Thermal analysis of chemically and mechanically modified pectins

Modification of sweet potato (Ipomoea batatas Lam.) residues soluble dietary fiber following twin-screw extrusion

Effect of twin-screw extrusion on soluble dietary fiber (SDF) from sweet potato residues (SPRs) were investigated using optimized conditions, at screw speed of 180 rpm, feed rate at 17 Hz, feed moisture at 40% and extrusion temperature at 150 °C. Extruded SDF, showed higher SDF levels (9.63%-29.25%), cholesterol and sodiumcholate adsorption capacity, radical scavenging capacity, and inhibition of digestive enzymes. Moreover, extrusion effectively reduced particle size and molecularweight of SDF, modulated monosaccharide ratios, and increased water retention capacity (WRC), oil retention capacity (ORC), swelling capacity (SC) and glucose absorption capacity (GAC). Additionally, scanning electron microscopy (SEM) demonstrated decomposition of macromolecules of SDF to smaller fractions and formation of a porous morphology following extrusion. Furthermore, the extruded SDF increased thermal stability as determined by differential scanning calorimetry (DSC). Overall, the SDF from SPRs with improved functional and physiochemical properties could be used as a functional additive in diverse food products.

Preparation and Characterization of Electrospun Pectin-Based Films and Their Application in Sustainable Aroma Barrier Multilayer Packaging

Pectin was first dissolved in distilled water and blended with low contents of polyethylene oxide 2000 (PEO2000) as the carrier polymer to produce electrospun fibers. The electrospinning of the water solution of pectin at 9.5 wt% containing 0.5 wt% PEO2000 was selected as it successfully resulted in continuous and non-defected ultrathin fibers with the highest pectin content. However, annealing of the resultant pectin-based fibers, tested at different conditions, developed films with low mechanical integrity, high porosity, and also dark color due to their poor thermal stability. Then, to improve the film-forming process of the electrospun mats, two plasticizers, namely glycerol and polyethylene glycol 900 (PEG900), were added to the selected pectin solution in the 2–3 wt% range. The optimal annealing conditions were found at 150 °C with a pressure of 12 kN load for 1 min when applied to the electrospun pectin mats containing 5 wt% PEO2000 and 30 wt% glycerol and washed previously with dichloromethane. This process led to completely homogenous films with low porosity and high transparency due to a phenomenon of fibers coalescence. Finally, the selected electrospun pectin-based film was applied as an interlayer between two external layers of poly(3-hydroxybutyrate-co-3-hydroxyvalerate) (PHBV) by the electrospinning coating technology and the whole structure was annealed to produce a fully bio-based and biodegradable multilayer film with enhanced barrier performance to water vapor and limonene.

Towards By-Product Utilisation of Pea Hulls: Isolation and Quantification of Galacturonic Acid

In order to evaluate by-products from food processing as alternative raw materials for pectin extraction, their amount of galacturonic acid (GalA) has to be analysed as a marker for pectin content. In the present study, significant differences in GalA release using different digestion methods are shown for pea hulls, as an example of by-products with a high content of cellulose. Complete digestion of the fibre matrix was assumed for Saeman hydrolysis as a reference protocol. Significantly lower GalA release was achieved by a treatment with trifluoracetic acid (TFA). An alternative treatment with ethylenediaminetetraacetic acid (EDTA) at pH 11 followed by an enzymatic digestion at pH 4.5 using a combination of polygalacturonase (Vegazyme M) and cellulase (Celluclast 1.5L) resulted in a similar release of GalA compared to Seaman hydolysis. Pea hull samples, analysed by this alternative protocol, showed on average a GalA content of 11.2%. Therefore, pea hulls may serve as new raw material for pectin extraction.

Extraction optimization of pectin from cocoa pod husks (Theobroma cacao L.) with ascorbic acid using response surface methodology

Cocoa husks were used as the source for the pectin extraction by sugar acid treatment. A full factorial design was applied to screen the independent variables influencing the yield and uronic acid content. Followed by response surface methodology (RSM) was conducted using central composite design to optimize the extraction conditions. The optimized extraction condition was denoted as pH 2.5/95 °C/45 min. The yield and the uronic acid content of the extracted pectin was determined as 4.2 ± 0.12% and 74.5 ± 0.3% respectively. The extracted pectin was proved to be low methoxy pectin (LM pectin) with an 8.1% degree of esterification (DE). The pectin solutions showed shear thinning behaviour which was explicated by Williamson model. This work promotes environmentally friendly technology for pectin isolation.

Manufacture and Characterization of Mucoadhesive Buccal Films Based on Pectin and Gellan Gum Containing Triamcinolone Acetonide

The treatment of canker sores can be quite compromised by the short period of the drug in the place of action. In this context, there is a need to develop drug dosage forms that allow more contact with the oral mucosa providing prolonged drug release. Therefore, the aim of this work was to obtain and characterize buccal films based on pectin and gellan gum in order to evaluate the potential use of these natural polymers in the production of pharmaceutical dosage forms for controlled release of TA in the oral mucosa. Using a 23 full factorial design, eight formulations were prepared by solvent casting method. The raw materials and films were characterized using techniques such as FTIR, DSC, and TG. In addition, thickness, mechanical properties, mucoadhesive strength, swelling, drug content, and dissolution profile of the films were evaluated. The results of FTIR, DSC, and TG showed that new chemical species are not formed in the production of films, and that these dosage forms have an adequate thermal behavior. All formulation showed a high degree of swelling, good mechanical resistance and elasticity, and a good mucoadhesive strength as well as able to act as a controlled release system.

Physico-chemical properties, rheology and degree of esterification of passion fruit (Passiflora edulis f. flavicarpa) peel flour

BACKGROUND

The peel of yellow passion fruit is as an agro-industrial waste of great environmental impact, representing more than 50% of the total weight of the fruit. For this reason, and also considering its importance as a source of functional components such as pectin, this organic waste is increasingly attracting the attention of researchers. The aim of this study was to investigate the physico-chemical composition and physical properties of this material, which may be of interest to the food industry.

RESULTS

We obtained two samples of passion fruit peel flour applying different processes: flour without treatment (FWOT) and flour with treatment by maceration (FWT). It was found that the flour samples contain, respectively, 372.4 g kg^-1 and 246.7 kg^-1 of soluble fiber and, according to the FTIR analysis, this material corresponds to high and low methoxyl pectins, respectively.

CONCLUSION

The flour obtained by maceration (FWT) offers greater benefits for industrial use, with 60% fewer tannins and greater thermal stability. In addition, this sample does not reabsorb moisture as easily, although FWOT also shows potential for use in dietary products. Considering the pseudoplastic properties of the flours, the application of both samples could be expanded to many industrial sectors. © 2017 Society of Chemical Industry.

Influence of Pectin as a green polymer electrolyte on the transport properties of Chitosan-Pectin membranes

Novel blend membranes have been prepared from Chitosan (CH), Pectin (PEC) and their mixtures. The obtained samples were cross-linked and sulfonated before characterization. The results show that CH/PEC membranes display structural changes on the chemical and physical properties as a function of composition. DSC analysis reveals an endothermic peak due to the scission of the ionic pairs between carboxylic groups and ammonium groups, which produces a strong change on physical properties such as methanol permeability and proton conductivity. The methanol permeability decreases with the amount of Pectin from (4.24±0.04)×10^-6cm²/s for pure Chitosan membrane to (1.51±0.03)×10^-6cm²/s for blend CH/PEC membranes when the amount of Pectin is 50% (v/v). The proton conductivities of the blend membranes follow a similar behavior. For a pure CH membrane the conductivity is 2.44×10^-3S/cm, decreasing with pectin content until the composition 50/50 (v/v), in which the conductivity drops almost one order of magnitude.

Dietary Fiber-Induced Changes in the Structure and Thermal Properties of Gluten Proteins Studied by Fourier Transform-Raman Spectroscopy and Thermogravimetry

Interactions between gluten proteins and dietary fiber supplements at the stage of bread dough formation are crucial in the baking industry. The dietary fiber additives are regarded as a source of polysaccharides and antioxidants, which have positive effects on human health. The fiber enrichment of bread causes a significant reduction in its quality, which is connected with changes in the structure of gluten proteins. Changes in the structure of gluten proteins and their thermal properties induced by seven commercial dietary fibers (fruit, vegetable, and cereal) were studied by FT-Raman spectroscopy and thermogravimetry (TGA), respectively. For this aim the bread dough at 500 FU consistency was made of a blend of wheat starch and wheat gluten as well as the fiber, the content of which ranged from 3 to 18% w/w. The obtained results revealed that all dietary fibers apart from oat caused similar changes in the secondary structure of gluten proteins. The most noticeable changes were observed in the regions connected with hydrogen-bonded β-sheets (1614 and 1684 cm(-1)) and β-turns (1640 and 1657 cm(-1)). Other changes observed in the gluten structure, concerning other β-structures, conformation of disulfide bridges, and aromatic amino acid microenvironment, depend on the fibers' chemical composition. The results concerning structural changes suggested that the observed formation of hydrogen bonds in the β-structures can be connected with aggregation or abnormal folding. This hypothesis was confirmed by thermogravimetric results. Changes in weight loss indicated the formation of a more complex and strong gluten network.

An experimental method to study emissions from heated tobacco between 100-200°C

Background

Cigarette smoke emissions are mainly produced by distillation, pyrolysis and combustion reactions when the tobacco is burnt. Some studies have shown that heating tobacco to temperatures below pyrolysis and combustion temperatures has the potential to reduce or eliminate some toxicants found in cigarette smoke. In this study, we designed a bench-top tube furnace that heats tobacco between 100-200°C and systematically studied the effects of heating temperatures on selected gas phase and aerosol phase compounds using an ISO machine-smoking protocol.

Results

Among a list of target chemical compounds, seven toxicants (nicotine, carbon monoxide, acetaldehyde, crotonaldehyde, formaldehyde, NNN and NNK) were quantifiable but not at all temperatures examined. The levels of the compounds generally displayed an increasing trend with increasing temperatures. The observed carbon monoxide and aldehydes represented the initial thermal breakdown products from the tobacco constituents. Water was the largest measured component in the total aerosol phase collected and appeared to be mainly released by evaporation; nicotine release characteristics were consistent with bond breaking and evaporation. Quantifiable levels of NNK and NNN were thought to be the result of evaporative transfer from the tobacco blend.

Conclusions

These results demonstrate the practical utility of this tool to study low-temperature toxicant formation and emission from heated tobacco. Between 100 to 200°C, nicotine and some cigarette smoke compounds were released as a result of evaporative transfer or initial thermal decomposition from the tobacco blend.

Electronic supplementary material

The online version of this article (doi:10.1186/s13065-015-0096-1) contains supplementary material, which is available to authorized users.

Mechanistic aspects of the nucleophilic substitution of pectin. On the formation of chloromethane

Chloromethane, accounting for approximately 16% of the tropospheric chlorine, is mainly coming from natural sources. However anthropogenic activities, such as combustion of biomass may contribute significantly as well. The present study focuses on the thermal solid state reaction between pectin, an important constituent of biomass, and chloride ions as found in alkali metal chlorides. The formation of chloromethane is evident with the amount formed being linear with respect to chloride if pectin is in great excess. Thus the reaction is explained as a pseudo first order SN2 reaction between the chloride ion and the methyl ester moiety in pectin. It is suggested that the polymeric nature of pectin plays an active role by an enhanced transport of halides along the carbohydrate chain. Optimal reaction temperature is around 210°C. At higher temperatures the yield of chloromethane decreases due to a thermal decomposition of the pectin. The possible influence of the type of cation is discussed.

Physicochemical property of starch-pectin conjugates with resistance to enzymatic activity

BACKGROUND

In view of the high nutritional values and bioactivities of resistant starch and pectin, it would be a good choice to chemically combine pectin and starch to give a new type of chemically modified resistant starch.

RESULT

A new type of chemically modified resistant starch has been prepared by cross-linking starch and pectin using sodium trimetaphosphate. Starch-pectin conjugates can well prevent the hydrolysis catalysed by different enzymes, such as α-amylase, amyloglucosidase, pancreatin as well as β-amylase and glucosidase. Although the conjugates do not change the crystal type of starch, they increase the degree of crystallinity. Moreover, thermal stability and structural homogeneity of the conjugates are positively correlated with double-helical order in the crystalline region.

CONCLUSION

This study gives a new method for the preparation of resistant starch-pectin conjugates which can be widely used as a new type of food additive in the industry.

Cholesterol and fat lowering with hydrophobic polysaccharide derivatives

Hydrophobic derivatives of highly methylated citrus pectin, chitosan and cellulose were prepared and tested as potential cholesterol lowering agents. Elemental analysis and spectroscopic methods confirmed high substitution degree for all of them. Substitution with long alkyl/acyl groups led to significant changes in physical and thermal properties of modified polysaccharides. Sorption of cholate and cholesterol by these polysaccharide-based sorbents was estimated in comparison with the synthetic drug cholestyramine. It was found that modified polysaccharides have high affinity to cholesterol. By contrast, cholestyramine was effective only in cholate sorption.

Formulation and characterization of silk fibroin films as a scaffold for adipose-derived stem cells in skin tissue engineering

Skin substitutes are epidermal, dermal or complete bilayered constructs, composed by natural or synthetic scaffolds and by adherent cells such as fibroblasts, keratinocytes or mesenchymal stem cells. Silk fibroin is a promising polymer to realize scaffolds, since it is biocompatible, biodegradable, and exhibits excellent mechanical properties in terms of tensile strength. Moreover, fibroin can be added of others components in order to modify the biomaterial properties for the purpose. The aim of this work is to prepare silk fibroin films for adipose-derived stem cell (ADSCs) culture as a novel feeder layer for skin tissue engineering. Pectin has been added to promote the protein conformational transition and construct strength, while glycerol as plasticizer, providing biomaterial flexibility. Eighteen formulations were prepared by casting method using fibroin, pectin (range 1-10% w/w), and glycerol (range 0-20% w/w); films were characterized by Fourier transform infrared spectroscopy and differential scanning calorimetry assay, to select the optimal composition. A stable fibroin conformation was obtained using 6% w/w pectin, and the best mechanical properties were obtained using 12% w/w glycerol. Films were sterilized, and human ADSCs were seeded and cultured for 15 days. Cells adhere to the support assuming a fibroblastic-like shape and reaching confluence. The ultrastructural analysis evidences typical active-cell features and adhesion structures that promote cell anchorage to the film, thus developing a multilayered cell structure. This construct could be advantageously employed in cutaneous wound healing or where the use of ADSCs scaffold is indicated either in human or veterinary field.

Characterization of sugar beet pectic-derived oligosaccharides obtained by enzymatic hydrolysis

Three pectic oligosaccharides (POS) obtained by enzymatic hydrolysis of sugar beet pectin by combining endopolygalacturonase and pectinmethylesterase, were characterized using high performance liquid chromatography, thermogravimetric analysis, Fourier transform infrared spectroscopy, differential scanning calorimetry and X-ray diffraction. According to chromatographic analyses, POS are composed of mixture of polymers with different molecular weights and different galacturonic acid contents. The thermal analysis showed no major variation in thermal behavior regarding POS composition but showed that POS were more sensitive to thermal degradation than the parent pectin as well as the deesterified pectin. No change in composition of the gaseous products was obtained through TGA-FTIR analysis. The X-ray pattern of POS clearly indicated a considerable decrease in crystallinity when compared to the native pectin. Thus, thermal characterization of POS may have practical repercussions if the formulation in which POS is incorporated is submitted to a high temperature treatment.