Waxy Maize Starch Research Articles

Mechanical properties and solubility in water of corn starch-collagen composite films: Effect of starch type and concentrations

This study investigated the possibility of enhancing the properties of collagen with three different maize starches: waxy maize starch, normal starch, and high amylose starch. Scanning electron microscopy images revealed that starch-collagen films had a rougher surface compared to pure collagen films which became smoother upon heating. Amylose starch and normal starch increased the tensile strength of unheated collagen films in both dry and wet states, while all starches increased tensile strength of collagen film by heating. Depending upon the amylose content and starch concentrations, film solubility in water decreased with the addition of starch. DSC thermograms demonstrated that addition of all starches improved the thermal stability of the collagen film. Moreover, X-ray diffraction results indicated that except for high amylose starch, the crystallinity of both starch and collagen was significantly decreased when subject to heating. FTIR spectra indicated that intermolecular interactions between starch and collagen were enhanced upon heating.

Effect of heat-moisture treatment under mildly acidic condition on fragmentation of waxy maize starch granules into nanoparticles

Waxy maize starch was modified by a heat-moisture treatment (HMT) under acidic conditions followed by homogenization to create starch nanoparticles. Waxy maize starch was heated at 130 °C for 3, 5, or 8 h under mildly acidic conditions (0.00, 0.10, or 0.15 N sulfuric acid solution) and homogenized for up to 60 min. The crystalline, molecular, and granular structures of starch were effectively changed without severe loss of starch substance (less than 25%) by the HMT under acidic conditions. The HMT under acidic conditions enhanced short-range order of starch granules based on the results of FT-IR but decreased the proportion of amylopectin long chains. The data suggest that the amorphous region of the starch granule was readily hydrolyzed by the acidic condition during the HMT. Moreover, homogenization after the HMT (0.15 N for 8 h) induced fragmentation of starch granules into nano-sized particles with diameters less than 40 nm.

Rheological properties of lactose-free dairy desserts.

People suffering from lactose intolerance cannot digest milk or lactose-containing foods. Lactose-free diet is essential for them since they do not have the ability to produce lactase to breakdown milk sugar. Physical properties of lactose-free dairy desserts will most probably be different than that of lactose containing ones because of lactose hydrolysis. In this study, it was aimed to analyze the rheological and textural behaviors of different lactose-free dessert formulations containing different gum types and different waxy maize starch and sucrose concentrations. Waxy maize starch was used at concentrations of 0.032 g·mL-1, 0.040 g·mL-1, and 0.048 g·mL-1 In addition to waxy maize starch, guar gum, gum arabic, or κ-carrageenan at two different concentrations (1.0% w/w and 0.5% w/w) was added. Sucrose was added at concentrations of 0.14 g·mL-1 and 0.10 g·mL-1 in lactose-free desserts. Power law model was found to be suitable to explain the flow behavior of desserts. The storage and loss modulus of lactose-free desserts were higher than that of lactose-containing desserts. The κ-Carrageenan was found to be the most effective gum for structure build-up.

Effects of salts on the gelatinization and retrogradation properties of maize starch and waxy maize starch

The objective of this study was to evaluate the effects of salts on the gelatinization and retrogradation of maize and waxy maize starch. Experimental results showed that the salting-out or structure-making ions, such as F− and SO42−, decreased the swelling power, solubility and transparency of both starches, but increased the gelatinization temperature, enthalpy, and syneresis, due to the tendency of these ions to protect the hydrogen bond links among starch molecules. On the other hand, the salting-in or structure-breaking ions, such as I− and SCN−, exhibited the opposite effects. Microscopic observations confirmed such effects of salts on both starches. Furthermore, the effects of salts were more significant on waxy maize and on normal maize starch. Generally, salts could significantly influence on the gelatinization and retrogradation of maize and waxy maize starch, following the order of the Hofmeister series.

Structure and pasting properties of alkaline-treated phosphorylated cross-linked waxy maize starches

The objectives of this study were to determine the stability of cross-linked bonds of starch at different pH values and their effects on the pasting property of waxy maize starch cross-linked by 0.05% and 3% sodium trimetaphosphate/sodium tripolyphosphate. The cross-linked waxy maize starch (CLWMS) was slurried (40%, w/w) and subjected to alkali treatments of pH 9, 10, 11, and 12 at 40°C for 4h. The phosphorus in 3% CLWMS decreased with increasing pH and remained unchanged in 0.05% CLWMS for all pH treatments. Decreased settling volumes indicated the reduction of swelling power for the alkali-treated CLWMS at pH 11 and 12. The 31P NMR spectra of 3% CLWMS at pH 12 showed decreased cyclic monostarch phosphate, monostarch monophosphate, and monostarch diphosphate, but significantly increased distarch monophosphate. Alkali treatments of phosphorylated cross-linked starches offer a way to manipulate the rheological properties of cross-linked starch for desired food applications.

Structure of branching enzyme- and amylomaltase modified starch produced from well-defined amylose to amylopectin substrates

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.

Retrogradation of Maize Starch after High Hydrostatic Pressure Gelation: Effect of Amylose Content and Depressurization Rate.

High hydrostatic pressure (HHP) has been employed to gelatinize or physically modify starch dispersions. In this study, waxy maize starch, normal maize starch, and two high amylose content starch were processed by a HHP of the order of 600 MPa, at 25°C for 15min. The effect of HHP processing on the crystallization of maize starches with various amylose content during storage at 4°C was investigated. Crystallization kinetics of HHP treated starch gels were investigated using rheology and FTIR. The effect of crystallization on the mechanical properties of starch gel network were evaluated in terms of dynamic complex modulus (G*). The crystallization induced increase of short-range helices structures were investigated using FTIR. The pressure releasing rate does not affect the starch retrogradation behaviour. The rate and extent of retrogradation depends on the amylose content of amylose starch. The least retrogradation was observed in HHP treated waxy maize starch. The rate of retrogradation is higher for HHP treated high amylose maize starch than that of normal maize starch. A linear relationship between the extent of retrogradation (phase distribution) measured by FTIR and G* is proposed.

Chemical structures in pyrodextrin determined by nuclear magnetic resonance spectroscopy

Glycosidic linkages in a pyrodextrin were identified by NMR spectroscopy for the first time. Pyrodextrin was prepared by slurrying waxy maize starch at pH 3, filtering and drying at 40°C to 10–15% moisture content, then heating at 170°C for 4h. 1H and 13C NMR resonances of the pyrodextrin were assigned with the assistance of 2D techniques including COSY, TOCSY, HSQC, and HMBC, all measured on a 500MHz instrument. During dextrinization, native waxy maize starch was hydrolyzed and extensively branched with new glycosidic linkages. The resulting pyrodextrin became 100% soluble in water and produced lower viscosity solutions at 30% solids. There were only 1.2% reducing ends (α-form) detected in the pyrodextrin, but 1,6-anhydro-β-d-glucopyranosyl units accounted for 5.2% of repeating units and they were thought to be at the potential reducing end. New glycosyl linkages including α-1,6, β-1,6, α-1,2, and β-1,2 were identified. The total non-α-1,4 linkages in the pyrodextrin were about 17.8% compared to 5.8% in a maltodextrin prepared by α-amylase digestion. Transglycosidation and depolymerization occurred during dextrinization, and the resulting pyrodextrin was highly branched.

Structural characterization of complexes prepared with glycerol monoestearate and maize starches with different amylose contents

Morphology and different structural features of V-amylose complexes prepared with different concentrations (1%, 2%, 3%) of glycerol monostearate (GMS) and normal maize (NMS), waxy maize (WMS), and high amylose maize (HAMS) starches were evaluated using X-ray diffraction, differential scanning calorimetry, scanning electronic microscopy (SEM), atomic force microscopy (AFM), and transmission electronic microscopy (TEM). There was inclusion complex formation between all starches and GMS regardless of emulsifier concentration, with exception of WMS-2%GMS and WMS-3%GMS samples. All of the inclusion complexes displayed a V-type crystalline pattern and endothermic dissociation peaks between 115 and 120°C. They also displayed faceted crystalline structures with a tendency of the crystals to aggregate and form agglomerates of various sizes. TEM images of the complexes showed an aggregated strand structure interwoven with the GMS. Emulsifier and amylose quantities directly influenced complex formation. At high GMS concentrations, there was higher tendency of emulsifier to self-associate rather than form complexes with amylose.

Rheological properties of fermented rice extract with probiotic bacteria and different concentrations of waxy maize starch

Fermented rice extracts (FRE) obtained from bran and broken grains in a proportion of 8:92, and probiotic bacteria with different concentrations of waxy maize starch (WMS) were elaborated. Pearson correlations and multivariate analysis by Principal Component Analysis (PCA) were applied to evaluate the rheological behaviour of FRE. A completely randomized design was used, with five treatments from FRE1 to FRE5 (0, 4, 8, 12 and 16 g 100 g−1 of WMS, respectively), in four original repetitions. The multivariate analysis using PCA found that the shear stress and the WMS percentage showed a higher contribution in the first component (CP1 47.5%), and the viscosity in the second component (CP2 29.0%). The FRE5 presented the highest hysteresis, 128.12 Pa s−1. The Ostwald-de Waele model showed the best fit for the flow curves with R2 > 0.99 and a relative approximate error of 3.14%. All FRE presented non-newtonian behaviour, with n < 1. The FRE with different concentrations of WMS presented rheological behaviour similar to yogurts and lactic beverages described in the literature, indicating that such products can be comparable to traditional yogurts in relation to viscosity and to the flow characteristics. The results also suggest an improvement in the sensory properties of FRE.

Polymeric tannins significantly alter properties and in vitro digestibility of partially gelatinized intact starch granule

Excess calorie intake is a growing global problem. This study investigated effect of complexing partially gelatinized starch with condensed tannins on in vitro starch digestibility. Extracts from tannin and non-tannin sorghum, and cellulose control, were reacted with normal and waxy maize starch in 30% (30E) and 50% ethanol (50E) solutions at 70°C/20min. More tannins complexed with the 30E than 50E starches (mean 6.2 vs 3.5mg/g, respectively). In the 30E treatments, tannins significantly increased crystallinity, pasting temperature, peak viscosity, and slow digesting starch (from 100 to 274mg/g) in normal, but not waxy starch, suggesting intragranular cross-linking with amylose. Tannins doubled resistant starch (RS) to approx. 300mg/g in both starches. In 50E treatments, tannins made both maize starches behave like raw potato starch (>90% RS), suggesting granule surface interactions dominated. Non-tannin treatments generally behaved similar to cellulose. Condensed tannins could be used to favorably alter starch digestion profile.

Effect of maize type and extrusion‐cooking conditions on starch digestibility profiles

SummaryThis study aimed at evaluating the influence of screw speed (250–600 rpm), barrel temperature (100–160 °C) and water content (16.4–22.5%) on rapidly digestible (RDS), slowly digestible (SDS) and resistant (RS) starch levels of waxy, normal and high‐amylose maize starches. In native starches, an increase in amylose content was correlated with lower SDS content. After extrusion, this trend was reversed. Both waxy and normal maize starches became rapidly digested. However, for normal maize starch, some SDS fraction remained. In contrast, the high‐amylose maize starch showed a significant increase in digestibility and an increase in SDS content from 20.4% in the native starch up to 27.5% after extrusion. This high level of SDS may be attributed to the presence of some remaining granular structures and formation of crystalline orders, which have slow digestion properties.

Processing of edible films based on nanoreinforced gelatinized starch

Fully biobased edible films were prepared using native potato starch plasticized with glycerol and further reinforced with catechin (Cat) and starch nanocrystals (SNC) obtained by acidic hydrolysis from waxy maize starch granules. The thermal stability of starch nanocrystals obtained at different pH was studied, resulting on a decreasing in thermal stability at higher pH values. The X-ray diffraction patterns of the plasticized reinforced materials display complete destructuration of starch by solvent casting process. Plasticized films showed lower onset degradation temperatures than non-plasticized starch film. The reduction of the inter- and intra-molecular bonds interaction within the polymer matrix due to glycerol presence leads to a decrease of the thermal stability of the whole system. On the other hand, Cat and SNC produced an increase on the thermal stability of the bionanocomposites delaying the beginning of the thermal decomposition of starch/glycerol systems of about 20 °C. The mechanical performance was also improved in the ternary bionanocomposite edible films. All the edible films were fully disintegrated in compost conditions suggesting their possible applications as biodegradable edible films for packaging.

Effects of adding resistant and waxy starches on cell density and survival of encapsulated biofilm of Lactobacillus rhamnosus GG probiotics

Herein we investigated the effects of adding resistant and waxy maize starches on the initial cell density and stress tolerance of alginate-gum microcapsules containing high-density biofilm colonies of Lactobacillus rhamnosus GG probiotics. The stress tolerance was evaluated for (1) freeze drying, (2) 30-min heating at 100 °C, (3) two-week storage at 4 °C, and (4) exposure to simulated gastric juice. The addition of resistant starch, which was postulated to stimulate biofilm growth owed to its prebiotic properties, had minimal impacts on the initial cell density and stress tolerance of the encapsulated probiotics, signifying that co-encapsulation of probiotics with prebiotics did not necessarily lead to capsule improvement. In contrast, the addition of modified waxy starch at 0.6% (w/v) enhanced the freeze-drying (2×), thermal (25×), and storage (6×) tolerances of the probiotic microcapsules, while the initial cell density remained unaffected. The waxy starch addition, however, compromised the microcapsules' chitosan coating, resulting in lower acid tolerance. Lastly, the microcapsules were able to maintain the viability of the probiotics upon their incorporation into soy milk.

Effects of high temperature during grain filling on physicochemical properties of waxy maize starch

AbstractUnderstanding the waxy maize starch physicochemical properties response to heat stress during grain filling could improve starch quality. The effects of heat stress during early (1–15 days after pollination, DAP) and late (16–30 DAP) grain filling stages on the starch physicochemical properties of four waxy maize varieties were evaluated. Crystallinity only increased in Suyunuo 5 after exposure to high temperature at late grain filling stage. The effects of heat stress on digestibility and swelling power were dependent on varieties and stages. Generally, swelling power was increased by heat stress at early grain development stage and digestibility was increased by high temperature at late grain filling stage, respectively. The results of correlation analysis indicated the starch with large granule size could swell well and easy digest. Peak, trough, final, and breakdown viscosities in response to heat stress were dependent on stages and varieties. In general, peak, trough and final viscosities were decreased and increased by heat stress at early grain formation and late grain filling stages, respectively; whereas the breakdown and setback viscosities were similar among the three treatments. Heat stress increased the gelatinization temperatures and retrogradation percentage. Gelatinization range decreased under heat stress at 1–15 DAP but remained constant under heat stress at 16–30 DAP in all varieties. The starch exposed to high temperature at 16–30 DAP presented higher digestibility and peak viscosity and lower retrogradation percentage than those at 1–15 DAP. Therefore, heat stress at early grain formation stage severely affects the physicochemical properties of starch.

Starch nanocrystals and starch nanoparticles from waxy maize as nanoreinforcement: A comparative study

The morphological, structural and thermal behavior of starch nanocrystals (SNCs) extracted from waxy maize starch through an acid hydrolysis were compared with those of starch nanoparticles (SNPs) obtained through an ultrasound treatment starting from the same waxy maize starch. The SNPs were found to be completely amorphous, slightly smaller and had no surface charge, whereas the SNCs had the expected platelet-like morphology with a negative surface charge introduced as a result of the use of sulphuric acid in the acid hydrolysis step. SNCs also showed better thermal stability than SNPs in the presence of water. As a result of their platelet-like morphology, the SNCs performed better in reinforcing a polymer film. On the other hand, SNPs reduced the transparency of the nanocomposite films to a lesser extent than the SNCs due to their smaller size.

Ionic liquids as novel solvents for biosynthesis of octenyl succinic anhydride-modified waxy maize starch

Biosynthesis of octenyl succinic anhydride (OSA) starch was investigated using ionic liquids (ILs) as reaction media. Waxy maize starch was pretreated in 1-butyl-3-methylimidazolium chlorine and then esterified with OSA in 1-octyl-3-methylimidazolium nitrate by using Novozyme 435as catalyst. The degree of substitution of OSA starch reached 0.0130 with 5wt% starch concentration and 1wt% lipase dosage based on ILs weight at 50°C for 3h. The formation of OSA starch was confirmed by fourier transform infrared spectroscopy. Scanning electron microscopy and X-ray diffraction revealed that the morphology and crystal structure of starch were significantly destroyed. Thermogravimetric analysis showed that esterification decreased the thermal stability of starch. The successful lipase-catalyzed synthesis of OSA starch in ILs suggests that ILs are potential replacement of traditional organic solvents for starch ester biosynthesis.

Preparation and characterization of starch nanoparticles via self-assembly at moderate temperature

Starch nanoparticles (SNPs) were fabricated via short glucan chains self-assembly at 50°C and their characteristics were evaluated by transmission electron microscopy, dynamic light scattering, molecular weight distributions, X-ray diffraction, differential scanning calorimetry, and Fourier transforms infrared spectroscopy. The results showed that SNPs exhibited spherical particles with a diameter of approximately 30–40nm. The molecular weight of the SNPs mainly distributed at degree of polymerization (DP) 12 and DP 30. The gelatinization temperature of the SNPs increased dramatically compared to that of native waxy maize starch. The crystallinity of the samples increased as the assembling time increased and showed the same A-type in the X-ray diffraction pattern as native starch. This newly proposed SNPs approach has potential application in starch nanocomposite films due to their high gelatinization temperature.

Preparation of starch–poly–glutamic acid graft copolymers by microwave irradiation and the characterization of their properties

Graft copolymers of waxy maize starch and poly-γ-glutamic acid (PGA) were produced in an aqueous solution using microwave irradiation. The microwave reaction conditions were optimized with regard to temperature and pH. The temperature of 180°C and pH7.0 were the best reaction conditions resulting in a PGA graft of 0.45% based on nitrogen analysis. The average graft content and graft efficiency for the starch–PGA graft copolymer prepared at 180°C and pH7.0 were 4.20% and 2.73%, respectively. The starch–PGA graft copolymer produced at 180°C and pH7.0 could absorb more than 20 times its own weight amount of water and form a gel. The preliminary rheology study revealed that the starch–PGA graft copolymer gel exhibited viscoelastic solid behavior while the control sample of waxy starch showed viscoelastic liquid behavior.

Molecular rearrangement of waxy and normal maize starch granules during in vitro digestion

The objective of the present study is to understand the changes in starch structures during digestion and the structures contributing to slow digestion properties. The molecular, crystalline, and granular structures of native waxy maize, normal maize, high-amylose maize, and normal potato starch granules were monitored using SEC, XRD, DSC, and SEM. The amylose and amylopectin molecules of all four starches were hydrolyzed to smaller dextrins, with some having linear molecular structure. Neither the A- nor B-type crystallinity was resistant to enzyme hydrolysis. Starch crystallites with melting temperature above 120°C appeared in waxy and normal maize starches after digestion, suggesting that the linear dextrins retrograded into thermally stable crystalline structure. These crystallites were also observed for high-amylose maize starch before and after digestion, contributing to its low enzyme digestibility. On the contrary, the enzyme-resistant granular structure of native normal potato starch was responsible for its low susceptibility to enzyme hydrolysis.