3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P68 ChARACTERIZATION OF “CZECh bEER” – A
PILOT STuDy
IVAnA MáROVá a , REnATA MIKULíKOVá b ,
ZBYněK ZDRáHAL c , HAnA KOnEČná c , KATEřInA
PAřILOVá a and AnDREA HALIEnOVá a
a Institute of Food Science and Biotechnology, Brno University
of Technology, Purkyňova 118, 612 00 Brno, Czech
Republic,
b Malting Institute, Brno, Czech Republic,
c Laboratory of Functional Genomics and Proteomics, Faculty
of Science, Kamenice 5, Brno, Czech Republic,
marova@fch.vutbr.cz
Introduction
The healthful and nutritive properties of beer have been
recognized by the medical profession for thousands of years.
Clinical and statistical evidence and laboratory studies have
shown that active substances in beer could influence immune
system, block cancer formation, protect against coronary
disease and even prolong life. Total benefitial effect of beer
and malt samples is a result of many individual contributions
of natural substances present in such complicated biological
material.
Within the last few years, development of modern instrumental
analytical methods has gained increasing importance
in authenticity control of food and food ingredients. The
characterization of beer samples has a lot of interest because
their composition can affect the taste and stability of beer and
consumer health. Many substances could contribute to final
taste of beer. To the most important probably belong proteins
and phenolic substances.
Polypeptides and proteins that influence, direct or indirectly,
beer foam quality are protein Z, LTP1 and hordein/glutelin
fragments, which originated from malt and have a direct
influence on beer foam quality. Other proteins, like malt
hordeins and albumins and wheat are, to some degree, also
important for beer quality. Protein hydrophobicity is pointed
out as a key parameter to enhance foam quality. Electrophoretic,
chromatographic and immunological analytical methods
are currently used to study polypeptides and proteins present
in barley, malt, wort, beer, and foam. Best results are obtained
when combinations of these methods are applied.
The aim of this pilot study is to compare composition
and to find specific and/or characteristic components in several
kinds of beer, malt and other brewing materials.
Material and Methods
13 samples of several types of malt (2 × Czech malt,
2 × German malt, 2 × carapils, 2 × caramel, 3 × dark-caramel,
2 × wheat) were gained from Malting Institute in Brno.
10 kinds of analyzed beer samples were obtained from retail
chain, additional 6 samples of Czech beer were gained from
breweries.
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A n t i o x i d a n t A n a l y s i s
Total phenolics were analyzed colometrically with Folin
Ciocalteu reagent (750 nm). Total flavonoid content was
analyzed colometrically with nanO 2 + AlCl 3 (510 nm).Total
antioxidant capacity was measured by Randox kit.
Individual flavonoids were analyzed by RP-HPLC/
UV-VIS method. Using extrenal standards concentration of
((-)catechin, catechin gallate, chlorogenic acid, epicatechin,
morin, quercetin, rutin was done. Samples (20 μl) were injected
into the RP-18 column (Biospher PSI 200 C18, 7 μm,
150 mm × 4.6 mm). Mobile phases were methanol/water
(55 : 45) for catechins and methanol/acetonitrile/water + 1%
phosporic acid (20 : 30 : 50) for flavonoid analysis. The flow
rate was maintained at 0.75 ml min –1 , analysis was performed
at 30 °C. Carotenoids (beta-carotene, lycopene, luteine) were
analyzed by RP-HPLC with spectrophotometric detection
using Hypersil C18, 5 μm, 250 mm × 4.6 mm column, isocratic
elution by methanol at the flow rate 1.1 ml min –1 and
at 45 °C.
Identifiaction of individual flavonoids and catechins was
performed by on-line LC/MS/ESI analysis (Mass spectrometer
LCQ Advantage Max). Optimalization of mass spectrometry
analysis in negative mode was done using chlorogenic
acid. Samples of beer were mixed with 5 times higher amount
of 2% HCl and extracted by SPE (Amid-2 column). Isocratic
elution was performed by mobile phase acetonitrol:1% acetic
acid 50 : 50 at flow rate 0.4 ml min –1 at 30 °C. Individual
components were detected in full scan module.
1 D G e l E l e c t r o p h o r e s i s
1D PAGE-SDS electrophoresis of proteins was carried
out by common procedure using 15% and 17.5% polyacrylamide
gels. Proteins were staining by Coomassie Blue and by
silver staining. For comparison, microfluidic technique using
1D Experion system (BioRad) and P260 chips was used for
yeast protein analysis too.
2 D G e l E l e c t r o p h o r e s i s a n d L C -
M S / M S
2D electrophoresis of proteins was optimized in cooperation
with Laboratory of Functional Genomics and Proteomics,
Faculty of Science, Masaryk University of Brno. 2D
gels were obtained using protein preparatives isolated from
lyophilized cells. After optimization of separation conditions
proteomes from lyophilized beer samples were analyzed.
Quantitative analysis was done using BioRad Laboratories
2D software. Identification of some spots was done using
LC-MS/MS.
Results
The content of total phenolics in malt was about 1.4 ×
higher than in wort and hop wort and 1.5–2.5 × higher than
in beer samples. Phenolic content decreased in sequence dark
caramel – caramel – Czech – German – wheat malt. The main
flavonoid detected in most of malt and wort samples was (–)
catechin followed by rutin and quercetin. Czech malt con-