C. LIU (1), G. Luan (1), X. Yin (2), Q. Li (1); (1) Jiangnan University, Wuxi, China; (2) Cargill Malt, Wayzata, MN, U.S.A.
Fermentation
Wednesday, June 4 - 10:00 a.m.-11:45 a.m.
Level 3, Crystal Room
Biogenic amines (BAs) are bioactive nitrogenous organic substances that
are produced by amino acid decarboxylation in fermented foods and have
been used as an indicator in the evaluation of food freshness and
microbial contamination status during fermentation. This study attempts
to clarify and quantify the sources of BAs during beer fermentation. The
content of 8 BAs in 29 beers, 5 malts, 5 hop pellets, 5 brewing water
samples, and fermentation broth samples from 3 fermentors were detected
using reversed-phase high-performance liquid chromatography (RP-HPLC)
optimized by the uniform design and modified simplex method. At the same
time, anaerobic bacteria colony forming units (CFU) in the fermentation
broth samples were also observed by the traditional spread plate
method. The derivatization reaction was carried out with benzoyl
chloride as the derivative reagent at 30°C for 20 min. The Agilent
Eclipse XDB-C18 column (250 mm × 4.6 mm i.d.) was chosen as the
chromatographic column, and mobile phases were ammonium acetate solution
(phase A, 0.01 mol/L) and acetonitrile (phase B) with a flow rate of
0.6 mL/min. The sample was analyzed at 254 nm with a column temperature
of 28°C. The results showed that eight BAs in most of beer samples could
be detected with a total content of 4.21–10.59 mg/L. The content of
histamine, tyramine, and total BAs in beer did not pose health risks for
consumers, however. The total content of BAs in barley malts fluctuated
between 66.03 and 148.32 mg/kg. Variety and origin were two important
factors affecting the BA content of malts. Meanwhile, histamine was not
detected in any of the hop pellets, and the total content of BAs in hop
pellets changed from 80.72 to 175.08 mg/kg. By contrast, no BAs was
detected in brewing water. Considering the very little addition of hops
(less than 0.3%) during brewing in China, malts were the main source of
BAs from brewing raw materials. Generally, the content of BAs from
fermentation stage only accounted for 10% of the total BAs in beer
fermentation broth, but it would vary among different fermentors. By
comparison, the CFUs of beer fermentation broth were directly
proportional to the total content of putrescine, cadaverine, tyramine,
and histamine, which illustrated that the content of the four BAs could
reflect the contamination status of anaerobic microorganisms. Therefore,
with the increasing in concerns about food safety, it will be of great
importance in the microbial control of brewing processes (especially for
draft beer without a pasteurization process) to monitor changes in BA
content.
Chunfeng Liu received a master’s degree in fermentation engineering
from Jiangnan University, Wuxi, China. She began employment with
Jiangnan University in 2008. She is now working as an assistant teacher
in the Lab of Brewing Science & Technology in the School of
Biotechnology. Since May 2011, she has functioned as an intermediate
experimentalist. At present, she is a Ph.D. on-the-job candidate with a
doctoral dissertation on “Biogenic Amines during Brewing Process.”
