Investigation of the Structure and Allergic Potential of Whey Protein by Both Heating Sterilization and Simulation with Molecular Dynamics

As the main allergens in milk, whey proteins are heat-sensitive proteins and are widespread in dairy products and items in which milk proteins are involved as food additives. The present work sought to investigate the effect of heating sterilization on the allergenicity of α-lactalbumin (α-LA) and β-lactoglobulin (β-LG), the main composite and allergen in whey protein isolate (WPI), by combining molecular dynamics with experimental techniques for detecting the spatial structure and IgE binding capacity. The structure of WPI was basically destroyed at heat sterilization conditions of 95 °C for 5 min and 65 °C for 30 min by SDS-PAGE analysis and spectroscopic analysis. In addition, α-lactalbumin (α-LA) may be more sensitive to temperature, resulting in exposure to allergic epitopes and increasing the allergic potential, while the binding capacity of β-lactoglobulin (β-LG) to IgE was reduced under 65 °C for 30 min. By the radius of gyration (Rg) and root-mean-square deviation (RMSD) plots calculated in molecular dynamics simulations, α-LA was less structurally stable at 368 K, while β-LG remained stable at higher temperatures, indicating that α-LA was more thermally sensitive. In addition, we observed that the regions significantly affected by temperatures were associated with the capacity of allergic epitopes (α-LA 80-101 and β-LG 82-93, 105-121) to bind IgE through root-mean-standard fluctuation (RMSF) plots, which may influence the two major allergens. We inferred that these regions are susceptible to structural changes after sterilization, thus affecting the allergenicity of allergens.

Mortality of Bark- and Wood-boring Beetles (Coleoptera: Buprestidae, Cerambycidae, and Curculionidae) in Naturally Infested Heat-treated Ash, Birch, Oak, and Pine Bolts

Firewood and wood packaging material (WPM) are major pathways for moving bark- and wood-infesting insects (borers). Heat treatment regulations for interstate firewood movement vary among U.S. states: from 56°C for 30 min to 71.1°C for 75 min. Current WPM international standards (ISPM 15) require heating to a minimum of 56°C for 30 min throughout the profile of the wood. Using bolts from infested ash (Fraxinus), birch (Betula), oak (Quercus), and pine (Pinus) trees in Michigan, we assessed borer mortality at core temperatures of 50, 53, 56, and 60°C maintained for 30 min in chambers set to 60, 65, 70, or 75°C. After treatment, bolts were monitored for adult emergence and later dissected to determine borer mortality rates. Mortality was high to complete for all heat treatments and increased with both increasing core and chamber temperatures. For the Agrilus (Buprestidae) species tested, there was complete mortality of Agrilus anxius on birch and Agrilus planipennis on ash when core temperatures of 56°C or higher were targeted regardless of chamber temperature. However, on oak, a few Agrilus bilineatus and Agrilus sulcicollis survived in bolts heated to 56°C in chambers at 60 and 65°C, and some A. sulcicollis survived in chambers set at 70 and 75°C. Similarly, a few pine-infesting borers survived heating to 56°C at all chamber temperatures. However, there was complete mortality in all hosts when bolts were heated to 60°C for 30 min, regardless of chamber temperature. Results are discussed in terms of current treatment regulations for firewood and WPM.

On-Slide Heat Sterilization Enables Mass Spectrometry Imaging of Tissue Infected with High-Threat Pathogens Outside of Biocontainment: A Study Directed at Mycobacterium tuberculosis

Mass spectrometry imaging investigations of tissues infected with agents that require high-security biocontainment, such as Mycobacterium tuberculosis, have been limited due to incompatible sterilization techniques. Here we describe an on-slide heat sterilization method that enables mass spectrometry imaging investigations of pharmaceuticals, lipids, and metabolites in infected tissue samples outside of biocontainment. An evaluation of different temperatures and incubation times determined that 100 °C for 1 h was essential to sterilize 5 times the bacterial burden observed in tuberculosis (TB) cavity sections. Laser-capture microdissection combined with liquid chromatography with tandem mass spectrometry quantitation, in addition to mass spectrometry imaging, showed that no degradation was observed following the on-slide heat sterilization protocol for a variety of drug classes covering a range of physicochemical properties. Utilizing the tissue mimetic model, we demonstrated that the detection of lipid and metabolite ions was not impacted by heat sterilization and that, for several metabolites, the on-slide heat sterilization method improved the sensitivity when compared to control samples. An application of the on-slide heat sterilization to M. tuberculosis infected tissue enabled the first detection and spatial distribution of lipids indicative of a lysosomal storage disease phenotype within TB granuloma macrophages, in addition to the differential distribution of metabolites central to the fatty acid oxidation pathway. These initial investigations detected a pronounced heterogeneity within the cellular regions and necrotic cores of individual TB granulomas and across different evolving granulomas. This study provides the framework for mass spectrometry imaging investigations of high-threat pathogens outside of biocontainment.

Extraction Optimization of Astragaloside IV by Response Surface Methodology and Evaluation of Its Stability during Sterilization and Storage

Radix Astragali is referred to as a variety of food-medicine herb, and it is commonly applied as Traditional Chinese Medicine (TCM). However, it is extremely difficult to extract its bio-active compounds (astragaloside IV) and apply it in food processing efficiently, which restricts its practical applications. In this study, the conditions required for the extraction of astragaloside IV were optimized by following the response surface methodology. More specifically, ammonia with a concentration of 24% was used as an extracting solvent, the solid-liquid ratio was 1:10 (w:v); the Radix Astragali was soaked at 25 °C for 120 min in advance and then stirred at 25 °C for 52 min (150 rpm) to extract astragaloside IV. This method promoted the transformation of other astragalosides into astragaloside IV and replaced the traditional approach for extraction, the solvent reflux extraction method. The yield of astragaloside IV reached the range of 2.621 ± 0.019 mg/g. In addition, the stability of astragaloside IV was evaluated by detecting its retention rate during sterilization and 60-day storage. As suggested by the results, the astragaloside IV in acidic, low-acidic, and neutral solutions was maintained above 90% after sterilization (95 °C and 60 min) but below 60% in an alkaline solution. High temperature and short-term sterilization approach is more appropriate for astragaloside IV in an alkaline solution. It was also found out that the astragaloside IV obtained using our method was maintained over 90% when stored at room temperature (25 °C), and there was no significant difference observed to low temperature (4 °C) in solutions regardless of acidity.

Unleashing the Biological Potential of Fomes fomentarius via Dry and Wet Milling

Fomes fomentarius, usually referred to as tinder conk, is a common wood-based fungus rich in many interesting phytochemicals and with an unique porous structure. Dry or wet ball milling of this sponge on a planetary mill results in small particles with sizes in the range of 10 µm or below. Suspended in water and without preservatives or other stabilizers, the resulting micro-suspensions are sterile for around six days, probably due to the increased temperatures of around 80 °C especially during the wet milling process. The suspensions also exhibit excellent antioxidant activities as determined in the DPPH, ferric reducing antioxidant potential (FRAP) and 2,2′-azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS) assays. In the DPPH assay, IC₅₀ values of 0.02–0.04% w/v and 0.04% w/v were observed for dry and wet milled samples, respectively. In the FRAP assay, IC₅₀ values of <0.02% w/v and 0.04% w/v were observed for dry and wet milled samples, respectively. In contrast, the ABTS assay provided IC₅₀ values of 0.04% w/v and 0.005% w/v, respectively. Notably, this activity is mostly—albeit not exclusively—associated with the highly porous particles and their large surfaces, although some active ingredients also diffuse into the surrounding aqueous medium. Such suspensions of natural particles carrying otherwise insoluble antioxidants on their surfaces provide an interesting avenue to unleash the antioxidant potential of materials such as sponges and barks. As dry milling also enables longer storage and transport, applications in the fields of medicine, nutrition, agriculture, materials and cosmetics are feasible.