Thermal and pasting properties and digestibility of blends of potato and rice starches differing in amylose content

Dynamic development of changes in multi-scale structure during grain filling affect gelatinization properties of rice starch

Rice was collected over the entire grain filling period (about 40 days) to explore the multi-structure evolution and gelatinization behavior changes of starch. During the early stage (DAA 6-14), the significant reduction in lamellar repeat distance (10.04 to 9.68 nm) and relative crystallinity (26.6 % to 22.7 %) was due to initial rapid accumulation of amylose (from 9.38 % to 14.05 %) and short amylopectin chains. Meanwhile, the decreased proportion of aggregation structure resulted in a decrease in the gelatinization temperature and a narrowed range of gelatinization temperature also indicated an increase in homogeneity as starch matured. Gelatinization enthalpy was mainly controlled by aggregation structure, which was negatively and positively related to the amylose content and the degree of order respectively. Peak viscosity of starch pasting increased and reached a maximum (924 cP) at DAA-21 due to larger granule size. Amylose and short amylopectin chains with degree of polymerization 6-12 showed positive and negative correlation with short-term retrogradation ability (setback value) respectively. The dynamics of different scale structure during grain filling had varying degrees of impact on gelatinization properties.

Facile preparation and characterization of biodegradable and biocompatible UV shielding transdermal patches based on natural rubber latex- dextrin blends

The physico-chemical and biological properties of natural rubber latex (NRL), entailing its biodegradability and biocompatibility, render it a promising material for various biomedical applications. This research explores the facile blending of NRL with dextrin in different compositions to investigate its potential as a prospective UV shielding transdermal patch for biomedical applications. The superior compatibility between the polymers after blending and the improved thermal stability have been established through FTIR, DSC, and TGA examinations, respectively. Optimization of blended polymers for compatibility, wettability, crystallinity, and static mechanical properties has been performed. Morphology characterization conducted via SEM and AFM techniques suggests a uniform morphology for the optimized blend system. The UV shielding ability of the blend has been confirmed by the evaluation of in-vitro UV shielding performance, UV protection factor (UPF), and the superior protection of the optimized system on living cells upon UV irradiation. The observed cell viability, swelling, erosion, porosity, hemocompatibility, and soil degradation properties suggest the NRL-DXT combination for the possible development of high-quality transdermal patches.

The evolution of granular surface structure and functional properties in rice starch during grain filling

The developmental changes in the granular surface structure and functional properties of starch during the entire grain filling period of rice (around 40 days) were investigated. The specific surface area of rice starch significantly decreased firstly then stabilized during growth due to increasing granular size. The pore volume decreased from 5.40 cm3/g at 6th day after anthesis (DAA-6) to 3.02 cm3/g (DAA-46). More starch granule-associated proteins (SGAPs) accumulated on the surface and in channels. Swelling power decreased by 46 %, whereas the flow behavior index (n) decreased by 32 % in upward curve during starch development from DAA-6 to DAA-30. Tan δ first dropped then remained steady at DAA 22-34 and lightly rebounded at the final stage, indicating that starch in the middle stage tended to have greater viscoelastic gel behavior at all sweeps. Mature starch showed lower in vitro hydrolysis rate and exhibited stronger enzymatic resistance. The results showed that granular surface features of rice starch may be an essential factor in determining rheological behavior and resistance to hydrolysis.

Impact of cyclic and continuous dry heat modification on the structural, thermal, technological, and in vitro digestibility properties of potato starch (Solanum tuberosum L.): A comparative study

Dry heat treatment (DHT) has been demonstrated as a viable method for starch modification, offering benefits due to its environmentally friendly process and low operational costs. This research modified potato starch using different DHT conditions (continuous-CDHT and cyclic-RDHT), with durations ranging from 3 to 15 h and 1 to 5 cycles, at 120 °C. The study investigated and compared the structural, thermal, pasting, and morphological properties of the treated samples to those of untreated potato starch, including in vitro digestibility post-modification. DHT altered the amylose content of the biopolymer. X-ray diffraction patterns transitioned from type B to type C, and a decrease in relative crystallinity (RC%) was observed. Morphological changes were more pronounced in starches modified by RDHT. Paste viscosities of both CDHT and RDHT-treated starches decreased significantly, by 61.7 % and 58.1 % respectively, compared to native starch. The gelatinization enthalpy of RDHT-treated starches reduced notably, from 17.60 to 16.10 J g-1. Additionally, starch digestibility was impacted, with cyclic treatments yielding a significant increase in resistant starch content, notably an 18.26 % rise. These findings underscore the efficacy of dry heat in enhancing the functional properties of potato starch.

Mechanistic insights into the enhanced texture of potato noodles by incorporation of small granule starches

Potato noodles are a popular food due to their unique texture and taste, but native potato starch often fails to meet consumer demands for precise textural outcomes. The effect of blending small granule (waxy amaranth, non-waxy oat and quinoa) starch with potato starch on the properties of noodles was investigated to enhance quality of noodles. Morphological results demonstrated that small granule starch filled gaps between potato starch granules, some of which gelatinized incompletely. Meanwhile, XRD and FTIR analysis indicated that more ordered structures and hydrogen bonding among starch granules increased with addition of small granule starch. The addition of oat or quinoa starch increased gel elasticity, decreased viscosity of the pastes, and increased the tensile strength of noodles, while addition of 30 % and 45 % waxy amaranth starch did not increase G' value of gel or tensile strength of noodles. These results indicated that amylose molecules played an important role during retrogradation, and may intertwine and interact with each other to enhance the network structure of starch gel in potato starch blended with oat or quinoa starch. This study provides a natural way to modify potato starch for desirable textural properties of noodle product.

Impact of Starch Concentration on the Pasting and Rheological Properties of Gluten-Free Gels. Effects of Amylose Content and Thermal and Hydration Properties

The pasting and rheological properties of starch gels from different botanical origins have been widely used to evaluate the application of these starches in pharmaceutical and food products. However, the ways in which these properties are modified by starch concentration and their dependence on amylose content and thermal and hydration properties have not been adequately established so far. An exhaustive study of the pasting and rheological properties of starch gels (maize and rice (normal and waxy in both cases), wheat, potato, and tapioca) at concentrations of 6.4, 7.8, 9.2, 10.6, and 11.9 g/100 g was performed. The results were evaluated in terms of a potential equation fit between each parameter and each gel concentration. The parameters determined for the gels at the studied concentrations were correlated with the hydration properties and thermal properties by applying principal component analysis (PCA). Wheat starch, followed by normal maize and normal rice starches, presented a greater capacity to modulate their gels' pasting and viscoelastic properties via their concentration in water. On the contrary, the characteristics of waxy rice and maize, potato, and tapioca starches were barely modified by concentration in pasting assays, but the gels of potato and tapioca showed noticeable changes in their viscoelastic properties as functions of concentration. In the PCA plot, the non-waxy cereal samples (wheat, normal maize, and normal rice) were located close to each other. Wheat starch gels were the most dispersed on the graph, which is consistent with the high dependence on the concentration of the gel shown in most of the studied parameters. The waxy starches had close positions not too distant from those of the tapioca and potato samples and with little influence from amylose concentration. The potato and tapioca samples were close to the vectors of the crossover point in rheology and peak viscosity in their pasting properties. The knowledge gained from this work allows a better understanding of the effects of starch concentration on food formulations.

Optimization of freezing methods and composition of frozen rice dough reconstituted by glutinous rice starch and gluten

This study investigated the effects of four different freezing methods on the texture of rice dough reconstituted by glutinous rice starch and gluten, and the changes of properties of rice dough with different gluten ratios after liquid nitrogen (LF) treatment. The profiles of frozen rice dough were studied by texture analyzer, low-field NMR, SEM, FT-IR, DSC, CLSM, X-RD and RVA. Results revealed that with the slowing down of freezing rate, the damage of freezing process to starch granules and protein structure in frozen rice dough increases, resulting in the increase of damaged starch, the decrease of protein ordered structure, the change of bound water in frozen rice dough to free water, the decrease of frozen rice dough hardness and elasticity, the decrease of storage modulus (G') and the deterioration of frozen rice dough texture. The addition of gluten in frozen rice dough will increase the short-range ordered structure and crystal structure of starch, reduce the digestibility of starch, and change the viscosity characteristics of frozen rice dough. Based on the experimental results, adding 10 % gluten is more suitable for making frozen rice dough, while LF has the least effect on frozen rice dough texture.

Different oil-modified cross-linked starches: In vitro digestibility and its relationship with their structural and rheological characteristics

This study investigated the structure, rheological behaviors and in vitro digestibility of oil-modified cross-linked starches (Oil-CTS). Gelatinized Oil-CTS were hard to be digested due to its intact granule shapes and the presence of surface-oil, which acted as physical barriers that inhibited the diffusion and penetration of enzymes to starch. Besides, the less amylose content in Oil-CTS (23.19-26.96%) than other starches (26.84-29.20%) contributed to its low digestibility because amylose with less α-1,6 linkages was more easily attacked by amyloglucosidase than amylopectin. Moreover, heat treatment during oil could shorten the amylopectin chain length and destroy the ordered structures, thus increasing enzymatic hydrolysis on starch. Pearson correlation analysis indicated rheological parameters were not significantly correlated with digestion parameters (p > 0.05). Overall, despite the damage caused by heat to molecular structures, physical barrier effect caused by surface-oil layers and integrity of swollen granules was the most critical contributor to the low digestibility of Oil-CTS.

Effect of sorbitol on the in vitro starch digestibility in semi-dried black highland barley noodles

Sorbitol is commonly used in semi-dried noodles for holding water, thus extending the shelf life. This research analyzed the effect of sorbitol on the in vitro starch digestibility in semi-dried black highland barley noodles (SBHBN). In vitro starch digestion revealed that the hydrolysis extent and digestive rate decreased with increasing sorbitol addition, although its inhibition abated when added >2 %. Compared with the control, adding 2 % of sorbitol lowered the equilibrium hydrolysis (C_∞) significantly (P < 0.05) from 75.18 to 66.57 % and decreased the kinetic coefficient (k) significantly (P < 0.05) by 20.29 %. Adding sorbitol increased the tightness of microstructure, relative crystallinity, V-type crystal, molecular structure order, and hydrogen bond strength of starch in cooked SBHBN. Meanwhile, gelatinization enthalpy change (ΔH) of starch in raw SBHBN was increased by adding sorbitol. In addition, the swelling power and amylose leaching in SBHBN added with sorbitol were reduced. Pearson correlations analysis observed significant (P < 0.05) correlations among short-range ordered structure, ΔH, and related in vitro starch digestion indexes of SBHBN after being added with sorbitol. These results revealed that sorbitol might form hydrogen bonds with starch, making it a potential additive to lower the eGI in starchy foods.

Study on structural characteristics and physicochemical properties of starches extracted from three varieties of kudzu root (Pueraria lobata starch)

Kudzu root (Pueraria lobata) is well known for its traditional use as a medicinal food homologous plant in China. Three varieties of kudzu roots, such as Gange-1, Gange-2, and Gange-6, are commonly used. Nowadays, kudzu starch (KS) is commercially available as satiating foods or product ingredients. Differentiation and selection of the variety are important components of quality control for KS-based products. Thus, the present work was aimed at comparing the physicochemical properties, such as thermodynamic properties, pasting properties, solubility, swelling, as well as the structural characteristics of the starches extracted from the three varieties of kudzu roots. The results show that KS-6 has a higher content of functional ingredients thus can be used as an ideal functional starch. However, KS-6 has a higher amylopectin:amylose ratio of 4.65, resulting in a better solubility, higher transition temperature, and higher gelatinization enthalpy. KS-2 showed lower transition temperature and gelatinization enthalpy, as well as higher peak viscosity, through viscosity, and final viscosity. KS-1 could result in a soft texture after pasting. The appropriate variety of KS should be differentiated and selected according to application scenarios. This study provided valuable insights into the potential use of different KS in the food and nonfood industries. PRACTICAL APPLICATION: 1. KS-1 was found to be suitable for use as a food supplement. 2. KS-6 has the highest nutritional value. 3. They can be used as a substitute for other similar starches.

Carboxymethylcellulose reinforced starch films and rapid detection of spoiled beverages

The integrity of the packaging of a liquid foodstuff makes it difficult to detect spoilage. Therefore, it is important to develop a sensitive, fast and real-time material for liquid food detection. CMC, as lignocellulose derivatives and starch are widely used in the food industry. In this study, starch films with pH-responsive properties are successfully prepared from full-component starch and corn amylopectin (CA) by adding CMC. The effects of CMC on the mechanical properties, morphology characteristics, physical and chemical structures, stability and pH responsiveness of the starch films are analyzed. The starch/CMC-1.0 g composite films display good electrical conductivity and reduce the resistance of the composite film by two orders of magnitude. The composite films have pH response ability; in the simulation of orange juice spoilage experiment, the CA/CMC composite film has a more sensitive current response and was more suitable for the application to liquid food quality detection. Additionally, the starch/CMC composite films have potential applications for rapid detection and real-time monitoring of the safety of liquid food.

Evaluation and characterization of starch nanoparticles for adsorption of urea from dialysates

Starch nanoparticles (SNPs) was produced from type-A, B and C native starches (corn, potato and Trichosanthes kirilowii pulp starches respectively), via the nanoprecipitation method. The SNPs showed different amylose contents, water contact angles, surface morphologies and urea clearance performances. In this work, to examine the parameters of SNPs that may change the urea adsorption capacity, urea adsorption performance in adsorption environments with different pH values, urea concentrations, and adsorption times was examined. Thereafter, the characteristics of SNPs were tested by water contact angle measurements (WCA), transmission electron microscopy, specific surface area measurements, gel permeation chromatography, and zeta potential analysis. The results showed that the Trichosanthes kirilowii pulp (C) SNPs show better adsorption than the corn (A) and potato (B) SNPs. The hydrophobicity of SNPs promotes the urea adsorption of the SNPs. Using grey relational analysis, it was found that WCA and Mn are the critical parameter affecting the adsorption performance, with WCA and Mn within the ranges of 31-33° and 1900-2100 kDa, respectively, were found to be the conditions for optimal urea adsorption.

Ultrasound-chilling assisted annealing treatment to produce a lower glycemic index of white rice grains with different amylose content

White rice samples, Chai-Nat1 (CN1) and Jasmin rice (KDML105), were treated with the ultrasound-chilling (UC) and combined with annealing treatments (UC + ANN 45, UC + ANN50, and UC + ANN55). Their physicochemical properties and in vitro glycemic index of rice samples were analyzed. UC + ANN treatments presented pasting temperature, gelatinization temperature and crystallinity increased whereas the glycemic index of both rice samples was decreased as compared to its native. Especially, UC + ANN55 treated rice produced the lowest glycemic index and starch hydrolysis. Moreover, UC + ANN treated CN1 rice exhibited delayed gelatinization temperature, increased gelatinization enthalpy, and decreased glycemic index than KDML105 rice. In addition, Pearson's correlation presented that UC + ANN and amylose content had a highly negative correlation with the glycemic index at p < 0.0.1. The result exhibited that UC followed by ANN show an effective way to modify starch granules with delayed starch hydrolysis reduced glycemic index and properties depending on annealing temperature and rice cultivar.

Multi-scale structure of A- and B-type granules of normal and waxy hull-less barley starch

The multi-scale structure of combined (A- and B- type granules), A-type, and B-type granules from normal (NHB) and waxy hull-less barley (WHB) starch was studied, including crystalline structure, molecular branching, nanostructural and fractal characteristics. Particle size distribution was applied to determine the separation purity (>95%), and micrography was used to distinguish between the A-type and B-type granules. Lacking amylose, WHB had higher relative crystallinity, gelatinization temperature, enthalpy, level of scattering intensity and uniformity of orientation of double helices than NHB starch. Generally, B-type granules had higher gelatinization temperature, lower enthalpy, greater relative crystallinity, higher ratio of crystalline to amorphous region, more fa chains in amylopectin, and thicker semi-crystalline lamellae than A-type and combined granules. The results showed that the multi-scale structure of A-type and B-type granules differed greatly, and the characteristics of combined granules were not the same as those of its two constituent granule fractions.

Microwave treatment alters the fine molecular structure of waxy hull-less barley starch

Waxy hull-less barley kernels and their isolated starches were exposed to different microwave conditions (power 640, 720, and 800 W, time 60, 120 and 180 s) and changes in morphology, particle size, digestibility, rheological properties, and molecular structure were measured and analyzed. Microwave treatment caused roughness and deformation of granular surfaces, and an increase in granule size. After treatment, the in vitro digestibility of starch was increased, i.e., the RDS increased, but the RS decreased. Microwave treatment decreased the K values of the in-kernel MWI WHBS. Dynamic rheological results showed that the in-kernel MWI WHBS pastes had lower T_G'max, and higher G'_max, G'_90°C, G'_25°C, G'_0.1Hz and G'_20Hz after treatment. The chain-length distribution did not significantly change after microwave treatment. However, the results for molecular size distributions showed that the peaks of amylopectin (R_h = ~100 nm) shifted left and right, indicating that the molecular volume might become smaller or larger under different processing conditions. The primary effects of microwave treatment may be loosening the molecular structure and cutting main chains of amylopectin.

Physicochemical properties and freeze-thaw stability of rice flour blends among rice cultivars with different amylose contents

The effectiveness of the rice flour blends (RFB) for improving the processing suitability of Dodamssal rice flour (DD), a functional rice variety with a relatively high amylose and resistance starch content, was investigated. Physicochemical properties and freeze-thaw stability of RFB composed of DD and four rice flour (RF) samples with different amylose contents were measured at different DD ratios. DD, which has low swelling power and low pasting viscosity properties, has improved some quality in terms of physicochemical properties by blending with other RF. Especially, non-additive behavior was observed in the blend with Geonyang No.2 RF (GY), a medium waxy variety, due to water competition caused by the difference in pasting temperature. The syneresis of DD was reduced by blending with 75% Hanareum No. 4 RF, with a gradual reduction effect observed following a repeated freeze-thaw cycle. GY significantly improved the low freeze-thaw stability of DD with only a 25% blend.

Supplementary Information

The online version contains supplementary material available at 10.1007/s10068-021-00989-7.

Octenyl succinic anhydride modification alters blending effects of waxy potato and waxy rice starches

This study compared blending effects of native and octenyl succinic anhydride (OSA) modified blends (waxy rice and waxy potato starch). OSA groups were observed to be present primarily in the outer layer of waxy potato starch granule, but throughout the whole waxy rice granule. A high linear correlation with blending ratio was observed for trough viscosity and final viscosity of native blends, but for peak viscosity (PV) and breakdown viscosity (BD) of esterified blends. PV and BD of esterified blends showed weaker non-additive effects than those of native blends. Consistency coefficient in downward curve, flow behavior index in downward curve, and loss tangent mainly showed non-additive effects in native blends, but additive effects in esterified blends. OSA modification affects interaction between molecules on the outer surfaces of two starch granules by altering molecular structures on the outer surfaces, resulting in different blending effects between native and esterified waxy starch blends.