scholarly journals Modified Rhamnogalacturonan-Rich Apple Pectin-Derived Structures: The Relation between Their Structural Characteristics and Emulsifying and Emulsion-Stabilizing Properties

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1586
Author(s):  
Jessika N. Humerez-Flores ◽  
Sarah H. E. Verkempinck ◽  
Clare Kyomugasho ◽  
Paula Moldenaers ◽  
Ann M. Van Loey ◽  
...  
Keyword(s):  
Emulsion Stability ◽  
Structural Characteristics ◽  
Stability Study ◽  
Natural Food ◽  
Apple Pectin ◽  
Oil Droplets ◽  
Food Ingredients ◽  
Acidic Conditions ◽  
Hydrolysis Of ◽  
Subsequent Acid

In the context of the increasing interest in natural food ingredients, the emulsifying and emulsion-stabilizing properties of three rhamnogalacturonan-rich apple pectin-derived samples were assessed by evaluating a range of physicochemical properties. An apple pectin (AP74) was structurally modified by a β-eliminative reaction to obtain a RG-I-rich pectin sample (AP-RG). Subsequent acid hydrolysis of AP-RG led to the generation of pectin material with partially removed side chains (in particular arabinose depleted) (AP-RG-hydrolyzed), thus exhibiting differences in rhamnose, arabinose, and galactose in comparison to AP-RG. All samples exhibited surface activity to some extent, especially under acidic conditions (pH 2.5). Furthermore, the viscosity of the samples was assessed in relation to their emulsion-stabilizing properties. In a stability study, it was observed that the non-degraded AP74 sample at pH 2.5 exhibited the best performance among all the apple pectin-derived samples evaluated. This emulsion presented relatively small oil droplets upon emulsion production and was less prone to creaming than the emulsions stabilized by the (lower molecular weight) RG-I-rich materials. The AP-RG and AP-RG-hydrolyzed samples presented a slightly better emulsion stability at pH 6.0 than at pH 2.5. Yet, neither pectin sample was considered having good emulsifying and emulsion-stabilizing properties, indicated by the presence of coalesced and flocculated oil droplets.

Preparation of Organized Mesoporous Silica from Sodium Metasilicate Solutions in Alkaline Medium Using Nonionic Surfactants

2003 ◽  
Vol 68 (10) ◽  
pp. 2019-2031 ◽  
Author(s):  
Markéta Zukalová ◽  
Jiří Rathouský ◽  
Arnošt Zukal
Keyword(s):  
Mesoporous Silica ◽  
Ethylene Oxide ◽  
Sodium Metasilicate ◽  
Spherical Particles ◽  
Structure Directing Agent ◽  
Inorganic Species ◽  
Poly Ethylene Oxide ◽  
Acidic Conditions ◽  
Poly Ethylene ◽  
Hydrolysis Of

A new procedure has been developed, which is based on homogeneous precipitation of organized mesoporous silica from an aqueous solution of sodium metasilicate and a nonionic poly(ethylene oxide) surfactant serving as a structure-directing agent. The decrease in pH, which induces the polycondensation of silica, is achieved by hydrolysis of ethyl acetate. Owing to the complexation of Na+ cations by poly(ethylene oxide) segments, assembling of the mesostructure appears to occur under electrostatic control by the S0Na+I- pathway, where S0 and I- are surfactant and inorganic species, respectively. As the complexation of Na+ cations causes extended conformation of poly(ethylene oxide) segments, the pore size and pore volume of organized mesoporous silica increase in comparison with materials prepared under neutral or acidic conditions. The assembling of particles can be fully separated from their solidification, which results in the formation of highly regular spherical particles of mesoporous silica.

scholarly journals The Hsp60 Protein of Helicobacter Pylori Exhibits Chaperone and ATPase Activities at Elevated Temperatures

BioChem ◽  
2021 ◽  
Vol 1 (1) ◽  
pp. 19-25
Author(s):  
Jose A. Mendoza ◽  
Julian L. Ignacio ◽  
Christopher M. Buckley
Keyword(s):  
Helicobacter Pylori ◽  
Heat Stress ◽  
Molecular Chaperone ◽  
Elevated Temperatures ◽  
Citrate Synthase ◽  
Gastric Epithelium ◽  
Acidic Conditions ◽  
H Pylori ◽  
Induced Aggregation ◽  
Hydrolysis Of

The heat-shock protein, Hsp60, is one of the most abundant proteins in Helicobacter pylori. Given its sequence homology to the Escherichia coli Hsp60 or GroEL, Hsp60 from H. pylori would be expected to function as a molecular chaperone in this organism. H. pylori is a type of bacteria that grows on the gastric epithelium, where the pH can fluctuate between neutral and 4.5, and the intracellular pH can be as low as 5.0. We previously showed that Hsp60 functions as a chaperone under acidic conditions. However, no reports have been made on the ability of Hsp60 to function as a molecular chaperone under other stressful conditions, such as heat stress or elevated temperatures. We report here that Hsp60 could suppress the heat-induced aggregation of the enzymes rhodanese, malate dehydrogenase, citrate synthase, and lactate dehydrogenase. Moreover, Hsp60 was found to have a potassium and magnesium-dependent ATPase activity that was stimulated at elevated temperatures. Although, Hsp60 was found to bind GTP, the hydrolysis of this nucleotide could not be observed. Our results show that Hsp60 from H. pylori can function as a molecular chaperone under conditions of heat stress.

scholarly journals Food Ingredients and Nutraceuticals from Microalgae: Main Product Classes and Biotechnological Production

Foods ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1626
Author(s):  
Regina Kratzer ◽  
Michael Murkovic
Keyword(s):  
Growth Conditions ◽  
Food Supplement ◽  
Natural Food ◽  
Biotechnological Production ◽  
Microalgal Biomass ◽  
Food Ingredients ◽  
Fishmeal Replacement ◽  
Economic Production ◽  
Energy Inputs ◽  
Food Dyes

Microalgal products are an emerging class of food, feed, and nutraceuticals. They include dewatered or dried biomass, isolated pigments, and extracted fat. The oil, protein, and antioxidant-rich microalgal biomass is used as a feed and food supplement formulated as pastes, powders, tablets, capsules, or flakes designed for daily use. Pigments such as astaxanthin (red), lutein (yellow), chlorophyll (green), or phycocyanin (bright blue) are natural food dyes used as isolated pigments or pigment-rich biomass. Algal fat extracted from certain marine microalgae represents a vegetarian source of n-3-fatty acids (eicosapentaenoic acid (EPA), docosahexaenoic acid (DHA), γ-linolenic acid (GLA)). Gaining an overview of the production of microalgal products is a time-consuming task. Here, requirements and options of microalgae cultivation are summarized in a concise manner, including light and nutrient requirements, growth conditions, and cultivation systems. The rentability of microalgal products remains the major obstacle in industrial application. Key challenges are the high costs of commercial-scale cultivation, harvesting (and dewatering), and product quality assurance (toxin analysis). High-value food ingredients are commonly regarded as profitable despite significant capital expenditures and energy inputs. Improvements in capital and operational costs shall enable economic production of low-value food products going down to fishmeal replacement in the future economy.

Theoretical study on the reaction mechanism for the hydrolysis of esters and amides under acidic conditions

Tetrahedron ◽  
2007 ◽  
Vol 63 (5) ◽  
pp. 1264-1269 ◽  
Author(s):  
Kenzi Hori ◽  
Yutaka Ikenaga ◽  
Kouichi Arata ◽  
Takanori Takahashi ◽  
Kenji Kasai ◽  
...  
Keyword(s):  
Reaction Mechanism ◽  
Theoretical Study ◽  
Acidic Conditions ◽  
Hydrolysis Of Esters ◽  
Hydrolysis Of

Effect of acidity on the properties of silica-aluminas synthesized by sol-gel method

2020 ◽  
Vol 63 (7) ◽  
pp. 126-132
Author(s):  
Lyubov V. Furda ◽  
◽  
Evgenia A. Tarasenko ◽  
Sofya N. Dudina ◽  
Olga E. Lebedeva ◽  
...  
Keyword(s):  
Surface Area ◽  
Sol Gel ◽  
Molar Ratio ◽  
Active Centers ◽  
Indicator Method ◽  
Synthesis Conditions ◽  
Alkaline Conditions ◽  
Acidic Conditions ◽  
Amphoteric Properties ◽  
Hydrolysis Of

In the present work amorphous silica-aluminas were synthesized by the coprecipitation method during the hydrolysis of an alcohol solution of tetraethoxysilane (with a tetraethoxysilane: alcohol mass ratio of 1: 1) and 6% aqueous solution of aluminum nitrate at pH values of 1, 3, and 10. The Si/Al molar ratio for all synthesized samples were 4.72 (± 0.29). The amorphous character of the investigated materials was confirmed by X-ray phase analysis. According to the results of scanning electron microscopy, it was found that the resulting powders have particles with a size of 1-20 μm. It was shown that the conditions of synthesis affected the specific surface area and porosity of the materials under study. By the method of low-temperature adsorption-thermodesorption of nitrogen it was established that silica-aluminas obtained under acidic conditions were microporous materials. For the sample obtained under alkaline conditions (pH = 10), the contribution of macropores is very significant. A decrease in surface area is observed as the pH of the synthesis increases. The Hammett indicator method was used to identify and quantify surface centers of different acidity. All studied silica-aluminas are characterized by the presence of both Brønsted basic (pKax from 7 to 12.8) and acidic (pKax from 0 to 7) centers, and Lewis basic (pKax from -4.4 to 0) with a pronounced maximum at pKax = 1.02. It was found that the synthesis conditions had a significant effect on the concentration of active centers. The values of the Hammett function are practically the same for the 3 studied silica-aluminas and describe the studied samples as materials of medium acidity. The variety of Lewis and Brønsted centers on the surface indicates the amphoteric properties of the materials under study. This gives the samples the properties of polyfunctional sorbents and catalysts.

Determination and Quantitation of Residual Solvents in Natural Food Ingredients Using a Static Headspace Gas Chromatography with Flame Ionization Detection and Mass Spectrometric Detection Method

2018 ◽  
Vol 81 (10) ◽  
pp. 1573-1581
Author(s):  
FADWA AL-TAHER ◽  
BORIS NEMZER
Keyword(s):  
Mass Spectrometric ◽  
Mass Spectrometric Detection ◽  
Natural Food ◽  
Flame Ionization Detection ◽  
Static Headspace ◽  
Food Ingredients ◽  
Residual Solvents ◽  
Ionization Detection ◽  
Flame Ionization ◽  
Relative Standard

ABSTRACT The determination of residual solvents is critical for quality control in food production and manufacturing processes. A gas chromatographic and mass spectrometric detection (MSD) method was developed and validated to complement the static headspace flame ionization detection (FID) technique for identification, confirmation, and quantitation of solvent residues in botanicals, using Coffeeberry extract and pomegranate powder as test samples. Relative standard deviations (RSDs) of less than 12% were obtained for residual solvents in water and dimethyl sulfoxide. Coffeeberry extract supplemented with10 μg/g of Residual Solvents Class 3 Mix showed MSD and FID recoveries mainly of 91 to 121% and 77 to 110%, respectively, while those samples supplemented with 100 μg/g of Residual Solvents Class 3 Mix displayed MSD and FID recoveries of 105 to 123% and 87 to 112%, respectively. For pomegranate samples supplemented with 10 μg/g of Residual Solvents Class 3 Mix, MSD and FID recoveries of 95 to 124% and 72 to 151% were observed, respectively. Those samples supplemented with 100 μg/g of Residual Solvents Class 3 Mix exhibited MSD and FID recoveries of 109 to 135% and 97 to 127%, respectively. Thus, the developed procedure was demonstrated to be suitable for the analysis of residual solvents in natural food ingredients and is expected to find numerous industrial applications (e.g., process control and impurity detection in final products).

scholarly journals Towards a Non-Biased Formaldehyde Quantification in Leather: New Derivatization Conditions before HPLC Analysis of 2,4-Dinitrophenylhydrazine Derivatives

Molecules ◽  
2020 ◽  
Vol 25 (23) ◽  
pp. 5765
Author(s):  
Caroline Bourgeois ◽  
Nicolas Blanc ◽  
Jean-Claude Cannot ◽  
Claire Demesmay
Keyword(s):  
Hplc Analysis ◽  
Orthophosphoric Acid ◽  
Reversed Phase ◽  
Precolumn Derivatization ◽  
Reversed Phase Liquid Chromatography ◽  
Formaldehyde Content ◽  
Buffer Solutions ◽  
Phase Liquid ◽  
Acidic Conditions ◽  
Hydrolysis Of

In leathers, formaldehyde is currently analyzed according to EN ISO 17226-1 standard, by reversed phase liquid chromatography after off-line precolumn derivatization with 2,4 dinitrophenylhydrazine (DNPH) in strong acidic conditions. We first demonstrate that this standard is not adapted to leather retanned with resins likely to release formaldehyde by hydrolysis. Indeed, formaldehyde content may be largely overestimated due to concomitant resin hydrolysis (in harsh acidic conditions) that releases formaldehyde during the derivatization step and during the waiting time on autosampler before analysis. Therefore, we thoroughly studied the derivatization step in order to propose new derivatization conditions. Replacing orthophosphoric acid by less acidic buffer solutions is not enough to avoid hydrolysis. A derivatization without adding acid is realized by solubilizing DNPH in acetonitrile instead of orthophosphoric acid. These conditions lead to a complete derivatization of formaldehyde in 3 h at 50 °C (in a water bath) while avoiding the hydrolysis of co-extracted dicyandiamide and melamine resins. The as-obtained leather extracts are stable over time. Formaldehyde contents found with this method agree with the formaldehyde content measured immediately at the end of derivatization reaction in standard conditions or with formaldehyde content measured by a home-designed flow injection analysis with acetylacetone online derivatization and UV detection.

scholarly journals PARÂMETROS FÍSICOS NO ESTUDO DA ESTABILIDADE DAS EMULSÕES PHYSICALS PARAMETERS IN THE EMULSION STABILITY STUDY

2001 ◽  
Vol 2 (2) ◽  
Author(s):  
Sandra Maria W. Zanin ◽  
Marilis Dallarmi Miguel ◽  
Márcio Chimelli ◽  
Ana Cláudia Dalmaz
Keyword(s):  
Low Temperature ◽  
Shelf Life ◽  
Emulsion Stability ◽  
Subjective Evaluation ◽  
Stability Study ◽  
Physical Parameters ◽  
Geographic Locations ◽  
Pharmaceutical Manufacturers ◽  
Regulatory Acceptance ◽  
Artificial Stress

A estabilidade de uma emulsão definida pelo consumidor e muitas vezes pelo próprio formulador está baseada inteiramente em parâmetros subjetivos. Por isso, é importante lembrar que o padrão de estabilidade depende em larga escala do observador, e é esta a razão porque as observações subjetivas ou opiniões por si só não são suficientes para definir parâmetros como estabilidade aceitável. O tempo de prateleira de um produto e as condições de estresse artificiais são termos úteis para descrever a avaliação subjetiva da estabilidade de uma emulsão, contudo, e por esta mesma razão, os formuladores devem ser cautelosos para estabelecer a segurança e as condições de regulamentação dos componentes de uma emulsão para uma aplicação particular. O aspecto ou as características organolépticas de uma emulsão como a homogeneidade, brilho, macio, fino e opacidade, bem como o comportamento reológico e a espalhabilidade, estão entre os parâmetros físicos que devem ser avaliados, porque os produtos emulsionados podem ser transportados e utilizados em diversos locais do planeta com diferentes climas e condições de temperatura extremamente altas e baixas. Assim, os farmacêuticos devem possuir conhecimento pré-determinado da estabilidade de suas emulsões antes que elas possam ser comercializadas. PHYSICALS PARAMETERS IN THE EMULSION STABILITY STUDY Abstract Emulsion stability as defined by the consumer or even by the formulator is based entirely in subjective judgments. It is important, therefore, to remember that the standard of stability dependes to a large extent on the observer, since subjective observations or opinions by themselves do not suffice to define such a parameter as acceptable stability. Shelf life and artificial stress conditions are useful terms to describe the subjective evaluation of an emulsion stability, therefore, formulators are cautioned to establish the safety and regulatory acceptance of emulsion ingredients for a particular application. The emulsion aspect such us homogeneity, gloss, smooth, thin and dull, and rheologic behavior and spreadability were among the physical parameters that must be observed because emulsion products may be transported to and used in various geographic locations having varying climates and conditions of extremely high and low temperature. Thus, pharmaceutical manufacturers must have predetermined knowledge of their emulsion stabililty before they may be shipped.

Potential GABAB Receptor Antagonists. III. Folded Baclofen Analogs Based on Phthalide

1989 ◽  
Vol 42 (6) ◽  
pp. 787 ◽  
Author(s):  
C Donati ◽  
RH Prager ◽  
B Weber
Keyword(s):  
Ethyl Acetoacetate ◽  
Gabab Receptor ◽  
Hydrazoic Acid ◽  
Receptor Antagonists ◽  
Keto Ester ◽  
Acidic Conditions ◽  
Gabab Receptor Antagonists ◽  
Hydrolysis Of ◽  
Parallel Series

Possible analogues of baclofen, 3-aminomethyl-5-chloro-, 3-aminomethyl-6-chloro- and 3-aminomethyl-5,6-dichloro-isobenzofuran-1(3H)-one, have been prepared for evaluation as antispasticity agents. The corresponding 3-hydroxyisobenzofuran-l(3H)-one was reacted with ethyl acetoacetate under acidic conditions, and the keto ester hydrolysed and decarboxylated to give the 3-(2-oxopropyl)isobenzofuran-l(3H)-one; this was treated with hydrazoic acid, and the product was hydrolysed. A parallel series of (3-oxo-1,3-dihydroisobenzofuran-1-y1)glycines was obtained by treating the keto ester first with hydrazoic acid, and hydrolysis of the resulting acetamides.

Limited hydrolysis of dehulled walnut (Juglans regia L.) proteins using trypsin: Functional properties and structural characteristics

LWT ◽  
2020 ◽  
Vol 133 ◽  
pp. 110035
Author(s):  
Feng Jin ◽  
Yaping Wang ◽  
Hengkuan Tang ◽  
Joe M. Regenstein ◽  
Fengjun Wang
Keyword(s):  
Functional Properties ◽  
Structural Characteristics ◽  
Juglans Regia ◽  
L Proteins ◽  
Hydrolysis Of
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