and others 1993). Soymilk
fermented with kefir grains can reduce the concentration of
n-hexanal, thus improving palatability.