3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
3. FOOD ChEMISTRy & bIOTEChNOLOGy 3.1. Lectures
Create successful ePaper yourself
Turn your PDF publications into a flip-book with our unique Google optimized e-Paper software.
Chem. Listy, 102, s265–s1311 (2008) Food Chemistry & Biotechnology<br />
P105 SEA buCKThORN – SOuRCE OF VITAMIN C<br />
MILEnA VESPALCOVá a , DAnA VRánOVá a , JIřInA<br />
EnDSTRASSEROVá a and VOJTěCH řEZníČEK b<br />
a Faculty of Chemistry, Brno University of Technology, Institute<br />
of Food Science and Biotechnology, Purkynova 118,<br />
612 00 Brno,<br />
b Faculty of Horticulture, Mendel University of Agriculture<br />
and Forestry, Department of Breeding and Propagation of<br />
Horticultural Plants, Valtická 337, 691 44 Lednice,<br />
vespalcova@fch.vutbr.cz<br />
Introduction<br />
Sea buckthorn (Hippophae rhamnoides) is a bush giving<br />
small orange fruits. The bush comes from Asia but it has<br />
spread almost all over the world during last century because<br />
it can be grown even in harsher climate conditions without<br />
special agrotechnical technology. The largest producers of<br />
sea buckthorn are China, Russia, Finland and Germany at<br />
present.<br />
Sea buckthorn has been used as a natural drug in Asia<br />
to treat heart diseases, digestive tract diseases, cough, etc.<br />
Today, sea buckthorn extract is added not only in homeopathic<br />
remedies and food supplements, but also into syrups,<br />
jams, sweets, oils, face creams, shampoos, soaps, teas and<br />
many other products all over the world. Sea buckthorn contains<br />
many substances beneficial to human health, particularly<br />
vitamin C in amount larger than in other kinds of fruit or<br />
vegetable. Among other substances, also carotenoids, flavonoids,<br />
essential unsatured fatty acids and phytosterols should<br />
be mentioned. Their content depends not only on individual<br />
genotypes and cultivars of this plant but also on the site at<br />
which the plant is growing. This, naturally, holds also for the<br />
vitamin C, which frequently serves as one of basic indicators<br />
of alimentary and economical attractivity of planted sea buckthorn<br />
cultivars.<br />
The aim of the presented work is therefore the comparison<br />
on the vitamin C content in the sea buckthorn cultivars<br />
and genotypes growed by Faculty of Horticulture, Mendel<br />
University of Agriculture and Forestry Brno. Two methods<br />
have been applied for the determination of the vitamin C<br />
content in the sea buckthorn juice: HPLC with photometric<br />
detection and the direct coulometric determination of the<br />
vitamin C.<br />
Fig. 1. Analysis of the Vitaminová cultivar<br />
s813<br />
Experimental<br />
T h e H P L C D e t e r m i n a t i o n<br />
The Liquid chromatograph Spectra System equipped<br />
with the UV 6000 LP detector and the Chromquest software<br />
(Thermo Separation Products, USA) were used. for analyses<br />
of sea buckthorn juices prepared from the sea buckthorn<br />
cultivars as described below. The juices were injected on<br />
the TESSEK Separon SGX RPS Column (TESSEK, Praha,<br />
Czech Republic). The separation bed of 5 μm particles was<br />
of 5 mm in diameter and of 250 mm in length. 0.01M oxalic<br />
acid was the mobile phase. The column effluent was monitored<br />
at 254 nm.<br />
D i r e c t c o u l o m e t r y<br />
The coulometric analyser PCA/C-Vit (ISTRAn, Bratislava,<br />
Slovak Republik) equipped with porous working<br />
electrode served for direct coulometric determination of vitamin<br />
C without preliminary separation of the compound from<br />
sea buckthorn juices. The determination utilizes oxidation of<br />
ascorbic acid to dehydroascorbic acid<br />
C 6 H 8 O 6 – 2e → C 6 H 6 O 6 + 2H + (1)<br />
T h e P r e p a r a t i o n o f J u i c e s<br />
We analysed 12 cultivars of sea buckthorn listed<br />
in Table I. The cultivars were planted in the breeding station<br />
of the Horticulture Faculty, Mendel University of Agriculture<br />
and Forestry Brno in Žabčice. Fruits harvested October<br />
4, 2006 were immediately freezed to –18 °C and stored<br />
at this temperature in the freezing box till the analyses started<br />
April 2007. Approximately 5 grams of dry fruits freely<br />
warmed to room temperature was weighed to five digits and<br />
homogenized in the mortar with small amount oxalic acid,<br />
quantitatively transfered to the 100 ml volumetric flask by<br />
2 % (w/v) solution of oxalic acid in water and than filled with<br />
the acid solution to the division line. For chromatographic<br />
analyses, aliquot part of solution was filtered using the Büchner<br />
slit-sieve funnel and by cellulose 3-μm microfilter. The<br />
filtered sample was enriched by the special reaction solution<br />
R-020T (ISTRAn, Bratislava, Slovak Republic) for coulometric<br />
analyses. The analysed sample were prepared daily<br />
just before use and stored in dark during analyses.<br />
Results and Discussion<br />
A typical chromatogram of C vitamin analysis at conditions<br />
specified in Experimental is given on at Fig. 1. Vitamin<br />
C is in second peak, first peak is a mixture of unindentified<br />
impurities.<br />
Main validation parameters of successively repeated<br />
chromatographic analyses are as follows: LOD and LOQ<br />
of ascorbic acid is 0.2 and 0.7 mg dm –3 , respectively. Correlation<br />
coefficient of ascorbic acid is R 2 = 0.9942 for the concentration<br />
range of vitamin C from 0.0007 to 500 mg dm –3 .<br />
Repeatability of analyses in concentration ranges<br />
151–200 mg dm –3 , 51–150 mg dm –3 and 10–50 mg dm –3 given<br />
by RSD vaules is 4 %, 6 % and 10 %, respectively. Mean<br />
recovery of used analysis is 89.5 %. However, repeatability