Low-amylose Starch Research Articles

Effects of the Amylose/Amylopectin Ratio of Starch on Borax-Crosslinked Hydrogels.

Herein, we simultaneously prepared borax-crosslinked starch-based hydrogels with enhanced mechanical properties and self-healing ability via a simple one-pot method. The focus of this work is to study the effects of the amylose/amylopectin ratio of starch on the grafting reactions and the performance of the resulting borax-crosslinked hydrogels. An increase in the amylose/ amylopectin ratio increased the gel fraction and grafting ratio but decreased the swelling ratio and pore diameter. Compared with hydrogels prepared from low-amylose starches, hydrogels prepared from high-amylose starches showed pronouncedly increased network strength, and the maximum storage modulus increased by 8.54 times because unbranched amylose offered more hydroxyl groups to form dynamic borate ester bonds with borate ions and intermolecular hydrogen bonds, leading to an enhanced crosslink density. In addition, all the hydrogels exhibited a uniformly interconnected network structure. Furthermore, owing to the dynamic borate ester bonds and hydrogen bonds, the hydrogel exhibited excellent recovery behavior under continuous step strain, and it also showed thermal responsiveness.

Effect of lecithin on the complexation between different botanically sourced starches and lauric acid

This research investigated the effect of lecithin on the complexation of lauric acid with maize starch, potato starch, waxy maize starch, and high amylose maize starch. Rapid visco analysis showed that lecithin altered the setback pattern of potato starch-lauric acid and maize starch-lauric acid mixtures but not waxy maize starch-lauric acid. Further investigation, including differential scanning calorimetry, complex index, and X-ray diffraction, showed that lecithin enhanced the complexation of maize starch, potato starch, and high amylose maize starch with lauric acid. Fourier transform infrared and Raman spectroscopy revealed increasingly ordered structures formed in maize starch-lauric acid-lecithin, potato starch-lauric acid-lecithin, and high amylose maize starch-lauric acid-lecithin systems compared to corresponding binary systems. These highly ordered complexes of maize starch, potato starch, and high amylose maize starch also demonstrated greater resistance to in vitro enzymatic hydrolysis. Waxy maize starch complexation however remained unaffected by lecithin. The results of this study show that lecithin impacts complexation between fatty acids and native starches containing amylose, with the starch source being critical. Lecithin minimally impacted the complexation of low amylose starch and fatty acids.

Chemical composition, structural features, and physicochemical properties of starches from Thai indigenous rice varieties

ABSTRACT Thai indigenous rice varieties provide valuable genetic resources due to their environmental resilience, but it is yet to be elucidated whether their endosperm starches are suitable for whole grain consumption or industrial applications. Here, 19 Thai indigenous rice starches were explored for compositional, structural, and physicochemical characteristics. Grain reducing sugar, protein, and amylose contents significantly differed among genotypes. Their starches were categorized as waxy, very low-, and low-amylose starches. The varieties with low-amylose starches displayed higher amylose content but lower crystallinity than the varieties with waxy and very low-amylose starches. The largest median starch granule size (d(0.5)) was also observed in most varieties with low-amylose starches. The starch compositional and structural variations contributed to substantial differences in starch physicochemical properties among these genotypes. The partial least squares discriminant analysis revealed that amylose content, setback, swelling power, reducing sugar, C- and A-type granules, d(0.5), and final viscosity could discriminate the low-amylose starches from the waxy and very low-amylose starches. Notably, correlation analyses revealed that amylose content was the most crucial factor determining starch physicochemical properties of these varieties. Starch compositional, structural, and physicochemical variations among the indigenous rice varieties can be adopted as alternative industrial raw materials and as genetic resources for future breeding programs.

Development and properties of biodegradable film from peach palm (Bactris gasipaes)

Formulations of biodegradable films using macrocarpa peach palm flour (low amylose starch), chitosan and glycerol, were developed and the effects of the drying temperature on films by assessing their physicochemical, mechanical, barrier, optical, structural, antioxidant properties, and the biodegradability in soil were evaluated. Chitosan enhanced the mechanical properties of the films, but they showed no antimicrobial activity against the tested food-borne pathogens, except for Listeria monocytogenes, for which the inhibition zone was from 0.1 to 0.6 cm. Films with higher concentrations of peach palm flour are opaquer, with better antioxidant characteristics and content of phenolic compounds compared to films made with lower concentrations of flour. The films presented a yellowish color because of the carotenoids found in peach palm flour, 29.63 μg 100 g−1, and exhibited a C-type X-ray pattern, characteristic peak of materials where amylose and amylopectin are present. After 15 days in soil, the films lost 30% of their initial weight. Therefore, these results suggest that the development of films as food preservative is a promising field and that the material used in the study are suitable for their formulation.

Low Amylose Starch from Discarded Jicama Tubers (Pachyrhizus erosus (L.) Urb.) and Its Techno-Functional Characterization

Low Amylose Starch from Discarded Jicama Tubers (Pachyrhizus erosus (L.) Urb.) and Its Techno-Functional Characterization

Composition of kernel-amylose and -resistant starch among subtropically adapted maize

High amylose starch has many benefits to human health besides diverse industrial applications. Traditional maize grains possess <35% amylose and <5% resistant starch. Here, 48 subtropically adapted maize inbreds were evaluated at three locations for various starch attributes. Wide genetic variation for total starch (66.8–74.1%), amylose (1.7–66.2%) and resistant starch (1.4–39.4%) was observed. Minor influence (<5% of total variation) of environment and genotype × environment interactions was observed across the traits. PMI-AML-146 and PMI-AML-147 possessed high amylose (66.2% and 64.2%) and resistant starch (39.4% and 38.0%). At the same time, PMI-WX1 and PMI-WX3 possessed low amylose (1.7% and 3.6%) and resistant starch (1.4% and 1.7%). Amylose was positively correlated with resistant starch (RS, r=0.81) except in a few inbreds. Though CML373 possessed comparatively higher amylose (47.7%), it had a low RS (16.8%). On the contrary, PMI-AML-150 had lower amylose (25.5%) but higher RS (21.4%), suggesting that besides amylose, other factors also play a role in constituting RS. The high amylose and RS inbreds identified here would serve as donors in the breeding programme. This is the first report on genetic variation in amylose and resistant starch in subtropically adapted maize.

Effect of Acetylation, Hydroxypropylation and Dual Acetylation-Hydroxypropylation on Physicochemical and Digestive Properties of Rice Starches with Different Amylose Content

Four rice (Oryza sativa L.) starches widely differing in amylose content were subjected to acetylation, hydroxypropylation, and dual modification involving acetylation followed by hydroxypropylation. The starches showed a higher affinity to hydroxypropyl substitution. However, acetylation caused a significant alteration in the glycosidic matrices. The changes in physicochemical properties were most prominent in the dual-modified samples. Hydroxypropylated and dual-modified granules showed greater swelling power with structural retention. Degrees of acetylation were high in the amorphous regions of waxy and low amylose starches (0.04 and 0.05). Minor granular swelling was observed under SEM. Substitution partially dissociated side-chain superhelices, lowering crystallinity values by 3.12-4.58%, however retaining the native A-type XRD patterns. Glycosidic dissociation and enhanced hydrophilicity caused a significant lowering of gelatinization temperature (To, Tp, Tc), enthalpy (H), and cooking time as observed from DSC and RVA results. Low setback viscosity and low syneresis during freeze-thaw cycles indicated the decreased tendency of modified starch chains to realign. Dual modified starches could be cooked to thinner and more precise pastes, which are highly resilient to retrogradation. Significant increases in enzyme-resistant RS and SDS (up to 20% of each) were recorded. The dual modification method could suitably alter the properties of starches for food use.

Varying amylose contents affect the structural and physicochemical characteristics of starch in mung bean

ABSTRACT Mung bean starches are widely used for producing transparent, good-quality noodles in the food industry. This study isolated starches from eight mung bean varieties and investigated how the amylose contents (19.1–32.9%) of the beans affected the structures, physicochemical properties, and resistant starch (RS) fractions of these starches. The starches were classified into three groups according to their amylose content: low-amylose starches with <25% amylose content (TN182, DXVN7, and DX208 varieties), intermediate-amylose starches with 25%-30% amylose contents (DX14, KPS1, and V123 varieties), and high-amylose starches with >30% amylose contents (T135 and DX044 varieties). The amylose content of mung bean starches negatively correlated with the average degree of polymerization () of the starch, whereas the mung bean variety dictated the average chain length (, degree of order, and short-range molecular order of the starch. All mung bean starches were found to have an A-type crystalline structure with a relative crystallinity of 25.8–34.7%. The starches with higher amylose contents exhibited higher peaks, final viscosities, and setbacks than the other starches. The contents of the RS fraction were in the range of 3.6–13.0%; the starches of the DX14, T135, and DX044 varieties had higher contents of the RS fractions (9.0%, 9.9%, and 13.0%, respectively) than the starches from the other mung bean varieties. Abbreviations: MB1, starch isolated from TN182 variety; MB2, starch isolated from DXVN7 variety; MB3, starch isolated from DX208 variety; MB4, starch isolated from DX14 variety; MB5, starch isolated from KPS1 variety; MB6, starch isolated from V123 variety; MB7, starch isolated from T135 variety; MB8, starch isolated from DX044 variety.

Structural and quantitative changes of starch in seed of Trigonella persica during germination

Starch, the most abundant carbohydrate reserve in plant seeds, is synthesized and stored in the cotyledons of some plants. In seeds of Trigonella persica (Fabaceae), starch appears during germination and forms granules that are composed of amylose and/or amylopectin. In this study, both quantitative and qualitative traits of starch were evaluated during the germination of T. persica seed. The quantitative assay and microscopic imaging showed that there was a low-amylose starch in the cotyledons and its amount reached the highest at 48 h after imbibition (HAI). According to the SEM images of hydrogels, FT-IR spectra, and analysis of extracted starches, the purity of this starch was decreased during germination. So that the extracted starch from cotyledons of non-germinated seeds (ESCN), with the highest purity and the lowest protein content, was different from all the extracted starches. Therefore, it seems that ESCN was an amylopectin rich type starch, which had low amylose to amylopectin ratio and as waxy starch typically, it can have a cohesive and gummy texture compared with ordinary starch.

Physicochemical properties and in vitro digestibility of mung-bean starches varying amylose contents under citric acid and hydrothermal treatments

In this study, starches of three mung bean cultivars (Vigna radiata) having different amylose contents were isolated and modified using a combination of citric acid and heat-moisture treatment (CA-HMT) or a combination of citric acid and annealing treatment (CA-ANN). Physicochemical properties and in vitro digestibility of native and treated mung bean starches were investigated. Resistant starch (RS) contents of the high-amylose, medium-amylose and low-amylose starches treated with CA-ANN were 41.1%, 35.7% and 27.1%, respectively, being higher than those treated with CA-HMT or native starches in the same variety. The CA-ANN did not affect the morphology and crystallinity of the starches. However, the starches treated by the CA-HMT were partly gelatinized and had higher degree of relative crystallinity as compared to the native starches. The DP¯s, swelling power, and viscosity of the treated starches were significantly lower than those of the native starches. The high-amylose mung bean starch was greatly affected by the treatments rather than medium- or low-amylose mung bean starch.

Crop plants with improved culture and quality traits for food, feed and other uses.

The large French research project GENIUS (2012-2019, https://www6.inra.genius-project_eng/ ) provides a good showcase of current genome editing techniques applied to crop plants. It addresses a large variety of agricultural species (rice, wheat, maize, tomato, potato, oilseed rape, poplar, apple and rose) together with some models (Arabidopsis, Brachypodium, Physcomitrella). Using targeted mutagenesis as its work horse, the project is limited to proof of concept under confined conditions. It mainly covers traits linked to crop culture, such as disease resistance to viruses and fungi, flowering time, plant architecture, tolerance to salinity and plant reproduction but also addresses traits improving the quality of agricultural products for industrial purposes. Examples include virus resistant tomato, early flowering apple and low-amylose starch potato. The wide range of traits illustrates the potential of genome editing towards a more sustainable agriculture through the reduction of pesticides and to the emergence of innovative bio-economy sectors based on custom tailored quality traits.

Effect of persimmon tannin on the physicochemical properties of maize starch with different amylose/amylopectin ratios.

The effects of persimmon tannin (PT) on the physicochemical properties of maize starch with different amylose/amylopectin ratios were studied. The results showed that PT remarkably altered the physicochemical properties of the starch. And the effects were dependent both on the concentration of PT and the amylose/amylopectin ratios. DSC analysis showed that PT slightly increased the gelatinization temperature of low-amylose (LAC) and intermediate-amylose maize starch (IAC), whereas the Tc and Tp of high-amylose maize starch (HAC) were decreased strikingly. XRD and SEM analysis demonstrated that PT retarded the retrogradation of the three kinds of starch. The hardness and adhesiveness values of the three kinds of starch decreased with increasing the PT concentration. The cohesiveness and springiness value of LAC starch gel were decreased by PT, whereas that of HAC starch gel were slightly increased by PT addition. Dynamic rheology analysis demonstrated that PT improved the viscoelasticity of LAC paste, but lowered the viscoelasticity of HAC and IAC paste. Taken together, PT had greater effects on the physicochemical properties for HAC starch than on LAC, revealing that PT has stronger interaction with amylose than with amylopectin. Our results indicated that PT might have a potential use in improving the quality of starch-based food.

Establishment of a modified CRISPR/Cas9 system with increased mutagenesis frequency using the translational enhancer dMac3 and multiple guide RNAs in potato

CRISPR/Cas9 is a programmable nuclease composed of the Cas9 protein and a guide RNA (gRNA) molecule. To create a mutant potato, a powerful genome-editing system was required because potato has a tetraploid genome. The translational enhancer dMac3, consisting of a portion of the OsMac3 mRNA 5′-untranslated region, greatly enhanced the production of the protein encoded in the downstream ORF. To enrich the amount of Cas9, we applied the dMac3 translational enhancer to the Cas9 expression system with multiple gRNA genes. CRISPR/Cas9 systems targeting the potato granule-bound starch synthase I (GBSSI) gene examined the frequency of mutant alleles in transgenic potato plants. The efficiency of the targeted mutagenesis strongly increased when the dMac3-installed Cas9 was used. In this case, the ratio of transformants containing four mutant alleles reached approximately 25% when estimated by CAPS analysis. The mutants that exhibited targeted mutagenesis in the GBSSI gene showed characteristics of low amylose starch in their tubers. This result suggests that our system may facilitate genome-editing events in polyploid plants.

Nanostructured starch combined with hydroxytyrosol in poly(vinyl alcohol) based ternary films as active packaging system

Novel ternary films have been realized by using poly(vinyl alcohol) (PVA) as polymeric matrix, nanostructured starch as reinforcement phase and hydroxytyrosol (HTyr), a low-molecular phenolic compound present in olive oil, as antioxidant agent. Nanostructured starch, in the form of starch nanocrystals (NC) and nanoparticles (NP) obtained by acid hydrolysis and ultrasound irradiation of starch derived from the bread wheat variety Cadenza (WT, amylose content 33%) and a derived-high amylose line (HA, amylose content 75%), was considered. The developed multifunctional films were characterized in terms of morphological, thermal and optical properties, water absorption capacity, overall and specific migration into a food simulant and antioxidant properties.Experimental data showed a prolonged release of HTyr from all ternary films and the released HTyr retained a strong antioxidant activity. The data, compared to those of PVA/HTyr binary films, demonstrated the key role of nanostructured starch in the ternary formulations in promoting a gradual release of HTyr. Overall, PVA fillm combined with nanoparticles from low amylose starch and hydroxytyrosol resulted as the most promising ternary formulation for food packaging applications.

Pasting, rheological, and retrogradation properties of low-amylose rice starch with date syrup.

Effects of date syrup on pasting, rheological, and retrogradation properties of low-amylose rice starch were investigated using three levels of date syrup (starch:syrup 1:1, 1:2, or 1:3). Measurements were carried out using HR-2 Discovery Rheometer equipped with a pasting cell and parallel plate geometry. The pasting measurements showed that the peak viscosity of the control is significantly higher than the samples with date syrup (p < 0.05), while the final viscosity increases with increased date syrup levels. Addition of date syrup increases the solid-like behavior of the gel in reverse order with increased date syrup levels. Low-amylose starch gel used in this study showed minor changes in elastic modulus (G') during one week cold storage indicting that low-amylose rice starch is resistant to retrogradation. Addition of date syrup slightly resulted in increased retrogradation compared to the control.

Structural features and thermal property of propionylated starches with different amylose/amylopectin ratio

This work concerned the effects of amylose/amylopectin ratio on the structure and thermal stability of propionylated starches with high degree of substitution (DS). Four starches with different amylose content were used to obtain propionylated starches. Acylation partly disrupted granule morphology of native starches, and the imperfection and porous structures of starch granule were intensified along with the increased amylose content. It was noted that the crystalline structure of starch was destroyed and thus intense acylation occurred in both amorphous and crystalline regions. The acylated starch with high-amylose content displayed more ordered region compared to low-amylose starch. Acylation enhanced the thermal stability of starch, and this effect became more evident as the amylose content increased. Thus, the amylose/amylopectin ratio has been confirmed capable of affecting the structure and thermal behaviors of hydrophobic propionylated starch, which is of value for the design of starchy materials with tailored thermal stability.

Registration of A/BN641 and RN642 waxy Grain Sorghum Genetic Stocks

Loss-of-function mutations in the granule-bound starch synthase gene result in an endosperm with a waxy appearance and a near absence of starch amylose. Three waxy grain sorghum [Sorghum bicolor (L.) Moench] lines, AN641 (Reg. No. GS-741, PI 672150), BN641 (Reg. No. GS-742, PI 672151), and RN642 (Reg. No. GS-743, PI 672152) were developed jointly by the USDA–ARS and the Agricultural Research Division, Institute of Agriculture and Natural Resources, University of Nebraska, and were released in June 2014. AN641 and BN641 have the waxyb (wxb) allele and are near-isogenic to ‘Wheatland’. RN642 has the waxya (wxa) allele and is near-isogenic to ‘Tx430’. Release of these lines with cytoplasmic male-sterile (A), maintainer (B), and fertility restorer (R) fertility reactions to A1 cytoplasm facilitates the production and evaluation of interallelic (wxb × wxa) waxy and heterowaxy [wxb × wild-type (WT) and WT × wxa] hybrids as a source of low-amylose starch for the ethanol and food industries.

Resistant starch alters colonic contractility and expression of related genes in rats fed a Western diet.

Dietary fiber shortens gut transit time, but data on the effects of fiber components (including resistant starch, RS) on intestinal contractility are limited. We have examined RS effects in male Sprague-Dawley rats fed either a high-amylose maize starch (HAMS) or a wholemeal made from high-amylose wheat (HAW) on ileal and colonic contractility ex vivo and expression of genes associated with smooth muscle contractility. Rats were fed diets containing 19 % fat, 20 % protein, and either low-amylose maize starch (LAMS), HAMS, wholemeal low-amylose wheat (LAW) or HAW for 11 week. Isolated ileal and proximal colonic sections were induced to contract electrically, or by receptor-independent (KCl) or receptor-dependent agents. Colonic gene expression was assessed using an Affymetrix microarray. Ileal contractility was unaffected by treatment. Maximal proximal colonic contractility induced electrically or by angiotensin II or carbachol was lower for rats fed HAMS and LAW relative to those fed LAMS (P < 0.05). The colonic expression of genes, including cholinergic receptors (Chrm2, Chrm3), serotonin receptors (Htr5a, Htr7), a protease-activated receptor (F2r), a prokineticin receptor (Prokr1), prokineticin (Prok1), and nitric oxide synthase 2 (Nos2), was altered by dietary HAMS relative to LAMS (P < 0.05). HAW did not significantly affect these genes or colonic contractility relative to effects of LAMS. RS and other fiber components could influence colorectal health through modulation of stool transit time via effects on muscular contractility.

Gamma irradiation of corn starches with different amylose-to-amylopectin ratio.

Corn starches with different amylose-to-amylopectin ratio (waxy, normal, Hylon V, and Hylon VII) were treated with five doses of gamma irradiation (1, 5, 10, 25, and 50kGy). The effects of gamma irradiation on the physicochemical properties of starch samples were investigated. Waxy samples showed an increase of amylose-like fractions when irradiated at 10kGy. The reduction in apparent amylose content increased with amylose content when underwent irradiation at 25 and 50kGy. Low amylose starches lost their pasting ability when irradiated at 25 and 50kGy. Results from thermal behavior and pasting profile suggested that low level of cross-linking occurred in Hylon VII samples irradiated at 5kGy. Severe reduction in pasting properties, gelatinization temperatures and relative crystallinity with increasing irradiation intensity revealed that waxy samples were affected more by gamma irradiation; this also indicated amylopectin was the starch fraction most affected by gamma irradiation. Alteration level was portrayed differently when different kind of physicochemical properties were investigated, in which the pasting properties and crystallinity of starches were more immensely influenced by gamma irradiation while thermal behavior was less affected. Despite the irradiation level, the morphology and crystal pattern of starch granules were found remain unchanged by irradiation.

Comparative study of film forming behaviour of low and high amylose starches using glycerol and xylitol as plasticizers

In this study, the film forming behaviour of low amylose (LA) and high amylose (HA) starches was studied. The starch-alone and a blend of plasticizer (polyol)–starch films were developed by gelatinising at various temperatures and casting at 25°C. The starch–plasticizer films contained glycerol and xylitol either individually or in 1:1 combination. The concentration of plasticizer used was 15%, 20% and 30% for LA films while it was 20%, 30% and 40% for HA films on dry solid basis. The HA-glycerol films retained the highest moisture content among all the films. The HA films exhibited higher glass transition temperature, higher tensile strength, higher modulus of elasticity and lower elongation at break than those obtained from LA starch. The tensile strength and modulus of elasticity decreased and the elongation increased with increasing plasticizer concentrations above 15% on dry solid basis regardless the starch type. Low water vapour permeability was evident in LA and HA films plasticized by combined plasticizers at 20% plasticizer concentration. Rheological measurements showed that most of the suspensions exhibited Herschel–Bulkley behaviour and some of the HA suspensions exhibited Bingham plastic behaviour. At 15% (on dry solid basis) plasticizer concentration, the films obtained from both the starches were brittle due to the anti-plasticization behaviour.