Impact Of Heat Treatment Research Articles

Evaluation of anti-yeast metabolites produced by Lactobacillus strains and their potential application as bio-preservatives in traditional yogurt drink

Consumer demand for minimal food processing and reduced use of chemical preservatives has sparked interest in the use of biological preservatives. This study aimed to assess the anti-yeast effects of Lactobacillus delbrueckii, Limosilactobacillus fermentum, and Lactiplantibacillus plantarum strains on Saccharomyces cerevisiae, Candida albicans, and Geotrichum candidum. The anti-yeast activity of lactic acid bacteria (LAB) cell-free supernatant (CFS) was evaluated using well diffusion agar, agar spot assay, and scanning electron microscopy (SEM). Heat treatment's impact on the inhibitory capacity of CFS was also examined. Ion chromatography measured the production of propionic acid, lactic acid, and acetic acid in the supernatant. Furthermore, a yogurt drink containing the L. fermentum strain was produced. L. fermentum exhibited the highest anti-yeast activity against G. candidum, with an inhibition halo diameter of 16.60 mm. SEM revealed morphological changes in S. cerevisiae, C. albicans, and G. candidum following treatment with L. fermentum CFS. The production rates of lactic, propionic, and acetic acids in the L. fermentum supernatant without heat treatment were 94885.78, 115233, and 5936.02 ppm, respectively. Examination of mold, yeast, and coliform counts in samples inoculated with L. fermentum during 14 days of storage indicated that the microbial population remained within acceptable limits compared to control.

Electroless Ni-P Plating of Carbon Steel via Hot Substrate Method and Comparison of Coating Properties with those for Conventional Method

In this study, Ni-P electroless coating was deposited on carbon steel by a new method called SLHS (substrate local heating system) which makes a higher rate of deposition possible without the risk of decomposition of electroless baths. The effects of pH and temperature on plating rate, composition, surface morphology, hardness and corrosion of the coating in SLHS condition (Tsub = 190 °C, Tbath = 80 °C) were investigated. In addition, the impact of heat-treatment at 400 °C for 1 h on hardness, morphology and microstructure was also studied. Samples prepared by this method were characterized by Scanning Electron Microscopy/Energy-Dispersive x-ray analysis, Light Microscope and x-ray diffraction. They were then submitted to Vickers microhardness and tribological tests. The deposition rates of electroless nickel (EN) coating were first estimated by weight gain method and then by light and scanning electron microscopy. Electrochemical Impedance Spectroscopy (EIS), Tafel polarization and salt spray tests were then used to evaluate the corrosion properties of the coatings. The study shows that maximum deposition rates for conventional and SLHS samples were approximately 20 µm/h and 32 µm/h, respectively. This increase in the plating rate reduces the phosphorus level by nearly 1.5 wt.% for SLHS sample. The corrosion resistance of SLHS sample is improved in comparison to the conventional one.

Quantitative In-Vitro Diagnostic NMR Spectroscopy for Lipoprotein and Metabolite Measurements in Plasma and Serum: Recommendations for Analytical Artifact Minimization with Special Reference to COVID-19/SARS-CoV-2 Samples.

Quantitative nuclear magnetic resonance (NMR) spectroscopy of blood plasma is widely used to investigate perturbed metabolic processes in human diseases. The reliability of biochemical data derived from these measurements is dependent on the quality of the sample collection and exact preparation and analysis protocols. Here, we describe systematically, the impact of variations in sample collection and preparation on information recovery from quantitative proton (1H) NMR spectroscopy of human blood plasma and serum. The effects of variation of blood collection tube sizes and preservatives, successive freeze–thaw cycles, sample storage at −80 °C, and short-term storage at 4 and 20 °C on the quantitative lipoprotein and metabolite patterns were investigated. Storage of plasma samples at 4 °C for up to 48 h, freezing at −80 °C and blood sample collection tube choice have few and minor effects on quantitative lipoprotein profiles, and even storage at 4 °C for up to 168 h caused little information loss. In contrast, the impact of heat-treatment (56 °C for 30 min), which has been used for inactivation of SARS-CoV-2 and other viruses, that may be required prior to analytical measurements in low level biosecurity facilities induced marked changes in both lipoprotein and low molecular weight metabolite profiles. It was conclusively demonstrated that this heat inactivation procedure degrades lipoproteins and changes metabolic information in complex ways. Plasma from control individuals and SARS-CoV-2 infected patients are differentially altered resulting in the creation of artifactual pseudo-biomarkers and destruction of real biomarkers to the extent that data from heat-treated samples are largely uninterpretable. We also present several simple blood sample handling recommendations for optimal NMR-based biomarker discovery investigations in SARS CoV-2 studies and general clinical biomarker research.

Effects of Technical and Technological Parameters on the Surface Quality when Milling Thermally Modified European Oak Wood

The impact of heat-treatment and plane milling parameters were evaluated relative to the surface quality of native and thermally modified oak wood (Quercus robur L.). Experimental wood samples were treated via ThermoWood technology at Volga State University of Technology in Yoshkar-Ola, Russia. The investigation focused on the impact of the tool (rake angle = 15°, 20°, and 30°), material (native wood, wood heat-treated at 160 °C, 180 °C, 200 °C, and 220 °C), cutting speed (20 m/s, 40 m/s, and 60 m/s), and feed rate (20 m/min, 40 m/min, and 60 m/min) on the machined surface quality (mean arithmetic deviation of the surface). The roughness measurement was performed via a contactless method with a laser profilometer. An analysis of variance and post-hoc Duncan test revealed the influence of the examined parameters on the surface roughness in the following order from highest to lowest: rake angle, cutting speed, heat treatment temperature, and feed rate. This research is part of a study of the properties of woodworking thermally modified wood that is focused on measuring the quality and energy of the machining process.

Effect of Tempering on the Oxidation Resistance of a Work Roll Grade High-Chromium White Cast Iron

The high-temperature oxidation resistance of as-cast and heat-treated specimens of a high-chromium white cast iron for hot mill work rolls was investigated by gravimetric means under isothermal oxidation conditions in dry air at 650 °C. Results from the experiments revealed that the chromium content of the matrix and the carbide area fraction of the samples significantly affect the extent of oxidation. Even so, the oxidation phenomenon could always be described by the parabolic rate law. The surface morphology and cross-section of the samples were studied by means of X-ray diffraction, scanning electron microscopy and energy dispersive X-ray analyses, confirming that the oxidation behaviour of the alloys is sensitive to tempering heat treatment schedule. The impact of heat-treatment on the oxidation resistance of the work roll alloys is discussed in terms of their microstructural modification.

The structural and hydration properties of heat-treated rice studied at multiple length scales

The impact of heat-treatment on structure and hydration properties of rice was studied at different length scales (μm–nm). Heat-treatment introduced micro- and macro-pores within rice kernels (μCT) and, within intact cell walls, disintegrated starch granules were observed (SEM, CSLM). In native kernels starch predominantly occurred as crystalline A-type starch and, upon heat treatment, amorphous and V-type starch appeared (XRD, 13C CP MAS NMR). Plasticization of amorphous starch by water was more pronounced for heat-treated than for native kernels (13C SPE MAS NMR). Within native kernels, more effective spin diffusion between water and starch chains was present (WISE-Exchange), confirming the inter-helical nanoscale order of amylose helices. Upon heat-treatment, this inter-helical nanoscale order was lost, as well as microscale granular compartmentalisation (TD NMR). These findings explain why, upon heat-treatment, vapour sorption is lower and starch is more prone to gelatinization (DSC).