Stanisław Mleko

New product development: Cellulose/egg white protein blend fibers

The aim of the research was to form mixed cellulose/egg white isolate (EWI) fibers. Cellulose was dissolved in the Schweitzers reagent. The blend fibers were obtained by simultaneous cellulose fiber formation and acid-induced gelation of EWI in 33% sulphuric acid solution. Increased storage modulus was noted for the blend fibers in comparison to the cellulose fibers. EWI alone formed fibers which were composed of microfibers with the average diameter of about 80 nm. Cellulose fibers had a loose microstructure with about 10 μm gaps and rough surface. The addition of EWI caused that the surface of the fiber was even more rough with a tendency to form microfibers, which were not observed for cellulose alone. EWI protein molecules had the tendency to bridge the voids between cellulose microfibers. Protein in the blend fibrils formed more branched aggregates than in the EWI fibrils, which was probably caused by interactions with copper ions. Both in cellulose and cellulose/EWI fibrils, the cellulose crystallized in cellulose II monoclinic system. Reduction in COH groups was noted, which was probably caused by interactions between the cellulose and proteins molecules. EWI/cellulose interactions caused formation of β-sheet type structures.

Surface Properties of Aerated Ion-induced Whey Protein Gels

Aerated whey protein gels were formed using calcium chloride, magnesium chloride or iron (II) chloride induced gelation of pre-denatured protein dispersions. The structure of the obtained gel surface depends on the type and concentration of added salt. Higher cation concentration produced gels a with higher quadratic mean of the surface roughness and maximum roughness height. Aerated gels of optimal properties for retaining air bubbles were characterized by similar surface roughness. The surface topography is mainly responsible for changes in the wettability. The contact angle of the probe liquid sample depends on the liquid surface tension components. An approach based on the contact angle hysteresis (CAH) is suitable for determining the total value of the apparent surface free energy of such materials. An approach based on the components of apparent surface free energy (LWAB) only allows the calculation of the dispersion component and electron donor parameter of energy in the case of added magnesium and iron salt. Wettability, depending on the nature of the surface, can be described for the hydrophilic surface by the Wenzel model, and for the hydrophobic surface by the Cassie – Baxter model.

The extrusion test and sensory perception revisited: Some comments on generality and the effect of measurement temperature

Relations between sensory perception, extrusion and fracture in shear, extension and compression are examined. Gelatin-based gels are perceived as less firm and less hard than expected based on their mechanical properties compared to polysaccharide gels that have the same mechanical properties at room temperature but melt well above body temperature, underlying the importance of the measurement temperature for gels that melt during mastication. Correlations between parameters from extrusion and compression, extension and shear are verified using mixed polysaccharide gels. PRACTICAL APPLICATIONS We previously reported a high correlation between several sensory attributes and parameters from an extrusion test. The extrusion test showed the most robust correlation, and could be used to assess samples at both extremes of the texture range with respect to elasticity, for example, both samples that could not be extended as their very low elasticity led to their fracture during handling, as well as samples that could not be fractured in compression. Here, we reexamine the validity of the relations reported. We demonstrate the generality of the relations between large deformation tests and extrusion, but the findings underscore the need to take into account the measurement temperature for samples that melt during mastication when correlating instrumental parameters with sensory perception.

Surface tension and wetting properties of rapeseed oil to biofuel conversion by-products

Abstract This work presents a study on the surface tension, density and wetting behaviour of distilled glycerol, technical grade glycerol and the matter organic non-glycerin fraction. The research was conducted to expand the knowledge about the physical properties of wastes from the rapeseed oil biofuel production. The results show that the densities of technical grade glycerol (1.300 g cm-3) and distilled glycerol (1.267 g cm-3) did not differ and were significantly lower than the density of the matter organic non-glycerin fraction (1.579 g cm-3). Furthermore, the surface tension of distilled glycerol (49.6 mN m-1) was significantly higher than the matter organic non-glycerin fraction (32.7 mN m-1) and technical grade glycerol (29.5 mN m-1). As a result, both technical grade glycerol and the matter organic non-glycerin fraction had lower contact angles than distilled glycerol. The examined physical properties of distilled glycerol were found to be very close to that of the commercially available pure glycerol. The results suggest that technical grade glycerol may have potential application in the production of glycerol/fuel blends or biosurfactants. The presented results indicate that surface tension measurements are more useful when examining the quality of biofuel wastes than is density determination, as they allow for a more accurate analysis of the effects of impurities on the physical properties of the biofuel by-products.

Biochemical changes in the recreational areas soil caused by the intensity of use

The aim of this study was to determine the effect of the intensity of selected recreational areas use on biochemical changes within soils. Soil samples were collected from different playgrounds, playing fields and horse farms. Granulometric composition of the soils was determined. Heavy metals concentration, organic carbon concentration, total nitrogen concentration and activities of dehydrogenases, phosphatase and urease were measured at unburdened and burdened sites of the investigated recreational areas. It was found, that the use of the recreations areas triggers the changes in biochemical composition of the soil. Greater burden decreases the enzymes concentration in the soil. For most sites, a positive correlation was found between enzymes and organic carbon concentration and between phosphatase and urease. The degree of heavy metals soils contamination was low and only the samples from one playing field and one horse farm had increased concentration of cadmium. Monitoring of biochemical changes in recreational areas soil (especially playgrounds) is very important to provide safe environment for human leisure time.