Pectin

The aim of the study was to establish a green protocol for pectin extraction from unripe papaya flour (UPF), comparing conventional acid hydrolysis (CONV) and compressed fluid extraction techniques, including Pressurized Hot Water Extraction (PHWE) and Enhanced Solvent Extraction (ESE). Highest pectin yields were achieved with ESE (216 ± 10.8 mg g −1) when CO 2 +H 2 O (20:80) + citric acid (0.05 mol L −1) was applied (40 MPa/80°C/ 60 min/300-710 µm), similar to that obtained by CONV (202 ± 49.5 mg g −1) and PHWE (208.0 ± 9.4 mg g −1) using oxalic acid. UPF pectin presented an average galacturonic acid (GalA) content of 73% (w/w) and degree of esterification (DE) of 57.8%, and it was composed predominantly of galactose, glucose and rhamnose. This pectic substance has been shown to contain two main types of pectic chains: rhamnogalacturonan-I (RG-I, average 58%) proportionally higher than homogalacturonan (HG, average 28%). Compressed fluid extraction techniques allowed obtaining high quality pectin with similar composition to other commercial products.

Cet ouvrage est destiné à faire le point sur les enzymes qui catalysent l'hydrolyse ou la dépolymérisation des molécules d'origine biologique. Il rassemble les textes d'une série de conférences prononcées au cours d'un séminaire animé par Annette Mouranche et Claude Costes au Centre de Grignon de l'Institut national agronomique. Lorsqu'il s'agit de macromoléeules, comme par exemple l'amidon, la cellulose ou les caséines, leur utilisation industrielle implique souvent une simplification chimique préalable. Cette simplification est souvent à l'origine l'hydrolyse d'une fonction ester ou amide. Cette réaction hydrolytique est à la base de bien des processus technologiques dans les industries alimentaires: fromagerie, industrie des viandes, industrie des jus de fruits, brasserie, amidonnerie. De même la valorisation de la biomasse lignocellulosique commence par une série de réactions de dépolymérisation. L'ensemble de ces réactions est le plus souvent réalisé par voie enzymatique. Une meilleure connaissance des enzymes concernées permettra un élargissement des technologies alimentaires, un renouvellement de certaines stratégies phytosanitaires, une exploitation plus rationnelle des déchets animaux et végétaux ou la fabrication de substances nouvelles par hémisynthèse industrielle. Quelle est l'origine biologique de ces enzymes? Que sait-on sur leur structure, leurs propriétés et leur mode d'action? Comment les met-on en œuvre ou comment peut-on élargir leur utilisation industrielle? Cet ouvrage essaie de présenter une analyse de ces problèmes et propose des perspectives nouvelles. La vaste catégorie des nucléases n'a pas été abordée dans ce travail qui s'adresse principalement à tous ceux qui, étudiants, ingénieurs, responsables d'entreprise ou enseignants, sont concernés par la transformation industrielle de la production agricole, végétale ou animale.

Pectins are a diverse family of biopolymers with an anionic polysaccharide backbone of-1,4-linked d-galacturonic acids in common. They have been widely used as emulsifiers, gelling agents, glazing agents, stabilizers, and/or thickeners in food, pharmaceutical, personal care and polymer products. Commercial pectin is classified as high methoxy pectin (HMP) with a degree of methylation (DM) >50% and low methoxy pectin (LMP) with a DM <50%. Amidated low methoxy pectins (ALMP) can be obtained through aminolysis of HMP. Gelation of HMP occurs by cross-linking through hydrogen bonds and hydrophobic forces between the methyl groups, assisted by a high co-solute concentration and low pH. In contrast, gelation of LMP occurs by the formation of ionic linkages via calcium bridges between two carboxyl groups from two different chains in close proximity, known as the 'egg-box' model. Pectin gels exhibit Newtonian behaviour at low shear rates and shear-thinning behaviour when the shear rate is increased. An overview of pectin from its origin to its physicochemical properties is presented in this review.

Pectins are natural complex heteropolysaccharide which comprise a functionally significant moiety of the primary cell walls of terrestrial plants. Pectin is a carbohydrate found in all fruits and vegetables and is necessary for plant growth. Industrially, it is extracted from citrus peels or apple pomace, and is used as a thickener, water binder and stabilizer in foods, etc. Considering this review sheds a light on the various extracting conditions, characterization, varying time, temperature, pH, functional properties and applications of pectin based polymer techniques.

Saffron petal, as a byproduct of saffron processing, contains a considerable amount of antioxidant compounds. In the present study, the effect of drying methods (spray and freeze) and different wall structures (maltodextrin and pectin) was investigated on the physicochemical characteristics of microcapsules of saffron petal extracts. Results showed that the increase of the pectin ratio in wall composition leads to the increase of polyphenols content and antioxidant activity of microcapsules. Microencapsulation efficiency and loading capacity in pectin-contained samples were higher than pure maltodextrin samples. Moreover, microcapsules obtained from spray drying method had higher microencapsulation efficiency and loading capacity in comparison with microcapsules obtained from freeze drying method. Also, scanning electron microscopy, X-ray diffraction, and differential scanning calorimetry have been shown to be useful tools for establishing the difference between produced microcapsules. High-performance liquid chromatography was used to evaluate the polyphenolic compounds of the microsphere. The chromatograms obtained from both encapsulation methods indicated high levels of routine in microcapsules of saffron petal extract. In addition, the release of polyphenols from microcapsules of saffron petal extract was evaluated under simulated gastrointestinal conditions. The results indicated that the release behavior of the microcapsules varied according to the type of drying method and wall composition. To assess the shelf life, the microcapsules were kept at different temperatures and relative humidities for 16 weeks. The microcapsules produced by freeze drying and containing high levels of pectin in wall composition had the highest antioxidant activity when kept in relative humidity of 11% and temperature of 4°C. Practical Application: Saffron petal is the huge amount of saffron by-product and contains a number of various antioxidant compounds. Microencapsulation of its valuable compounds results in preventing the destruction of these compounds by environmental factors and their increased bioavailability. Indeed, this paper focuses on the release of microencapsulated powder in the simulated system of the digestive system that helps us to improve the shelf life of the final product during the process and controlled release of compounds in the food and pharmaceutical industries.

Natural polymer-based hydrogel films have great potential for biomedical applications and are good candidates for wound dressings. In this study, we aimed to develop simvastatin-loaded crosslinked alginate-pectin hydrogel films by ionic crosslinking to improve the mechanical characteristics, wound fluid uptake and drug release behavior. Alginate-pectin hydrocolloid films were chemically crosslinked by immersing in different concentrations of CaCl 2 (0.5–3% w/v) for 2–20 min. The degree of crosslinking was influenced by both contact time and CaCl 2 concentration. The optimized conditions for crosslinking were 0.5% and 1% (CaCl 2) for 2 min. The optimized hydrogel films were then characterized for their physical , mechanical, morphological, thermal, in vitro drug release, and cytocompatibility profiles. Crosslinking improved the mechanical profile and wound fluid uptake capacity of dressings. The hydrogel films were able to maintain their physical integrity during use, and the best results were obtained with the film in which the extent of crosslinking was low (0.5%). Thermal analysis confirmed that the crosslinking process enhanced the thermal stability of hydrogel films. Sustained, slow release of simvastatin was obtained from the crosslinked films and in vitro cytotoxicity assay demonstrated that the hydrogel films were non-toxic.

Carboxymethyl sago pulp (CMSP)/pectin hydrogel beads were synthesized by calcium crosslinking and further crosslinked by electron beam irradiation to form drug carrier for colon-targeted drug. Sphere-shaped CMSP/pectin 15%/5% hydrogel beads is able to stay intact for 24 h in swelling medium at pH 7.4. It shows pH-sensitive behavior as the swelling degree increases as pH increases. Fourier transform infrared spectroscopy analysis confirmed the absence of chemical interaction between hydrogel beads and diclofenac sodium. Differential scanning calorimetric and X-ray diffraction studies indicate the amorphous nature of entrapped diclo-fenac sodium. The drug encapsulation efficiency is up to about 50%. Less than 9% of drug has been released at pH 1.2 and the hydrogel beads sustain the drug release at pH 7.4 over 30 h. This shows the potential of CMSP/pectin hydrogel beads as carrier for colon-targeted drug. V

Anthocyanins are secondary metabolites synthesized in grape berry skins via the phenylpropanoid pathway, with functions ranging from skin coloration to protection against pathogens or UV light. Accumulation of these compounds is highly variable depending on genetics, environmental factors and viticultural practices. Besides their biological functions, anthocyanins improve wine quality, as a high anthocyanin content in berries has a positive impact on the color, total phenolic concentration and, ultimately, the price of wine. The present work studies the effect of the pre-veraison application of pectin derived oligosaccharides (PDO) on the synthesis and accumulation of these compounds, and associates the changes observed with the expression of key genes in the phenylpropanoid pathways. To this end, pre-veraison Cabernet Sauvignon bunches were treated with PDO to subsequently determine total anthocyanin content, the anthocyanin profile (by HPLC-DAD) and gene expression (by qRT-PCR), using Ethrel and water treatments for comparison. The results show that PDO were as efficient as Ethrel in generating a significant rise in total anthocyanin content at 30 days after treatment (dat), compared with water treatments (1.32, 1.48 and 1.02 mg e.Mv-3G/g FW respectively) without any undesirable effect on berry size, soluble solids, tartaric acid concentration or pH. In addition, a significant alteration in the anthocyanin profile was observed. Specifically, a significant increase in the relative concentration of malvidin was observed for both PDO and Ethrel treatments, compared with water controls (52.8; 55.0 and 48.3%, respectively), with a significant rise in tri-hydroxylated forms and a fall in di-hydroxylated anthocyanins. The results of gene expression analyses suggest that the increment in total anthocyanin content is related to a short term increase in phenylalanine ammonia-lyase (PAL) expression, mediated by a decrease in MYB4A expression. A longer term increase in UDP-glucose flavonoid 3-O-glucosyltransferase (UFGT) expression, probably mediated by a rise in MYBA1 was also observed. Regarding the anthocyanin profile, despite the increase observed in MYB5A expression in PDO and Ethrel treatments, no changes in flavonoid 3 0-hydroxylase (F-3 0-H); flavonoid 3 0 5 0-hydroxylase (F-3 0 5 0-H) or O-methyltransferase (OMT) could be related with the profile modifications described. Overall, this study highlights that application of PDO is a novel means of altering specific grape berry anthocyanins, and could be a means of positively influencing wine quality without the addition of agrochemicals.

BACKGROUND AND AIMS: Species and hybrids of the genus Miscanthus contain attributes that make them front-runners among current selections of dedicated bioenergy crops. A key trait for plant biomass conversion to biofuels and biomaterials is cell-wall quality; however, knowledge of cell-wall composition and biology in Miscanthus species is limited. This study presents data on cell-wall compositional changes as a function of development and tissue type across selected genotypes, and considers implications for the development of miscanthus as a sustainable and renewable bioenergy feedstock. METHODS: Cell-wall biomass was analysed for 25 genotypes, considering different developmental stages and stem vs. leaf compositional variability, by Fourier transform mid-infrared spectroscopy and lignin determination. In addition, a Clostridium phytofermentans bioassay was used to assess cell-wall digestibility and conversion to ethanol. KEY RESULTS: Important cell-wall compositional differences between miscanthus stem and leaf samples were found to be predominantly associated with structural carbohydrates. Lignin content increased as plants matured and was higher in stem tissues. Although stem lignin concentration correlated inversely with ethanol production, no such correlation was observed for leaves. Leaf tissue contributed significantly to total above-ground biomass at all stages, although the extent of this contribution was genotype-dependent. CONCLUSIONS: It is hypothesized that divergent carbohydrate compositions and modifications in stem and leaf tissues are major determinants for observed differences in cell-wall quality. The findings indicate that improvement of lignocellulosic feedstocks should encompass tissue-dependent variation as it affects amenability to biological conversion. For gene-trait associations relating to cell-wall quality, the data support the separate examination of leaf and stem composition, as tissue-specific traits may be masked by considering only total above-ground biomass samples, and sample variability could be mostly due to varying tissue contributions to total biomass.

Development of materials for medical applications using biologically derived materials by green approaches is emerging as an important focus in the present healthcare scenario. Herein the first time, we report the plant extract mediated ultra-rapid biosynthesis of silver nanoparticles using whole plant extracts of Biophytum sensitivum. Synthesized nanoparticles were immobilized in nano-micro dual-porous calcium pectinate scaffolds for wound dressing application. Pectinate wound dressings containing silver nanoparticles have shown excellent antibacterial property and exudate uptake capacity while being biocompatible to the human cells.