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Investigations were carried out into the effect of sonication of bee honeys on the course of their crystallization during storage. Use was made of ultrasounds with a frequency of 40 kHz and intensity of ca. 2 W/cm2. Analyses were carried out for physicochemical characteristics of honeys, including: viscosity, texture, conductance and crystallization degree. After 30-min sonication, an increase in viscosity by ca. 30 mPa.s and a reduction in conductance by 0.6 mS/cm were observed in the solution examined. Analyses of the texture (hardness) of honey subjected to the sonication process demonstrated an initial increase of hardness and then its stabilization and even a slight decrease, as compared to the control samples. The degree of crystallization was proportional to the exposure time to ultrasound treatment. The biggest crystals were observed in the non-sonicated samples. Sonication modified the crystallization process of the examined sugar solutions to a significant extent. Observations of the solutions after the sonication demonstrated the formation of a high number of crystals in the whole volume of the sample, whereas the non-sonicated solutions were observed to crystallize unevenly forming large crystals. It was shown that the ultrasound treatment modified the course of recrystallization and, as a result, texture of the recrystallized honeys by decreasing their hardness.
The electrical properties of honey such as impedance, permittivity and dielectric loss factor are now often used for honey quality assessment. The measurement of electrical honey features can be very interesting alternative to time-consuming and expensive methods based on chemical parameters measurement. In this paper, the influence of temperature and crystallization on honey’s electrical properties is investigated. The electrical parameters that are potentially useful for honey crystallization detection and their measurement conditions are indicated. The multifloral, rape and goldenrod honey was used for this study. The impedance was measured in the frequency range from 10 Hz to 1 MHz, and at temperatures of 20, 25 and 30°C. The permittivity and dielectric loss factor values were then calculated. The results show that impedance can be a useful electrical parameter for honey crystallization detection, and in order to reduce the impact of temperature the measurements should be taken at a frequency of about 8–10 kHz.
The rapeseed oil was hydrogenated with sulphur modified nickel catalyst. The parameters of hydrogénation process were found not to affect the physical properties of fats having the same hydrogénation degree. The conditions of fractional crystallisation from acetone of hydrogenated rapeseed oil were optimised for a high yield of the fat replacing cocoa butter. At 22°C and 2°C for the first and second crystallisation, respectively, such product was obtained with an over 60% yield as the middle fraction out of three that were isolated. The degree of hydrogenation of the fractionated fat did not affect the physical properties of the cocoa butter replacer, although it affected the yield. The physical properties of the fractions after the crystallisation of hydrogenated fat resulted mostly from high differences in the content of saturated and trans-unsaturated fatty acids.
A new crystal form of papain from the latex of Carica papaya, complexed with an inhibitor (Z-Arg-Leu-Val-Gly-CHN2) was obtained by the vapor-diffusion method using a methanol/ethanol mixture as a precipitant. The slat-like crys­tals are monoclinic, space group P2 1, with unit cell parameters a = 42.6 A, b = 49.8 A, c = 50.5 A, β= 111.9°, and contain one molecule in the asymmetric unit. The crystals are stable in the X-ray beam and diffract beyond 1.8 A. A molecular model has been placed in the unit cell by molecular replacement.
Two genes of the extreme thermophilic archaeon Thermococcus litoralis homologous to those that code for Cpn60 chaperonins were cloned and expressed in Escherichia coli. Each of the Cpn60 subunits as well as the entire Cpn60 complex crystallize in a variety of morphological forms. The best crystals diffract to 3.6 resolution at room temperature and belong to the space group I422 with unit cell parameters a = b = 193.5 A, c = 204.2 A.
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