3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures

Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology
P99 ThE IMPACT OF FERMENTATION PROCESS
ON AMINO ACID PROFILE OF GRÜNER
VELTLINER whITE wINE
LEnKA ŠťAVíKOVá and MIROSLAV HTKA
Department of Food Chemistry and Biotechnology, Faculty
of Chemistry, Brno University of Technology, Purkyňova 118,
612 00 Brno, Czech Republic,
stavikova@fch.vutbr.cz
Introduction
Amino acids represent 30–40 % of total wine nitrogen.
It is generally accepted, that they may act as nutrients for both
yeast and malolactic bacteria during the wine fermentation.
In the yeasts’ growing phase, they can be either partially or
totaly metabolised, excreted by living yeasts at the end of the
fermentation or released by proteolysis during the autolysis
of the dead yeasts. In addition, amino acids can serve as substrate
for the production of aroma compounds 3–5 or biogenic
amines 6,7 in wine. On the contrary, their production by enzymatic
degradation of the grape proteins was described 1,2 .
There is no doubt, that their content in wines is dependent
on the fertilization and climatic conditions, duration of
skin maceration in the must, field treatments and on other
factors 2,6–8 . Recently, amino acids’ content in wines is studied
extensively for several reasons, e. g, due to the differentiation
of Champagnes and sparkling wines 2 , the determination
of geographic origin, variety and vintage 2,7,8 , the assessment
of substances with enological interest (e.g., of aroma
compounds) 3–5 , or toxicological interest (biogenic amines
etc.) 6,7,9,10 , the monitoring of nitrogen metabolism during
the fermentation 5,11 or their changes during the ageing of
wines 12,13 .
The determination of amino acid in wines is usually
employed by HPLC with precolumn derivatization using
o-phthaldialdehyde (OPA), fluorenylmethyl-chloroformate
(FMOC) or 6-aminoquinolyl-n-hydroxysuc-cinimidyl carbamate
(AQC). 2,4,6–8,10–14 Ion-exchange chromatography with
post-column derivatization with ninhydrin reagent 1,9,15 or comprehensive
two-dimensional gas chromatography 16 was successfully
applied, as well.
In this contribution, the impact of spontaneous and
inoculated fermentations on amino acids profile of Grüner
Veltliner (Vitis vinifera) white wine is presented, applying
an ion exchange chromatography with post-column derivatization
with ninhydrin and spectrophotometric detection
system.
Experimental
W i n e S a m p l e
Grüner Veltliner (Veltlínské zelené) white wine variety
from Velké Pavlovice sub-region (South Moravia region,
Czech Republic) was investigated. Wine samples were prepared
by two different technological processes. In the first
one, the spontaneous fermentation was used, whereas in the
second, wine was prepared by inoculated fermentation. The
s800
sampling procedure was performed every other day continuously,
starting from cider up to the final young wine.
C h r o m a t o g r a p h i c C o n d i t i o n s
Respective wine sample was analysed to free amino
acids (FAA) content after its filtration and dilution in Li-citric
buffer (pH 2.2), employing the AAA T339 amino acid analyser
(Mikrotechna, Prague, Czech Republic) equipped with
Ostion LG AnB ion-exchange resin column. Amino acids
separation was achiewed by stepwise gradient elution using
the Li-citric buffer system. Post-column derivatization with
ninhydrin reagent and spectrophotometric measurement was
used for their determination.
Results
Concentration profile of the following 36 compounds
potentially present in wine samples under study was
investigated: cysteic acid (CystAC), tautine (Tau), phosphoethanolamine
(PE), urea, aspartic acid (Asp), hydroxyproline
(Hpro), threonine (Thr), serine (Ser), asparagine (Asn), glutamic
acid (Glu), glutamine (Gln), α-aminoadipic acid (α-
AAD), proline (Pro), glycine (Gly), alanine (Ala), citrulline
(Cit), α-aminobutyric acid (α-ABA), valine (Val), cysteine
(Cys), methionine (Met), cystathionine (Cysne), isoleucine
(Ile), leucine (Leu), tyrosine (Tyr), phenylalanine (Phe), αalanine
(α-ALA), β-aminobutyric acid (β-ABA), γ-aminobutyric
acid (GABA), ethanolamine (EA), ammonium (nH 3 ),
ornithine (Orn), lysine (Lys), histidine (His), 1-methyl histidine
(1-met His), 3-methyl histidine (3-met His), arginine
(Arg).
Results obtained showed, that total FAA concentration
in wine samples prepared by spontaneous fermentation
ranged from 302.30 mg dm –3 up to 1,578.25 mg dm –3 ,
whereas in those prepared by inoculated fermentation, from
289.64 mg dm –3 up to 1,371.41 mg dm –3 .
In the sample prepared by a spontaneous fermentation,
the total concentration of free amino acids slowly increased
during the first three days from 1,299.75 g dm –3 to the maximum
of 1,371.47 mg dm –3 , then in next six days of fermen-
Fig. 1. Total free amino acids content monitored during 24 days
in the wine samples prepared by spontaneous (�) and inoculated
(�) fermentation processes