KI HYUN MYOUNG (1), Ha Jong Choi (1), Kyu Hun Lim (1), Jung Hun Oh (2), Jae Soon Kang (2), Sihyeock Lee (2)
(1) Hite Brewery, Hongchon-gun, Kangwon-Do, Korea; (2) Seoul National University, Gwnak-gu, Seoul, Korea
Insects or insect remains found in beer are one of the major issues
in consumer claim. Accurate estimation of inflow time is a critical
factor for the settlement of such claims related with beer-contaminating
insects but no reliable methods have been developed. In an attempt to
establish a molecular marker-based diagnostic method, the degradation
rates of 18S rRNA genes in the insects soaked in 500 ml of beer were
investigated by quantitative real-time PCR (qPCR) over a one-month
period at room temperature. Among the six insect species tested, the
house fly (Musca domestica) and honey bee (Apis mellifera) revealed high correlations (r2
= 0.974–0.990) between the degradation of 18S rRNA gene and inflow
time. Experiments using house flies at three different temperatures (4,
25, and 37°C) disclosed that the degradation rate of the 18S rRNA gene
was relatively higher at higher temperatures. In these insects,
statistically significant distinction was possible between the samples
stored in beer less than 7 days and more than 7 days. Other insects,
including the fruit fly, common house mosquito, German cockroach, and
Indian meal moth, displayed poor correlations, which appeared to be
attributed to the inconsistent genomic DNA extraction likely due to
small sample size or/and disintegration of body parts during storage in
beer. With proper improvement in DNA extraction, this 18S rRNA-based
diagnostic method would be applicable for estimating the inflow time of
beer-contaminating insects.
Ki Hyun Myoung received a bachelor’s degree in food science
technology from Kyunghee University in South Korea. He began employment
with Hite brewery in 1993 as an analyst in the analytical laboratory of
the Quality Control Center. He moved to the Department of Brewing, and
he participated in building a new plant in Kanwon Do in 1997. He moved
to the Research & Development Center in 2001 and worked on quality
control of brewing and raw materials until 2007. He has attended a
six-month intensive course from March 2005 through August 2005 at the
Scandinavian School of Brewing, Copenhagen, Denmark; Feldschlosschen,
Rheinfelden, Switzerland; Carlsberg Brewery, Northampon, UK; and
Carlsberg Brewery Malaysia Berhad, Malaysia, as part of an in-depth
process and quality course designed for Hite by the Scandinavian School
of Brewing. In 2008 he became the executive general manager in the
laboratory of the Research & Development Center.
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