Characterisation of the substituent distribution in starch and cellulose derivatives

Butyryl group distribution modulates the structure and properties of butyrylated maize starch focused on amylose contents

In this study, four types of maize starch with different amylose contents (3 %, 25 %, 40 %, and 70 %) were used to prepare butyrylated starches. Based on amylose contents, the influence of butyryl group distribution on the structure, thermal and digestive properties of butyrylated maize starch was investigated. The butyrylation reaction mainly substituted butyryl groups on amylose, and the butyryl groups were most easily substituted for the hydroxyl group at the C6 position. The degree of substitution of butyrylated starch reached its maximum when the amylose content was 40 %, and the degree of substitution did not correlate linearly with the amylose content. The butyrylation reaction increased the surface roughness, decreased the crystallinity, enthalpy value and molecular weight of native starch granules, resulting in a decrease in the degree of internal order of the starch and inducing the rearrangement of the amylose molecular chains in the amorphous region of the starch. The combination of the amylose content and the substitution of butyryl groups on amylose affected the digestibility of starch and ultimately increased its resistance. The Pearson correlation coefficient further confirmed the correlation between the distribution of butyryl groups and the structure and properties of butyrylated starch.

Analysis of environmental biodegradability of cellulose-based pharmaceutical excipients in aqueous media

Pharmaceutical cellulosic polymers will inevitably reach natural water systems if they are not removed after entering wastewater. Biodegradation of organic chemicals in sewage or in the aquatic environment is an important removal mechanism. In this study, we investigated the environmental biodegradation of 14 cellulose derivatives commonly utilized as pharmaceutical excipients using three different test systems that are based on the closed bottle test (OECD 301D) and the manometric respirometry test (OECD 301F). For the different cellulose derivatives tested, we observed varying degrees of biodegradation ranging from 0 to 20.4 % chemical oxygen demand (COD). However, none met the criteria for classification as 'readily biodegradable'. In addition, 10 out of 14 cellulose derivatives and/or their possible transformation products formed during the experiments, may exhibit possible toxic inhibitory effects on the inoculum. This includes one or several derivatives of hydroxy propyl methyl cellulose, hydroxy propyl cellulose, methyl cellulose, ethyl cellulose, and hydroxy ethyl cellulose. Based on the results obtained, we have developed a graded classification score ('traffic light system') for excipient biodegradation. This could help streamline the assessment and classification of cellulose derivatives concerning risk of persistence and potential adverse environmental effects, thereby assisting in the prioritization of more favorable compounds. In the long term, however, excipients should be designed from the very beginning to be biodegradable and mineralizable in the environment ('benign by design').

Nutritional and Technological Properties of Albino Peach Palm (Bactris gasipaes) from the Amazon: Influence of Cooking and Drying

This study aimed to subject the albino peach palm to cooking and drying processes and characterize the raw pulp (RP), cooked pulp (CP), raw pulp flour (RPF), and cooked pulp flour (CPF). The product's chemical composition, bioactive compounds, and physicochemical, color, thermal, morphological, and functional-technological properties were evaluated. The proximate composition showed that carbohydrates were the main constituents of all the products (69.59-72.08 g/100 g). The cooking process decreased the lipids (10.21 to 8.63 g/100 g), dietary fiber (13.64 to 12.81 g/100 g), and total sugar content (59.18 to 49.10 g/100 g) of the CP. The colorimetric parameters indicated a significant browning of the CP and CPF, which can be attributed to the Maillard reaction and lipid oxidation. After cooking, the total phenolic compound and ascorbic acid content decreased in the pulp. The RPF and CPF displayed different thermogravimetric behaviors. The spectral patterns in the infrared region showed the characteristic bands of organic compounds that are present in the structure of starches. The scanning electron microscopy showed amyloplast and fiber bundles with starches in the RP and gelatinized starch granules in the CP and CPF. The RPF presented small and heterogeneous starch granules with isolated amyloplast. The RPF and CPF showed different granulometric patterns and technological indices. The results suggest that the pulp and flour from the pulp of albino peach palms can be exploited by the food, pharmaceutical, and biotechnological industries.

Composition mapping of highly substituted cellulose-ether monomers by liquid chromatography-mass spectrometry and probability-based data deconvolution

Cellulose ethers (CEs) are semi-synthetic polymers produced by derivatization of natural cellulose, yielding highly substituted products such as ethyl hydroxyethyl cellulose (EHEC) or methyl ethyl hydroxyethyl cellulose (MEHEC). CEs are commonly applied as pharmaceutical excipients and thickening agents in paints and drymix mortars. CE properties, such as high viscosity in solution, solubility, and bio-stability are of high interest to achieve required product qualities, which may be strongly affected by the substitution pattern obtained after derivatization. The average and molar degree of substitution often cannot explain functional differences observed among CE batches, and more in-depth analysis is needed. In this work, a new method was developed for the comprehensive mapping of the substitution degree and composition of β-glucose monomers of CE samples. To this end, CEs were acid-hydrolyzed and then analyzed by gradient reversed-phase liquid chromatography-mass spectrometry (LC-MS) using an acid-stable LC column and time-of-flight (TOF) mass spectrometer. LC-MS provided monomer resolution based on ethylene oxide, hydroxyl, and terminating methyl/ethyl content, allowing the assignment of detailed compositional distributions. An essential further distinction of constitutional isomer distributions was achieved using an in-house developed probability-based deconvolution algorithm. Aided by differential heat maps for visualization and straightforward interpretation of the measured LC-MS data, compositional variation between bio-stable and non-bio-stable CEs could be identified using this new approach. Moreover, it disclosed unexpected methylations in EHEC samples. Overall, the obtained molecular information on relevant CE samples demonstrated the method's potential for the study of CE structure-property relationships.

Effect of chemical treatments on the functional, morphological and rheological properties of starch isolated from pigeon pea (Cajanus cajan)

Different chemical treatments (cross-linking, oxidation, and hydroxypropylation) were used to modify pigeon pea starch, and its effect on physiochemical, pasting and rheological properties were studied. Cross-linking and oxidation decreased while hydroxypropylation increased the swelling power of pigeon pea starch. All starch samples showed a decrease in their paste clarities. FTIR spectra of all starch samples displayed characteristic absorption bands of starch at wave numbers 1076, 1148, 1376, and 1632 cm⁻¹. A significant reduction occurred in peak, cold paste, hot paste, and setback viscosity after chemical modification. Rheological determinations showed that starch pastes had viscoelastic behaviour. G′ and G″ of all starch paste increased after chemical modification. Native and chemically treated starches revealed oval to elliptical-shaped granules and no change was observed after modification when examined in SEM. These results confirmed that the undesirable properties of native pigeon starch can be suitably altered via chemical treatments to make them suitable for several food applications.

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Chemical modifications significantly (p˂0.05) affect the amylose content, paste clarity, gel hardness, swelling power, and solubility.

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SEM analysis showed no significant changes after modifications.

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Pasting properties of starches were significantly reduced (p˂0.05) after the modification, whereas pasting time and peak time were increased.

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The cross-linked starch structure was more stable than the other modified starches.

A more efficient synthesis and properties of saturated and unsaturated starch esters

This work presents a series of starch esters synthesized via 1,5,7-triazabicyclo[4.4.0]-dec-5-ene (TBD) catalyzed transesterifications in dimethyl sulfoxide (DMSO). The reaction was performed with saturated and unsaturated fatty acids (8, 11, and 18 carbon atoms). The degree of substitution (DS) was raised by purging the reaction flask with nitrogen instead of simply performing the reaction under a nitrogen atmosphere. The increase of DS was most obvious for long-chain fatty acids, as an almost complete DS was observed for starch stearate (2.8) and starch oleate (2.7). The products were characterized by differential scanning calorimetry (DSC), thermogravimetric analysis (TGA), and X-ray diffraction. Starch esters from unsaturated fatty acids have a lower T_g than their saturated analogues. Moreover, contact angle and moisture uptake measurements showed increased hydrophobicity for all starch esters in comparison to pristine starch. Our results show a more efficient method for synthesizing a biobased material that steers into the direction of a material that could replace conventional plastics.

Liquefaction of Cellulose for Production of Advanced Porous Carbon Materials

Cellulose is a renewable resource for the production of advanced carbonaceous materials for various applications. In addition to direct carbonization, attention has recently been paid to the preparation of porous carbons from liquid cellulose-based precursors. Possible pathways of cellulose conversion to a liquid state suitable for the preparation of porous carbons are summarized in this review. Hydrothermal liquefaction leading to liquid mixtures of low-molecular-weight organics is described in detail together with less common decomposition techniques (microwave or ultrasound assisted liquefaction, decomposition in a strong gravitation field). We also focus on dissolution of cellulose without decomposition, with special attention paid to dissolution of nonderivatized cellulose. For this purpose, cold alkalines, hot acids, ionic liquids, or alcohols are commonly used.

Revealing substitution priority and pattern of octenylsuccinic groups along the starch chain under a continuous mode

Octenylsuccinic (OS) groups distribution was considered random under traditional batch mode (BM) process due to excessive available octenyl succinic anhydride (OSA) at early stage, making the functionality optimization of OSA starch under restricted substitution degree (DS) difficult. To reveal the priority rule of substituent position at starch molecular level, a continuous mode (CM, dropwise OSA addition) was applied for OSA starch preparation. Initial OSA substitution was predominately at the branching points of amylopectin backbone, then successive at the branching points of shorter and longer chains with increasing DS. As DS increased over 1.49%, substitution started occurring along the chains and moved towards the non-reducing ends until DS reached 6.65%. At similar DS, more branching point substitutions occurred at CM starch, showing superior emulsifying property over BM starch. OSA substitution priority rule does exist under controlled OSA supply, which would facilitate OSA starch design with specific substitution pattern and favored functionality.

In situ monitoring of cellulose etherification in solution: probing the impact of solvent composition on the synthesis of 3-allyloxy-2-hydroxypropyl-cellulose in aqueous hydroxide systems

Cellulose etherification can be affected by tuning the solvent composition as indicated by monitoring the reaction using in situ IR spectroscopy and rheology measurements together with NMR characterisation.

Designing cellulose hydrogels from non-woody biomass

Hydrogels are an attractive system for a myriad of applications. While most hydrogels are usually formed from synthetic materials, lignocellulosic biomass appears as a sustainable alternative for hydrogel development. The valorization of biomass, especially the non-woody biomass to meet the growing demand of the substitution of synthetics and to leverage its benefits for cellulose hydrogel fabrication is attractive. This review aims to present an overview of advances in hydrogel development from non-woody biomass, especially using native cellulose. The review will cover the overall process from cellulose depolymerization, dissolution to crosslinking reaction and the related mechanisms where known. Hydrogel design is heavily affected by the cellulose solubility, crosslinking method and the related processing conditions apart from biomass type and cellulose purity. Hence, the important parameters for rational designs of hydrogels with desired properties, particularly porosity, transparency and swelling characteristics will be discussed. Current challenges and future perspectives will also be highlighted.

Ethyl cellulose particles loaded with α-tocopherol for inhibiting thermal oxidation of soybean oil

Most endogenous antioxidants degrade and lose efficiency during frying. The study aimed to inhibit thermal oxidation of soybean oil by fabricating α-tocopherol loaded particles with ethyl cellulose (EC) of different viscosity grades (M9, M70 and M200) via anti-solvent method. As the viscosity of ethyl cellulose increased, particle size decreased from micrometer to nanometer. Confocal laser scanning microscope confirmed successful encapsulation and uniform distribution of α-tocopherol in the loaded particles. Differential scanning calorimetry and thermogravimetric analysis demonstrated that loaded particles protected α-tocopherol from oxidation and degradation. Meanwhile, Fourier transformed infrared demonstrated that α-tocopherol interacted with EC through hydrogen bond and hydrophobic effects. With excellent dispersibility in soybean oil, loaded particles effectively inhibited thermal oxidation of soybean oil and loaded M200 nanoparticles was the most effective, which performed far better than tert-butylhydroquinone (TBHQ). Therefore, the nanoparticles offered a promising way to enhance oxidative stability of oils during thermal processing.

Substituent distribution of propyl cellulose studied by nuclear magnetic resonance

A series of propyl cellulose (PC) samples with different degrees of substitution (DS) ranging from 0.34 to 2.02 were prepared by a slurry method using propyl bromide as the etherification reagent. Two-dimensional nuclear magnetic resonance (NMR) studies were performed to identify the ¹H and ¹³C chemical shifts of eight anhydroglucose units (AGUs) in PC chains including un-, 2-mono-, 3-mono-, 6-mono-, 2,3-di-, 2,6-di-, 3,6-di-, and 2,3,6-tri-substituted ones. In addition, the mole fractions (χ) of these AGUs in the studied PC samples and their changes with DS were determined from the quantitative ¹³C NMR spectra. The obtained χ-DS profiles were different from those of methyl and ethyl celluloses prepared by a similar slurry method, indicating that the molecular sizes of the substituent reagents utilized for cellulose ethers strongly affected their substituent distributions.

Multiscale Structure of Starches Grafted with Hydrophobic Groups: A New Analytical Strategy

Starch, an abundant and low-cost plant-based glucopolymer, has great potential to replace carbon-based polymers in various materials. In order to optimize its functional properties for bioplastics applications chemical groups need to be introduced on the free hydroxyl groups in a controlled manner, so an understanding of the resulting structure-properties relationships is therefore essential. The purpose of this work was to study the multiscale structure of highly-acetylated (degree of substitution, 0.4 < DS ≤ 3) and etherified starches by using an original combination of experimental strategies and methodologies. The molecular structure and substituents repartition were investigated by developing new sample preparation strategies for specific analysis including Asymmetrical Flow Field Flow Fractionation associated with Multiangle Laser Light Scattering, Nuclear Magnetic Resonance (NMR), Raman and Time of Flight Secondary Ion Mass spectroscopies. Molar mass decrease and specific ways of chain breakage due to modification were pointed out and are correlated to the amylose content. The amorphous structuration was revealed by solid-state NMR. This original broad analytical approach allowed for the first time a large characterization of highly-acetylated starches insoluble in aqueous solvents. This strategy, then applied to characterize etherified starches, opens the way to correlate the structure to the properties of such insoluble starch-based materials.

Cationic starches in paper-based applications-A review on analytical methods

This review focuses on cationic starches with a low degree of substitution (<0.06) which are mainly used for production of paper-based products. After a brief introduction on starch in general, cationization pathways and importance of cationic starches in paper production, this review emphasizes on the analytical challenges from different perspectives. These include the different length scales of starches when in solution: the macromolecular level, their assembly into nm aggregates and finally hydrocolloids with hundreds of nanometers of diameter. We give an overview on the current state of the art on the analysis of such challenging samples and aim at providing a guideline for obtaining and presenting reliable analytical data.

Structural, Physicochemical, and Functional Properties of Electrolyzed Cassava Starch

Cassava starch was oxidized using the electrolysis system. Sodium chloride was added to this system at various concentrations from 0.5 to 5.0 % (w/v). The whiteness of modified starches proportionally increased based on the NaCl concentration and human eyes could recognize the difference of color. Under treatment, dents occurred on the surface of starch granule. Concentration of carbonyl and carboxyl groups was increased compared to native starch. Based on X-ray diffraction pattern, oxidized starch kept its A-type. Besides, the ratios of alpha-helix/amorphous regions remained indicating oxidation reaction mainly subjected on amorphous region. Intrinsic viscosity was used to indirectly calculate the average molecular weight of sample. Furthermore, results showed that average molecular weight was significantly reduced (from 2.09-fold to 13.22-fold) based on the reacting NaCl concentration. The increase of NaCl content related to the increase of retrogradation of treated starches. At various temperatures (30-95°C), swelling factor and clarity reflected negative and positive correlations to NaCl concentration.

Influence of oxidized starch on physicomechanical, thermal properties, and atomic force micrographs of cassava starch bioplastic film

Oxidized starch was produced and its effect on starch-based bioplastic film has been evaluated. The produced oxidized starch was coarse, brownish with 15.68% carbonyl content, insoluble in cold water and has a positive influence on bioplastic films. The film thickness increased with increase in the amount of added oxidized starch from 0.21% (film_O) to 0.23% (film_6O). The film moisture content dropped from 7.93% (film_O) to 5.36% (film_6O), likewise the film water solubility decreased from 13.48% (film_O) to 5.75% (film_6O). Addition of oxidized starch led to longer biodegradability and enduring water absorption kinetics. The mechanical property was improved by the addition of oxidized starch. The derivative thermogravimetry analysis indicates five degradation stages for all the bioplastic films, while films surface roughness was shown by AFM. The research has revealed that oxidized starch can be used to improve the physicomechanical properties of starch based bioplastic film.

Strategy for Structural Elucidation of Polysaccharides: Elucidation of a Maize Mucilage that Harbors Diazotrophic Bacteria

The recruitment of a bacterial consortium by the host is a strategy not limited to animals but is also used in plants. A maize aerial root mucilage has been found that harbors nitrogen fixing bacteria that are attracted to the carbohydrate rich environment. This synbiotic relationship is facilitated by a polysaccharide, whose complicated structure has been previously unknown. In this report, we present the characterization of the maize polysaccharide by employing new analytical strategies combining chemical depolymerization, oligosaccharide sequencing, and monosaccharide and glycosidic linkage quantitation. The mucilage contains a single heterogeneous polysaccharide composed of a highly fucosylated and xylosylated galactose backbone with arabinan and mannoglucuronan branches. This unique polysaccharide structure may select for the diazotrophic community by containing monosaccharides and linkages that correspond to the glycosyl hydrolases associated with the microbial community. The elucidation of this complicated structure illustrates the power of the analytical methods, which may serve as a general platform for polysaccharide analysis in the future.

Spectroscopic and Thermodynamic Study of Biopolymer Adsorption Phenomena in Heterogeneous Solid-Liquid Systems

Molecular selective adsorption processes at the solid surface of biopolymers in mixed solvent systems are poorly understood due to manifold interactions. However, the ability to achieve adsorptive fractionation of liquid mixtures is posited to relate to the role of specific solid-liquid interactions at the adsorbent interface. The hydration of solid biopolymers (amylose, amylopectin, cellulose) in binary aqueous systems is partly governed by the relative solvent binding affinities with the biopolymer surface sites, in accordance with the role of textural and surface chemical properties. While molecular models that account for the surface area and solvent effects provide reliable estimates of hydration energy and binding affinity parameters, spectroscopic and thermal methods offer a facile alternative experimental approach to account for detailed aspects of solvation phenomena at biopolymer interfaces that involve solid-liquid adsorption. In this report, thermal and spectroscopic methods were used to understand the interaction of starch- and cellulose-based materials in water-ethanol (W-E) binary mixtures. Batch adsorption studies in binary W-E mixtures reveal the selective solvent uptake properties by the biomaterials, in agreement with their solvent swelling in pure water or ethanol. The nature, stability of the bound water, and the thermodynamic properties of the biopolymers in variable hydration states were probed via differential scanning calorimetry and Raman spectroscopy. The trends in biopolymer-solvent interactions are corroborated by dye adsorption and scanning electron microscopy, indicating that biopolymer adsorption properties in W-E mixtures strongly depend on the surface area, pore structure, and accessibility of the polar surface groups of the biopolymer systems, in agreement with the solvent-selective uptake results reported herein.

Liquid Chromatography-Tandem Mass Spectrometry Approach for Determining Glycosidic Linkages

The structural analysis of carbohydrates remains challenging mainly due to the lack of rapid analytical methods able to determine and quantitate glycosidic linkages between the diverse monosaccharides found in natural oligosaccharides and polysaccharides. In this research, we present the first liquid chromatography-tandem mass spectrometry (LC-MS/MS)-based method for the rapid and simultaneous relative quantitation of glycosidic linkages for oligosaccharide and polysaccharide characterization. The method developed employs ultrahigh-performance liquid chromatography coupled with triple quadrupole mass spectrometry (UHPLC/QqQ-MS) analysis performed in multiple reaction monitoring (MRM) mode. A library of 22 glycosidic linkages was built using commercial oligosaccharide standards. Permethylation and hydrolysis conditions along with LC-MS/MS parameters were optimized resulting in a workflow requiring only 50 μg of substrate for the analysis. Samples were homogenized, permethylated, hydrolyzed, and then derivatized with 1-phenyl-3-methyl-5-pyrazolone (PMP) prior to analysis by UHPLC/MRM-MS. Separation by C18 reversed-phase UHPLC along with the simultaneous monitoring of derivatized terminal, linear, bisecting, and trisecting monosaccharide linkages by mass spectrometry is achieved within a 15 min run time. Reproducibility, efficacy, and robustness of the method was demonstrated with galactan ( Lupin) and polysaccharides within food such as whole carrots. The speed and specificity of the method enables its application toward the rapid glycosidic linkage analysis of oligosaccharides and polysaccharides.

A functional chitosan-based hydrogel as a wound dressing and drug delivery system in the treatment of wound healing

Functional active wound dressings are expected to provide a moist wound environment, offer protection from secondary infections, remove wound exudate and accelerate tissue regeneration, as well as to improve the efficiency of wound healing. Chitosan-based hydrogels are considered as ideal materials for enhancing wound healing owing to their biodegradable, biocompatible, non-toxic, antimicrobial, biologically adhesive, biological activity and hemostatic effects. Chitosan-based hydrogels have been demonstrated to promote wound healing at different wound healing stages, and also can alleviate the factors against wound healing (such as excessive inflammatory and chronic wound infection). The unique biological properties of a chitosan-based hydrogel enable it to serve as both a wound dressing and as a drug delivery system (DDS) to deliver antibacterial agents, growth factors, stem cells and so on, which could further accelerate wound healing. For various kinds of wounds, chitosan-based hydrogels are able to promote the effectiveness of wound healing by modifying or combining with other polymers, and carrying different types of active substances. In this review, we will take a close look at the application of chitosan-based hydrogels in wound dressings and DDS to enhance wound healing.

Drug nanocarrier agents based on starch-g-amino acids

Introduction: In the recent decades, starch has been modified using different methods for the various forms of applications. Some new starch derivatives were prepared through a simple and convenient method in the grafting of amino acids: L-alanine, L-leucine and L-phenyl alanine to starch. Methods: First, the amine groups of amino acids were protected using phthalic anhydride then the acidic side of amino acids were activated with chlorination using thionyl chloride, and the resultant acid chlorides were reacted with starch in aqueous media at room temperature. Results: Performing the various spectroscopy experiments on the obtained compounds showed that the new derivative of starch has been formed. The structure of all synthesized materials was determined and confirmed using common spectroscopy methods and their thermal behavior was examined using DSC experiment. Conclusion: New amino acid derivatives of starch and their nanocarriers successfully prepared through a simple and convenient method. The size of nanocarriers evaluated using DLS and TEM experiments. The spherical shape of particles shows that nanocarriers have been formed and the size of these particles are approximately 92, 137 and 97 nm. Performing the wettability test determined that all the resulted materials are soluble in water. Nanocarriers of the obtained modified starches were prepared using dialysis method and naproxen was utilized as a model drug molecule. The drug release dynamics in buffered solution were studied and investigation of the drug release mechanism showed that in case of L-alanine- and L-phenylalanine-modified starches, drug release followed the Fickian diffusion with a slight deviation.

Finding Biomass Degrading Enzymes Through an Activity-Correlated Quantitative Proteomics Platform (ACPP)

The microbial secretome, known as a pool of biomass (i.e., plant-based materials) degrading enzymes, can be utilized to discover industrial enzyme candidates for biofuel production. Proteomics approaches have been applied to discover novel enzyme candidates through comparing protein expression profiles with enzyme activity of the whole secretome under different growth conditions. However, the activity measurement of each enzyme candidate is needed for confident "active" enzyme assignments, which remains to be elucidated. To address this challenge, we have developed an Activity-Correlated Quantitative Proteomics Platform (ACPP) that systematically correlates protein-level enzymatic activity patterns and protein elution profiles using a label-free quantitative proteomics approach. The ACPP optimized a high performance anion exchange separation for efficiently fractionating complex protein samples while preserving enzymatic activities. The detected enzymatic activity patterns in sequential fractions using microplate-based assays were cross-correlated with protein elution profiles using a customized pattern-matching algorithm with a correlation R-score. The ACPP has been successfully applied to the identification of two types of "active" biomass-degrading enzymes (i.e., starch hydrolysis enzymes and cellulose hydrolysis enzymes) from Aspergillus niger secretome in a multiplexed fashion. By determining protein elution profiles of 156 proteins in A. niger secretome, we confidently identified the 1,4-α-glucosidase as the major "active" starch hydrolysis enzyme (R = 0.96) and the endoglucanase as the major "active" cellulose hydrolysis enzyme (R = 0.97). The results demonstrated that the ACPP facilitated the discovery of bioactive enzymes from complex protein samples in a high-throughput, multiplexing, and untargeted fashion. Graphical Abstract ᅟ.

Value-additive utilization of agro-biomass: preparation of cellulose triacetate directly from rice straw as well as other cellulosic materials

An efficient environmentally benign single-step procedure for the preparation of cellulose triacetate from cellulosics, including rice straw agro-biomass, is described.

Potato starch oxidation induced by sodium hypochlorite and its effect on functional properties and digestibility

The effects of different concentrations of sodium hypochlorite (active chlorine content at 0.1, 0.2, 1.0, 2.0, 3.0, and 4.0 g/100 g) on the properties of potato starch (PS) were investigated by determining the morphological, physicochemical, crystallinity, pasting, gel texture and digestive properties. The starch granules of PS oxidized with high oxidant concentrations caused cracks and pores, and oxidation mainly acts on the amorphous regions of the starch granules. As the sodium hypochlorite concentration increases, the carbonyl content, carboxyl content, solubility, and pasting temperature of PS increased, as measured using a Rapid Visco Analyser (RVA). The swelling power, breakdown, setback, and peak and final viscosities decreased according to the RVA (P<0.05). The gel strength increased under low-intensity oxidative treatments and decreased under high-intensity oxidative treatments. Oxidative treatment decreased the digestibility of gelatinized potato starch. The slowly digestible starch and resistant starch contents increased significantly, while the rapidly digestible starch content decreased after the oxidation modification (P<0.05). Overall, PS oxidation with sodium hypochlorite improved the functional characteristics of starch and decreased starch digestibility.

Understanding and managing the impact of HPMC variability on drug release from controlled release formulations

The purpose of this study is to identify critical physicochemical properties of hydroxypxropyl methylcellulose (HPMC) that impact the dissolution of a controlled release tablet and develop a strategy to mitigate the HPMC lot-to-lot and vendor-to-vendor variability. A screening experiment was performed to evaluate the impacts of methoxy/hydroxypropyl substitutions, and viscosity on drug release. The chemical diversity of HPMC was explored by nuclear magnetic resonance (NMR), and the erosion rate of HPMC was investigated using various dissolution apparatuses. Statistical evaluation suggested that the hydroxypropyl content was the primary factor impacting the drug release. However, the statistical model prediction was not robust. NMR experiments suggested the existence of structural diversity of HPMC between lots and more significantly between vendors. Review of drug release from hydrophilic matrices indicated that erosion is a key aspect for both poorly soluble and soluble drugs. An erosion rate method was then developed, which enabled the establishment of a robust model and a meaningful HPMC specification. The study revealed that the overall substitution level is not the unique parameter that dictates its release-controlling properties. Fundamental principles of polymer chemistry and dissolution mechanisms are important in the development and manufacturing of hydrophilic matrices with consistent dissolution performance.

Properties of Edible Films Based on Oxidized Starch and Zein

The objective of this work was to investigate the effect of zein and film formulation on mechanical and structural properties of native (FNS), and oxidized with 2.5% (FOSA) and 3.5% (FOSB) banana starch. The oxidized starch showed differences from native starch due to the oxidation process, showing a decrease in lipids, proteins, and amylose. The increase of the sodium hypochlorite increased the content of carbonyl and carboxyl groups in the ranges 0.015–0.028% and 0.022–0.031%, respectively. The film obtained from FOSB displayed the highest tensile strength (5.05 MPa) and satisfactory elongation value (27.1%). The zein addition caused a decrease in these mechanical properties, as well as a significant decrease in water vapour permeability (WVP). However, films from FOSA and FOSB showed higher permeability than that of the native starch. The addition of glycerol and the level of oxidation increased the films moisture. Micrographs showed that, during the oxidation process, impurities were largely eliminated from the starch granule, noting more homogeneous structures both in granules and films.

Industrial applications of marine carbohydrates

Biomaterials have been used increasingly in various fields, such as drug delivery, imaging, and tissue engineering. The main reason justifying the widespread use of biomaterials relies on its valuable and low-cost source of new drugs. Current research goals are focused on identifying more potent and specific compounds with antitumor, immunomodulatory, antihyperlipidemic, anticoagulant, and antiviral activities. The increasing knowledge of structural analysis and chemical modifications enables the use of these marine carbohydrates in a newer way for the human welfare. This chapter focuses on the recent developments related to industrial and biomedical applications using chitin, chitosan, alginate, agar, and carrageenan derivatives and reports the main advances published over the last 10-15 years.

Position of modifying groups on starch chains of octenylsuccinic anhydride-modified waxy maize starch

Octenylsuccinic anhydride (OSA)-modified starches with a low (0.018) and high (0.092) degree of substitution (DS) were prepared from granular native waxy maize starch in aqueous slurry. The position of OS substituents along the starch chains was investigated by enzyme hydrolysis followed by chromatographic analysis. Native starch and two OS starches with a low and high DS had β-limit values of 55.9%, 52.8%, and 34.4%, respectively. The weight-average molecular weight of the β-limit dextrin from the OS starch with a low DS was close to that of the β-limit dextrin from native starch but lower than that of the β-limit dextrin from the OS starch with a high DS. Debranching of OS starches was incomplete compared with native starch. OS groups in the OS starch with a low DS were located on the repeat units near the branching points, whereas the OS substituents in the OS starch with a high DS occurred both near the branching points and the non-reducing ends.