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White wines of Debina cultivar were made from musts clarified by flotation using nitrogen as foaming agent. Flotation using air as the foaming agent (must hyperoxidation), without SO₂ addition, was also applied. Turbidity and suspended solids were lower in must clarified by flotation using nitrogen than in that clarified by sedimentation (control). Flotation with hyperoxidation led to a reduction of must phenolics. All experimental wines exhibited similar gross compositions (alcohol, reducing sugars, total acidity, and volatile acidity). Wines made from musts clarified by flotation using nitrogen had similar total phenolic content, browning capacity, and organoleptic quality as the control wines. Wines made from musts clarified by flotation using air had lower total phenolic contents and browning capacity than were those in control wines. These wines were of well acceptable quality but exhibited a slightly oxidised aftertaste. The results indicate that flotation using nitrogen can be effective in the production of typical Debina wine, while flotation using air may be useful in that of table wine without SO₂ addition. Orange juice was clarified by flotation using nitrogen or air as the foaming agent. Orange juice clarified by flotation using nitrogen as the foaming agent exhibited lower turbidity and a similar pulp content to that clarified by centrifugal separator (control). It had an acceptable taste and aroma. Juice clarified by flotation using air as the foaming agent, along with pectolytic enzyme treatment, exhibited much lower turbidity and pulp content compared to control. The clear juice had an acceptable taste but no aroma. The fermented clear juice was averagely rated, exhibiting a pleasant aroma and only a slightly bitter taste. The results indicate that flotation using nitrogen can be effective in the production of natural orange juice, while flotation using air may be useful in the production of orange drink.

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

The possibility of the increase of the natural folate content in fermented milk products by the fermentation process and by the addition of fruit component was evaluated. 5-methyltetrahydrofolate (5-MTHF) content was followed after the inoculation of pasteurised milk with the butter starter and the selected strains of Streptococcus thermophilus in combination with Bifidobacterium longum or Propionibacterium freudenreichii subsp. shermanii followed by fermentation at 30°C and 37°C for 12 and 18 h. 5-MTHF was determined by HPLC method after deconjugation with hog kidney conjugase and SPE SAX purification. The highest 5-MTHF content increase of 4.03 ± 0.44 µg/100 g was found at cofermentation with Streptococcus thermophilus No. 144 and Propionibacterium freudenreichii subsp. shermanii No. 160 at 37°C after 12 h of fermentation. 9 commercial fruit components used in dairy industry contained between 0.17-9.11 µg 5-MTHF/100 g. The components produced with pineapple, sour cherry, apricot, and apple contained low amounts of 5-MTHF - less than 1 µg/100 g. Among the rest of the components tested, the strawberry component proved to be the best source of folate with the content of 9.11 µg 5-MTHF/100 g. The values in 7 varieties of fresh fully ripe strawberries fluctuated between 25.5 and 54.0 µg/100 g fresh sample, i.e. 272 and 554 µg/100 g dry matter with the highest content found in the varieties Elsanta and Honeyoe. Fully ripe berries of the variety Senga Sengana contained by 63% more 5-MTHF in comparison with unripe berries. In order to reach maximum folate content in the fruit component, fully ripe strawberries of the cultivars Elsanta and Honeyoe are recommended for the processing. The folate content in the fermented milk product may be increased in this way by 4.8 µg/100 g, with 69% originating from the fermentation and 31% from the fruit component addition.

In this research, the growth and survival of E. coli O157:H7, Salmonella typhimurium and Staphylococcus aureus were investigated during kefir fermentation. Two different levels of inoculation of the strains were conducted; the levels of 102 CFU/ml (EC-1, SA-1 and S-1) and 103 CFU/ml (EC-2, SA-2 and S-2). At 0, 2, 6, 12, and 24 hours of kefir fermentation at 23 ± 1°C, samples were taken and the counts of E. coli O157:H7, S. typhimurium, and S. aureus were determined. EC-1 grew from 2.29 ± 0.02 log CFU/ml to 4.13 ± 0.18 log CFU/ml whereas EC-2 grew from 3.22 ± 0.04 log CFU/ml to 6.78 ± 0.99 log CFU/ml. Both S-1 and S-2 viable populations grew during the fermentation period, where sample S-1 grew from 2.37 ± 0.20 log CFU/ml to 4.64 ± 0.67 log CFU/ml and sample S-2 grew from 3.52 ± 0.07 log CFU/ml to 5.60 ± 0.10 log CFU/ml. SA-2 strains grew from 3.06 log CFU/ml to 3.64 log CFU/ml, SA-1 strains grew from 2.28 log CFU/ml to 2.66 log CFU/ml. According to the findings, E. coli O157:H7, S. typhimurium, and S. aureus can survive in kefir during fermentation.

This investigation deals with the antifungal activity of naturally occurring phenolic compounds and the metabolism of plant phenolics during the cold storage. In the experiment the apple cultivars with different diseases resistance were analyzed in the relation to changes in phenolic content.

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.

In this review article it is given an information about the composition of flavonoid complex of apples (Malus pumila Mill.). It is discussed the influence of extrinsic and intrinsic factors on polyphenolic antioxidant content (varietal differences, influence of locality, year, maturity, pre-harvest treatment, storage, technological ways of processing) and the relation between the polyphenol content and the resistance of apple varieties. During storage there is an apparent decrease of both ascorbic acid and polyphenols. Contents of anthocyanins and chalcones are in positive correlation with resistance of apple trees to low and variable temperatures. During maturation of apple fruits synthesis and accumulation of polyphenols, esp. anthocyanins, and ascorbic acid was determined. Meanwhile polyphenols are substrates of polyphenol oxidases in the process of enzymic browning, ascorbic acid is a natural inhibitor of this browning deterioration. Process of enzymic browning of apple fruits and juices could be inhibited with ascorbic and citric acid addition to apple products. Polyphenol content could be influenced by pre-harvest and technological procedures.

Research in the quality of horticultural products commonly applies sensory analysis which under minimized subjectivity approaches or coincides with other analytical methods with respect to its accuracy. Sensory analysis comprises many methods and tests. This article considers the test of textural polarity profile. Polarity profilograms are constructed for 29 varieties and new breeds of apple. The descriptors used characterize the textural quality of fresh and stored apples. The main advantage of polarity profiles is that they enable to determine not only differences between samples and varieties but also to find out changes in the textural quality during storage. In addition to textural profilogram, polarity profiles enable to construct also optical, olfactological and gustative profilograms.

Commercial orange juices samples obtained from the Czech market were analysed in the years 1996-2001. The quality and authenticity of samples was evaluated according to the Code of Practice of AIJN (selected main analytical criteria were followed - K+, Na+, Ca2+, Mg2+, citric, isocitric and malic acid, citric acid/isocitric acid ratio, glucose, fructose, saccharose, sorbitol, formol number, flavonoid glycosides - according to Davis and HPLC procedure, refractive index and other). The approach of producers to the quality and authenticity of juices developed during the years of observation. The main cases of adulteration in 1996 were as follows: (i) lower fruit content in juice, (ii) massive addition of sugars masked with addition of citric acid, (iii) several examples of "synthetic" orange juice were found. In the subsequent years the authenticity slightly improved, the main problems in 2000/2001 were: (i) lower refractive index, (ii) pulp wash addition, (iii) lower quality of water used for juice reconstitution, (iv) undeclared addition of sugar. The deviations were found not only in the case of the juices of Czech producers, but also in several discount and low-end products of foreign producers. Possible ways of improving the quality and authenticity are discussed (e.g. the preparation of a Czech National Standard taking over the requirements for juices and nectars according to the Code of Practice of the AIJN, Participation in the European Quality Control System [EQCS], etc.).

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\