C. Liu (1), H. Shi (1), X. Yin (2), Q. LI (1); (1) Jiangnan University, Wuxi, China; (2) Cargill Malt, Wayzata, MN, U.S.A.
Sensory II
Thursday, June 5 - 10:00 a.m.-11:45 a.m.
Lobby Level, Empire Ballroom
Many components in beer are prone to formation of hydrogen bonding.
Flavor substances in beer can affect the chemical shift of hydrogen
bonding according to their different concentrations. To increase brewing
capacity, reduce operating costs, and improve beer stability,
high-gravity brewing technology is used all over the world. However,
beer flavor after dilution does not match very well due to the addition
of dilution water that may disturb the balance of flavor substances. In
this study, high-resolution nuclear magnetic (NMR) spectroscopy with
water suppression was applied in the observation of hydrogen bonding
associations among different flavor substances in 30 commercial beers
and beer samples during the dilution process. Along with the analysis of
chemical shift and sensory evaluation, several key factors, including
the content of four alcohols, two esters, and six organic acids, were
determined in this research, which could be used to investigate the
relationship between hydrogen bonding intensity and flavor components
through correlation, principal component, and multiple regression
analyses. The results showed that the content of ethanol, ethyl acetate,
isoamyl acetate, malic acid, and lactic acid were positively related to
sensory evaluation scores (correlation coefficients were 0.773, 0.604,
0.855, 0.582, and 0.769, respectively). Meanwhile, the variations of
chemical shift (delta chemical shift) were also positively related to
the sensory evaluation scores, especially for ethyl acetate, isoamyl
acetate, n-propanol, isobutanol, and isoamylol (correlation coefficients
were 0.637, 0.688, 0.643, 0.834, and 0.607, respectively). As a result,
a multiple nonlinearity model could be obtained as follows: sensory
evaluation score = 4.219 + 0.701 × PC1 + 0.078 × PC2 + 0.150 × PC3,
where PC1, PC2, and PC3 represented the chemical shift factor,
alcohols-esters factor, and organic acid factor, respectively. The
average error was 1.21% in the validated experiment. Furthermore, the
dilution beer samples from different high-gravity brewing crafts were
evaluated by this methodology. In the end, the two step dilution craft
with dilution ratio of the first step in 100% and the hydration time of
24 hr (at 0°C) proved to be the better process for high-gravity brewing.
Qi Li received a Ph.D. degree in brewing engineering from Jiangnan
University, Wuxi, China. She began working in the School of Biological
Engineering in 1999. She is now in charge of the beer brewing lab and
has functioned as vice president of the School of Biological Engineering
since 2009. Qi is one of the key members of the China Beer Industry
Association and China Standardization Professional Association. In
recognition of her contribution to ASBC serving international members,
in 2012 the ASBC Board honored Qi with a lifetime membership.
