Changes in volatile compounds produced during thua nao
production
Arunsri Leejeerajumnean
Department of Food Science and Technology, Faculty of Engineering
and Industrial Technology, Silpakorn University, Nakorn Pathom, 73000
Thailand
Email: arunsri@su.ac.th
Abstract
Thua nao, a traditional proteolytic fermented soybean condiment in northern
Thailand, was prepared from whole soybeans by natural flora fermentation.
The formation of volatile compounds in thua nao during fermentation of
cooked soybeans by mix culture of Bacillus was studied. Hexanal and 2pentyl furan were the main volatile compounds in cooked soybeans. After 12
h of fermentation, 3-hydroxy-2-butanone was the main volatile compound and
after 24 h, butanone and 3-hydroxy-2-butanone were the most abundant
volatile compounds. Following 72 h of fermentation, acids and esters (2methyl butanoate), dimethyl disulphide, pyrazines, butanone and
benzaldehyde were the volatiles produced in the greatest quantities. The
volatile compound in dry thua nao was a mixture of many compounds, not
mainly only ketones, pyrazines and sulphur containing compounds, but also
acids and esters, alsohols and aldehydes and furans. The volatlies in thua
nao were different from those in natto (used in this experiment), which were
mainly only pyrazines and ketones.