Fakulta technologická

Early-stage degradation of electrolytic iron particle-based magnetorheological elastomer under natural weathering conditions

2026-01-01T00:00:00Z

Early-stage degradation of electrolytic iron particle-based magnetorheological elastomer under natural weathering conditions Viension, Rehnupreya Hentry; Nordin, Nur Azmah; Mazlan, Saiful Amri; Johari, Mohd Aidy Faizal; Wereley, Norman M.; Fatah, Abdul Yasser Abd; Zaini, Nursyafiqah; Sedlačík, Michal Magnetorheological elastomer (MRE) is a smart composite possessing properties that can be tuned by an external magnetic field, making them highly attractive for vibration isolation applications. Their reliable use in outdoor environments, however, requires a clear understanding of how natural weathering influences their performance and durability. While most previous research has addressed long-term or accelerated ageing conditions, the onset of environmental degradation of MRE remains insufficiently explored. Therefore, this study investigated the early-stage degradation of MRE, embedded with irregular electrolytic iron particles (MRE-EIP) over six weeks of natural weathering exposure. Weekly samples (W0-W6) were analysed using vibrating sample magnetometer (VSM), rheometer and low vacuum scanning electron microscope and the results were correlated with weathering data from the Malaysian Meteorological Department, Kuala Lumpur. The saturation magnetization, Ms finding shows minimal change from 111.63 Am2/kg in W0 to 113.79 Am2/kg in W6, likely attributed to the exposure of EIP following the removal of the aged localized surface over the six week exposure. Strain sweep results meanwhile, revealed the progressive stiffening, with the storage modulus (G′) increased from 0.22 MPa (W0) to 0.53 MPa (W6), accompanied by a narrowing linear viscoelastic (LVE) region, indicative of early embrittlement of the samples. Nevertheless, a temporary reduction in G′ for W3 suggested a moisture-induced plasticisation, from increased rainfalls that week. Besides, the absolute MR effect, ΔG′ increased from 0.23 MPa (W0) to 0.34 MPa (W6), indicating greater responsiveness of exposed EIP to the magnetic fields which enhanced the G′ accordingly. Morphological analysis confirmed the development of localized surface depressions suggests combine effects of UV-driven embrittlement and moisture plasticisation from rainfall, leading to localised EIP exposure, while the cross-sectional structure integrity remained intact. These findings provide the first detailed account of early-stage degradation in MRE-EIP under natural weathering, offering valuable insights into early failure mechanisms and guiding durability driven material design for outdoor smart material applications.

The Influence Of Polyphosphate Mixture On The Growth Of Bacteria Significant In The Food Industry

2026-01-01T00:00:00Z

The Influence Of Polyphosphate Mixture On The Growth Of Bacteria Significant In The Food Industry Buňková, Leona; Jaššo, Miroslav; Kuchař, Dalibor; Buňka, František Phosphates are frequently used in the food processing, especially in the dairy and meat industries. They act as emulsifying salts, crucial in the manufacturing of processed cheeses. The effect of Cremosal AB4, a commercially used polyphosphate mixture, was tested in vitro on the growth of nine bacterial strains significant in the food industry: Staphylococcus, Bacillus, Geobacillus, Clostridium, Enterococcus, Lactococcus, Lactobacillus, and Escherichia. Five phosphate concentrations (0.1, 0.2, 0.3, 0.4, and 0.5% w/v, calculated on P2O5) were selected to assess the effect of the polyphosphate mixture on bacterial growth. The susceptibility of each bacterial strain to Cremosal AB4 phosphate was evaluated in a liquid culture medium enriched with the appropriate salt concentration. Subsequently, cell growth was assessed by measuring optical density at 850 nm. The results indicate that even at the lowest tested concentration of 0.1% w/v, Cremosal AB4 polyphosphate effectively inhibited the growth of all bacteria examined, except Lactococcus lactis subsp. lactis CCDM 141 and Escherichia coli CCM 3954.

Study of changes in unripened soft rennet-curd cheeses caused by the addition of dried nettle leaves: Physicochemical properties, microbial quality, polyphenol content, and sensory characteristics

2026-01-01T00:00:00Z

Study of changes in unripened soft rennet-curd cheeses caused by the addition of dried nettle leaves: Physicochemical properties, microbial quality, polyphenol content, and sensory characteristics Pluta-Kubica, Agnieszka; Najgebauer-Lejko, Dorota; Pająk, Paulina Maria; Sobolewska-Zielińska, Joanna; Skoczylas, Łukasz; Aththota Gamage, A. C.K.; Kratochvílová, Alena; Salek, Richardos-Nicolaos; Duda, Iwona; Domagała, Jacek The objectives of the study were to investigate changes in the number of selected groups of microorganisms and the level of antioxidant activity during storage of model unripened cheeses with the addition of dried nettle leaves, to compare their sensory characteristics, as well as to determine the antioxidant properties of the obtained whey. Three groups of model unripened rennet-curd cheeses were produced: I—a control sample without a plant additive, II and III—samples with the addition of dried nettle leaves in the amount of 0.165% and 0.330% (g/100 g of milk), respectively. Advantageously, no effects of nettle addition on total microbial and Lactococcus counts were determined. Moreover, the application of this herb slowed down the yeast and mold growth in cheese, increased the antioxidant activity, and elevated the contents of total polyphenols, caffeic acid, p-coumaric acid, rutin, and ferulic acid. Additionally, the antioxidant properties of the obtained whey were also higher in comparison to control. Sensory analysis revealed that the addition of a lower amount (0.165%) of dried nettle leaves appeared to be the most favorable option, balancing improved nutritional and antioxidant value with acceptable sensory characteristics and acceptability. The study demonstrated that the application of dried nettle leaves as an addition to cheese offers many benefits.

The effect of selected hydrocolloids on the physicochemical, viscoelastic, and organoleptic properties of full-fat processed cheese sauces

2026-01-01T00:00:00Z

The effect of selected hydrocolloids on the physicochemical, viscoelastic, and organoleptic properties of full-fat processed cheese sauces Lazárková, Zuzana; Gryger, Tomáš; Salek, Richardos-Nicolaos The current study investigated the effects of three polysaccharide hydrocolloids [pectin (PE), agar (AG), and guar gum (GG)] at varying concentrations (0.25, 0.50, 0.75, and 1.00 % w/w) on the physicochemical, viscoelastic, and organoleptic properties of full-fat processed cheese sauces (PCS). The hydrocolloid (HC) type and concentration affected the PCS properties. The values of emulsion stability (ES) enhanced progressively with higher HC concentrations (P < 0.05). Rheological analysis revealed an increase in elastic, viscous, and complex moduli, as well as in complex viscosity, gel strength, and interaction factor, with higher HC levels (P < 0.05). Furthermore, sensory analysis of viscosity supported rheological findings. Additionally, sensory assessors preferred sauces with AG and GG concentrations of 0.50 and 0.75 % w/w the most (P < 0.05). These results confirm that the tested HCs act as effective gel-forming/thickening and stabilizing agents in full-fat PCS, enhancing both ES and viscoelastic properties, while also improving texture, as demonstrated by sensory evaluation.