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The solutions of cellulolytic enzymes designated as standards for the cellulase activity assay were exposed in sealed glass ampoules (containing at least 100 Cx-units per ml in 30% w/w glycerol) to gamma radiation within the dose interval of 0-18 kGy. Glycerol was found to be the best enzyme stabiliser, however, the dose for the decontamination had to be increased in comparison with the original solution because glycerol protected also the contaminating microflora. The preparation after such treatment (30% of glycerol, dose 7 kGy) retained about 95% of the initial enzymatic activity without any decrease taking place in the following 6 months. The loss of the side activities did not exceed 10.5% and no bacterial contamination was detected either after 6 months of storage following the irradiation. No difference was found in the immunoreactivity of cellulases or in protein chromatografic (FPLC) pattern between the original and the irradiated enzyme preparations.

Campylobacter species, in particular C. jejuni and C. coli, cause infections which vary in symptoms, ranging from asymptomatic to severe chronic illness. The only ISO method for the detection of Campylobacter spp. until now has been the cultivation by selective enrichment and distinct conditions of growth taking several days to complete. We compared the Singlepath^® Campylobacter test which involved 24 h of enrichment in Bolton broth, with PCR-based identification. Chicken meat salad with mayonnaise was spiked with C. jejuni and C. coli and the detection limit was determined. PCR provided the same detection limit of 10² CFU/ml for both strains. The immunotest Singlepath^® was positive with C. jejuni only, the quantity of cells being 10³ CFU/ml. C. coli was undetectable by Singlepath^®, even the concentration of 10⁵ did not reveal a positive reaction.

Phenolic compounds were extracted from rye caryopses with 80% (v/v) methanol. Phenolic acids were determined as free compounds and those liberated from soluble esters and glycosides. The analyses were performed using a Waters HPLC system equipped with a diode array detector (DAD). The following free phenolic acids were found: p-coumaric, ferulic and sinapic; the phenolic acids liberated from soluble esters were as follows: vanillic, caffeic, p-coumaric, ferulic and sinapic; and those liberated from soluble glycosides were the following: vanillic, p-coumaric, ferulic and sinapic. In rye caryopses, phenolic acids were chiefly in the form of soluble esters. A diode array detector was especially useful for the determination of vanillic acid: the UV spectrum of this compound showed a maximum at 260 nm whereas UV spectra of other phenolic acids were characterised by maxima at longer wavelengths.

Commercial defatted soy flour (DSF) was dispersed in distilled water at pH 7 to prepare 5% aqueous dispersion. Soy protein hydrolysates (SPH) were obtained by enzymatic hydrolysis of the DSF using three different proteases (Flavourzyme 1000 L, No-vozym FM 2.0 L and Alcalase 2.4 L FG). The highest degree of hydrolysis (DH 39.5) was observed in the presence of protease Flavourzyme. SPH were used for measuring functional properties (foaming stability, gelation). Treatment with Flavourzyme improved foaming of proteins of DSF. Foaming stability was low in the presence of Novozym. Proteases treated DSF showed good gelation properties, mainly in the case of treatment with Flavourzyme. SDS-PAGE analysis showed that after enzyme ad-dition to the 5% aqueous dispersion of DSF each enzyme degraded both b-conglycinin and glycinin. In general, the basic polypeptide from glycinin showed the highest resistance to proteolytic activity. The most abundant free amino acids in the hydrolysates were histidine (30%), leucine (24%) and tyrosine (19%) in the case of the treatment with proteases Alcalase and Novozym, and arginine (22.1%), leucine (10.6%) and phenylalanine (12.9%) in the case of the treatment with Flavourzyme.

The purpose of this study was to compare the composition and contents of phenolic acids and condensed tannin in the seed coats of white and coloured varieties of pea and to examine the antioxidant properties of methanol and acetone extracts containing these phenolic compounds. The contents of phenolic acids were quantified by the HPLC analysis. The sum of free phenolic acids, those liberated from soluble esters and those liberated from soluble glycosides, was higher for coloured seed coat (78.53 g per g dry matter) than for the white seed coat (17.17 g/g dry matter). Protocatechuic, gentisic and vanillic acids were found dominant in the coloured seed coat, while ferulic and coumaric acids in the white seed coat. The content of condensed tannins was 1560 mg of catechin equivalent/100 g of coloured seed coat as determined by a vanillin assay. No condensed tannins were detected in the white seed coat. The antioxidant activity of extracts was measured by the oxidation of phosphatidylcholine to hydroxyperoxidephosphatidyl choline in the liposome system. Strong antioxidant properties were observed in a crude tannin extract from the coloured seed coat. These properties were slightly changed after the seed coat was cooked in water for 30, 60 and 90 min.

Tyrosine was oxidised with either potassium peroxodisulphate or glyoxal. Volatile reaction products were isolated and analysed by GC/FID and GC/MS, derivatised with diazomethane and analysed by the same methods. Eight reaction products were identified. The major products were the expected Strecker aldehyde (4-hydroxyphenylacetaldehyde) and its lower homologue 4-hydroxybenzaldehyde. They were followed by 1-(4-hydroxyphenyl)-3-propionaldehyde, phenylacetaldehyde, benzaldehyde, phenol, 4-hydroxybenzoic, and benzoic acid. Analogously, the oxidation of 3,4-dihydroxyphenylalanine yielded the corresponding Strecker aldehyde (3,4-dihydroxyphenylacetaldehyde), its lower homologue 3,4-dihydroxybenzaldehyde, 3,4-dihydroxybenzoic, 3,4-dihydroxyphenylacetic, and caffeic acid. An identification of these oxidation products of tyrosine and 3,4-dihydroxyphenylalanine assumes homolytic cleavage of the Strecker aldehydes and a recombination of free radicals formed by this cleavage. As minor products, six O- and N-heterocyclic compounds arose in systems containing glyoxal (pyrazine, methyl- and ethylpyrazine, 3-furancarbaldehyde, 5-methyl-2-furancarbaldehyde, 2-pyrrolcarbaldehyde).

Aspartic and glutamic acids, asparagine and glutamine were oxidised with either potassium peroxodisulphate or glyoxal. Nonvolatile products were derivatised and analysed by GC/FID and GC/MS. Volatile reaction products were isolated and analysed by the same methods. It was found that the degradation reactions of amino acids are complex. Amino acids are principally degraded via the corresponding a-keto acids to Strecker aldehydes (aspartic acid to oxalacetic and 3-oxopropionic acids and glutamic acid to a-ketoglutaric and 4-oxobutyric acids), which are unstable and decomposed by decarboxylation to the corresponding aldehydes. Aspartic acid also eliminates ammonia and yields fumaric acid whereas glutamic acid gives rise to an imine, pyroglutamic acid. A recombination of free radicals leads to dicarboxylic acids (succinic acid from aspartic acid, succinic, glutaric and adipic acids from glutamic acid). The major volatile products (besides the aldehydes) are lower carboxylic acids (acetic acid from aspartic acid and propionic acid acid from glutamic acid) that can at least partly arise by radical reactions. In both quality and quantity terms, a higher amount of degradation products arises by oxidation of amino acids by peroxodisulphate.

Resveratrol is a substance of a natural character, naturally present in some foods, namely in wine. The grape peels of Vitis vinifera contain about 50 to 100 mg of resveratrol/g and the average resveratrol concentration in red wines produced in the world fluctuates between 1.0 to 3.0 mg/l. A few biological activities were discovered with resveratrol in the last few years such as positive action against some cardiovascular diseases described as so called French paradox and anti-cancer chemo-preventive activity. The denominators of those activities are anti-oxidizing and free radical scavenging features of resveratrol molecule. As expected, red wines from vines originating in the Czech vineyard regions appear to contain relatively high levels of resveratrol (from 1.4 to 9.4 mg/l.

Ascorbic acid (AA) and total polyphenol content (TP) are important plant antioxidants with many healthy effects, such as "scavengers of free radicals", they inhibit oxidation of low-density lipoproteins, lower cholesterol levels, decrease fragility of blood vessels and increase their permeability, decrease heart coronary risk, etc. One of important sources of these compounds in human nutrition are apples. In two years (1997 and 1998) was investigated ascorbic acid content (AA) and total polyphenol content (TP) in three apple varieties (Idared, Gloster and Ontario) cultivated under equal conditions on the experimental plot of Czech University of Agriculture in Prague-Suchdol. AA content was determined by titration method with 2,6-dichlorphenolindophenol and TP content spectrophotometrically with Folin-Ciocalteau's reagent. In two years' trials AA and TP contents were estimated immediately after harvest in September and then monthly during storage for six months at +5°C. Statistically high significant differences were determined both in AA and TP contents during storage period - there was observed meaningful AA and TP decrease. The highest antioxidant content showed in both years early variety Ontario (in average 12.05 mg/kg AA, 2011.5 mg/kg TP), the lowest semi-early variety Gloster (in average 5.45 mg/kg AA, 1738.0 mg/kg TP). In this context the variety Ontario is the most favourable. The highest decrease of AA content was in variety Ontario (-30.05 %rel), the lowest in variety Gloster (-22.93 %rel ); in TP contents were differences negligible (-27.14 and -27.82 %rel). In spite of this decrease were in Ontario variety both values after six months storage the most favourable (8.45 mg/kg AA, 1466.5 mg/kg TP). Results were statistically evaluated with F-test and t-test. There could be seen differences among varieties and years of cultivation, but these differences were under the level of statistical significance showing only apparent tendencies. While varietal differences in decreasing of AA content during storage were greater (in interval from -22.93 %rel in Gloster variety to -30.05 %rel in Ontario variety), decreasing of TP contents during storage was nearly the same (about -27 %rel of original content

An HPLC method with refractometric detection was worked out for the determination of the limiting contents of marker saccharides (free mannitol and total glucose and xylose) used for the proof of authenticity of pure instant coffee. This method, even though more laborious, yields results comparable with those obtained by the HPAE-PAD method and is intended mainly for those laboratories where the current HPLC technique with refractometric detection is presently used for saccharide analysis. The survey of market supply showed that instant coffee imported in bulk and subsequently packaged in the Czech Republic is most frequently adulterated - only one out of 7 samples examined contained authentic coffee. On the other hand, only one out of 10 samples of instant coffee imported in original packaging did not meet the authenticity criteria. The samples of instant coffee by domestic producers indicated that one producer placed on the market an adulterated product, whereas the other brand is authentic coffee.

In the framewort of the quantitative histologic evaluation of poultry products, the size and the number of bone fragments have been determined using the image analysis. Bone fragments were identified by their colour and analysed automatically. The samples contained 135 to 2167 bone particles the length of which varied from 5 to 2088 μm. Comparing products of the same kind, we found differences in the contents of bone fragments; this fact was possibly due to inadequate observance of the technological procedure by some producers.

Folic acid and its biologically active derivates (folacin or folates) rank among the B-group vitamins due to their hydrophilic character. This acid occurs in nature either in the free form or it is bound to proteins or polysaccharides. Folic acid belongs to the group of vitamins which, in the past were not considered important because the relevance of the acid in biological processes of the living cell has been discovered by the scientific research only in recent years. Folates play an important role as co-enzymes in the synthesis of RNA, DNA, proteins and of some essential amino acids. Therefore they are inevitable for the haematopoiesis, growth and reproduction of cells. In this sense a widely oriented research named "Maternal Folate Status" is proceeding in the U.S.A., Australia and France.

The content of ferulic acid in sugar beet pulp was determined by reverse phase high-pressure liquid chromatography (HPLC) and UV/VIS-spectroscopy. The acid extracts of pectin carrying feruloyl groups were prepared for analysis. To release ferulic acid from pectin the hydrolysis in alkaline medium (pH = 12.5) was performed. Both non-hydrolysed and hydrolysed extracts were measured by UV/VIS-spectroscopy after pH adjustment to the value of 10. The absorbance maximum was observed at 372 nm (ester of ferulic acid) for non-hydrolysed extracts and at 345 nm (sodium ferulate) for hydrolysed extracts. The HPLC estimation of ferulic acid was made in hydrolysed extracts only. The content of ferulic acid in sugar beet pulp was in the range of 0.3-0.9% (m/m). The data obtained by application of the particular methods to one set of samples were statistically compared. The results of all methods were in good agreement with each other\

Several ways are recommended how to avoid iodine deficiency in food of many countries' population. In addition to the common use of salt fortified with KI, KJO₃ can also be used in bakery products. It is also a strong oxidizer improving rheological properties of dough. In this paper the effect of KJO₃ on rheological properties of wheat dough and baked products was studied using farinograph and extensograph data and the baking test. The effect of KJO₃ was tested in combination with a commercial complex improver. Loaf volume was increased by the addition of 2 or 3 ppm of iodate to flour. The dose of iodine improving bread volume showed satisfactory correspondence to 50% of recommended daily intake that is allowed for bakery products by the Czech law.