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The study examined gel strength of the native egg white as a function of pH and the dry matter content. The egg white samples were isolated from fresh eggs and the eggs in different stages of storage. The gel strength was measured with Texture Analyser of TA-XT2i type. The study has shown that the gel strength increases with rising pH and the content of dry matter. The influence of the egg age is more complicated. The gel strength increases over the first 14 days after egg laying and slowly decreases afterwards. Mathematical dependence of the gel strength was predicted on the basis of the measured data by the method of non-linear regression: gel strength (p/cm²) = exp[0.00674*time (days) + 0.289*dry matter (%) + 0.1165*pH + 1.433].

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Kučerová Z., Kýhos K., Aulický R., Stejskal V. (2013): Low-pressure treatment to control food-infesting pests (Tribolium castaneum, Sitophilus granarius) using a vacuum packing machine. Czech J. Food Sci., 31: 94-98.Since recently, the food industry has been faced with serious problems regarding pest-infested food commodities and deregistration of many chemical biocides by the EU Biocide Directive. These conditions have created an urgent need for a physical method of protecting food against pests. Therefore, a vacuum packing machine was used for laboratory testing of the effectiveness of vacuum packaging on the mortality of the red flour beetle (Tribolium castaneum) and granary weevil (Sitophilus granarius) at different temperatures and exposure times. There were significant differences in the susceptibility to low pressure (vacuum) between the adult insects of both tested species: T. castaneum was approximately 10 times more susceptible to low pressure than S. granarius. A higher temperature significantly shortens the vacuum exposure time necessary to reach 100% mortality in the tested beetles under a constant low-pressure value (1 kPa). The lethal times (LT 99 ) for adult T. castaneum were 15.1 h at 25°C and 30.8 h at 15°C. The lethal times (LT 99 ) for adult S. granarius were 160.1 hours at 25°C and 274 h at 15°C.

Houška M., Kýhos K., Landfeld A., Průchová J., Schlemmerová L., Šmuhařová H., Špelina V., Novotná P. (2007): Dry heat inactivation of Bacillus cereus in rice. Czech J. Food Sci., 25: 208-213.The aim of this work was to validate the method of decontamination of rice at the temperature of 120°C (determined as optimal in previous experiments). Bacillus cereus was selected as the marker micro-organism for the monitoring of decontamination. The spores of Bacillus cereus are moderately heat resistant. In order to show the efficacy of our decontamination process, we artificially contaminated the rice under study with B. cereus. Decontamination was carried out in a homogenising steriliser about 20 h after contamination. The sample was first heated to 90°C and held at this temperature for 70 minutes. Then the temperature was increased to 120°C and held for 3 hours. Five samples were taken for microbiological analyses as follows: before the experiment, on reaching 120°C, and then after 1, 2, and 3 h of decontamination. Decontamination of rice from vegetative forms and spores of B. cereus present at the level of 400 CFu/ml was effected by heating to 120°C and holding for 1 hour.