Maltodextrin-Based Cross-Linked Electrospun Mats as Sustainable Sorbents for the Removal of Atenolol from Water.

Maltodextrins are products of starch hydrolysis that can be processed into dry fibres through electrospinning and subsequently cured via mild thermal treatment to obtain nonwoven cross-linked polysaccharide-based mats. The sustainability of the process and the bioderived nature make this class of materials suitable candidates to be studied as renewable sorbents for the removal of contaminants from water. In this work, electrospinning of water solutions containing 50% wt. of commercial maltodextrin (Glucidex 2®) and 16.6% wt. of citric acid was carried out at 1.2 mL/h flow and 30 kV applied voltage, followed by thermal curing at 180 °C of the dry fibres produced to obtain cross-linked mats. Well-defined fibres with a mean diameter of 1.64 ± 0.35 µm were successfully obtained and characterised by scanning electron microscopy, thermogravimetric analysis, and attenuated total reflectance Fourier transform infrared spectroscopy. Afterwards, a series of sorption tests were conducted to evaluate the effectiveness of the mats in removing atenolol from water. The results of the batch tests followed by HPLC-UV/Vis showed high sorption rates, with over 90% of the atenolol removed, and a maximum removal capacity of 7 mg/g. Furthermore, continuous fixed-bed sorption tests proved the positive interaction between the polymers and atenolol.

Characterization of molar mass and conformation of relevant (non-)starch polysaccharides in cereal-based beverages.

Arabinoxylans, ß-glucans, and dextrins influence the brewing industry's filtration process and product quality. Despite their relevance, only a maximum concentration of ß-glucans is recommended. Nevertheless, filtration problems are still present, indicating that although the chemical concentration is essential, other parameters should be investigated. Molar mass and conformation are important polymer physical characteristics often neglected in this industry. Therefore, this research proposes an approach to physically characterize enzymatically isolated beer polysaccharides by asymmetrical flow field-flow fractionation coupled to multi-angle light scattering and differential refractive index detector. Based on the obtained molar masses, root-mean-square radius (rrms from MALS), and hydrodynamic radius (rhyd), conformational properties such as apparent density (ρapp) and rrms/rhyd can be calculated based on their molar mass and size. Consequently, the ρapp and rrms/rhyd behavior hints at the different structures within each polysaccharide. The rrms/rhyd 1.2 and high ρapp values on low molar mass dextrins (1-2·105 g/mol) indicate branches, while aggregated structures at high molar masses on arabinoxylans and ß-glucans (2·105 -6·106 g/mol) are due to an increase of ρapp and a rrms/rhyd (0.6-1). This methodology provides a new perspective to analyze starch and non-starch polysaccharides in cereal-based beverages since different physical characteristics could influence beer's filtration and sensory characteristics.

Scalable and Degradable Dextrin-Based Elastomers for Wearable Touch Sensing.

Elastomer-based wearables can improve people's lives; however, frictional wear caused by manipulation may pose significant concerns regarding their durability and sustainability. To address the aforementioned issue, a new class of advanced scalable supersoft elastic transparent material (ASSETm) is reported, which offers a unique combination of scalability (20 g scale), stretchability (up to 235%), and enzymatic degradability (up to 65% in 30 days). The key feature of our design is to render native dextrin hydrophobic, which turns it into a macroinitiator for bulk ring-opening polymerization. Based on ASSETm, a self-powered touch sensor (ASSETm-TS) for touch sensing and non-contact approaching detection, possessing excellent electrical potential (up to 65 V) and rapid response time (60 ms), is fabricated. This work is a step toward developing sustainable soft electronic systems, and ASSETm's tunability enables further improvement of electrical outputs, enhancing human-interactive applications.

Dextrin-Based Adsorbents Synthesized via a Sustainable Approach for the Removal of Salicylic Acid from Water.

Pharmaceuticals such as salicylic acid are commonly detected in wastewater and surface waters, increasing concern for possible harmful effects on humans and the environment. Their difficult removal via conventional treatments raised the need for improved strategies, among which the development of bioderived adsorbents gained interest because of their sustainability and circularity. In this work, biobased cross-linked adsorbents, synthesized via a sustainable approach from starch derivatives, namely beta-cyclodextrins and maltodextrins, were at first characterized via FTIR-ATR, TGA, SEM, and elemental analysis, showing hydrophilic granular morphologies endowed with specific interaction sites and thermal stabilities higher than 300 °C. Subsequently, adsorption tests were carried out, aiming to assess the capabilities of such polymers on the removal of salicylic acid, as a case study, from water. Batch tests showed rapid kinetics of adsorption with a removal of salicylic acid higher than 90% and a maximum adsorption capacity of 17 mg/g. Accordingly, continuous fixed bed adsorption tests confirmed the good interaction between the polymers and salicylic acid, while the recycling of the adsorbents was successfully performed up to four cycles of use.

Debranched waxy maize resistant dextrin: Synthesis, ethanol fractionation, crystallization, and characterization.

Waxy maize (Zea mays L.) dextrins (WMD), prepared by enzymatic debranching, were fractionated through precipitation in different concentrations of aqueous ethanol (50 %, 60 %, and 80 %). The fractionated WMDs were then crystallized at 4 °C or 50 °C for 2 days to prepare resistant dextrins (RD). Recovery yield, chain distribution, crystalline structure, thermal transition, and in vitro digestibility of the fractionated/crystallized WMDs were evaluated. Crystallization at 4 °C resulted in higher yields (>90 %) than that at 50 °C, regardless of the fractionation condition. The chain profile of the dextrins recovered at different temperatures appeared similar, but the longer chains had a greater tendency to associate. Crystal arrangement (A- or B-type) depended on the fractionation and crystallization conditions. Most crystals showed a typical B-type arrangement, except for the crystals prepared at 50 °C with 80 % ethanol (A-type). The enzyme resistance ranged from 49.9 % to 92.4 % depending on the fractionation and crystallization conditions.

A Comparative Study of Resistant Dextrins and Resistant Maltodextrins from Different Tuber Crop Starches.

The anti-digestibility of resistant dextrin (RD) and resistant maltodextrin (RMD) is usually significantly affected by processing techniques, reaction conditions, and starch sources. The objective of this investigation is to elucidate the similarities and differences in the anti-digestive properties of RD and RMD prepared from three different tuber crop starches, namely, potato, cassava, and sweet potato, and to reveal the associated mechanisms. The results show that all RMDs have a microstructure characterized by irregular fragmentation and porous surfaces, no longer maintaining the original crystalline structure of starches. Conversely, RDs preserve the structural morphology of starches, featuring rough surfaces and similar crystalline structures. RDs exhibite hydrolysis rates of approximately 40%, whereas RMDs displaye rates lower than 8%. This disparity can be attributed to the reduction of α-1,4 and α-1,6 bonds and the development of a highly branched spatial structure in RMDs. The indigestible components of the three types of RDs range from 34% to 37%, whereas RMDs vary from 80% to 85%, with potato resistant maltodextrin displaying the highest content (84.96%, p < 0.05). In conclusion, there are significant differences in the processing performances between different tuber crop starches. For the preparation of RMDs, potato starch seems to be superior to sweet potato and cassava starches. These attributes lay the foundation for considering RDs and RMDs as suitable components for liquid beverages, solid dietary fiber supplements, and low glycemic index (low-GI) products.

Production of highly branched α-limit dextrins with enhanced slow digestibility by various glycogen-branching enzymes.

α-Limit dextrins (α-LDx) are slowly digestible carbohydrates that attenuate postprandial glycemic response and trigger the secretion of satiety-related hormones. In this study, more highly branched α-LDx were enzymatically synthesized to enhance the slowly digestible property by various origins of glycogen branching enzyme (GBE), which catalyzes the transglycosylation to form α-1,6 branching points after cleaving α-1,4 linkages. Results showed that the proportion of branched α-LDx in starch molecules increased around 2.2-8.1 % compared to α-LDx from starch without GBE treatment as the ratio of α-1,6 linkages increased after different types of GBE treatments. Furthermore, the enzymatic increment of branching points enhanced the slowly digestible properties of α-LDx at the mammalian α-glucosidase level by 17.3-28.5 %, although the rates of glucose generation were different depending on the source of GBE treatment. Thus, the highly branched α-LDx with a higher amount of α-1,6 linkages and a higher molecular weight can be applied as a functional ingredient to deliver glucose throughout the entire small intestine without a glycemic spike which has the potential to control metabolic diseases such as obesity and type 2 diabetes.

Enzymatic synthesis, structure of isomalto/malto-polysaccharides from linear dextrins prepared by retrogradation.

Isomalto/malto-polysaccharides (IMMPs) with degree of polymerization (DP) 10-100 have novel potential applications, including enhanced solubility and anti-inflammatory. However, there are minimal synthetic methods for preparing IMMPs with a relatively higher DP, which is due to the lack of suitable molecular weight linear dextrins (I-LDs). The existing I-LDs preparation methods have disadvantages, such as low yield and uncontrollable molecular weight. Therefore, this study proposes a method for preparing soluble linear dextrins (S-LDs, Mw = 2.1 kDa) by low-temperature retrogradation from debranched waxy corn starch (Mw = 3.0 kDa). S-LDs reacted with 4,6-α-glucanotransferase GtfB-ΔN from Limosilactobacillus reuteri 121 to yield IMMPs with 12.3 kDa Mw and 83.8% α1 â†’ 6 linkages content. Process monitoring revealed the synthesis mechanism and a detailed reaction process. Finally, IMMPs were identified by enzyme fingerprinting as α1 â†’ 6 chains with α1 â†’ 4 fragments inlaid at the reducing, non-reducing end, and middle part. This study provides a new synthesis method and more structural information for IMMPs.

Effect of highly branched α-glucans synthesized by dual glycosyltransferases on the glucose release rate.

Increasing α-1,6 linkages in starch molecules generates a large amount of α-limit dextrins (α-LDx) during α-amylolysis, which decelerate the release of glucose at the intestinal α-glucosidase level. This study synthesized highly branched α-glucans from sucrose using Neisseria polysaccharea amylosucrase and Rhodothermus obamensis glycogen branching enzyme to enhance those of slowly digestible property. The synthesized α-glucans (Mw: 1.7-4.9 × 107 g mol-1) were mainly composed of α-1,4 linkages and large proportions of α-1,6 linkages (7.5%-9.9%). After treating the enzymatically synthesized α-glucans with the human α-amylase, the quantity of branched α-LDx (36.2%-46.7%) observed was higher than that for amylopectin (26.8%) and oyster glycogen (29.1%). When the synthetic α-glucans were hydrolyzed by mammalin α-glucosidases, the glucose generation rate decreased because the amount of embedded branched α-LDx increased. Therefore, the macro-sized branched α-glucans with high α-LDx has the potential to be used as slowly digestible material to attenuate postprandial glycemic response.

Slowly digestible property of highly branched α-limit dextrins produced by 4,6-α-glucanotransferase from Streptococcus thermophilus evaluated in vitro and in vivo.

Starch molecules are first degraded to slowly digestible α-limit dextrins (α-LDx) and rapidly hydrolyzable linear malto-oligosaccharides (LMOs) by salivary and pancreatic α-amylases. In this study, we designed a slowly digestible highly branched α-LDx with maximized α-1,6 linkages using 4,6-α-glucanotransferase (4,6-αGT), which creates a short length of α-1,4 side chains with increasing branching points. The results showed that a short length of external chains mainly composed of 1-8 glucosyl units was newly synthesized in different amylose contents of corn starches, and the α-1,6 linkage ratio of branched α-LDx after the chromatographical purification was significantly increased from 4.6% to 22.1%. Both in vitro and in vivo studies confirmed that enzymatically modified α-LDx had improved slowly digestible properties and extended glycemic responses. Therefore, 4,6-αGT treatment enhanced the slowly digestible properties of highly branched α-LDx and promises usefulness as a functional ingredient to attenuate postprandial glucose homeostasis.

Influence of two functional dextrins on the gel properties of kappa-carrageenan.

The physicochemical properties of κ-carrageenan (KC) can be improved by incorporation with small-molecule cosolvents. The texture and rheological properties, micromorphology, and crystallinity of KC incorporating indigestible dextrin (IDD) and beta-limit dextrin (BLD) were investigated. The rheological properties and sol-gel transition temperatures of the gels were slightly improved and the hardness of KC gels was significantly increased after the two dextrins were mixed in. Fourier transform infrared spectroscopy results indicated hydrogen-bonding interactions were strengthened in the presence of the dextrins. Confocal laser scanning microscope images revealed that a more homogenous structure was formed of the KC gel after the addition of dextrins. Moreover, X-ray diffraction patterns indicated the crystallinity of KC gel decreased upon dextrin addition. At the same dextrin content, IDD exerted a greater influence than BLD. IDD contents exceeding 3% (w/w) led to undesirable effects, whereas up to 5% (w/w) of BLD could be added. The two dextrins affected the rearrangement of the KC random coils in the sol state, and facilitated aggregation of the KC chains during cooling to form gel network structures after gelation. Therefore, the appropriate addition of these two dextrins can improve the texture and stability of KC gels and expand their application in functional foods.

Different gelatinization characteristics of small and large barley starch granules impact their enzymatic hydrolysis and sugar production during mashing.

This study investigates the impact of different gelatinization characteristics of small and large barley starch granules on their enzymatic hydrolysis and sugar production during mashing. Therefore, a barley malt suspension was consecutively incubated at 45, 62, 72 and 78 °C to monitor starch behavior and enzymatic starch hydrolysis and sugar production. The combination of microscopic and rapid visco analyses showed that small starch granules persisted longer in the system and were present non-gelatinized at temperatures higher than 62 °C. HPAEC-PAD analysis showed that 8% of the total amount of starch, predominantly small granules, gelatinized at temperatures between 62 °C and 78 °C. Due to their delayed gelatinization in this system, their enzymatic hydrolysis yielded relatively more dextrins compared to what was observed for large granules. It was concluded that small granules should be taken into account when optimizing enzymatic hydrolysis of barley starch, like in brewing, distilling or bio-ethanol production.

Enzyme-resistant dextrins from potato starch for potential application in the beverage industry.

The objective of this study was to produce soluble enzyme-resistant dextrins by microwave heating of potato starch acidified with small amounts of hydrochloric and citric acids and to characterize their properties. Twenty five samples were initially made and their solubility was determined. Three samples with the highest water solubility were selected for physico-chemical (dextrose equivalent, molecular weight distribution, pasting characteristics, retrogradation tendency), total dietary fiber (TDF) analysis, and stability tests. TDF content averaged 25%. Enzyme-resistant dextrins practically did not paste, even at 20% samples concentration, and were characterized by low retrogradation tendency. The stability of the samples, expressed as a percentage increase of initial and final reducing sugar content, at low pH and during heating at low pH averaged 10% and 15% of the initial value, respectively. The results indicate that microwave heating could be an effective and efficient method of producing highly-soluble, low-viscous, and enzyme-resistant potato starch dextrins.

Number of branch points in α-limit dextrins impact glucose generation rates by mammalian mucosal α-glucosidases.

α-Amylase first hydrolyzes starch structures to linear maltooligosaccharides and branched α-limit dextrins, then complete hydrolysis to glucose takes place through the mucosal α-glucosidases. In this study, we hydrolyzed waxy corn starch (WCS) by human pancreatic α-amylase to determine the digestion and structural properties of different size fractions of the branched α-limit dextrins. The α-amylolyzed WCS was separated by size exclusion chromatography, and the analyzed chromatograms showed four main hydrolyzate fractions. The first three eluted peaks (regions I-III) corresponded to branched α-limit dextrins, while region IV was the linear maltooligosaccharides. Based on the chromatographic and NMR analyses of the individual peaks, Region I, II, and III had multiple (>2), two, and one α-1,6 linkages, respectively, and region I was the most slowly hydrolyzed to glucose by mucosal α-glucosidases (hydrolysis rate: Region I

Oxidized dextrins as alternative crosslinking agents for polysaccharides: application to hydrogels of agarose-chitosan.

Hydrogel networks that combine suitable physical and biomechanical characteristics for tissue engineering scaffolds are in demand. The aim of this work was the development of hydrogel networks based on agarose and chitosan using oxidized dextrins as low cytotoxicity crosslinking agents, paying special attention to the study of the influence of the polysaccharide composition and oxidation degree of the dextrins in the final characteristics of the network. The results show that the formation of an interpenetrating or a semi-interpenetrating polymer network was mainly dependent on a minimum agarose content and degree of oxidation of dextrin. Spectroscopic, thermal and swelling analysis revealed good compatibility with an absence of phase separation of polysaccharides at agarose:chitosan proportions of 50:50 and 25:75. The analysis of atomic force microscopy images showed the formation of a fibrillar microstructure whose distribution within the crosslinked chitosan depended mainly on the crosslinker. All materials exhibited the viscoelastic behaviour typical of gels, with a constant storage modulus independent of frequency for all compositions. The stiffness was strongly influenced by the degree of oxidation of the crosslinker. Cellular response to the hydrogels was studied with cells of different strains, and cell adhesion and proliferation was correlated with the homogeneity of the samples and their elastic properties. Some hydrogel formulations seemed to be candidates for tissue engineering applications such as wound healing or soft tissue regeneration.

(1)H NMR spectroscopy for profiling complex carbohydrate mixtures in non-fractionated beer.

A plethora of biological and biotechnological processes involve the enzymatic remodelling of carbohydrates in complex mixtures whose compositions affect both the processes and products. In the current study, we employed high-resolution (1)H NMR spectroscopy for the analysis of cereal-derived carbohydrate mixtures as exemplified on six beer samples of different styles. Structural assignments of more than 50 carbohydrate moieties were obtained using (1)H1-(1)H2 groups as structural reporters. Spectroscopically resolved carbohydrates include more than ''20 different'' small carbohydrates with more than 38 isomeric forms in addition to cereal polysaccharide fragments with suspected organoleptic and prebiotic function. Structural motifs at the cleavage sites of starch, ß-glucan and arabinoxylan fragments were identified, showing different extent and specificity of enzymatic polysaccharide cleavage during the production of different beer samples. Diffusion ordered spectroscopy supplied independent size information for the characterisation and identification of polysaccharide fragments, indicating the presence especially of high molecular weight arabinoxylan fragments in the final beer.

Investigations on the Maillard reaction of dextrins during aging of Pilsner type beer.

Although Maillard reaction plays a pivotal role during preparation of food, only few investigations concerning the role of carbohydrate degradation in beer aging have been carried out. The formation of Maillard specific precursor structures and their follow-up products during degradation of low molecular carbohydrate dextrins in the presence of proline and lysine was studied in model incubations and in beer. Twenty-one α-dicarbonyl compounds were identified and quantitated as reactive intermediates. The oxidative formation of 3-deoxypentosone as the precursor of furfural from oligosaccharides was verified. N-Carboxymethylproline and N-formylproline were established as novel proline derived Maillard advanced glycation end products. Formation of N-carboxymethylproline and furfural responded considerably to the presence of oxygen and was positively correlated to aging of Pilsner type beer. The present study delivers an in-depth view on the mechanisms behind the formation of beer relevant aging parameters.

Structural and physical properties of granule stabilized starch obtained by branching enzyme treatment.

Chemical cross-linking of starch is an important modification used in the industry for granule stabilization. It has been demonstrated that treatment with branching enzyme (BE) can stabilize the granular structure of starch and such treatment thereby provides a potential clean alternative for chemical modification. This study demonstrates that such BE-assisted stabilization of starch granules led to partial protection from BE catalysis of both amylose (AM) and amylopectin (AP) in their native state as assessed by triiodide complexation, X-ray diffractometry (XRD) and differential scanning calorimetry (DSC). The granule stabilizing effects were inversely linked to hydration of the starch granules, which was increased by the presence of starch-phosphate esters and suppressed by extreme substrate concentration. The data support that the granule stabilization is due to the intermolecular transglycosylation occurring in the initial stages of the reaction prior to AM-AP phase separation. The enzyme activity needed to obtain granule stabilization was therefore dependent on the hydration capability of the starch used.