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Two samples of commercial wheat flour from the last year's harvest were stored for three months (in the period from November to April) under different conditions. The ambient temperature and humidity varied during the storage in the dependence on the year season. Certain analytical characteristics (moisture, wet gluten and its extensibility, acidity and falling number) and alveograph behaviour of flour were determined at regular intervals. Flour moisture, acidity, and falling number changed with the time of storage but no explicit influence of the storehouse conditions and the initial flour properties was proved. Viscoelastic properties of weaker flour samples changed during storage more markedly than those of stronger flours in the sense of a significant improvement of their quality.

The cabbage-carrot juices were inoculated with Lactobacillus plantarum 92H at the concentration of 8 × 106 CFU/ml and fermented in a thermostat at 24°C for 150 hours. During the fermentation, both analytical (pH, total acidity, reducing sugars, l-ascorbic acid, lactic, acetic and citric acids, biogenic amines) and sensory (appearance, colour, turbidity, sediment and taste) parameters were followed. For the evaluation of the results of the chemical and sensory (taste) analyses of these juices the multivariate statistical methods were applied. PCA and FA reduced the 7 original analytical variables to 1 independent component (factor) that accounted for 96.92% of the total variance, and CA divided samples into 2 groups according to the contents of lactic and acetic acids. PCA and FA reduced the 8 taste and mixture taste descriptors to 2 components (factors) that accounted for 97.28% of the total variance.

Nowadays manufacturers are facing rapid and fundamental changes in the ways business is done. Producers are looking for simulation systems increasing throughput and profit, reducing cycle time, improving due-date performance, reducing WIP, providing plant-wide synchronization, etc. Planning and scheduling of coffee production is important for the manufacturer to synchronize production capacity and material inputs to meet the delivery date promised to the customer. A simulation model of coffee production was compiled. It includes roasting, grinding and packaging processes. Using this model the basic features of the coffee production system are obtained. An optimization module of the simulation SW is used for improving the current structure of the production system. Gantt charts and reports are applied for scheduling. Capacity planning problems related to coffee production are discussed.

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.

The changes in microbiological and chemical parameters during the fermentation and ripening of sheep cheese were observed. The cheese was produced from raw sheep's milk at different temperatures on the sheep farm. The following parameters were determined: total plate count, coliform count, Staphylococcus aureus count, pH value, titrimetric acidity, and the amount of lactic acid. As our results indicate, the fermentation at temperatures of between 18-22°C reduces the number of undesirable micro-organisms due to the presence of lactic acid being produced by lactic-acid bacteria. During the fermentation at lower temperatures (below 18°C) the amount of lactic acid is insufficient, and the undesirable microorganisms can survive.

The storage of lipid foods is mostly affected by the oxidation of lipid fraction. Dry foods are particularly sensitive because lipids are not protected by hydrated proteins against oxidation. A method suitable for testing dry foods was studied in model mixtures of rapeseed oil with albumin or cellulose. Oxipres apparatus was used, where the course of oxidation is monitored by changes of oxygen pressure. The end of induction period was more evident than in bulk oils as the contact of lipids with oxygen is better. The induction period was longer in mixtures of edible oil with albumin than in mixtures with cellulose. The induction period moderately decreased with increasing oxygen pressure, while the effect of sample weight was nearly negligible. The induction period length was a semilogarithmic function of reaction temperature. Variation coefficients and differences between the duplicates showed good reproducibility; they were lower in mixtures with albumin than in mixtures with cellulose, but both were of the same order as the respective values in bulk oils. At 120°C and 0.5 MPa oxygen, the induction periods could be usually measured within a working day.

The goal of this work was to verify the spice adulteration by the microscopic analysis. The samples of black powdered pepper and its meat product that did not have the expected spice and aromatic properties were controlled. The results of sensory and chemical investigation corresponded with microscopic findings. The suspected sample of spice and meat product with spice contained pronounced coloured parts that were not present in the usual structure of powdered pepper.

The bread-making quality of forty commercial winter wheat samples, grown in the western region of the CzechRepublic, and their flours (white flours with ash content of about 0.5%) prepared in a commercial mill was studied. Standard analytical methods (ash and protein content, wet gluten), amylolytic activity measurement (falling number), rheological investigation (alveograph, gluten index), sedimentation test and laboratory baking test were used for characterization of wheats and flours. In addition NIR method was used to calculate ash, wet gluten, sedimentation value and protein content. Statistically significant correlations were found practically between all tested quality parameters of wheat and corresponding flour samples. However, the strongest correlation (r = 0.69-0.70) significant at 0.01 level exists between specific bread volume and protein and wet gluten content, determined both by standard or by NIR methods.

Total content and composition of essential oils in caraway seed (Carum carvi L.) from a selection of caraway varieties grown in different production areas were determined after supercritical fluid extraction (SFE) and steam distillation. Different procedures of sample pretreatment (homogenization) and methods of isolation were compared from the point of view of efficiency, reproducibility and accuracy. The effect of storage period was also examined.

The astringent taste is important for the sensory quality of beverages. Perception thresholds of two important astringent compounds - tannic acid and (+)-catechin were determined using two procedures. The concentration-intensity dependence was linear at low concentrations and up to medium intensities of the astringent taste if unstructured graphical scales were used, but the saturation threshold was soon attained in the case of tannic acid. Recording the results on printed forms gave similar results as using a touch-sensitive monitor. The optimum tasting was achieved at swallowing after degustation of 5 s. The duration of degustation increased the intensity. The astringent flavour was suppressed by sugar, but was not significantly influenced by ethanol, citric acid or quinine hydrochloride. Astringent substances were accurately perceived and rated in wine, tea infusion and orange drink, but the increase of astringency was smaller than in model solutions. The astringent taste was easily distinguished from the bitter taste.

A simple 1-D mathematical model for prediction of local temperatures in a layer of solid material during microwave heating (Houšová et al. 1998) and a sensitivity analysis were used to evaluate the influence of process and material parameters on vertical temperature profiles in a layer of material during heating. The results of calculations are presented in graphs and discussed. The incident microwave power and heat capacity and density of heated material are parameters with great effect on all local and average temperatures and local and average heating rates. The shape of temperature profile is influenced only to a small extent by a change in the value of applied microwave power and also in the value of heat capacity or density of heated material. The whole profiles shift to higher or lower temperature values when the incident microwave power is changing. The distribution of applied microwave power between the upper and bottom layer surface very much influences the shape of the profile and the values and position of the highest and the lowest temperature in the layer. Depth of penetration and thermal conductivity of heated material influence on the shape of temperature profiles and the temperature spread in the layer (evenness of temperature distribution). Effect of penetration depth also depends on the relation to the layer thickness - its effect increases with the increasing layer thickness. At the low values of penetration depth relative to the layer thickness, an uneven temperature profile is to be expected. Effect of thermal conductivity value on temperature profile depends on the time of heating. Because of a short time of microwave heating, the effect of this parameter on temperature distribution is smaller compared to the conventional heating methods. At the beginning of heating its influence is quite negligible. Temperature of the air surrounding the layer and intensity of heat exchange between the air and layer surface are parameters with only small local effect on temperature distribution.

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.

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.

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\