Hot Alkaline Treatment Research Articles

Effects of combined hot alkaline and pH-shift treatments on structure and functionality of legume protein-EGCG conjugates: Soybean-, pea-, and chickpea protein-EGCG systems

Legume proteins are appealing in the food industry for their nutrition and sustainability, but their low solubility due to the compact structure makes their applications in food industry limited. In this study, three commonly used legume proteins in food industry were selected as samples to be tested: soy protein (SP), pea protein (PP), and chickpea protein (CP). This study aims to improve the structural properties of these three proteins, so that it could promote effective grafting with epigallocatechin gallate (EGCG) through a combined hot alkaline and pH-shift treatments. Legume protein solutions were adjusted to pH 12 and heated at 80 °C for 30 min, resulting to a 13%–19% increase in free thiol content and a 59%–610% increase in surface hydrophobicity. This kind of change in structure leads to a 19%–46% increase in EGCG grafting degree. Treated protein-EGCG conjugates exhibited smaller and more uniform particle sizes, improved emulsification activity by 27%–218%, and additionally enhanced solubility, thermal stability, and antioxidant activity. Among all the tested proteins, pre-treated SP-EGCG conjugates showed the best solubility, emulsification, and thermal stability due to their highest surface hydrophobicity, highest EGCG grafting degree, and loose structure. These results indicate that combined hot alkaline and pH-shift treatment enhances the functional properties of legume proteins, expanding their potential applications as functional ingredients in the food industry.

Taguchi method and Box-Behnken design approach for process parameter optimization of magnetite (Fe3O4) coating developed on stainless steel 410 grade by hot alkaline treatment

The blackening of materials is widely used in the automobile industry, defense applications, aerospace applications, and solar applications. Methods such as electroless chemical process, conversion coating, physical vapor deposition, chemical vapor deposition, and diamond-like carbon are some of the commonly employed techniques to produce black coatings on various metals. Hot aqueous alkaline treatment is a chemical conversion coating process. In this study, hot alkaline treatment is used to blacken surgical equipment made of stainless steel 410, which is a novel approach. The effect of process variables such as immersion time, salt solution temperature, and wt% of sodium dichromate on the anti-reflective property of ferrous ferric oxide (magnetite, Fe3O4) coating has been optimized using the Taguchi method and response surface methodology. The experiments were designed using a Taguchi orthogonal array and a Box-Behnken design. The influences of coating parameters on average percentage reflectance were quantified by the signal-to-noise ratio, main effect plot, analysis of variance, and two-dimensional and three-dimensional plots. The comparison of experimental and confirmatory tests shows that both procedures optimized the parameters successfully. The lowest average percentage reflectance value of 8.013% was obtained at 56.976 min immersion time, 124.998°C salt solution temperature, and 348.689 g/l wt% of sodium dichromate in the composition by Box-Behnken design methodology.

Isolation of protein-free chitin spore coats of Nosema ceranae and its application to screen the interactive spore wall proteins.

Nosema ceranae is the pathogen of nosemosis in the honey bee, which can bring great economic loss to apiculture. Chitin acts as a major component of the endospore of microsporidia and plays an essential role to form the bridges across the endospore. Here, Chitin Spore Coats (CSCs) of N. ceranae were successfully extracted by optimized hot alkaline treatment. SDS-PAGE and Calcofluor White Stain (CWS) staining indicated that the obtained CSCs were protein-free and the transmission electron microscopy analysis showed that CSCs performed the intact and loose chitin spore coats. Western blotting and indirect immunofluorescence analysis (IFA) demonstrated that CSCs could interact with three spore wall proteins (rNcSWP7, rNcSWP8, and rNcSWP12). Our method was effective to extract CSCs of N. ceranae and this could be very useful for screening spore wall proteins involved in endospore composition, which could be helpful to uncover the biological structure and pathogenesis of microsporidia.

Fermented Cassava Residue Lignin Prepared by Sequential Acid Steam-Explosion and Hot-Alkaline Treatment and Its Antioxidant Properties

Fermented cassava residue (FCR) is a solid waste generated in cassava-based ethanol production that constitutes a major environmental challenge and wastes a natural resource. In the present study, a process involving sequential acid steam-explosion and hot-alkaline treatment was developed to prepare an antioxidant lignin in high yield and purity from FCR. Two-dimensional NMR analysis indicates that FCR lignin belongs to a guaiacyl/syringyl/hydroxyphenyl (G/S/H) class of lignin. 31P NMR analysis, after hydroxyl group phosphorylation, indicates that phenolic hydroxyl in FCR lignin attributable to mostly G-OH. One FCR lignin (No. 3) possessed the antioxidant activity similar to that of butylated hydroxytoluene. This FCR lignin may have potential applications as a food antioxidant or in other industrial processes as an antioxidant.

Surface-treated oil palm empty fruit bunch fiber improved tensile strength and water resistance of wheat gluten-based bioplastic

This study evaluated the morphology, chemical composition and color parameters of oil palm empty fruit bunch (OPEFB) fiber after surface treatment with hot water (90 °C) and alkali treatments (1 w/v% and 5 w/v% NaOH). Treatment of the fiber with a 5 w/v% solution of NaOH more effectively eliminated residual surface contaminants than hot water treatment and alkaline treatment with 1 w/v% NaOH. However, color parameters were slightly reduced. The tensile strength and water absorption of composites of wheat gluten and surface-modified fiber were compared with the same properties of composites loaded with unmodified fiber. The highest tensile strength and lowest water absorption were obtained with a composite of wheat gluten and 15 wt% OPEFB fiber treated with 5 w/v% NaOH. The good adhesion between the fiber and the wheat gluten matrix enabled a more effective transfer of stress from the wheat gluten matrix to the fiber and also reduced water absorption into the wheat gluten matrix. Therefore, composites of wheat gluten and oil palm empty fruit bunch fiber have potential to be developed for use as green composite materials.

Examining Free Jump Parameters under the Effect of Two Vertical Overlapping Gates (TVOG)

The effect of Solid State Fermentation (SSF) on Chitosan production by A. niger was investigated. A. niger BBRC 20004 from Biochemical and Bioenvironmental Research Centre of Sharif University of Technology (Tehran, Iran), was grown on corn residue. Chitosan was extracted from the fungal mycelia using hot alkaline and acid treatment. A. niger was incubated for 12 days on corn residue with moisture content of 35 % and 1.12 % of nitrogen. The Chitosan was obtained and 10.9 g/kg of Urea dry residue was added in various amounts to the medium in order to evaluate the effect of the nitrogen concentration in the production of Chitosan. The highest amount of Chitosan obtained by 6.5 g of urea after 12 days of incubation was 16.15 g/kg.

Activation behavior of an AB2 type metal hydride alloy for NiMH batteries

Activation behavior of an AB2, namely (Ti0.36Zr0.64) (V0.15Ni0.58Mn0.20Cr0.07)2 Laves phase alloy, was investigated with regards to; particle size, ball milling and hot alkaline treatments. Galvanostatic cycling in open cells showed that an untreated alloy initially had almost no capacity, but reached a value of 220 mAh/g after 14 cycles. Experiments with different particle sizes showed that coarse particles activate faster yielding an improved capacity. In terms of activation more pronounced effect was obtained with boiling the alloy powder in a hot KOH solution. A capacity in excess of 300 mAh/g is reached in the first cycle after a 20 min treatment. The capacity was highest after 80 min, yielding a value of 390 mAh/g well above that expected from the gas-phase storage in the alloy. This was attributed to the formation of rough surface in the powder, which may stabilize hydrogen bubbles allowing pressures above 1 atm to be reached locally in the surface.

Fractionation of organic substances from the South African Eucalyptus grandis biomass by a combination of hot water and mild alkaline treatments

An alternative way of fractionating lignocellulose biomass into its individual components, hemicelluloses, lignin and cellulose, was investigated. South African Eucalyptus grandis wood chips were fractionated using a combination of hot water and alkaline treatments with or without AQ. Initially, the biomass samples were treated in hot water to remove hemicelluloses. At optimum pre-fraction conditions, the data acquired revealed that almost 12 % of the E. grandis wood biomass could be recovered as hemicelluloses. When the hemicelluloses pre-extracted biomass was further treated using sodium hydroxide with or without AQ, the data indicated that the amount of lignin and cellulose that could be recovered was 22 and 36 %, respectively (as % of the wood mass). The substrate was characterised by a higher amount of α-cellulose (91–93 %), lower kappa no (12–13), viscosity (327–450 η mg/L) and DP (1078–1536). It was then presumed that such pulp could meet end-user requirement of the dissolving pulps. Industrial acceptance of this biomass fractionation concept, however, will further require careful assessments of various options for treating and purifying the hemicelluloses and lignin in their respect streams.

Chitin–glucan complex production by Komagataella pastoris: Downstream optimization and product characterization

Purified chitin–glucan complex (CGCpure) was extracted from Komagataella pastoris biomass using a hot alkaline treatment, followed by neutralization and repeated washing with deionized water. The co-polymer thus obtained had a β-glucan:chitin molar ratio of 75:25 and low protein and inorganic salts contents (3.0 and 0.9wt%, respectively). CGCpure had an average molecular weight of 4.9×105Da with a polydispersity index of 1.7, and a crystallinity index of 50%. Solid-state NMR provided structural insight at the co-polymer. X-ray diffraction suggests that CGCpure has α-chitin in its structure. CGCpure presented an endothermic decomposition peak at 315°C, assigned to the degradation of the saccharide structures. This study revealed that K. pastoris CGC has properties similar to other chitinous biopolymers and may represent an attractive alternative to crustacean chitin derived-products, being a reliable raw material for the development of new/improved pharmaceutical, cosmetic or food products.

Identification of a novel chitin-binding spore wall protein (NbSWP12) with a BAR-2 domain fromNosema bombycis(microsporidia)

The spore wall of Nosema bombycis plays an important role in microsporidian pathogenesis. Protein fractions from germinated spore coats were analysed by two-dimensional polyacrylamide gel electrophoresis and MALDI-TOF/TOF mass spectrometry. Three protein spots were identified as the hypothetical spore wall protein NbHSWP12. A BAR-2 domain (e-value: 1.35e-03) was identified in the protein, and an N-terminal protein-heparin interaction motif, a potential N-glycosylation site, and 16 phosphorylation sites primarily activated by protein kinase C were also predicted. The sequence analysis suggested that Nbhswp12 and its homologous genes are widely distributed among microsporidia. Additionally, Nbhswp12 gene homologues share similar sequence features. An indirect immunofluorescence analysis showed that NbHSWP12 localized to the spore wall, and thus we renamed it spore wall protein 12 (NbSWP12). Moreover, NbSWP12 could adhere to deproteinized N. bombycis chitin coats that were obtained by hot alkaline treatment. This novel N. bombycis spore wall protein may function in a structural capacity to facilitate microsporidial spore maintenance.

A rapid and general method for measurement of protein in micro-algal biomass

A convenient small-scale extraction method for lyophilized micro-algae is described that dispenses with labor-intensive homogenization and is widely applicable to algae from different phyla. The procedure employs an optimized sequential extraction in trichloroacetic acid (TCA) and NaOH to achieve chemical lysis. Conditions were tested using several micro-algal strains to develop a method that was generally applicable. Incubation of lyophilized material in 24% (w/v) TCA at 95°C followed by a hot alkaline treatment was found to be effective for strains that are resistant to conventional extraction approaches, such as the Chlorella and the Eustigmatophycean species. The single-tube extraction procedure can be complete in 4h and is conveniently followed by the Lowry assay, requiring a further 30min. Overall, this method proved to be generally applicable and ideal either for single samples or for high-throughput screening of multiple algal strains for protein content.

Fe2O3‐Modified Hydrogen Storage Alloys as Electrocatalyst for Borohydride Oxidation

AbstractThe effects of hot alkaline treatment and Fe2O3 modification of hydrogen storage alloy on the electrocatalytic activity for oxidation of borohydride have been investigated using linear sweep voltammetry. The performance of borohydride electrochemical oxidation was significantly influenced by the hot alkaline treatment and Fe2O3 modification of the hydrogen storage alloy. The results showed that the current density of the Fe2O3‐modified hot alkaline‐treated hydrogen storage alloy electrode containing 5 wt% Fe2O3 reached 125 mA·cm−2 in 0.10 mol·L−1 NaBH4 and 2 mol·L−1 NaOH solution at −0.55 V vs. saturated Ag/AgCl, KCl electrode.

Influence of Different Nitrogen Sources on Amount of Chitosan Production by Aspergillus niger in Solid State Fermentation

In this study the effect of different nitrogen source substrates on the amount of chitosan production by Aspergillus niger was investigated. A. niger PTCC 5012 from the Persian Type Culture Collection (PTCC) was grown on soy bean, corn seed and canola residues at 30 °C for specified cultivation days under sterilized conditions. Chitosan was extracted from the fungal mycelia using hot alkaline and acid treatment. The results were shown that soy bean residue at moisture of 37% and 8.4 ± 0.26 % of nitrogen content produced the highest amount of chitosan (17.053 ± 0.95 g/kg of dry substrate), after 12 days of incubation. Corn seed residue produced very low amount of chitosan (1.9 ± 0.4 % of nitrogen content). The chitosan was analyzed by FTIR spectroscopy and its spectrum was recorded.

Structure of large arteries: Orientation of elastin in rabbit aortic internal elastic lamina and in the elastic lamellae of aortic media

This study was designed to further our understanding of the elastic ultrastructure of vessels. Scanning electron microscopy and transmission electron microscopy were used to study the histomorphologic properties of the elastic fibers of rabbit aorta after purification of the elastin by means of hot alkaline treatments. The elastic fibers of whole rabbit aorta samples were also studied using confocal microscopy. Morphological assessment revealed that the elastin fibers contained in the elastic lamellae of media are perpendicular to the blood flow, and that the elastic fibers of the internal elastic lamina are parallel to the luminal flow. In conclusion, the structure of the elastin making up the elastic lamellae of the media is oriented in such a way as to sustain the circumferential mechanical stress of pulsation. By contrast, the structure of the elastin fibers that make up the internal elastic lamina provides little mechanical support for the circumferential tension, but can support longitudinal loading and act as a fenestrated membrane.

The formation of aromatic end group structures in O-alkyl substituted celluloses under alkaline pulping conditions

Abstract UV resonance Raman (UVRR) spectroscopy was used to study changes in the structure of reducing end groups of O-alkyl substituted celluloses under conditions simulating the initial phase of soda pulping. The derivatives studied were carboxymethyl cellulose (CMC) with a degree of substitution (DS) of 0.58 and methyl cellulose (MC) with DS of 1.64–1.95. Hot alkaline treatments were carried out in solutions of sodium hydroxide (0.1–1 M) at 95°C in the presence of creosol as a lignin model compound. Alkali-stable aromatic end groups were generated in both cellulose ethers. Moreover, the end groups of methyl cellulose were extensively condensed with creosol. The results demonstrate that aromatisation and condensation depend on the pH and reaction time.

Formation of Aromatic and Other Unsaturated End Groups in Carboxymethyl Cellulose During Hot Alkaline Treatment

Carboxymethyl cellulose (CMC, DS 0.58) was treated in solutions of sodium hydroxide (0.001–1 M) at 95 °C. The treated (1–12 h) CMC samples were purified by dialysis and analyzed by UV spectroscopy and by UV resonance Raman spectroscopy (UVRRS) with excitation at 244 nm. A UV absorption maximum at 265 nm and a UVRR signal at 1650 cm−1 were indicative of formation of \(\alpha,\beta\)-conjugated aldehyde end groups in CMC through \(\beta\)-elimination. Another strong UVRR band at 1610 cm−1 gave evidence on conversion of some of the \(\alpha,\beta\)-conjugated aldehyde end groups to alkali stable aromatic structures.

Isolation and mass spectrometric characterization of dimeric adenine photoproducts in oligodeoxynucleotides.

UVC irradiation of oligodeoxynucleotides (ODNs) at 254 nm generates two types of DNA photoproducts, A=A and (AA)*, at adjacent adenine sites in DNA. Kumar et al. previously proved the structure of these adducts in dinucleoside monophosphates [Kumar, S., et al. (1987) Nucleic Acids Res. 15, 1199-1216; Kumar, S., et al. (1991) Nucleic Acids Res. 19, 2841-2847]. Product-ion spectra of ESI-produced [M - 2H](2-) ions of the ODNs containing the dimeric adenine photoproducts show distinctive fragmentation that is informative of the structures of the photoproducts. The gas-phase cleavages of ODNs at sites of those photoproducts and thymine thymine or thymine adenine ((TA)*) photoproducts are analogous to cleavages induced by hot alkaline treatment. Nuclease-P1 digestions of ODNs containing dimeric adenine photoproducts give shorter pieces of ODNs bearing the photoproducts, which fragment under collisional activation conditions in a similar way to the large ODNs containing the photoproducts. The tandem mass spectrometric results show that the yield of (AA)* is lower than that of A=A when adjacent adenines are in the middle of an ODN sequence, and the yield of the latter is similar to that of (TA)*.

Hot alkaline treatment on hydrogen storage alloys in sealed Ni/MH batteries

In the production of Ni/MH batteries the activation after sealing process was adopted and the free internal space is closed to the limit margin, which usually results in quality problems, including high internal pressure, electrolyte leakage and short cycle life during the activation and overcharging at high rates. In the present research we have directed our attention to the hot alkaline treatment conditions and the electrochemical properties of the treated Ni/MH batteries using AB5 or AB2 alloys as the negative electrodes. It is found that for Ni/MH batteries the hot alkaline treatment can decrease the internal pressure significantly, even when the battery is overcharged at high rates, for example 1 C, and the comprehensive characteristics are improved, especially the durability of Ni/MH batteries. The hot alkaline treatment can also shorten the activation to one single charge and discharge cycle at 0.2 C. The hot alkaline treatment also offers the possibility to provide more internal space for positive and negative electrodes to increase the battery capacity.

A method for direct harvest of bacterial cellulose filaments during continuous cultivation of Acetobacter xylinum

Continuous filamentation of bacterial cellulose (BC) was successfully achieved by using shallow pan for the incubation to regulate thickness of the BC gel produced by Acetobacter xylinum. The BC filament was harvested and prepared directly by picking up BC pellicles, the thin BC gel, and winding slowly from the surface of the culture medium passed through a preliminary bactericidal washing bath. The X-ray diffraction analysis and scanning electron microscopic observation of the BC filament thus obtained showed that the filament was smooth and the fairly good orientation of BC molecules. The average tensile strength was 4.4 g denier −1 for the filament prepared by hot alkaline treatment and subsequent washing with distilled water and dried under tension (Filament W): 3.4 g denier −1 for washing with 10% aqueous ethylene glycol after alkaline treatment followed by drying under tension (Filament E) and 2.4 g denier −1 for the treatment with 10% ethylene glycol after normal water-washing followed by drying under tension.

Activation of Zr 0.5Ti 0.5V 0.75Ni 1.25 alloy electrodes by hot alkaline solutions

Hot alkaline treatment of the multiphase alloy Zr 0.5Ti 0.5V 0.75Ni 1.25 results in significant surface corrosion, with at least some of the corrosion products being soluble in the treating solution. The corrosion process generates hydrogen that is largely absorbed by the alloy during treatment, resulting in heterogeneous particle cracking and significant electrochemical discharge capacity ( C 0) even before the first deliberate charge. The discharge capacity ( C 1) after the first deliberate charge is significantly increased by hot alkaline treatment. C 0 is a direct measure of alloy corrosion during the hot alkaline treatment and should be minimized in practice. C 1 is a measure of the electrochemical activation rate and should be maximized in practice. Another important parameter is the maximum capacity C max. The effects of treatment time and temperature as well as solution (KOH vs. NaOH) on C 0, C 1and C max are presented, along with some long-time cyclic capacity data.