Rheological properties of starches from grain amaranth and their relationship to starch structure

Food LEGO: Building hollow cage and sheet superstructures from starch

The idea of building large structures from small building blocks has had a long history in the human imagination, from the beautifully intricate shells assembled from silica by unicellular algae to the Egyptian pyramids built from stone. Carrying this idea into the food industry has important implications. Here, we introduce a Pickering emulsion platform for building superstructures like hollow cages and sheets using starch granules as building blocks. In food, these superstructures occupy up to six times more space than their constituent parts, thereby delivering a viscosity greater by an order of magnitude than unstructured starch. To achieve this higher viscosity, they use an alternative superstructure mechanism as opposed to the classic swelling mechanism of individual particles. These super-thickeners may reduce calories, cut production costs, and stretch the global food supply, demonstrating how we can design the future by playing with our food.

Influence of the structure and physicochemical properties of OSA modified highland barley starch based on ball milling assisted treatment

This study aimed to investigate the influence of ball milling assisted treatment on the degree of substitution of octenyl succinic anhydride (OSA) modified highland barley starch (HBS) and on the physicochemical properties and structure of HBS. Scanning electron microscopy (SEM) findings showed that with the increasing of ball milling time, the surface morphology of OSA modified HBS became rougher and rougher and the particle morphology and crystal structure were damaged. When the pretreatment time of ball milling was 40 min, the degree of substitution of OSA modified HBS was 1.32 times higher than that of the conventional modification method. In addition, the longer the ball milling assistant, the longer the short-range ordering of the OSA modified HBS significantly decreased, and the relative crystallinity decreased (from 16.68 % to 7.93 %), leading to a decrease in thermal stability too. However, it greatly enhanced the aging resistance and flowability. In terms of emulsification properties, the emulsification properties of OSA modified HBS increased from 60.67 % to 75.67 %. Therefore, the HBS with better freeze-thaw stability and higher degree of substitution can be prepared by ball milling pretreatment and OSA modification, which provides technical support for further development of starch resources.

Impact of granule-associated lipid removal on the property changes of octenylsuccinylated small-granule starches

Starch granule associated lipids (GALs) are known to alter the properties and functions of small granule starches. To test the hypothesis that the removal GALs from small granule starches could increase the overall reactive surface and improve octenyl-succinylation (OSA) modification efficiency, four small granules starches from rice, oat, quinoa, amaranth and a waxy maize starch were subjected to defat, OSA esterification and combined defatted and OSA treatment. The combined treatment showed a significant improvement in the degree of substitution for all starches from both tritration and 1H NMR methodologies. Confocal microscopy revealed a more uniform distribution of OSA groups on the starch surface. After GALs removal, the bimodal granule size distribution was diminished but reappeared during OSA modification. Pasting viscosity increased for the OSA and GALs removed quinoa, waxy maize and amaranth starches, but it decreased on modified rice and oat starches. OSA treatment alone significantly altered the gelling and rheological properties towards a more soft and less stable starch structure. The combined treatment compensated these changes to some extent and filled the property gap between the native and OSA modified starches. This study demonstrated that removing GALs can achieve more profound OSA derivatization.

Impact of long-term ultrasound treatment on structural and physicochemical properties of starches differing in granule size

Granule size is a critical parameter affecting starch processing properties. Ultrasound treatments of up to 22 h were applied on two starches differing in granule size (quinoa starch and maize starch). The two starches showed significantly different trends in both structural and physicochemical aspects affected by the ultrasound treatments. For the small granule starch (volume-weighted mean particle size of 1.79 μm), short-term ultrasonication caused an increase of swelling power. As the treatment time increased, the physicochemical properties were influenced by the degradation of amylopectin external chains. The X-ray diffraction results showed a decrease of relative crystallinity and changes of peak areas with long-term treatment. On the other hand, a balance between amylose leaching and surface damages was seen for the large granule starch (volume-weighted mean particle size of 18.3 μm). The effect of ultrasound modification on starches with different molecular and granular structures was discussed. A possible mechanism of the ultrasound effect was proposed.

Molecular structure and linear-non linear rheology relation of rice starch during milky, dough, and mature stages

Immature rice has potential to be used as healthy food. The relation between molecular structure and rheological properties was investigated. The lamellar repeating distance (8.42-8.63 nm) and crystalline thickness (4.60-4.72 nm) were not different among stages indicating a complete lamellar structure even at early stage. The relative crystallinity was higher in dough (39.62 %) than milky (36.69 %) and mature starch (35.22 %) caused by molecular structure, amylose, and amylose-lipid complex. The short amylopectin branched chains (A and B1) in dough starch were easily entangled resulted in higher Payne effect and elastic dominant. Dough starch paste exhibited higher G'_Max (738 Pa) than milky (685 Pa) and mature (645 Pa) starch. In a non-linear viscoelastic regime, small strain hardening was found in milky and dough starch. Mature starch showed the highest plasticity and shear thinning at high-shear strains as the long-branched chains (B3) microstructure was disrupted, disentangled, followed by chain orientation along shear.

Preparation of Neohesperidin-Taro Starch Complex as a Novel Approach to Modulate the Physicochemical Properties, Structure and In Vitro Digestibility

Neohesperidin (NH), a natural flavonoid, exerts multiple actions, such as antioxidant, antiviral, antiallergic, vasoprotective, anticarcinogenic and anti-inflammatory effects, as well as inhibition of tumor progression. In this study, the NH-taro starch complex is prepared, and the effects of NH complexation on the physicochemical properties, structure and in vitro digestibility of taro starch (TS) are investigated. Results showed that NH complexation significantly affected starch gelatinization temperatures and reduced its enthalpy value (ΔH). The addition of NH increased the viscosity and thickening of taro starch, facilitating shearing and thinning. NH binds to TS via hydrogen bonds and promotes the formation of certain crystalline regions in taro starch. SEM images revealed that the surface of NH-TS complexes became looser with the increasing addition of NH. The digestibility results demonstrated that the increase in NH (from 0.1% to 1.1%, weight based on starch) could raise RS (resistant starch) from 21.66% to 27.75% and reduce RDS (rapidly digestible starch) from 33.51% to 26.76% in taro starch. Our work provided a theoretical reference for the NH-taro starch complex's modification of physicochemical properties and in vitro digestibility with potential in food and non-food applications.

Starch Janus Particles: Bulk Synthesis, Self-Assembly, Rheology, and Potential Food Applications

Although incredible progress in the field of Janus particles over the last three decades has delivered many promising smart-material prototypes, from cancer-targeting drug delivery vehicles to self-motile nanobots, their real-world applications have been somewhat tempered by concerns over scalability and sustainability. In this study, we adapt a simple, scalable 3D mask method to synthesize Janus particles in bulk using starch as the base material: a natural biopolymer that is safe, biocompatible, biodegradable, cheap, widely available, and versatile. Using this method, starch granules are first embedded on a wax droplet such that half of the starch is covered; then, the uncovered half is treated with octenyl succinic anhydride, after which the wax coating is removed. Janus particles with 49% Janus balance can be produced in this way and were observed to self-assemble into wormlike strings in water due to their hydrophobic/hydrophilic nature. Our Janus starch granules outperform the non-Janus controls as thickening and gelling agents: they exhibit a fourfold increase in water-holding capacity, a 30% lower critical caking concentration, and a viscosity greater by orders of magnitude. They also form gels that are much firmer and more stable. Starch Janus particles with these functional properties can be used as novel, lower-calorie, highly efficient, plant-based super-thickeners in the food industry, potentially reducing starch use in food by 55%.

Effects of selenium solution on the crystalline structure, pasting and rheological properties of common buckwheat starch

Selenium is an important element that affects human growth and development, and also affects the yield and quality of common buckwheat. In our study, two common buckwheat varieties were sprayed with different concentrations (0 g/hm², 5 g/hm², 20 g/hm²) of sodium selenite solution at the initial flowering period and the full flowering period, respectively, to determine the effects of selenium solution on the physicochemical properties of common buckwheat starch. With increasing selenium levels, the amylose content, peak viscosity, breakdown, relative crystallinity, pasting temperature and gelatinization enthalpy first decreased and then increased, while the transparency showed a trend of increasing and then decreasing. All samples exhibited a typical A-type pattern, while at high selenium level, the degree of short-range order of common buckwheat starches changed. From the rheological properties, it can be seen that the starch paste is dominated by elastic properties, while the low selenium treatment decreases the viscosity of the starch paste. These results showed that spraying different concentrations of selenium solutions at different periods significantly affected the physicochemical properties of common buckwheat starch.

Structural, physicochemical and rheological properties of starches isolated from banana varieties (Musa spp.)

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High starch content in green banana can be extracted for industry and avoid waste.

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Banana starch from Tanzania was rich in amylose and resistant starch.

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Banana starch paste presented great structural stability.

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Banana starch had potential to produce edible films and replace chemical binder.

Banana starches were isolated from five banana varieties in Tanzania to analyze the proximate composition, structure, physicochemical and rheological properties. The amylose content of banana starches was 29.92 ± 0.17 %–39.50 ± 0.08 % and the resistant starch content of cooked banana starches ranged from 44.74 ± 1.72 % to 55.43 ± 1.52 %. Banana starch granules presented irregular shapes with particle size of 21.73 to 24.67 μm and showed B-type or C-type crystalline patterns with crystallinity of 36.69 % to 41.83 %. The solubility and the swelling power were 2.5 ± 0.42 %–4.4 ± 0.57 % and 11.27 ± 0.04 %–12.48 ± 0.71 %, respectively. Mzuzu and Malindi starches possessed lower gelatinization temperature. The high gelatinization peak viscosity (2248 ± 67–2897 ± 71 cP), low breakdown (556 ± 7–960 ± 41 cP) and low setback (583 ± 29–864 ± 118 cP) indicated banana starch could replace chemically cross-linked starch for applications that require stable viscosity. The rheological analysis showed that banana starches exhibited shear thinning behavior and had great processing adaptability. The results all above will provide basic data for the development and utilization of banana starch.

Valorization of unpopped Foxnut starch in stabilizing Pickering emulsion using OSA modification

Starch was isolated from unpopped fox nut (Euryale ferox) and the effect of octenyl succinic anhydride (OSA) concentration (1, 2 and 3%) on physiochemical, functional, pasting, rheological and structural properties of was examined. The amylose content of native starch (22.9%) was higher than the modified starch (13.7%) for 3% OSA treatment. The water absorption capacity (1.29-0.9 g/g) significantly reduced, while oil absorption capacity (0.15-0.61 g/g), solubility (5-48%) and swelling power (2.77-13.60 g/g) increased after modification. The modification also altered the pasting properties by increasing the peak viscosity and reducing the pasting temperature. The cooked gel of all starch showed shear-thinning flow behavior and dynamic rheology confirmed reduction in storage and loss modulus after modification. Modified starch became rougher and irregular in shape and showed type A pattern as confirmed by SEM and XRD. Soybean oil-in-water Pickering emulsions were prepared by ultrasonication (US, 30 and 40% amplitude for 2 and 4 min) using starch as particle stabilizer and major factors influencing emulsion stability were investigated. Pickering emulsions prepared at 30 and 40% amplitude for 4 min US, produced the smaller droplet size, stable up to 15 days. However, all OSA modified starches were able to separate the oil and water even after the size of droplets increased with storage. The microstructure of the Pickering emulsions confirmed that starch particles aggregated in a tightly packed layer at the oil-water interface.

New Type of Food Processing Material: The Crystal Structure and Functional Properties of Waxy and Non-Waxy Proso Millet Resistant Starches

Resistant starch (RS) is widely used in the food industry because of its ability to regulate and protect the small intestine, but their distinct effects on the structural and functional properties of waxy and non-waxy proso millet starches are not completely understood. The crystalline structure and physicochemical properties of waxy and non-waxy proso millets' starch samples were analyzed after heat-moisture treatment (HMT). The analysis revealed significant differences between the RS of waxy and non-waxy proso millets. The crystal type of proso millets' starch changed from type A to type B + V. The relative crystallinity of the RS of waxy proso millet was better than that of non-waxy proso millet. The gelatinization temperature and thermal stability of RS significantly increased, and the pasting temperature (PTM) of the RS of waxy proso millet was the highest. The water solubility and swelling power of the RS in proso millet decreased, and the viscoelasticity improved. The correlation between the short-range ordered structure of RS and ΔH, and gelatinization properties has a stronger correlation. This study provides practical information for improving the nutritional benefits of waxy and non-waxy proso millet in food applications.

Emerging opportunities in exploring the nutritional/functional value of amaranth

Amaranthusspp. is a highly nutritive pseudocereal, rich in macronutrients and micronutrients, including vitamins and minerals.

Effects of gamma irradiation on physicochemical properties of native and acetylated wheat starches

Effects of gamma irradiation on the physicochemical and crystalline properties of the native and acetylated wheat starches were investigated. Peak, hot paste, cool paste and setback viscosities of both native and acetylated wheat starches decreased continuously and significantly with the increase of the irradiation dose, whereas breakdown viscosity increased after irradiation. However, gamma irradiation only exerted slight effects on thermal and retrogradation properties of both native and acetylated wheat starches. X-ray diffraction and fourier transform infrared spectroscopy revealed that acetylation modification had considerable effects on the molecular structure of wheat starch, and the crystallinity of both untreated and acetylated starches increased slightly with the increase of irradiation dose. However, the V-type crystallinity of amylose-lipid complex was not affected by gamma irradiation treatments with doses up to 9kGy.

Effect of grain moisture content during milling on pasting profile and functional properties of amaranth fractions

Evaluation of functional properties of milled fractions of grain amaranth may be useful to decide the end uses of the grain. Hence, pasting profiles of amaranth fractions obtained by milling the grains at different moisture contents were studied in relation with their starch profile and also with their swelling power and solubility indices. It was observed that, for flour fraction, the viscosity parameters were lowest at 14-16 % moisture content. Swelling power and solubility indices of the samples varied as a function of grain moisture content. The middling fraction also showed similar pasting pattern with the variation of grain moisture content. The seed coat fractions showed higher gelatinization temperature compared to that of fine flour and middling fractions. However, starch content of the fine seed coat fraction was comparable with that of the flour and middling fractions. The coarse seed coat fraction showed lower viscosity parameters than the other samples. Viscosity parameters correlated well among themselves while, they did not show significant correlation with the starch content. However, the viscosity parameters showed negative correlation with the soluble amylose content. The study revealed that, the fractions obtained by milling the grains at different moisture content show differential pasting profiles and functional properties.

Physical properties and enzyme susceptibility of rice and high-amylose maize starch mixtures

BACKGROUND

Resistant starch has promising health benefits and possesses great potential as a functional ingredient in diverse food formulation and production. Here, 10-50% high-amylose maize starch with 70% amylose content (H7) representing type 2 resistant starch was incorporated into three types of rice starch with varying amylose content (1.6-32%). Thermal properties, rheology, and enzyme susceptibility to porcine pancreatic α-amylase of the starch mixtures were analyzed.

RESULTS

Addition of H7 at levels of 10-50% decreased the yield stress and consistency coefficient of rice starches for the flow properties as modeled by the Herschel-Bulkley equation. Dynamic rheological analysis showed that addition of H7 decreased the storage modulus during heating and increased it during cooling and frequency sweeping for all rice starches tested. Gelatinization, retrogradation, and enzyme susceptibility of the resulting mixtures appeared additive of that of individual components.

CONCLUSION

A desirable reduction in the digestibility of starchy foods could be achieved by adding high-amylose maize starch. The physical modifications in properties of the starch blends are dependent on the addition level of resistant starch.