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BACKGROUND: Yam is a major staple food that provides both energy (starch) and bioactive compounds. However, there is a lack of knowledge on its cooking quality. We have determined the cooking quality of five varieties of water yam (among those most appreciated by consumers), when they were steamed or boiled. The yams were grown in two contrasting locations with regard to pedoclimatic conditions. RESULTS: Ratio of length to mean circumference of the tuber, difficulty to peel, cooking time, color attributes, hardness of steamed pulp, and dry matter (DM) and starch contents significantly varied among varieties. Cooking time and hardness of the cooked pulp, either steamed or boiled, were higher for tubers grown at the drier location, with vertisols, than at the rainy one, with a ferralitic soil. The raw pulp was richer in starch at the rainy location. We found no correlation between either textural properties or DM and the cooking time. A slight (r = 0.44) but significant correlation was recorded between the DM of the raw pulp and the hardness of the steamed product. CONCLUSION: We propose a comprehensive multicriteria approach for determination of yam cooking quality, textural properties, color attributes and chemical composition, along with varietal and environmental influences. This approach takes into consideration the complexity of food quality, allows a better understanding of its determinants and provides a basis for useful guidelines for breeders. © 2023 The Authors. Journal of The Science of Food and Agriculture published by John Wiley & Sons Ltd on behalf of Society of Chemical Industry. [ABSTRACT FROM AUTHOR]

Highlights • Amylomaltase (AM) reaction time and substrate constituents greatly affect the AM action modes. • AM-treatment decreases starch molar mass and produces various cyclo-structures. • Starches with various structures can be obtained by controlling AM reaction time and substrates. Abstract This work investigates the macromolecular structure of native and amylomaltase (AM) treated cassava starch at various reaction times. AM-treated starches showed lower amylose content compared to their parental starch. Long chain proportions (DP 25–80) increased with reaction time up to 4 h and then slightly decreased at 24 h. Macromolecular and fine structure of AM-treated starches for 5 min (AM5min) and 4 h (AM4 h) were characterized more deeply by using HPSEC-MALLS and H1 NMR combined with β-amylolysis and MALDI-TOF-MS. Molar mass and dispersity of both AM-treated starches were lowered. Nevertheless, AM5min had longer external chains whereas AM4 h exhibited a larger and denser macromolecular core. A cyclo-structure with DP 8 was found in both AM-treated starches; however, AM4 h contained cyclo-structures with various sizes (DP 8–32). Finally, by controlling reaction time and substrate constituents, which are important factors affecting the AM action modes, AM-treated starch with various structural features can be obtained. [ABSTRACT FROM AUTHOR]

Polysaccharide-surfactant blends are widely used in foods. However, their possible mutual interactions have not been extensively studied. The purpose of this work was to examine how the anionic surfactant sodium stearoyl lactylate (SSL) affects different properties of κ-carrageenan solutions and gels. Rheometry, differential scanning calorimetry, asymmetrical flow field-flow fractionation coupled with multiangle laser light scattering, among others, were used to determine the flow and viscoelastic behavior, thermal transitions, and conformation changes, respectively. Interference caused by SSL is postulated as the primary factor to explain the variations in the conformation of κ-carrageenan in gels and solutions. However, electrostatic repulsions between κ-carrageenan and SSL can also be involved. These latter interactions are more important for high SSL concentrations (13 mmol dm −3 ) without addition of KCl, because of the higher net negative charge density of the system. SSL significantly modifies the properties of κ-carrageenan in aqueous media. [ABSTRACT FROM AUTHOR]

Native starch containing 12% water was melt processed in presence of 23% of various plasticizers at 120 °C, either by simple compression molding or by extrusion using a laboratory scale microcompounder. Glycerol, a typical starch plasticizer, was used as a reference and compared to three choline salts: raw choline chloride (which is a solid in dry state with a melting point above 300 °C), and two ionic liquids synthesized from this precursor (choline acetate and choline lactate, liquids below 100 °C). These ionic plasticizers were shown to allow a more efficient melting of native starch in both processes. The investigation of macromolecular structure changes during processing shows that this efficiency can be ascribed to a starch chain scission mechanism, resulting in lower specific mechanical energy input need for starch thermoplasticization compared to glycerol plasticized starch. Compared to the synthesized ionic liquids, raw commercial choline chloride leads to a good compromise between limited chain scission, and final water uptake and thermomechanical properties. [ABSTRACT FROM AUTHOR]

Asymmetrical flow field flow fractionation (AF4), when coupled with multi-angle laser light scattering (MALLS), is a very powerful technique for determination of the macromolecular structure of high molar mass (branched) polysaccharides. AF4 is a size fractionation technique just as size exclusion chromatography (SEC), nevertheless can overcome some crucial problems found in SEC analysis especially in starch like structures. This paper describes a detailed investigation of the macromolecular structure of two groups of well-defined synthetic amylopectin analogs – synthesized via an in vitro enzyme-catalyzed reaction using the enzymes phosphorylase b from rabbit muscle and Deinococcus geothermalis glycogen branching enzyme (Dg GBE). Size, molar mass distributions and structural data were studied by AF4 coupled with online quasi-elastic light scattering (QELS) and multi-angle light scattering (MALLS). [ABSTRACT FROM AUTHOR]

Asymmetrical flow field flow fractionation (AF4) has proven to be a very powerful and quantitative method for the determination of the macromolecular structure of high molar mass branched biopolymers, when coupled with multi-angle laser light scattering (MALLS). This work describes a detailed investigation of the macromolecular structure of native glycogens and hyperbranched α-glucans (HBPs), with average molar mass ranging from 2 × 10 to 4.3 × 10 g mol, which are not well fractionated by means of classical size-exclusion chromatography. HBPs were enzymatically produced from sucrose by the tandem action of an amylosucrase and a branching enzyme mimicking in vitro the elongation and branching steps involved in glycogen biosynthesis. Size and molar mass distributions were studied by AF4, coupled with online quasi-elastic light scattering (QELS) and transmission electron microscopy. AF4-MALLS-QELS has shown a remarkable agreement between hydrodynamic radii obtained by online QELS and by AF4 theory in normal mode with constant cross flow. Molar mass, size, and dispersity were shown to significantly increase with initial sucrose concentration, and to decrease when the branching enzyme activity increases. Several populations with different size range were observed: the amount of small size molecules decreasing with increasing sucrose concentration. The spherical and dense global conformation thus highlighted was partly similar to native glycogens. A more detailed study of HBPs synthesized from low and high initial sucrose concentrations was performed using complementary enzymatic hydrolysis of external chains and chromatography. It emphasized a more homogeneous branching pattern than native glycogens with a denser core and shorter external chains. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

Highlights: [•] The molecular features of the non-conventional starches must be studied in order to understand its functional properties. [•] This study focuses the characterization of starches isolated from wild yams to be applied in different industries. [•] Increasing information on wild starches sources will increase its applications. [•] The study denotes the molecular and functional properties of non-conventional starches. [ABSTRACT FROM AUTHOR]

Abstract: The aim of this work was to characterize the amylopectin of low amylose content cassava starches obtained from transgenesis comparatively with a natural waxy cassava starch (WXN) discovered recently in CIAT (International Center for Tropical Agriculture). Macromolecular features, starch granule morphology, crystallinity and thermal properties of these starches were determined. of amylopectin from the transgenic varieties are lower than WXN. Branched and debranched chain distributions analyses revealed slight differences in the branching degree and structure of these amylopectins, principally on DP 6–9 and DP>37. For the first time, a deep structural characterization of a series of transgenic lines of waxy cassava was carried out and the link between structural features and the mutated gene expression approached. The transgenesis allows to silenced partially or totally the GBSSI, without changing deeply the starch granule ultrastructure and allows to produce clones with similar amylopectin as parental cassava clone. [Copyright &y& Elsevier]

Abstract: Two new mutant cassava starches with extreme amylose contents (0 and 30–31%) have been recently reported. These mutants are drastically different from normal cassava starch whose amylose content typically ranges between 15 and 25%. The new mutants were compared with five normal cassava starches (ranging from 16.8 to 21.5% amylose) and commercial versions of amylose-free or normal potato and maize starch. Macromolecular features, crystallinity, granule sizes, and thermal properties of these starches were compared. The structure of cassava amylopectin was not modified by the waxy mutation and waxy cassava starch exhibited properties similar to the ones of waxy maize starch. Waxy cassava and maize show similar and of amylopectin (between 408×106 gmol−1 and 520×106 gmol−1; 277–285nm, respectively), whereas waxy potato amylopectin has lower and . On the contrary, the higher-amylose mutations induced by gamma rays radiation in cassava, modified deeply the branching pattern of amylopectin as well as the starch characteristics and properties: and decreased, while branching degree increased. These modifications resulted in changes in starch granule ultrastructure (e.g. decreased starch crystallinity), a weak organized structure, and increased susceptibility to mild acid hydrolysis. The distinctive properties of the new cassava starches demonstrated in this article suggest new opportunities and commercial applications for tropical sources of starch. [Copyright &y& Elsevier]

Starch consists of a mixture of two α-glucans built mainly upon α-(1,4) linkages: amylose, an essentially linear polymer, and amylopectin, a branched polymer containing 5-6% of α-(1,6) linkages. The aim of the present work was to analyze the structural properties of native starches displaying different amylose-to-amylopectin ratios and arising from different botanical sources, using asymmetrical flow field flow fractionation (A4F) and a combination of hydrodynamic and size-exclusion chromatography (HDC-SEC) coupled with multiangle laser light scattering, online quasi-elastic light scattering, and differential refractive index techniques. The procedure, based upon dimethyl sulfoxide pretreatment and then solubilization in water, generates a representative injected sample without altering the initial degree of polymerization. The amylopectin weight-average molar masses and radii of gyration were around 1.0 × 10-4.8 × 10 g mol and 110-267 nm, respectively. For each starch sample, the hydrodynamic radius ( R) distributions and the molar mass distributions obtained from the two fractionation systems coupled with light scattering techniques were analyzed. The size determination scales were extended by means of R calibration curves. HDC-SEC and A4F data could be matched. However, A4F enabled a better separation of amylopectins and therefore an enhanced structural characterization of the starches. The two advantages of this experimental approach are (1) it can directly obtain distributions as a function of both molar mass and size, while taking account of sample heterogeneity, and (2) it is possible to compare the results obtained using the different techniques through the direct application of R distributions. [Figure not available: see fulltext.] [ABSTRACT FROM AUTHOR]

The relationship between fruit and puree's characteristics is still poorly understood. In particular, it is not understood how pectin solubilisation and degradation alter the texture of plant-cell dispersions and how a targeted application of processing conditions can be used to design naturally textured food products. Systematic combinations of thermal and mechanical treatments with three different temperatures (70, 83, 95 °C) and grinding speeds (300, 1000, 3000 rpm), applied on one-month (T1) and six-months stored (T6) apples, were used to generate apple purees with contrasted structural and textural characteristics. For T1, serum viscosity increased with increasing temperature (8–104 mPa.s) with a marked increase in pectin solubilisation (1–6 mg/g serum). Pectin macromolecular size and (arabinose + galactose)/rhamnose ratio, estimating pectin side chain branching, decreased with temperature. For T6, pectin showed decreased galactose, leading to facilitated cell separation, low serum viscosity (~16 mPa.s) and restricted impact of process conditions on pectin composition and structure. Grinding had limited impact on pectin solubilisation for T1 and T6 but strongly impacted particle size (498–1096 μm for T1 or 320–1068 μm for T6) and puree's viscosity (871–1475 mPa.s for T1 or 853–1453 mPa.s for T6). Tissue fragmentation was favoured by temperature increase for T1 and by the maturation of raw apples. Process parameters induced differences in the puree's structure and texture depending on the maturation level of raw apples. The observed changes were linked to pectin degradation and substantial side chain loss. [Display omitted] • Elevated temperature and apple maturation induced pectin degradation. • Pectin degradation and solubilisation enhanced cell separation during processing. • The interaction storage duration × temperature had a major impact on pectins. • Mechanical processes altered pectin composition and structure only slightly. • Mechanical treatments highly affected puree's texture but not serum viscosity. [ABSTRACT FROM AUTHOR]

How cellular and molecular structure of raw fruits impact puree's texture is still an unresolved question. Texture variations of purees obtained from four apple cultivars of contrasted texture (Braeburn, Gala, Golden Delicious, Granny Smith) and two modalities (mealiness, fruit load) after two contrasted processes were investigated. Although puree's viscosity strongly varied between cultivars (562–1368 mPa s), it did not correlate with apple firmness, except for Granny Smith. This cultivar had the firmest fruits (3.2 N) and the most viscous purees (1368 mPa.s), in accordance with large particles (around 650 μm), high pulp wet mass and serum viscosity. Mealy Braeburn apples showed lower puree's viscosity (562 mPa.s) than their not-mealy homologues (779 mPa.s). This was due to reduced cell adhesion, maybe because of lower (arabinose + galactose)/rhamnose ratio, leading to smaller particles during processing. Process also impacted puree's viscosity (692–939 mPa s), with more viscous purees obtained with the high temperature-low shear process. • Fruit firmness could not predict puree's viscosity. • Cultivars highly affected puree's viscosity. • Granny Smith revealed particularly high fruit and puree's textures. • Mealy apples generated less viscous purees because of reduced cell adhesion. • High temperature-low shear process produced more viscous purees. [ABSTRACT FROM AUTHOR]

The texture of pureed fruits and vegetables depends primarily on the original tissue structure and cell wall (CW) properties. However, how variations in the raw fruits' cellular and molecular structure determine the rheological behaviour of the purees is little understood, though pectin degradation appears to play a key role. Cultivars, fruit load and post-harvest storage were used to obtain raw apples with different tissue structures, which were processed into purees under simulation of an industrial process. The rheological behaviour of the purees was then compared to particle size, pulp wet mass and serum viscosity. The polysaccharide composition of soluble and insoluble CW material were determined after preparation of alcohol insoluble residue. Macromolecular size and molar mass distributions of soluble pectins were analysed using high performance size-exclusion chromatography coupled to multi-angle laser light scattering and online viscometry. Variations in the raw material, especially induced by post-harvest storage, generated a wide range of different puree's textures. Rheological behaviour of apple purees was driven by particle size, which decreased during prolonged post-harvest storage due to reduced cell adhesion. This was correlated with pectic side chain hydrolysis and modifications in pectin molar mass and structure. Similar trends during storage were observed with different apple cultivars and agricultural practices. Image 1 • Post-harvest storage was the main factor affecting puree's texture and pectins. • Pectic side chain hydrolysis was correlated with tissue fragmentation over storage. • Water retention capacities of apple cell wall polysaccharides increased when aged. • Post-harvest storage enhanced extractability of high molar mass pectins. • Pectic main chain was not degraded during puree processing. [ABSTRACT FROM AUTHOR]

Potato and pea starches were processed on a twin-screw extruder under various moisture and thermomechanical conditions, chosen to keep material temperature T e close to starch melting temperature, T m , whilst avoiding die expansion. Extruded rods were analysed by asymmetrical flow field flow fractionation coupled with light scattering, X-ray diffraction, DSC, and light microscopy with image analysis. Molar mass of extruded materials decreased more for potato than for pea starch, when specific mechanical energy SME increased, likely because of larger amylopectin sensitivity to shear. No crystallinity was detected when ΔT   =   (T m -T e )  ≤ 0. Residual gelatinization enthalpy ΔH g decreased with ΔT . As illustrated by larger ΔT values for ΔH g  = 0, decreasing moisture favored melting, likely by increasing solid friction. The fraction of granular remnants of potato starch was inversely correlated to SME . These results could be explained by considering starch melting during extrusion as a suspension of solid particles embedded in a continuous amorphous matrix. [ABSTRACT FROM AUTHOR]

In this paper, a detailed characterization of the mechanisms at the origin of the shape-memory effect in amorphous potato starch is presented. Using different treatments (annealing) and preparation methods (hot casting and extrusion), the local structures responsible for the shape-memory were disrupted, as evidenced in the first part of the article detailing the macroscopic properties: mechanical, calorimetric and shape-memory. In the second part the macromolecular scale is investigated using X-rays diffraction and CP-MAS NMR, and thus allows making the link between the structural differences and the macroscopic properties. Finally we discuss the origin of shape-memory in amorphous starch. [ABSTRACT FROM AUTHOR]

Debranched waxy rice starch (DWRS) and debranched normal rice starch (DNRS) were crystallized into spherulites from aqueous solutions. DNRS, which contained extra-long chains, yielded small sintered-like spherulites with rough surface, which exhibit positive birefringence and, therefore, had radial orientations. Large spherulites with smooth surfaces, negative birefringence and tangential orientation were formed with DWRS which essentially contained short linear chains. Both spherulites showed a B-type crystalline structure with an exceptionally high crystallinity and a similar melting behavior. However, DWRS spherulites had higher resistance to enzymatic hydrolysis than DNRS spherulites. The higher enzyme resistance of DWRS spherulites was attributed to their tangential organization and their smoother and denser surface as observed by light microscopy and scanning electron microscopy. The impact of the different structural features of the two types of spherulites is discussed in relation to their resistance to enzymatic hydrolysis. [ABSTRACT FROM AUTHOR]

The effects of chain distribution, concentration, temperature and hydrothermal treatments on the recrystallization behavior and formation of resistant starch (RS) were investigated. Waxy and normal rice starches were debranched at 10 and 21% w/w solid concentrations, incubated at 25 or 50 °C, and further subjected to annealing or heat moisture treatment (HMT) to enhance RS formation. The crystallization at 25 °C favored the formation of the B-type structure, whereas crystallization at 50 °C led to the A-type structure with a higher melting temperature (100-120 °C) and a higher RS content (52%). All incubated samples showed an increase in RS content after subsequent hydrothermal treatments. The sample incubated at a high temperature contained the highest RS content (74.5%) after HMT with larger/perfect crystallites. These results suggested that the RS formation could be manipulated by crystallization conditions and improved by hydrothermal treatments which are dependent on the initial crystalline perfection. [ABSTRACT FROM AUTHOR]

Starch-clay bionanocomposites containing 1–10% of natural montmorillonite were elaborated by melt processing in the presence of water. A complex macromolecular dynamics behavior was observed: depending on the clay content, an increase of the glass transition temperature and/or the presence of two overlapped α relaxation peaks were detected. Thanks to a model allowing the prediction of the average interparticle distance, and its comparison with the average size of starch macromolecules, it was possible to associate these phenomena to different populations of macromolecules. In particular, it seems that for high clay content (10%), the slowdown of segmental relaxation due to confinement of the starch macromolecules between the clay tactoïds is the predominant phenomenon. While for lower clay contents (3–5%), a significant modification of chain relaxation seems to occur, due to the formation of an interphase by the starch macromolecules in the vicinity of clay nanoparticles coexisting with the bulk polymer. [ABSTRACT FROM AUTHOR]

During processing of plant-based foods, cell wall polysaccharides and polyphenols, such as procyanidins, interact extensively, thereby affecting their physicochemical properties along with their potential health effects. Although hemicelluloses are second only to pectins in affinity for procyanidins in cell walls, a detailed study of their interactions lacks. We investigated the interactions between representative xylose-containing water-soluble hemicelluloses and procyanidins. Turbidity, ITC and DLS were used to determine the relative affinities, and theoretical calculations further ascertained the interactions mechanisms. Xyloglucan and xylan exhibited respectively the strongest and weakest interactions with procyanidins. The different arabinoxylans interacted with procyanidins in a similar strength, intermediate between xyloglucans and xylans. Therefore, the strength of the interaction depended on the structure itself rather than on some incidental properties, e.g., viscosity and molar mass. The arabinose side-chain of arabinoxylan did not inhibit interactions. The computational investigation corroborated the experimental results in that the region of interaction between xyloglucan and procyanidins was significantly wider than that of other hemicelluloses. [Display omitted] [ABSTRACT FROM AUTHOR]

[Display omitted] • Variety and break process affect puree viscosity without specific rheological signatures. • Impacts of variety and break process can be differentiated by sensory analysis. • Structural vs soluble sugar proportions vary by cultivar. • Cold break soluble pectins are more compact and spherical than hot break pectins. • Processing method modifies aggregation between cell wall materials and lycopene. The texture of tomato products can be modified by choice of variety, their growing conditions and/or processing method, but no clear explanation exists of the mechanisms that transform fruit tissue, how they act on texture, or whether genetics and processing impact the same physical parameters. We therefore conducted a study that processed 4 varieties produced under low/high nitrogen supply, into puree using both hot and cold break processes. No specific rheological signature allows discrimination between cultivar-induced or process-induced textural changes, but that they can be distinguished by sensory analysis. Growth conditions impacted but was not sensory distinguished. Both caused significant variations in 7 of 11 physico-chemical parameters, but the order of importance of these traits controlling texture varied, depending on whether the cause was genetic or process-related. Analysis of alcohol insoluble solids revealed a specific signature in pectin composition and conformation that could be linked to particle aggregation in the presence of lycopene-rich particles. [ABSTRACT FROM AUTHOR]

Abstract: A new α-amylase from Anoxybacillus flavothermus (AFA) was found to be effective in hydrolyzing raw starch in production of glucose syrup at temperatures below the starch gelatinization temperature. AFA is very efficient, leading to 77% hydrolysis of a 31% raw starch suspension. The final hydrolysis degree is reached in 2–3h at starch concentrations lower than 15% and 8–24h at higher concentrations. AFA is also very efficient in hydrolyzing the crystalline domains in the starch granule. The major A-type crystalline structure is more rapidly degraded than amorphous domains in agreement with the observed preferential hydrolysis of amylopectin. Amylose–lipid complexes are degraded in a second step, yielding amylose fragments which then re-associate into B-type crystalline structures forming the final α-amylase resistant fraction. The mode of action of AFA and the factors limiting complete hydrolysis are discussed in details. [Copyright &y& Elsevier]

During fruit and vegetable processing, procyanidins interact with cell walls and form complexes, which further impact their potential health effects. Among cell wall polysaccharides, pectins have the highest affinity for procyanidins. Binding of two procyanidin fractions with twelve pectins of different linearity and size was investigated by ITC, UV–Visible spectrophotometry and HPSEC-MALLS. Pectins interacted preferentially with highly polymerized procyanidins except beet pectins probably because of steric hindrance due to abundant feruloylated arabinans. Linear pectins had higher affinity for procyanidins: this was verified both for comparison between botanical origins (kiwifruit > apple > beet pectins) and between extraction conditions. Debranched pectins, extracted at pH 2.0, had higher affinity and aggregation capacities with procyanidins than those extracted at other pHs. However, the factors affecting pectins of different origins seemed to be different. High molar mass, intrinsic viscosity and hydrodynamic radius contributed more to increased adsorption of procyanidins by apple and beet pectins. Highly linear kiwifruit pectins, with high homogalacturonan content and lower branching ratio bound preferentially to procyanidins. The enthalpy/entropy proportion of the interaction between kiwifruit pectins and procyanidins was higher than that of apple and beet pectins, which suggested more hydrogen bonding. Predominance of homogalacturonan regions and high degree of methylation thus appeared key structural features of pectins for high affinity for procyanidins, while high degree of branching was detrimental. These findings provide the structural foundation for selectivity of interactions in molecular-level. Image 1 • Pectin linearity, molar mass and size influenced procyanidin adsorption. • Highly branched beet pectins had the lowest interaction with procyanidins. • Highest interactions were found with kiwifruit pectins, richest in homogalacturonans. • High degree of polymerization might hinder procyanidins' binding to beet pectins. [ABSTRACT FROM AUTHOR]

Cell wall (CW) degradation causes texture loss of plant-based products after processing. However, these losses differ in intensity, which could be due to cell wall structure or plant tissue internal pH conditions. To distinguish these two factors, CWs isolated from apple, beet and kiwifruit were subjected to boiling at pH 2.0, 3.5 and 6.0. Pectin depolymerization was the least pronounced at pH 3.5, while galacturonic acid contents of all CWs decreased at pH 6.0 due to the β-elimination. Pectins were solubilized, and their size decreased with increased pH during CW treatment. At pH 6.0, degrees of methylation decreased mostly in apple and beet CWs while galactose decreased more in kiwifruit CW. At pH 2.0, arabinan was lost in apple and beet CW due to acid hydrolysis. Apple CW was the most susceptible to degradation either at pH 2.0 or 6.0, while beet CW was more degraded at pH 2.0. In contrast, kiwifruit CW was the least susceptible to degradation whichever the pH. Acid hydrolysis and β-elimination appeared to be common mechanisms that cause loss of neutral sugars, often from pectin side chains, and galacturonic acid, respectively, but their effects were of different intensities. This work has a guiding significance for improving texture in the thermally canning process. Image 1 • All tested cell walls were susceptible to β-elimination. • The arabinans of apple and beet cell walls were susceptible to acid hydrolysis. • Treatment at pH 6.0 led to a decrease in galactose in kiwifruit cell wall. • Boiling at pH 3.5 involved less pectin depolymerization in cell walls. • Apple pectins were the most sensitive to pH treatment. [ABSTRACT FROM AUTHOR]

Summary: This study aimed at understanding users' demand for raw and boiled plantains in rural and urban areas in West and Littoral regions of Cameroon. Surveys conducted in eight rural localities consisted of key informant interviews, gender‐disaggregated focus group discussions, market and individual interviews. Processing and cooking diagnoses were done with restaurant cooks in urban areas, to know the details of plantain processing and boiling and to understand the quality characteristics of raw plantain that give a most‐liked boiled plantain. Local favourite landraces, most cultivated landraces in Cameroon (Batard and Big ebanga) and a new CARBAP/CIRAD hybrid (CARBAP K74) were used. The preference for plantain cultivars was both gender and region‐dependent. High‐quality plantain should be mature, with big fingers and having a dark green peel colour. The fruit length and girth, pulp pH, dry matter content and firmness were found to be relevant postharvest quality characteristics for plantain breeding improvement. [ABSTRACT FROM AUTHOR]

[Display omitted] • The inhibition of digestion of starch pastes by gallic acid (GA) was measured. • This inhibition was modest when GA was cooked with starch. • It was significant when GA was added to starch paste after cooking. • This latter effect increased with paste viscosity for potato and wheat starches. • This latter effect did not depend on paste viscosity for rice and maize starches. Phenolic compounds are known inhibitors of starch digestion through binding with α-amylase. However, a growing body of research shows that phenolic-starch interactions at the molecular level may interfere with this inhibition potential. In this study, we evaluated the effect of Gallic Acid (GA) as a model phenolic compound on starch digestion kinetics carried out in vitro in a Rapid ViscoAnalyzer (RVA). The results showed that when GA was added before cooking of starch in order to promote starch-GA complexation, the rate of digestion of starch was similar to that of starch alone, and faster than when GA was added after cooking of starch. The results demonstrated that when GA was introduced after cooking of starch, GA inhibited α-amylase strongly and that inhibition increased with starch paste viscosity only for potato and wheat starches. No correlation was found between starch molecular characteristics and the inhibiting capacity of GA at different starch concentrations. However, the apparent influence of starch chain length distribution suggested that physical effects (such as the absorption of GA at the surface of the starch paste) may play a role in the capacity of GA to inhibit α-amylase. [ABSTRACT FROM AUTHOR]

[Display omitted] • The inhibition of digestion of starch pastes by gallic acid (GA) was measured. • This inhibition was modest when GA was cooked with starch. • It was significant when GA was added to starch paste after cooking. • This latter effect increased with paste viscosity for potato and wheat starches. • This latter effect did not depend on paste viscosity for rice and maize starches. Phenolic compounds are known inhibitors of starch digestion through binding with α-amylase. However, a growing body of research shows that phenolic-starch interactions at the molecular level may interfere with this inhibition potential. In this study, we evaluated the effect of Gallic Acid (GA) as a model phenolic compound on starch digestion kinetics carried out in vitro in a Rapid ViscoAnalyzer (RVA). The results showed that when GA was added before cooking of starch in order to promote starch-GA complexation, the rate of digestion of starch was similar to that of starch alone, and faster than when GA was added after cooking of starch. The results demonstrated that when GA was introduced after cooking of starch, GA inhibited α-amylase strongly and that inhibition increased with starch paste viscosity only for potato and wheat starches. No correlation was found between starch molecular characteristics and the inhibiting capacity of GA at different starch concentrations. However, the apparent influence of starch chain length distribution suggested that physical effects (such as the absorption of GA at the surface of the starch paste) may play a role in the capacity of GA to inhibit α-amylase. [ABSTRACT FROM AUTHOR]

Most studies on the effects of climate change have been conducted on grain yield and composition; few have focused on seed germination and storage ability, especially in temperate crops. However, projected higher temperatures at the end of crop cycle are expected to affect not only seed nutritional quality but also seed germination and storage ability. In this study, experiments were conducted on wheat (Triticum aestivum L.) and pea (Pisum sativum L.) in controlled conditions to assess the effects of high maximum daytime temperatures, between 25°C and 35°C, on mother plants during grain filling or only during grain desiccation. Grain composition and seed characteristics related to germination and seed storage were investigated. When the stress occurred during grain filling, seed dry weight decreased, and protein and total fatty acid concentrations increased. Higher contents of vicilins in pea and polyunsaturated fatty acids in both crops were observed. Total starch content decreased in wheat. Sucrose: oligosaccharides ratio decreased, seed conductivity increased and germination was altered in both crops whenever the stress occurred. All of these modifications were mainly detrimental to the seed nutritional and end-use values. Further investigations should be carried out to assess genetic diversity, to characterise other species, and to introduce the impact of high temperatures on these seed characteristics into crop models. [ABSTRACT FROM AUTHOR]

New α(1 → 2) or α(1 → 3) branched dextrans with high molar masses and controlled architecture were synthesized using a dextransucrase and branching sucrases. Their molecular structure, solubility, conformation, film-forming ability, as well as their thermal and mechanical properties were determined. These new dextrans present structures with low densities from 9,500 to 14,000 g m −3 in H 2 O/DMSO medium, their molar mass, size and dispersity increase with increasing branching degree (weight-average molar mass up to 10 9 g mol −1 and radius of gyration around 500 nm). Dextrans exhibit a glass transition between 40.5 and 63.2 °C for water content varying from 12.2 to 14.1%. The effect of branching is mainly observed on the ability of dextran to crystallize. They have a good film-forming ability with a storage modulus which varies from 2 to 4 GPa within a relative humidity range of 10–50%. [ABSTRACT FROM AUTHOR]

During heat treatment, whey proteins (WP) are denatured and form different kinds of whey protein aggregates (WPA) depending on the physico-chemical conditions. In the presence of casein micelles, mixed aggregates (MA), resulting from the interaction of κ-casein and WP, are formed. The aim of this study is to understand the effect of pH on the WPA structure and the impact of the casein/whey proteins (Cas/WP) ratio on MA morphology. In this work, WP solutions were heated at pH 5.8 or 7 to produce WPA. On the other hand, aqueous mixtures containing three Cas/WP ratios (82/18, 56/44 and 30/70) were heated at 80 °C during 1 h at pH 6.3 to obtain MA. Milk protein aggregates were analyzed by Transmission Electron Microscopy (TEM) and Asymmetrical Flow Field-Flow Fractionation coupled with Multiangle Laser Light Scattering and Differential Refractometer (AF4-MALLS-DRi). Dense and spherical WPA were formed at pH 5.8 whereas branched and fractal aggregates were obtained at pH 7. Regarding MA, results suggested that they were mainly produced with the 82/18 Cas/WP ratio whereas a majority of WPA was obtained with the 30/70 ratio. At intermediate ratio, the mixture was composed of small MA and WPA that did not interact with κ-casein. Moreover, WP seem to interact preferentially with larger casein micelles. Thereby, AF4-MALLS-DRi proved to be a powerfull technique to characterize the complex structure of milk protein aggregates and an interesting alternative to size exclusion chromatography especially for MA and casein micelles which interact with the stationary phase and are retained in the column. [ABSTRACT FROM AUTHOR]

A gene encoding a novel dextransucrase was identified in the genome of Oenococcus kitaharae DSM17330 and cloned into E. coli . With a kcat of 691 s −1 and a half-life time of 111 h at 30 °C, the resulting recombinant enzyme -named DSR-OK- stands as one of the most efficient and stable dextransucrase characterized to date. From sucrose, this enzyme catalyzes the synthesis of a quasi linear dextran with a molar mass higher than 1 × 10 9 g·mol −1 that presents uncommon rheological properties such as a higher viscosity than that of the most industrially used dextran from L. mesenteroides NRRL-B-512F, a yield stress that was never described before for any type of dextran, as well as a gel-like structure. All these properties open the way to a vast array of new applications in health, food/feed, bulk or fine chemicals fields. [ABSTRACT FROM AUTHOR]

Xyloglucan from tamarind seed has been submitted to an ultrasound treatment that reduces its molecular size to investigate the impact of molar mass on the interaction with cellulose. A low molar mass xyloglucan fraction (XGu, 1.04 × 10 5 g mol −1 ) was purified and its adsorption on the cellulose nanocrystal (CNC) surface has been investigated comparatively to the native fraction that presents high molar mass (XGn, 10.28 × 10 5 g mol −1 ). XGn arranged as loops and tails on CNCs whereas XGu formed trains onto the cellulose surface. Despite the extended conformation, XGu is able to cross-link cellulose nanocrystals in the layer-by-layer CNC-XG-CNC assemblies. Hydrolysis of model films by a xyloglucan-specific endoglucanase confirmed the greater accessibility of XGn loops and tails compared to the XGu trains. More importantly, in situ ellipsometry revealed that the presence of loops and tails facilitated swelling of CNC layers linked by XGn whereas the CNC-XGu-CNC structure did not experience swelling. [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]

Waxy cassava starch (WS) from a spontaneous mutation offer enough advantages to encourage the development of commercial varieties. However, breeding work is limited because only one source of WS was available. This article reports the discovery of five new sources of WS which were compared with commercial (CC) and high amylose (HA) cassava starches (19.9 and 30.2% amylose, respectively). Waxy starch gels were considerably clearer and had higher solubility and swelling power than those from CC. Pasting temperature and peak viscosity in WS were higher (68.5 °C and 1149 cP) than in CC (64.2 °C and 993 cP). No retrogradation or syneresis could be detected in refrigerated gels or after freeze/thaw cycles in any WS gel. Average λ max for WS, CC and HA were 540.2, 591.3 nm, and 607.0 nm, respectively. Amylopectins from WS displayed M ¯ w between 271 × 10 6 and 551 × 10 6 g mol −1 , R ¯ G ranged between 229 and 298 nm and ν G values ranged between 0.38 and 0.40 (between the sphere and the random coil). The apparent density distributions in all WS suggested close densities and branching structure. The corrected average number of glucosyl units in a linear chain averaged 21.2 in WS and 23.1 in CC. Amylopectins from WS showed a slightly more branched structure (average 4.8%) than in CC (average 4.3%), but lower than in HA (7.0%). WS exhibited larger average granule size (15.9 μm) compared with CC (14.3 μm). New sources of WS will contribute the breeding efforts to develop successful commercial varieties. [ABSTRACT FROM AUTHOR]

The many studies about amylolysis have collected considerable information regarding the contribution of the starch physico-chemical properties. But the inherent elaborate and variable structure of granular starch and, consequently, the multifactorial condition of the system hinders the interpretation of the experimental results. The immediate benefit of multivariate statistical analysis approaches with that regard is twofold: considering the factors, possibly interrelated, all together and not independently, providing a first estimation of the magnitude and confidence level of the relations between factors and amylolysis kinetic parameters. Based on data of amylolysis of 13 starch samples from wild type, single and double mutants of maize by porcine pancreatic α-amylase (PPA), a multivariate analysis is proposed. Amylolysis progress-curves were fitted by a Weibull function, as proposed in a previous work, to extract three kinetic parameters: the reaction rate coefficient during the first time-unit, k , the reaction rate retardation over time, h , and the final hydrolysis extent, X ∞ . Multivariate models relate the macromolecular composition and the fractions of crystalline polymorphic types to the kinetic parameters. h and X ∞ are found to be highly related to the measured properties. Thus the amylose content appears to be significantly correlated to the hydrolysis rate retardation, which sheds some light on the probable contribution of the amylose molecules contained in the granules. The multivariate models give correct prediction performances except for k whose a part of variability remains unexplained. A further analysis points out the extent of the characterisation effort of the granule structure needed to extend the fraction of explained variability. [ABSTRACT FROM AUTHOR]

Puroindolines (PINs) A and B were purified from soft (Paledor) and hard (Recital, Courtot) wheat cultivars. Their purity and heterogeneity due to post-translational processing were characterized by SDS- and acid-PAGE, reversed-phase HPLC and mass spectrometry. By using dynamic light scattering (DLS), asymmetrical flow field-flow fractionation (AF4) and size exclusion chromatography (SEC), we showed that the size distributions of PINA are similar for the three varieties and that, in solution, they self-assembled into small aggregates, mainly dimers. Conversely, PINB isolated from hard varieties (PINB-D1b and PINB-D1d) are assembled into large aggregates while PINB-D1a formed small aggregates, mainly monomers. Mixed solutions of PINA and PINB formed heteromeric aggregates. The large PINB-D1b aggregates were retained even at a high (4:1) PINA/PINB weight ratio. Reversible dissociation of large aggregates into small aggregates suggested that weak interactions control the self-assembly of PINs. The aggregative properties of PINs have now to be taken into account when studying their interactions with other components to decipher the causal relationships between these proteins and grain hardness. [ABSTRACT FROM AUTHOR]

Abstract: Background: Glycogen and starch branching enzymes catalyze the formation of α(1→6) linkages in storage polysaccharides by rearrangement of preexisting α-glucans. This reaction occurs through the cleavage of α(1→4) linkage and transfer in α(1→6) of the fragment in non-reducing position. These enzymes define major elements that control the structure of both glycogen and starch. Methods: The kinetic parameters of the branching enzyme of Rhodothermus obamensis (RoBE) were established after in vitro incubation with different branched or unbranched α-glucans of controlled structure. Results: A minimal chain length of ten glucosyl units was required for the donor substrate to be recognized by RoBE that essentially produces branches of DP 3–8. We show that RoBE preferentially creates new branches by intermolecular mechanism. Branched glucans define better substrates for the enzyme leading to the formation of hyper-branched particles of 30–70nm in diameter (dextrins). Interestingly, RoBE catalyzes an additional α-4-glucanotransferase activity not described so far for a member of the GH13 family. Conclusions: RoBE is able to transfer α(1→4)-linked-glucan in C4 position (instead of C6 position for the branching activity) of a glucan to create new α(1→4) linkages yielding to the elongation of linear chains subsequently used for further branching. This result is a novel case for the thin border that exists between enzymes of the GH13 family. General significance: This work reveals the original catalytic properties of the thermostable branching enzyme of R. obamensis. It defines new approach to produce highly branched α-glucan particles in vitro. [Copyright &y& Elsevier]

Biopolymers from agricultural starchy commodities can be raw materials for edible, biologically degradable plastics. They have promising uses, having been proposed for replacing synthetic films. There are several starchy sources not yet quite exploited such as tropical roots and tubers that could be excellent starch sources to produce edible films with distinctive functional properties. The objective of this study was to formulate edible films from six tropical starchy crops. Starches were extracted and purified to 97–99% purity from Ipomoea batatas, Arracacia xanthorriza roots, Colocasia esculenta, Xanthosoma sagittifolium corms, and Dioscorea trifida tubers (white and purple) cultivated in the Venezuelan Amazons. The non-conventional starches were characterized for purity, amylose content and gelatinization profile by differential scanning calorimetry, starch granular morphometry and rheological properties. Starch-based films were processed by casting solutions prepared with each starch, glycerol, and distilled water. Starch suspensions were gelatinized by heat, degassed, poured in plates and dried. In the films, studies performed were water vapor, oxygen and carbon dioxide permeability, and mechanical properties in terms of tensile strength. Crystallinity patterns of native starches and films were also obtained. Ipomoea batatas and Colocasia esculenta exhibited polymorphism A+B type X-ray pattern, Xanthosomasagittifolium, an A-type X-ray pattern, and Arracacia xanthorriza and both Diosocrea trifida, B-type patterns; while starch-based films had all a B-type X-ray pattern. As expected, the potential for these types of films are more in the area of decreasing gas exchange rather than retardation of water loss due to their hydrophilic nature. Films from these non-conventional starch sources with barrier and mechanical characteristics tailored for specific uses can be of interest as plastics for the food industry and results may be of significance also, for starch-based foams. [ABSTRACT FROM PUBLISHER]

Abstract: Thermoplastic starch (TPS) plasticized by 1-butyl-3-methylimidazolium chloride ([BMIM]Cl) was obtained by melt processing. The resulting electrically conductive TPS samples were less hygroscopic than glycerol plasticized TPS samples. Despite this lower water uptake, [BMIM]Cl seems to be intrinsically a more efficient plasticizer of starch. [BMIM]Cl plasticized TPS samples show a much higher elongation at break in the rubbery state than the glycerol plasticized TPS samples. Their unusually low rubbery Young''s modulus for thermoplastic starch (0.5MPa) suggests a strong reduction of hydrogen bonds between the starch chains due to the presence of the ionic liquid. A detailed IR spectroscopy analysis supports this interpretation. [Copyright &y& Elsevier]

Abstract: Characterisation of the distribution functions describing size-related parameters of individual whole starch molecules in solution is important for establishing biosynthesis–processing–structure–property relations, for improvements in human and animal nutrition, and for industrial applications of starch. Current techniques for obtaining these distributions suffer from a number of problems in dissolution procedures, size separation, detection, data processing and data reporting. The need is for techniques that have been shown to give an unbiased sampling of the distribution of the starch in its original state, and which are reproducible (i.e., the same results can be obtained with a given sample in a different laboratory and different experimental set-up). The problems with current methodologies are summarized here by an IUPAC-sponsored international group of specialists in the field. Steps to resolving these problems are also discussed. [Copyright &y& Elsevier]

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. [ABSTRACT FROM AUTHOR]