Amylose-lipid complex as a measure of variations in physical, mechanical and barrier attributes of rice starch- ι -carrageenan biodegradable edible film

Improvements in the hygroscopic properties of starch based films are important to strengthen their mechanical properties. The effects of different hydrophobic components-butyric acid (BA, C4:0), lauric acid (LA, C12:0), palmitic acid (PA, C16:0), oleic acid (OA, C18:1), stearic acid (SA, C18:0) and sucrose fatty acid ester (FAEs) on the rice starch (RS)-ι-carrageenan (ι-car) composite films were investigated. Scanning electron microscopy (SEM), differential scanning calorimetry (DSC), thermogravimetric analysis (TGA) in combination with amylose-lipid complexing index (CI) were used to characterise the changes in structure and properties of edible films. The SEM results showed that the surface of films became smoother after the incorporation of fatty acids. Carbon-chain length was a major determinant of CI formation which further influenced the attributes of RS-ι-car films. The addition of FAEs to RS-ι-car improved film thickness, permeability, transparency, tensile properties (TS) and could be used to tailor biodegradable edible films with enhanced properties and future fruit coating applications

Application of Texture Analysis technique in formulation development of lyophilized orally disintegrating tablets containing mannitol, polyvinylpyrrolidone and amino acids

The file attached to this record is the author's final peer reviewed version. The Publisher's final version can be found by following the DOI link.Orally disintegrating tablets (ODTs) attract a great attention as this easy swallowing dosage form often improves patient compliance. In the current work, orally disintegrating tablets comprising mannitol, polyvinylpyrrolidone (PVP) and an amino acid (alanine, glycine or serine) with various PVP-to-amino acid ratios were formulated. The combination of mannitol and an amino acid was aimed to use the advantages of mannitol, the matrix-supporting and disintegration agent, and to reduce the total amount of sugar/polyol in tablets. Tablets were manufactured by freeze-drying and their properties (appearance, internal structure, disintegration, mechanical and texture properties, moisture uptake, shrinkage, thermal properties) were assessed. In the work, great emphasis was placed on illustrating the applicability of the Texture Analysis of the freeze-dried cakes directly in vials in formulation development. The results show that the appearance, mechanical properties, disintegration and shrinkage of the freeze-dried ODTs depend significantly on the excipient composition with PVP playing the leading role. Partial mannitol replacement with an amino acid has a limited impact on the tablet properties. The presence of an amino acid also has no impact on the PVP-mannitol interaction. The mechanical and texture properties of freeze-dried ODTs depend non-linearly on the PVP content. The transition between the different types of textures occurs in a narrow range of PVP concentrations regardless of the type of amino acid in a formulation. The non-linear effect of PVP on various tablet properties should be taken into account when designing ODT formulations as it can compromise the robustness of the manufacturing process

Influence of citric acid and water on thermoplastic wheat flour/poly(lactic acid) blends. I: Thermal, mechanical and morphological properties

Wheat flour was plasticized with glycerol and compounded with poly(lactic acid) in a one-step twin-screw extrusion process in the presence of citric acid with or without extra water. The influence of these additives on process parameters and thermal, mechanical and morphological properties of injected samples from the prepared blends, was then studied. Citric acid acted as a compatibilizer by promoting depolymerization of both starch and PLA. For an extrusion without extra water, the amount of citric acid (2 parts for 75 parts of flour, 25 parts of PLA and 15 parts of glycerol) has to be limited to avoid mechanical properties degradation. Water, added during the extrusion, improved the whole process, minimizing PLA depolymerization, favoring starch plasticization by citric acid and thus improving phases repartition

3-N-oxalyl-L-2,3-diaminopropanoic acid, a multifunctional plant metabolite of toxic reputation

3-N-oxalyl-L-2,3-diaminopropanoic acid (beta-ODAP) is a neuroexcitatory non- protein amino acid identified in grass pea (Lathyrus sativus L.) and in ginseng (Panax spp). Its presence in the drought tolerant grass pea is thought to be responsible for the crippling disease neurolathyrism, while in the longevity promoting ginseng it is named dencichine and praised for its haemostatic properties. Some properties of beta-ODAP are put in perspective

Effect of charged lipids on the ionization behavior of glutamic acid containing transmembrane helices

Transmembrane proteins make up critical components of living cells. Protein function can be greatly impacted by the charged state of its respective components, the side chains of amino acid residues. Thus far, in the lipid membrane, little is known about the properties of residues such as glutamic acid. To explore these properties, I have included glutamic acid in a suitable model peptide-lipid system for fundamental biophysical experiments. Within the system, I have placed a glutamic acid residue instead of leucine in the L14 position of the helical hydrophobic peptide GWALP23 (acetyl-GGALWLALALALAL14ALALWLAGA-amide). Substitutions of glutamine and aspartic acid serve as controls for the properties of the peptide helix in lipid bilayer membranes. The GWALP23 peptide derivatives are placed in various lipid bilayer environments. Specifically, I investigated the impact of glutamic acid (position E14) when differently charged lipids are present in the bilayer. The underlying importance is to understand the charged or neutral state behavior of glutamic acid under conditions where it is important for the functioning of several types of membrane proteins, such as ion channels, drug transporters and others. For the experimental plan, core alanine resides of GWALP23 were labeled with deuterium to enable detection of helix characteristics by solid-state 2H NMR spectroscopy. The peptide-lipid samples included primarily the neutral lipid DMPC, 1,2-dimyristoylphosphatidylcholine, (with 14-carbon acyl chains), along with 10% of a charged lipid. For each membrane system, I confirmed lipid bilayer formation for the particular peptide-lipid mixture by solid-state 31P NMR. The charged lipids consisted of the negatively charged lipid DMPG, 1,2-dimyristoylphosphatidylglycerol, and the positively charged lipid DMTAP, 1,2-dimyristoyl-3-trimethylammonium-propane. These charged lipids were found to influence the properties of the GWALP23 helix when E14 was present. DMTAP, in particular, improves the 2H NMR spectra and the prospects for characterizing helix dynamics when a glutamic acid residue is present. While some experiments were cut short due to a global emergency, the results show promise for characterizing glutamic acid in model helices and actual membrane proteins

Terpenylic Acid and Related Compounds from the Oxidation of α-Pinene: Implications for New Particle Formation and Growth above Forests

Novel secondary organic aerosol (SOA) products from the monoterpene α-pinene with unique dimer-forming properties have been identified as lactone-containing terpenoic acids, i.e., terpenylic and 2-hydroxyterpenylic acid, and diaterpenylic acid acetate. The structural characterizations were based on the synthesis of reference compounds and detailed interpretation of mass spectral data. Terpenylic acid and diaterpenylic acid acetate are early oxidation products generated upon both photooxidation and ozonolysis, while 2-hydroxyterpenylic acid is an abundant SOA tracer in ambient fine aerosol that can be explained by further oxidation of terpenylic acid. Quantum chemical calculations support that noncovalent dimer formation involving double hydrogen bonding interactions between carboxyl groups of the monomers is energetically favorable. The molecular properties allow us to explain initial particle formation in laboratory chamber experiments and are suggested to play a role in new particle formation and growth above forests, a natural phenomenon that has fascinated scientists for more than a century

Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes

Oxygen reduction and transport properties of the electrolyte in the phosphoric acid fuel cell are studied. A theoretical expression for the rotating ring-disk electrode technique; the intermediate reaction rate constants for oxygen reduction on platinum in phosphoric acid electrolyte; oxygen reduction mechanism in trifluoromethanesulfonic acid (TFMSA), considered as an alternate electrolyte for the acid fuel cells; and transport properties of the phosphoric acid electrolyte at high concentrations and temperatures are covered

Electrocatalysis of fuel cell reactions: Investigation of alternate electrolytes

Oxygen reduction and transport properties of the electrolyte in the phosphoric acid fuel cell are studied. The areas covered were: (1) development of a theoretical expression for the rotating ring disk electrode technique; (2) determination of the intermediate reaction rate constants for oxygen reduction on platinum in phosphoric acid electrolyte; (3) determination of oxygen reduction mechanism in trifluoreomethanesulfonic acid (TFMSA) which was considered as an alternate electrolyte for the acid fuel cells; and (4) the measurement of transport properties of the phosphoric acid electrolyte at high concentrations and temperatures

Chemical characterization and biological properties of royal jelly samples from the mediterranean area

Royal jelly (RJ) is a bee product that has high nutritional value and is beneficial for the human health, earning importance as a functional food. Thus, the characterization of its main biological properties is with high importance. In this work, 6 RJ samples obtained in Morocco, Portugal, and Spain were evaluated in terms of total phenol and flavone/flavonol contents; total protein; 10-hydroxy-2-decenoic acid (10-HDA); volatiles composition; antioxidant and anti-inflammatory properties; and inhibition of tyrosinase, xanthine oxidase (XO), and acetylcholinesterase (AChE) activities. Total phenolic content ranged from 3 to 9 mg gallic acid equivalent/g RJ, and flavone/flavonol content from 0.1 to 0.5 mg quercetin equivalent/g RJ. 10-Hydroxy-2-decenoic acid content varied from 0.9% to 1.2% and total protein from 5.5% to 29.7%. Gas chromatography-flame ionization detector and gas chromatography-mass spectrometry analysis showed RJ volatiles dominated by linolenic acid, 2-decenoic acid, and octanoic acid in variable amounts. The antioxidant activity was monitored through nitric oxide (NO) scavenging activity and hydrogen peroxide (H2O2) scavenging capacity, where the IC50 ranged from 2.3 to 3.4 and 0.2 to 1.5 mg/mL, respectively. Anti-AChE activity IC50 ranged from 0.7 to 4.6 mg/mL, while XO inhibition IC50 ranged from 3.3 to 11.9 mg/mL. The results showed that phenols and flavonoids highly contributed to the RJ biological properties in contrast to 10-HDA and proteins.UID/AMB/50017/2019 UIDB/05183/2020info:eu-repo/semantics/publishedVersio