P-11
Thermoanalytical approach to identification of foreign substances in
beer. For the past several years, the number of complaints brought by consumers has
been increasing rapidly in Japan, as they become more aware of the quality and
safety of food products. One of the most predominant cases of complaints is the
alleged contamination of foreign substances in the products. To deal with the
complaint amicably and alleviate the misunderstanding, it is important to
provide customers with swift and detailed feedback. On extremely rare occasions,
foreign substances are found from raw materials and work-in-process products in
the breweries. In the latter cases, the rapid determination of the identity and
source of contamination is essential to prevent a problem from recurring. But we
encountered difficulties with the conventional analytical methods in the
following cases: 1) A trace amount of foreign substance is analyzed; 2)
Time-consuming procedures are involved; 3) The risk of sample loss and inadvertent
contamination during analysis is conceivable; 4) Samples are not dissolved in
any solvents. To overcome these difficulties, we have developed new methods for
the analysis of foreign substances. For this purpose, we evaluated the thermal
analysis methods, using pyrolizer and GC/MS systems, such as thermal
desorption-GC/MS, pyrolysis-GC/MS and reactive pyrolysis-GC/MS. In this investigation, the
specific peaks or the chromatographic profiles were obtained from foreign
substances and compared with those from the references. As a consequence, it was
demonstrated that the identity and, in some cases, the source of contamination
were successfully determined for various unknown samples. In our presentation,
we will illustrate some applications of the Py-GC/MS to the identification of
foreign substances, including synthetic high-polymers such as rubbers and
plastics, and natural organic compounds such as polyphenols and lipids. Our
newly developed methods have overcome the four difficulties described earlier
and provide practical solutions to the analysis of foreign substances. It should
also be noted that they are well suited to characterizing unknown trace
materials and complex compounds. In addition, our methods offer the following
advantages: 1) As little as 1 microgram sample can be analyzed; 2) The analysis
is performed easily and swiftly within approximately 20 minutes; 3) The risk of
sample loss and contamination is low; 4) Solvents are not required for analysis.
Kazutoshi Kitai graduated from the University of Tokyo with a masters
degree, Department of Applied Biological Chemistry, and joined Asahi Breweries
Ltd. in 1996. He has been engaged in research and development of brewing
technology, especially in analytical chemistry.
KAZUTOSHI KITAI, Minoru Kobayashi, Yuji Onagawa, Isao Nadaoka, Yutaka Miyamoto,
and Hiroshi Yamashita. Analytical Technology Laboratory, Asahi Breweries Ltd.,
1-1-21, Midori, Moriya, Ibaraki, 302-0106, Japan.