Pectin and Pectin-Based Composite Materials: Beyond Food Texture.

Pectins are plant cell wall natural heteropolysaccharides composed mainly of α-1-4 d-galacturonic acid units, which may or may not be methyl esterified, possesses neutral sugars branching that harbor functional moieties. Physicochemical features as pH, temperature, ions concentration, and cosolute presence, affect directly the extraction yield and gelling capacity of pectins. The chemical and structural features of this polysaccharide enables its interaction with a wide range of molecules, a property that scientists profit from to form new composite matrices for target/controlled delivery of therapeutic molecules, genes or cells. Considered a prebiotic dietary fiber, pectins meetmany regulations easily, regarding health applications within the pharmaceutical industry as a raw material and as an agent for the prevention of cancer. Thus, this review lists many emergent pectin-based composite materials which will probably palliate the impact of obesity, diabetes and heart disease, aid to forestall actual epidemics, expand the ken of food additives and food products design.

Electrosprayed Core⁻Shell Composite Microbeads Based on Pectin-Arabinoxylans for Insulin Carrying: Aggregation and Size Dispersion Control.

Aggregation and coalescence are major drawbacks that contribute to polydispersity in microparticles and nanoparticles fabricated from diverse biopolymers. This study presents the evaluation of a novel method for the direct, electrospray-induced fabrication of small, CaCl2/ethanol-hardened low methoxy pectin/arabinoxylans composite microbeads. The electrospray method was evaluated to control particle size by adjusting voltage, flux, and crosslinking solution content of CaCl2/ethanol. A bead diameter of 1µm was set as reference to test the capability of this method. Insulin was chosen as a model carried molecule. Statistical analysis was a central composite rotatable design (CCRD) with a factorial arrangement of 24. The variables studied were magnitude and particle size dispersion. For the determination of these variables, light diffraction techniques, scanning electron microscopy, transmission electron microscopy, and confocal laser scanning microscopy were used. Major interaction was found for ethanol and CaCl2 as well as flow and voltage. Stable spherical structures of core⁻shell beads were obtained with neither aggregation nor coalescence for all treatments where ethanol was included in the crosslinking solution, and the average diameter within 1 ± 0.024 µm for 11 KV, 75% ethanol with 11% CaCl2, and flow of 0.97 mL/h.

Chemical composition and antioxidant-prooxidant potential of a polyphenolic extract and a proanthocyanidin-rich fraction of apple skin.

The apple is a food rich in diverse classes of polyphenols (PP), among which the proanthocyanidins (PCs), which are primarily concentrated in the skin, are one of the most abundant. These compounds are of considerable interest for their possible positive health effects because of their antioxidant properties. However, depending on the classes of PP present (chemical composition) and their relative concentrations in the apple skin, their antioxidant effects vary and some of their components can even generate prooxidant effects. This work determined the chemical composition and antioxidant-prooxidant potential of a polyphenolic extract (PPE) and a proanthocyanidin-rich fraction (PRF) of apple skin, along with the contribution of their most abundant individual compounds, based on their copper chelating ability, ease in reducing peroxidase-generated free radicals and TEAC (Trolox-Equivalent Antioxidant Capacity) assay. For this purpose, chromatographic and colorimetric methods were used. The majority compounds identified in PPE were flavan-3-ols (44.58%), flavonols (42.89%) and dihydrochalcones (11.60%). In PRF, we detected monomers and oligomers from dimers to heptamers, which were composed of 97% (-)-epicatechin and 3% (+)-catechin. The antioxidant potential was notably higher in PRF than in PPE. The (-)-epicatechin monomer and the procyanidin B2 dimer showed more ease in reducing peroxidase-generated free radicals compared to other compounds of the apple skin, whereas phloridzin dihydrochalcone produced prooxidant effects.

Computational study of the structure-free radical scavenging relationship of procyanidins.

Procyanidins (PCs) are effective free radical scavengers, however, their antioxidant ability is variable because they have different degrees of polymerisation, are composed by distinct types of subunits and are very susceptible to changes in conformation. In this work the structure-free radical scavenging relationship of monomers, dimers and trimers of PCs was studied through the hydrogen atom transfer (HAT), sequential proton-loss electron-transfer (SPLET) and single electron transfer followed by proton transfer (SET-PT) mechanisms in aqueous phase, employing the Density Functional Theory (DFT) computational method. The structure-free radical scavenging relationship of PCs showed a very similar behaviour in HAT and SET-PT mechanisms, but very different in the SPLET mechanism. The structural factor that showed more effects on the ability of PCs to scavenge free radicals in aqueous phase was the conformation.

Propiedades y posibles aplicaciones de las proteínas de salvado de trigo / Properties and application possibilities of wheat bran proteins

Resumen El salvado de trigo se destina principalmente al consumo animal, por lo que algunos de sus componentes son subutilizados, representando oportunidades de valor agregado. Constituye las capas externas del grano y contiene hasta 18 % en peso de proteínas con mejor calidad que las de la harina. Estas proteínas no son aprovechadas debido a que la mayoría están protegidas por una matriz de polisacáridos, indigerible para el sistema gastrointestinal humano, por lo que es necesaria su extracción. Tradicionalmente, las proteínas de salvado han sido recuperadas mediante extracción alcalina y se han propuesto como ingredientes para la elaboración de productos alimenticios. Sin embargo, su uso es casi inexistente, debido a que los procesos de extracción son agresivos y no redituables. El objetivo del presente trabajo fue describir las propiedades de las proteínas del salvado de trigo, así como sus usos potenciales. Entre sus propiedades destacan la digestibilidad, el perfil de aminoácidos y la capacidad de absorción de grasa. La fracción soluble en agua de estas proteínas, por su fácil extracción, podría tener valor agregado al utilizarse en tecnologías emergentes: como fuente de péptidos bioactivos, en la producción de nanopartículas con aplicaciones industriales o como matrices para procesos de biomineralización artificial.

Abstract Wheat bran is mainly intended for animal consumption and some of its components are underutilized, representing value-added opportunities. It forms the outer layers of the grain and contains up to 18 % by weight of proteins of better quality than those of flour. These proteins are not exploited because most are protected by a matrix of polysaccharides, which is indigestible by the human gastrointestinal system" so their extraction is necessary. Traditionally, wheat bran proteins have been recovered by alkaline extraction and have been proposed as ingredients for the manufacture of foodstuffs. However, their use is almost non-existent because the extraction processes are aggressive and not profitable. The aim of the present review is to present the proper ties of wheat bran proteins, as well as, their potential uses. Among their properties, the digestibility, lipid absorption capacity and aminoàcid pattern are highlighted. The water soluble fraction of these proteins, because of their easy extraction, could have an added value from the perspetive of emerging technologies, for example, as a source of bioactive peptides, in the production of nanoparticles with industrial applications or as matrices for artificial biomineralization processes.

Spectroscopic and computational study of the major oxidation products formed during the reaction of two quercetin conformers with a free radical.

The goal of this research was to determine whether there are differences between the major oxidation products formed during the reaction of quercetin unhydrate (QUH) or quercetin dihydrate (QDH) with the 2,2-diphenyl-1-picrylhydrazyl free radical (DPPH), as well as to identify some properties of these products. The study was carried out employing spectroscopic and computational methods, in order to know the effect of different conformations of quercetin on the mechanism of free radical scavenging. The results demonstrated that although the same oxidation products may be formed from QUH and QDH, their properties and the predominant product were different in each. The o-quinone was the predominant oxidation product of QUH, whereas in QDH it was established an equilibrium between o-quinone and extended p-quinone.

Irreversibility of chilling injury in zucchini squash (Cucurbita pepo L) could be a programmed event long before the visible symptoms are evident.

Zucchini fruits were subjected to 2.5 or 10 degrees C for 16d, followed by transfer to 20 degrees C for 24h in order to evaluate the relationship between ripening pattern, measured as CO(2) evolution and ethylene (C(2)H(4)) production, and metabolic heat production (q). Chilling injury (CI) visible symptoms were evident after 8d at 2.5 degrees C, but none were recorded on fruits kept at 10 degrees C. In fruits held at 10 degrees C, q, C(2)H(4) production, and CO(2) evolution diminished in the course of 16d, whereas in those at 2.5 degrees C CO(2) evolution showed an early burst peaking at 8d. Both C(2)H(4) production and q also showed a burst at 2.5 degrees C but they started at 4 and 8d, respectively, and peaked at 12d. The results showed that irreversibility of chilling injury in zucchini could occur long before the appearance of visible symptoms, although the metabolic activity accompanying the irreversibility process was not noticeable by isothermal calorimetry.

Effect of pectic oligomers on physiological responses of chilling injury in discs excised from zucchini (Cucurbita pepo L.).

The effect of pectic oligomers (OG) on ethylene biosynthesis, electrolyte leakage (EL), and CO(2) production was studied in discs excised from zucchini fruit (Cucurbita pepo L.) and stored at 20 or 2.5 degrees C. At 20 degrees C, OG enhanced ethylene biosynthesis and had a transient effect on decreasing EL, but showed little effect on respiratory rate; both the amount and size of the oligomer were important in changing both ethylene synthesis and EL. At 2.5 degrees C, OG increased both ethylene biosynthesis and respiratory rate with a maximum effect at 100 microg of oligomer and peaking at 6 h; shorter oligomers demonstrated an even greater effect on ethylene biosynthesis, but differences were smaller in respiratory rate. EL at 2.5 degrees C was affected most by 1 microg of OG and by monomeric galacturonic acid, with transient increases that peaked at 8 h. We suggest a signaling role for OG in the early steps of cold acclimation or chilling injury.

Nanotubus de carbono y bionanotecnología / Carbon nanotubes and bionanotechnology

Los nanotubos de carbono (NTC) son estructuras artificiales novedosas que presentan propiedades físicas inusuales. Estas propiedades han hecho a los NTC objeto de una gran cantidad de estudios, los cuales han revelado un inmenso potencial de aplicación en diferentes áreas, tales como la electrónica, la física y la biología. En este trabajo se revisan los conceptos básicos sobre la química, obtención y modificación de los NTC, y se discute su posible utilización en sistemas biológicos.