scholarly journals Molecular velocity auto-correlations in glycerol/water mixtures studied by NMR MGSE method

2020 ◽  
Vol 553 ◽  
pp. 124171 ◽  
Author(s):  
Janez Stepišnik ◽  
Carlos Mattea ◽  
Siegfried Stapf ◽  
Aleš Mohorič
Keyword(s):  
Glycerol Water ◽  
Molecular Velocity

scholarly journals Pressurized Hot Liquid Extraction with 15% v/v Glycerol-Water as an Effective Environment-Friendly Process to Obtain Durvillaea Incurvata and Lessonia Spicata Phlorotannin Extracts with Antioxidant and Antihyperglycemic Potential

Antioxidants ◽  
2021 ◽  
Vol 10 (7) ◽  
pp. 1105
Author(s):  
Fernanda Erpel ◽  
María Salomé Mariotti-Celis ◽  
Javier Parada ◽  
Franco Pedreschi ◽  
José Ricardo Pérez-Correa
Keyword(s):  
Brown Seaweed ◽  
Dry Weight ◽  
Liquid Extraction ◽  
Southern Chile ◽  
Polyphenol Content ◽  
Glycerol Water ◽  
Environment Friendly ◽  
Dry Extract ◽  
First Time ◽  
Anatomical Part

Brown seaweed phlorotannins have shown the potential to promote several health benefits. Durvillaea incurvata and Lessonia spicata—species that are widely distributed in central and southern Chile—were investigated to obtain phlorotannin extracts with antioxidant and antihyperglycemic potential. The use of an environmentally friendly and food-grade glycerol-based pressurized hot liquid extraction (PHLE) process (15% v/v glycerol water) was assessed for the first time to obtain phlorotannins. Multiple effects were analyzed, including the effect of the species, harvesting area (Las Cruces and Niebla), and anatomical part (holdfast, stipe, and frond) on the extracts’ polyphenol content (TPC), antioxidant capacity (AC), and carbohydrate-hydrolyzing enzyme—α-glucosidase and α-amylase—inhibitory activity. Contaminants, such as mannitol, heavy metals (As, Cd, Pb, Hg, and Sn), and 5-hydroxymethylfurfural (HMF), were also determined. The anatomical part used demonstrated a significant impact on the extracts’ TPC and AC, with holdfasts showing the highest values (TPC: 95 ± 24 mg phloroglucinol equivalents/g dry extract; DPPH: 400 ± 140 μmol Trolox equivalents/g dry extract; ORAC: 560 ± 130 μmol TE/g dry extract). Accordingly, holdfast extracts presented the most potent α-glucosidase inhibition, with D. incurvata from Niebla showing an activity equivalent to fifteen times that of acarbose. Only one frond and stipe extract showed significant α-glucosidase inhibitory capacity. No α-amylase inhibition was found in any extract. Although no HMF was detected, potentially hazardous cadmium levels (over the French limit) and substantial mannitol concentrations—reaching up to 50% of the extract dry weight—were found in most seaweed samples and extracts. Therefore, further purification steps are suggested if food or pharmaceutical applications are intended for the seaweed PHLE extracts obtained in this study.

Characteristics of air entrainment during dynamic wetting failure along a planar substrate

2014 ◽  
Vol 747 ◽  
pp. 119-140 ◽  
Author(s):  
E. Vandre ◽  
M. S. Carvalho ◽  
S. Kumar
Keyword(s):  
High Speed ◽  
Water Solution ◽  
Air Entrainment ◽  
Dynamic Contact ◽  
Operating Conditions ◽  
Dynamic Wetting ◽  
Glycerol Water ◽  
Planar Substrate ◽  
Wide Range ◽  
Stationary Plate

AbstractCharacteristic substrate speeds and meniscus shapes associated with the onset of air entrainment are studied during dynamic wetting failure along a planar substrate. Using high-speed video, the behaviour of the dynamic contact line (DCL) is recorded as a tape substrate is drawn through a bath of a glycerol/water solution. Air entrainment is identified by triangular air films that elongate from the DCL above some critical substrate speed. Meniscus confinement within a narrow gap between the substrate and a stationary plate is shown to delay air entrainment to higher speeds for a wide range of liquid viscosities, expanding upon the findings of Vandre, Carvalho & Kumar (J. Fluid Mech., vol. 707, 2012, pp. 496–520). A pressurized liquid reservoir controls the meniscus position within the confinement gap. It is found that liquid pressurization further postpones air entrainment when the meniscus is located near a sharp corner along the stationary plate. Meniscus shapes recorded near the DCL demonstrate that operating conditions influence the size of entrained air films, with smaller films appearing in the more viscous solutions. Regardless of size, air films become unstable to thickness perturbations and ultimately rupture, leading to the entrainment of air bubbles. Recorded critical speeds and air-film sizes compare well to predictions from a hydrodynamic model for dynamic wetting failure, suggesting that strong air stresses near the DCL trigger the onset of air entrainment.

scholarly journals Effects of water activity on the performance of potassium sorbate and natamycin as preservatives against cheese spoilage moulds

2017 ◽  
Vol 56 (1) ◽  
pp. 85-92 ◽  
Author(s):  
P. Marín ◽  
C. Ginés ◽  
P. Kochaki ◽  
M. Jurado
Keyword(s):  
Sodium Chloride ◽  
Water Activity ◽  
Penicillium Chrysogenum ◽  
Potassium Sorbate ◽  
Mucor Racemosus ◽  
Food Preservatives ◽  
Glycerol Water ◽  
Fungal Inhibition ◽  
Growth Of Fungi ◽  
Different Levels

AbstractThis work investigated the effects of the food preservatives potassium sorbate and natamycin, combined with different levels of ionic (sodium chloride) and non-ioinic (glycerol) water activity (aw), on growth of fungi involved in cheese spoilage. In general, the combined effect of water stress and presence of preservatives enhanced fungal inhibition. However, some doses of potassium sorbate (0.02%) and natamycin (1, 5 and 10 ppm) were able to stimulate growth of Aspergillus varians, Mucor racemosus, Penicillium chrysogenum and P. roqueforti at awvalues in the range of 0.93–0.97. P. solitum was the only species whose growth was consistently reduced by any doses of preservative. The results also showed that sodium chloride and glycerol differentially affected the efficacy of preservatives. This study indicates that awof cheese is a critical parameter to be considered in the formulation of preservative coatings used against fungal spoilage.

An experimental study of rheological properties and stability characteristics of biochar-glycerol-water slurry fuels

2016 ◽  
Vol 153 ◽  
pp. 37-42 ◽  
Author(s):  
Pengfei Liu ◽  
Mingming Zhu ◽  
Zhezi Zhang ◽  
Yee-kwong Leong ◽  
Yang Zhang ◽  
...  
Keyword(s):  
Experimental Study ◽  
Rheological Properties ◽  
Glycerol Water ◽  
Water Slurry

scholarly journals Comparative Fingerprint and Extraction Yield of Medicinal Herb Phenolics with Hepatoprotective Potential, as Determined by UV-Vis and FT-MIR Spectroscopy

2011 ◽  
Vol 39 (2) ◽  
pp. 82 ◽  
Author(s):  
Simona ZAVOI ◽  
Florinela FETEA ◽  
Floricuta RANGA ◽  
Raluca M. POP ◽  
Anca BACIU ◽  
...  
Keyword(s):  
Phenolic Acids ◽  
Extraction Yield ◽  
Bioactive Molecules ◽  
Chelidonium Majus ◽  
Glycerol Water ◽  
Lycopodium Clavatum ◽  
Mir Spectroscopy ◽  
Polyphenolic Composition ◽  
Solvent Dependence ◽  
Fingerprint Region

The present study was aimed to compare the polyphenolic composition of six medicinal herbs, from wild flora of Romania. The plants investigated, Cynara scolimus (artichoke), Taraxacum officinalis (dandelion), Chelidonium majus (celandine), Hypericum perforatum (St. John’s wort), Silybum marianum (Mary thistle) and Lycopodium clavatum (Wolf’s claw) are known, to have hepatoprotective action. Using in parallel glycerol-water, ethanol-water and methanol, the solvent-dependence of the extract fingerprint and composition in bioactive molecules was studied by UV-Vis and Infrared (FT-MIR) spectrometry. The extraction yields, calculated as an extraction factor (EF) were superior in acidic methanol comparative to glycerin and ethanol, favorising the increase in phenolic acids against flavonoid derivatives . Based on the differences of polarity between the three solvents used, higher EF values were obtained for dandelion, artichoke, celandine and St. John wort, more rich in phenolic acids than flavonoids. Mary thistle and Wolf’s claw had lower concentrations of phenolics, but higher content of lignans and terpenoids. Based on the FT-MIR peaks from 8 regions, for each plant extract, has been determined the fingerprint region between 900 and 1500 cm-1and identified the specific functional groups. A good, significant correlation was found between the concentration of total phenolics calculated by UV-Vis spectrometry and FTIR methods, after calibration with gallic acid. The value of the MIR signal at 1743 cm-1 may be considered a good indicator of phenolics concentration in such extracts. Combined UV-Vis and FTIR spectroscopy are recommended as rapid and reliable tools to investigate the fingerprint and to predict the composition of medicinal plants or to evaluate the quality and authenticity of different standardized formulas.

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