MICHAEL J. HOLEWA (1), Roland H. Pahl (1)
(1) VLB Berlin, Berlin, Germany
Breweries put a lot of effort on the quality control of raw materials
and the product itself at the different process steps. On the other
hand, hardly any testing is carried out at filling plants regarding the
packaging means. This is common practice due to extensive testing
equipment necessary for each single packaging material and property. In
the presented research work, the possibilities of near-infrared
spectroscopy in determining chemical and/or physical features of a large
variety of packaging materials of the beverage industry are
investigated. The study is carried out with a Fourier transformation
spectrometer covering the whole near-infrared spectrum from 780 to 2,500
nm at a resolution of 4 cm–1. Transmission measuring of
liquid samples in glass vials as well as reflection measuring of solids
is applicable. Using intricate multivariate calibration procedures,
methods are developed for the analysis of labeling glue (contents of
casein, urea, total nitrogen, starch, and solids as well as viscosity),
bottle crates made of HDPE (UV-resistance), PET-bottles (content of
additives like polyamide or oxygen scavengers and detection of
coatings), and closures (material and additive identification). Two
important components of labeling glue, urea and casein, both contain
amine groups. In order to tell these nitrogen sources apart, 50 model
solutions were produced containing different amounts of casein or urea
only. Quantitative calibration led to good results and revealed the
decisive spectral regions. In the next step, 30 model solutions
containing casein and urea in varying concentrations and ratios were
produced and calibrated successfully. To take another matrix effect of
labeling adhesives into account, 15 more model solutions were produced
with starch added. With these mixtures, methods for all three components
could be developed that hit the actual concentration better than ±1%.
Similar results were obtained in calibrations for total nitrogen,
starch, and solids in 25 professional labeling glues when compared to
the values of the reference analyzes. A proper method for the
determination of the viscosity of these adhesives could not be
established, though. Further studies on the other packaging means
mentioned above are still in progress.
Michael Holewa was born in 1971 and apprenticed to become a brewer
and maltster from 1990 to 1992 at the Holsten Brewery in Hamburg,
Germany. Subsequently he was employed there until he started his studies
in brewing technology in 1993 at the Technical University of Berlin.
After graduating in 2001, he went to the Binding Brewery in Frankfurt,
Germany, for one year, working on analytics in the laboratory. In 2002
he changed to the Kölner Verbund Breweries in Cologne, Germany, doing
quality assurance and project management. This engagement was followed
by a job at the Pfungstädter Brewery in Pfungstadt, Germany, from 2005
to 2008, where he was responsible for quality management and process
optimization. Since 2009 he has benn employed at the Research Institute
for Engineering and Packaging of VLB Berlin, where he is currently doing
research, consulting, and teaching.
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