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The biosynthesis of starch granules in plant plastids is coordinated by the orchestrated action of transferases, hydrolases, and dikinases. These enzymes either contain starch-binding domain(s) themselves, or are dependent on direct interactions with co-factors containing starch-binding domains. As a means to competitively interfere with existing starch–protein interactions, we expressed the protein module Carbohydrate-Binding Motif 20 (CBM20), which has a very high affinity for starch, ectopically in barley plastids. This interference resulted in an increase in the number of starch granules in chloroplasts and in formation of compound starch granules in grain amyloplasts, which is unusual for barley. More importantly, we observed a photosystem-independent inhibition of CO2 fixation, with a subsequent reduced growth rate and lower accumulation of carbohydrates with effects throughout the metabolome, including lower accumulation of transient leaf starch. Our results demonstrate the importance of endogenous starch–protein interactions for controlling starch granule morphology and number, and plant growth, as substantiated by a metabolic link between starch–protein interactions and control of CO2 fixation in chloroplasts. [ABSTRACT FROM AUTHOR]

Possible inhibitory effects on wheat starch amylolysis of native and hydrolysed pea protein, in an extruded wheat snack matrix were investigated by using a combined in vitro dynamic gastric model (DGM) and a static duodenal digestion model (SDM). The matrix was prepared by blending wheat flour and pea proteins (12%, w/w) in their native or proteolyzed forms. Extruded snacks were ground, mixed with saliva and poured in the DGM-fundus. The slurry in the antrum was released simulating the in vivo emptying of the stomach and subsequently transferred to the SDM. Native pea protein did not influence the release of soluble glucans and glucose after complete gastric emptying into the vessel. However, the addition of hydrolysed pea protein significantly reduced starch amylolysis at the first 40 min of digestion. No inhibitory effect was observed at later digestion times. Fourier-Transform Infrared (FTIR) analysis of the extruded samples clearly indicated enhanced starch-protein interactions, where the magnitude of interaction found to be greatest in the blend with hydrolysed pea protein through hydrogen bonding. At our knowledge, this is the first study using DGM to determine the effect of exogenous protein on the digestibility of extruded wheat starch. The data suggested the possibility of using protease hydrolysed pea protein as an ingredient to formulate low glycemic food products. [ABSTRACT FROM AUTHOR]

Bio-plastics and bio-materials are composed of natural or biomass derived polymers, offering solutions to solve immediate environmental issues. Polysaccharide-based bio-plastics represent important alternatives to conventional plastic because of their intrinsic biodegradable nature. Amylose-only (AO), an engineered barley starch with 99% amylose, was tested to produce cross-linked all-natural bioplastic using normal barley starch as a control. Glycerol was used as plasticizer and citrate cross-linking was used to improve the mechanical properties of cross-linked AO starch extrudates. Extrusion converted the control starch from A-type to Vh- and B-type crystals, showing a complete melting of the starch crystals in the raw starch granules. The cross-linked AO and control starch specimens displayed an additional wide-angle diffraction reflection. Phospholipids complexed with Vh-type single helices constituted an integrated part of the AO starch specimens. Gas permeability tests of selected starch-based prototypes demonstrated properties comparable to that of commercial Mater-Bi© plastic. The cross-linked AO prototypes had composting characteristics not different from the control, indicating that the modified starch behaves the same as normal starch. The data shows the feasibility of producing all-natural bioplastic using designer starch as raw material. [ABSTRACT FROM AUTHOR]

Grain polysaccharides represent potential valuable raw materials for next-generation advanced and environmentally friendly plastics. Thermoplastic starch (TPS) is processed using conventional plastic technology, such as casting, extrusion, and molding. However, to adapt the starch to specific functionalities chemical modifications or blending with synthetic polymers, such as polycaprolactone are required (e.g. Mater-Bi). As an alternative, all-natural and compostable bio-plastics can be produced by blending starch with other polysaccharides. In this study, we used a maize starch (ST) and an oat β-glucan (BG) composite system to produce bio-plastic prototype films. To optimize performing conditions, we investigated the full range of ST:BG ratios for the casting (100:0, 75:25, 50:50, 25:75 and 0:100 BG). The plasticizer used was glycerol. Electron Paramagnetic Resonance (EPR), using TEMPO (2,2,6,6-tetramethylpiperidine-1-oxyl) as a spin probe, showed that the composite films with high BG content had a flexible chemical environment. They showed decreased brittleness and improved cohesiveness with high stress and strain values at the break. Wide-angle X-ray diffraction displayed a decrease in crystallinity at high BG content. Our data show that the blending of starch with other natural polysaccharides is a noteworthy path to improve the functionality of all-natural polysaccharide bio-plastics systems. [ABSTRACT FROM AUTHOR]

Isomaltooligosaccharides (IMOs) is a mixture of branched-maltooligosaccharides (MOSs), classified as a functional food ingredient with prebiotic potential. The objective of this study was to investigate alternative enzymatic methods to produce a sweetness/viscosity/degradability balance product containing soluble carbohydrate ranging from glucose, maltose, isomaltose and linear and branched MOS (IMOs), of different digestibility. The modified samples were produced using two main routes: 1. simultaneous catalysis by α-amylase and branching enzyme (BE) followed by α-transglucosidase (ABT) treatment, 2. simultaneous catalysis by α-amylase and BE followed by simultaneous β-amylase and α-transglucosidase (ABbT). For both routes, 30% or 50% (w v −1 ) cassava starch were used and a commercial IMO (comIMO) preparation was used as a positive control. The 30ABbT and 50ABbT showed the highest α-1,6 glucosidic linkages, panose and branched MOS (Degree of Polymerisation (DP) 4–7) compared to all other samples. All ABT and ABbT products showed decreased molecular weight and increased resistance to degradation by amylolytic enzymes as compared to cassava starch. The 50ABbT sample demonstrated the lowest digestion rate constant. Due to their high solubility and structural composition, containing-balanced-glucose, maltose, isomaltose and linear and branched MOS (IMOs), of different digestibility, these compositions can be suitable especially in soft drink- and sport drink formulations. [ABSTRACT FROM AUTHOR]

Transgenically-produced amylose-only (AO) starch was used to manufacture bioplastic prototypes. Extruded starch samples were tested for crystal residues, elasticity, glass transition temperature, mechanical properties, molecular mass and microstructure. The AO starch granule crystallinity was both of the B- and Vh-type, while the isogenic control starch was mainly A-type. The first of three endothermic transitions was attributed to gelatinization at about 60 °C. The second and third peaks were identified as melting of the starch and amylose-lipid complexes, respectively. After extrusion, the AO samples displayed Vh- and B-type crystalline structures, the B-type polymorph being the dominant one. The AO prototypes demonstrated a 6-fold higher mechanical stress at break and 2.5-fold higher strain at break compared to control starch. Dynamic mechanical analysis showed a significant increase in the storage modulus (E′) for AO samples compared to the control. The data support the use of pure starch-based bioplastics devoid of non-polysaccharide fillers. [ABSTRACT FROM AUTHOR]

Thermostable branching enzyme (BE, EC 2.4.1.18) from Rhodothermus obamensis in combination with amylomaltase (AM, EC 2.4.1.25) from Thermus thermophilus was used to modify starch structure exploring potentials to extensively increase the number of branch points in starch. Amylose is an important constituent in starch and the effect of amylose on enzyme catalysis was investigated using amylose-only barley starch (AO) and waxy maize starch (WX) in well-defined ratios. All products were analysed for amylopectin chain length distribution, α-1,6 glucosidic linkages content, molar mass distribution and digestibility by using rat intestinal α-glucosidases. For each enzyme treatment series, increased AO content resulted in a higher rate of α-1,6 glucosidic linkage formation but as an effect of the very low initial branching of the AO, the final content of α-1,6 glucosidic linkages was slightly lower as compared to the high amylopectin substrates. However, an increase specifically in short chains was produced at high AO levels. The molar mass distribution for the enzyme treated samples was lower as compared with substrate WX and AO, indicating the presence of hydrolytic activity as well as cyclisation of the substrate. For all samples, increased amylose substrate showed decreased α- and β-amylolysis. Surprisingly, hydrolysis with rat intestinal α-glucosidases was higher with increasing α-1,6 glucosidic linkage content and decreasing M ¯ w indicating that steric hindrance towards the α-glucosidases was directed by the molar mass rather that the branching density of the glucan per se. Our data demonstrate that a higher amylose content in the substrate starch efficiently produces α-1,6 glucosidic linkages and that the present of amylose generates a higher M ¯ w and more resistant product than amylopectin. The combination of BE → AM → BE provided somewhat more resistant α-glucan products as compared to BE alone. [ABSTRACT FROM AUTHOR]

[Display omitted] • Use of a green and sustainable synthetic strategy to CHA-based polyesters. • Low temperature (35–55 °C) polycondensation in scCO 2 achieved. • The valuable epoxy groups of the monomers were preserved. • Our process led to reasonably high molecular weight polyesters. There is significant potential for industrial use of renewables for a wide range of materials demanded by society. Plants, trees and algae are increasingly attracting attention as sustainable sources for functionalised and polymerizable building blocks. In particular, the outer bark of the birch tree (Betula pendula) is a side stream of the forestry industry with so far very little utilisation besides energy recovery. It is composed of a macromolecular network, suberin, that could provide a renewable, low cost and competitive resource. Within raw suberin is the potentially very useful multifunctional extract cis -9,10-epoxy-18-hydroxyoctadecanoic acid (CHA). Our drive has been to develop a green and sustainable synthetic strategy to CHA-based polyesters, by exploiting supercritical carbon dioxide (scCO 2) as a reaction medium and leveraging the regio- and chemo-selective properties of the biocatalyst Novozym 435 (Lipase B). Low temperature (35–55 °C) polycondensation in scCO 2 shows significant advantages compared to traditional polymerisation methods leading to reasonably high molecular weight polyesters. The mild synthetic conditions also preserve the valuable epoxy groups of the CHA which we show can be exploited by post-polymerisation functionalisation to create sustainable resins for bio-renewable coatings. [ABSTRACT FROM AUTHOR]

The efficiency of photomobile polymers (PMP) in the conversion of light into mechanical work plays a fundamental role in achieving cutting-edge innovation in the development of novel applications ranging from energy harvesting to sensor approaches. Because of their photochromic properties, azobenzene monomers have been shown to be an efficient material for the preparation of PMPs with appropriate photoresponsivity. Upon integration of the azobenzene molecules as moieties into a polymer, they act as an engine, allowing fast movements of up to 50 Hz. In this work we show a promising approach for integrating ZnO nanoparticles into a liquid crystalline polymer network. The addition of such nanoparticles allows the trapping of incoming light, which acts as diffusive points in the polymer matrix. We characterized the achieved nanocomposite material in terms of thermomechanical and optical properties and finally demonstrated that the doped PMP was better performing that the undoped PMP film. [ABSTRACT FROM AUTHOR]

• Engineered amylose and waste CNF generate good bioplastics. • CNF enhanced crystallinity, mechanics and permeability. • Cellulose nanofibers and amylose showed domain phase separation. Thermoplastic, polysaccharide-based plastics are environmentally friendly. However, typical shortcomings include lack of water resistance and poor mechanical properties. Nanocomposite manufacturing using pure, highly linear, polysaccharides can overcome such limitations. Cast nanocomposites were fabricated with plant engineered pure amylose (AM), produced in bulk quantity in transgenic barley grain, and cellulose nanofibers (CNF), extracted from agrowaste sugar beet pulp. Morphology, crystallinity, chemical heterogeneity, mechanics, dynamic mechanical, gas and water permeability, and contact angle of the films were investigated. Blending CNF into the AM matrix significantly enhanced the crystallinity, mechanical properties and permeability, whereas glycerol increased elongation at break, mainly by plasticizing the AM. There was significant phase separation between AM and CNF. Dynamic plasticizing and anti-plasticizing effects of both CNF and glycerol were demonstrated by NMR demonstrating high molecular order, but also non-crystalline, and evenly distributed 20 nm-sized glycerol domains. This study demonstrates a new lead in functional polysaccharide-based bioplastic systems. [ABSTRACT FROM AUTHOR]

Brucella is a foodborne pathogen globally affecting both the economy and healthcare. Surface Enhanced Raman Spectroscopy (SERS) nano-biosensing can be a promising strategy for its detection. We combined high-performance quasi-crystal patterned nanocavities for Raman enhancement with the use of covalently immobilized Tbilisi bacteriophages as high-performing bio-receptors. We coupled our efficient SERS nano-biosensor to a Raman system to develop an on-field phage-based bio-sensing platform capable of monitoring the target bacteria. The developed biosensor allowed us to identify Brucella abortus in milk by our portable SERS device. Upon bacterial capture from samples (104 cells), a signal related to the pathogen recognition was observed, proving the concrete applicability of our system for on-site and in-food detection. [ABSTRACT FROM AUTHOR]

Starch provides our main dietary caloric intake and over-consumption of starch-containing foods results in escalating life-style disease including diabetes. By increasing the content of α-1,6 branch points in starch, digestibility by human amylolytic enzymes is expected to be retarded. Aiming at generating a soluble and slowly digestible starch by increasing the content and changing the relative positioning of the branch points in the starch molecules, we treated cassava starch with amylomaltase (AM) and branching enzyme (BE). We performed a detailed molecular analysis of the products including amylopectin chain length distribution, content of α-1,6 glucosidic linkages, absolute molecular weight distribution and digestibility. Step-by-step enzyme catalysis was the most efficient treatment, and it generated branch structures even more extreme than those of glycogen. All AM- and BE-treated samples showed increased resistance to degradation by porcine pancreatic α-amylase and glucoamylase as compared to cassava starch. The amylolytic products showed chain lengths and branching patterns similar to the products obtained from glycogen. Our data demonstrate that combinatorial enzyme catalysis provides a strategy to generate potential novel soluble α-glucan ingredients with low dietary digestibility assets. [ABSTRACT FROM AUTHOR]

New bio-based polymers capable of either outperforming fossil-based alternatives or possessing new properties and functionalities are of relevant interest in the framework of the circular economy. In this work, a novel bio-based polycarvone acrylate di-epoxide (PCADE) was used as an additive in a one-step straightforward electrospinning process to endow the fibres with functionalisable epoxy groups at their surface. To demonstrate the feasibility of the approach, poly(vinylidene fluoride) (PVDF) fibres loaded with different amounts of PCADE were prepared. A thorough characterisation by TGA, DSC, DMTA and XPS showed that the two polymers are immiscible and that PCADE preferentially segregates at the fibre surface, thus developing a very simple one-step approach to the preparation of ready-to-use surface functionalisable fibres. We demonstrated this by exploiting the epoxy groups at the PVDF fibre surface in two very different applications, namely in epoxy-based carbon fibre reinforced composites and membranes for ω-transaminase enzyme immobilisation for heterogeneous catalysis. [ABSTRACT FROM AUTHOR]