Waxy Maize Starch Research Articles

Distribution of acetyl groups in acetylated waxy maize starches prepared in aqueous solution with two different alkaline concentrations

Waxy maize starch acetates with the same degree of substitution (DS) were produced in aqueous medium with 3% or 20% (w/w) sodium hydroxide. The distribution of acetyl groups on amylopectin was studied by enzymatic hydrolysis in combination with chromatographic techniques. Product prepared with 20% NaOH was more resistant to β-amylase but less resistant to α-amylase and isoamylase, indicating more acetyl groups distributed over the external chains or located closer to the non-reducing end of external chains. Settling volume and viscosity of acetylated starch slurry indicated the product prepared with 20% NaOH swelled more than that prepared with 3% NaOH during acetylation. Considering the structure of waxy maize starch, reaction conditions, crystallinity and thermal properties of the acetylated products, it was proposed that high concentration NaOH could improve the reaction process and acetyl groups were more uniformly distributed in amorphous and crystallinity regions of amylopectin in waxy maize starch.

Fabrication and characterization of food‐grade fibers from mixtures of maltodextrin and whey protein isolate using needleless electrospinning

ABSTRACTFood‐grade fibers were fabricated from dispersions of maltodextrin and whey protein isolate (WPI) using needleless electrospinning. Two maltodextrins (DE 2) from different starch sources were used and the maltodextrin/WPI ratio was varied. Molecular weight, intrinsic viscosity, entanglement concentration, shear stability, and electrical conductivity were studied as function of maltodextrin type and mixing ratio and correlated to fiber production rate and morphology. The results show that a high molecular weight of the maltodextrin was beneficial to its spinnability. Waxy potato starch maltodextrin (P‐MD) (Mw = 129.6 kDa) and WPI produced fibers with diameters between 1.40 and 1.67 µm at production rates up to 1.65 g/h; while the dispersions with waxy maize starch maltodextrin (M‐MD) (Mw = 85.9 kDa) showed poor spinnability and ruptured fibers. P‐MD/WPI dispersions had a higher viscosity and stronger shear thinning behavior attributed to a stronger entangled polymer network which is beneficial to electrospinning. © 2018 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2018, 135, 46328.

Changes in gelatinisation and pasting properties of various starches (wheat, maize and waxy maize) by the addition of bacterial cellulose fibrils

The aim of this work was to analyse the effect of bacterial cellulose fibrils (BCF) on the gelatinisation profile and pasting properties of starches from different sources (wheat, maize and waxy maize) and amylose contents. Blends of 8% starch with different BCF levels (0, 0.5, 2, 6 and 10% based on the dry weight of starch) were prepared and tested by Rapid Visco-Analysis (RVA), Differential Scanning Calorimetry (DSC) and both Optical and Polarized Light Microscopy. Results showed that BCF produce a significant modification of pasting properties. The pasting temperature was reduced but viscosities (peak, final, trough, breakdown and final) increased. The reduction in pasting temperature at the highest BCF addition was 20 °C higher for maize and wheat starches but only 2 °C higher for waxy maize starch. In contrast to the pasting temperature, the gelatinisation temperature by DSC for all three starches slightly varied upon BCF addition, but the gelatinisation enthalpy was reduced to a greater extent than values reported for the addition of other hydrocolloids to starch blends. Optical and polarized light microscopy showed the presence of domains rich in starch and highly aggregated BCF in all three starches evaluated. The increase in viscosity and decrease in pasting temperature are discussed in terms of changes in starch concentrations in the starch rich domain. These results open interesting perspectives in the use of bacterial cellulose and plant cell walls to design novel bio-composites to structure foods.

Nature of phase transitions of waxy maize starch in water-ionic liquid mixtures

The nature of phase transitions of waxy maize starch heated in mixtures of water and ionic liquid (IL) was elucidated using a variety of analytical methods. The transition from a single endotherm to an exotherm followed by an endotherm, and then to a single exotherm was observed with the increasing concentration of IL. The results showed that at To of DSC phase transition no structural disruption had occurred. Except for the water/IL ratios of 1.5:1 and 1:1, there was considerable structural disruption of starch samples that were preheated to Tp or Tp2 of gelatinization transition. No residual structural order was observed at Tc of the gelatinization transition. An exothermic transition at water:IL ratios of 3:1 and 2:1 was attributed to the interaction of ionic liquid and amorphous regions in starch. The molecular disassembly of starch granules during gelatinization in different water:IL mixtures proceeded to completion at different rates.

A mechanistic model for swelling kinetics of waxy maize starch suspension

The evolution of 8% suspension of waxy maize starch granule size distribution when subjected to heating to 65, 70, 75, 80, 85 and 90 °C at a heating rate of 15 °C/min were measured. Granule swelling was more pronounced at higher temperatures with an increase in the average size from 13 μm to 25–28 μm, eventually approaching equilibrium. Cryo SEM images revealed porous structure of swollen granule. The proposed model for starch swelling accounts for entropy of mixing, enthalpy of water-starch interaction and elastic restoring force. The second virial coefficient of waxy maize in aqueous medium was characterized by static light scattering. Chemical potential profile as well as the temperature profile within the granule were predicted from the solution of unsteady state diffusion and heat conduction respectively. The granule size was then inferred from the chemical potential profile. The proposed model predicts the evolution of average granule size and granule size distribution accurately.

Pasting and gel characteristics of normal and waxy maize starch in glucose syrup solutions

Sugars are among the constituents which significantly affect the process of starch gelatinization and settle properties of the resulting gels. The information about the influence of sugar mixture like glucose syrup (GS) on starch pasting, as well as on properties and stability of the resulting gel is important for wide range of food applications. In order to determine role of amylose in observed phenomena the study involved normal (MS) and waxy maize (WS) starches. Starch suspensions were pasted in GS solutions, and the texture of resulting gels was also evaluated.In the presence of glucose syrups pastes and gels of MS and WS change their rheological properties. This involves an increase in pasting temperature and viscosity of the pastes, and modification of texture properties of stored gels. In the case of MS application of GS led to incremental decrease of gel hardness, while an opposite effect could be seen for weak WS gels. All these effects were highly dependent on starch type, and concentration of GS. It is assumed that the main factor for observed differences was amylose content. This difference clearly shows that amylose containing starch granules require more water for full gelatinization than their amylopectin counterparts.

Acid hydrolysis of waxy starches with different granule size for nanocrystal production

Acid hydrolysis of waxy maize and amaranth starches was achieved for nanocrystal production. Both starches are of the waxy type with an A-type crystallinity pattern. The mean granule sizes were ∼1–2 μm for amaranth starch and ∼15–18 μm for waxy maize. The starches (15 g dry basis) were subjected to acid hydrolysis with 100 mL of 3.16 M H2SO4 at 40 °C for 3, 5 and 10 days. The hydrolysis extent was higher for amaranth starch, which had a smaller granule size, although the nanocrystal yield was lower because the hydrolysis reactions were more likely to destroy the more crystalline regions. The X-ray diffraction analysis showed that the relative crystallinity increased by approximately 50% after ten days of hydrolysis, although the intrinsic crystallinity order as indicated by the Miller indices was greatly affected. A determination of the chain length distribution showed that a smaller granule size favoured the formation of shorter chains because the hydrolysis reactions were promoted by the relatively small resistance of proton transport to the inner granule region.

Preparation and characterization of starch nanocrystals combining ball milling with acid hydrolysis

Waxy maize starch was mechanically treated with a planetary ball mill. X-ray diffraction analysis was employed to determine the optimal ball milling time. After ball milling, the pretreated starch was hydrolyzed with H2SO4. The hydrolysates were obtained and their relative crystallinity, morphology, and particle size were estimated by X-ray diffraction analysis, atomic force microscopy, and nanoparticle size analyzer, respectively. The results revealed that it is possible to obtain starch nanocrystals (SNCs) after a combination of ball milling and 3days of H2SO4 hydrolysis with a yield of 19.3wt% with a shape similar to those acquired by the conventional procedure after 5days of sulfuric acid hydrolysis, with a yield of 15.8wt%. Round-edge SNCs with an average diameter of approximately 31nm were observed. The results revealed that by controlling some parameters, certain mechanical processing methods considered unsuitable could also be applied to the preparation of SNCs.

Bivariate flow cytometric analysis and sorting of different types of maize starch grains.

Particle-size distribution, granular structure, and composition significantly affect the physicochemical properties, rheological properties, and nutritional function of starch. Flow cytometry and flow sorting are widely considered convenient and efficient ways of classifying and separating natural biological particles or other substances into subpopulations, respectively, based on the differential response of each component to stimulation by a light beam; the results allow for the correlation analysis of parameters. In this study, different types of starches isolated from waxy maize, sweet maize, high-amylose maize, pop maize, and normal maize were initially classified into various subgroups by flow cytometer and then collected through flow sorting to observe their morphology and particle-size distribution. The results showed that a 0.25% Gelzan solution served as an optimal reagent for keeping individual starch particles homogeneously dispersed in suspension for a relatively long time. The bivariate flow cytometric population distributions indicated that the starches of normal maize, sweet maize, and pop maize were divided into two subgroups, whereas high-amylose maize starch had only one subgroup. Waxy maize starch, conversely, showed three subpopulations. The subgroups sorted by flow cytometer were determined and verified in terms of morphology and granule size by scanning electron microscopy and laser particle distribution analyzer. Results showed that flow cytometry can be regarded as a novel method for classifying and sorting starch granules. © 2017 International Society for Advancement of Cytometry.

Physicochemical properties of maize and sweet potato starches in the presence of cellulose nanocrystals

The goal of this research was to evaluate the effect of cellulose nanocrystals (CNC) on the gelatinization, pasting, and short- and long-term retrogradation properties of normal maize starch (NMS), waxy maize starch (WMS), and sweet potato starch (SPS). Differential scanning calorimetry (DSC) data indicated that the addition of CNC did not significantly change the gelatinization temperatures of starch, but the enthalpy change values slightly decreased. Rapid visco-analyzer (RVA) data suggested that CNC slightly increased the peak viscosity of NMS and SPS, while it reduced the setback values of SPS, indicating the retardation of short-term SPS retrogradation. Further, the dynamic time sweep of starches with CNC demonstrated remarkable inhibition of the short-term retrogradation of NMS and SPS. DSC results showed that 10% (w/w, based on starch) addition of CNC significantly (p < 0.05) decreased the retrogradation enthalpy change of NMS, WMS, and SPS. X-ray diffraction (XRD) results exhibited that the relative crystallinity of retrograded NMS, WMS, and SPS decreased as the content of CNC increased. Both DSC and XRD results suggested that there was really a dominant inhibiting influence of CNC on the recrystallization of amylopectin, and thus, the long-term retrogradation of starch was hindered. It could therefore be concluded that CNC apparently inhibited not only the short-term retrogradation of amylose, but also the long-term retrogradation of amylopectin.

Syneresis and chemical characteristics of fermented rice extract with probiotic bacteria and waxy maize starch

Abstract The objective of this work was to elaborate fermented extracts using rice bran and broken rice grains (proportion 8:92) with probiotic bacteria and different concentrations of waxy maize starch (WMS) in order to obtain products with low level of syneresis and desirable physical-chemical characteristics, and to evaluate the content of phenolic compounds, antioxidant capacity and chemical composition of the extract selected and flavored with strawberry aroma and strawberry syrup. A randomized design was used with five treatments (0, 4, 8, 12 and 16 g 100 g–1 of WMS) and four replications. The fermented rice extract had increased soluble solids (from 12.97 to 14.23 °Brix) and total acidity (from 0.29 to 0.30 g 100 g–1), whereas total soluble sugars (from 9.24 to 8.73 g 100 g–1) and syneresis (from 10.16 to 0.99 g 100 g–1) decreased with gradual increments of waxy maize starch. The fermented rice extract containing 12 g 100 g–1 WMS reduced the syneresis by 89% compared to the control without waxy maize starch. The fermented rice extract with 12 g 100 g-1 of waxy maize starch flavored with strawberry aroma and strawberry syrup shows high nutritional value, antioxidant capacity, content of total phenolic compounds, and marketing potential, particularly for consumers with special needs, such as those allergic to lactose or soybean proteins, as an alternative food ready for consumption.

Effects of short‐term heat stress at the grain formation stage on physicochemical properties of waxy maize starch

Waxy maize (Zea mays L. sinensis Kulesh) suffers short-term exposure to high temperature during grain filling in southern China. The effects of such exposure are poorly understood. Starch granule size was increased by 5 days' short-term heat stress (35.0 °C) and the increase was higher when the stress was introduced early. Heat stress increased the iodine binding capacity of starches and no difference was observed among the three stages. Starch relative crystallinity was increased and swelling power was decreased only when heat stress was introduced early. Heat stress also increased the pasting viscosity, and this effect became more pronounced with later applications of stress. Heat stress reduced starch gelatinization enthalpy, and the reduction gradually increased with later exposures. Heat stress increased the gelatinization temperature and retrogradation enthalpy and percentage of the samples, with the increases being largest with earlier introduction of high temperature. Heat stress increased the pasting viscosities and retrogradation percentage of starch by causing change in granule size, amylopectin chain length distribution and crystallinity, and the effects observed were more severe with earlier introduction of heat stress after pollination. © 2017 Society of Chemical Industry.

Effect of dual modification of HMT and crosslinking on physicochemical properties and digestibility of waxy maize starch

Waxy maize starch was subjected to crosslinking, HMT, crosslinking-HMT and HMT-crosslinking, and physicochemical properties and digestibility were examined. Crosslinked-HMT and HMT-crosslinked starch exhibited lower and higher phosphorus contents than crosslinked starch at the same concentrations of STMP/STPP (99:1, w/w), respectively. A low swelling power, a low paste clarity, a high melting temperature and a low ΔH were observed in crosslinked-HMT starch and HMT-crosslinked starch like crosslinked and/or HMT starch. Crosslinking-HMT and HMT-crosslinking mitigated the reduced XRD peak intensity observed for HMT. Crosslinked-HMT starch effectively produced RS, showing 28.7–41.5% RS in raw starch and 23.3–25.0% in gelatinized starch. The RS proportion of crosslinking-HMT was similar to that of crosslinking in raw starch, but HMT and crosslinking-HMT showed similar RS proportions in gelatinized starch. Crosslinking-HMT advantageously produced RS from both crosslinking and HMT; however, this was not observed in HMT-crosslinking.

Dietary starch types affect liver nutrient metabolism of finishing pigs.

This study aimed to evaluate the effect of different starch types on liver nutrient metabolism of finishing pigs. In all ninety barrows were randomly allocated to three diets with five replicates of six pigs, containing purified waxy maize starch (WMS), non-waxy maize starch (NMS) and pea starch (PS) (the amylose to amylopectin ratios were 0·07, 0·19 and 0·28, respectively). After 28 d of treatments, two per pen (close to the average body weight of the pen) were weighed individually, slaughtered and liver samples were collected. Compared with the WMS diet, the PS diet decreased the activities of glycogen phosphorylase, phosphoenolpyruvate carboxykinase and the expression of phosphoenolpyruvate carboxykinase 1 in liver (P0·05). Compared with the WMS diet, the PS diet reduced the expressions of glutamate dehydrogenase and carbamoyl phosphate synthetase 1 in liver (P<0·05). PS diet decreased the expression of the insulin receptor, and increased the expressions of mammalian target of rapamycin complex 1 and ribosomal protein S6 kinase β-1 in liver compared with the WMS diet (P<0·05). These findings indicated that the diet with higher amylose content could down-regulate gluconeogenesis, and cause less fat deposition and more protein deposition by affecting the insulin/PI3K/protein kinase B signalling pathway in liver of finishing pigs.

Measurement and characterization of external oil in the fried waxy maize starch granules using ATR-FTIR and XRD

Concerns regarding increased dietary oil uptake have prompted efforts to investigate the oil absorption and distribution in fried starchy foods. In the present study, attenuated total reflection Fourier transform infrared (ATR-FTIR) spectroscopy, together with a chloroform–methanol method, was used to analyze the external and internal oil contents in fried starchy samples. The micromorphology of fried starchy samples was further investigated using scanning electron microscope (SEM), polarized light microscope (PLM) and confocal laser scanning microscopy (CLSM). The results indicated that large amounts of oil were absorbed in or within waxy maize starch, but the majority of oil was located near the surface layer of the starch granules. After defatting, the internal oil was thoroughly removed, while a small amount of external oil remained. As evidenced by the changes of the crystalline characteristics with the help of X-ray diffraction (XRD), the interaction between starch and lipids on the surface was confirmed to form V-type complex compounds during frying at high moisture.

Structure of pyrodextrin in relation to its retrogradation properties

Pyrodextrins were prepared by heating waxy maize starch at 170°C and pH 3.0 for 0.5, 1, 2, 3 and 4h. Structural changes of pyrodextrins were determined by gel permeation chromatography and 1H NMR. Gelatinization and retrogradation of pyrodextrins were measured by differential scanning calorimetry. The water solubility of pyrodextrins increased from 48.9 to 99.4% as heating time increased from 0.5 to 4h. The molecular size, melting enthalpy of pyrodextrin, and the degree of retrogradation decreased as pyrodextrin solubility increased. The level of 1,6-anhydro-β-d-glucopyranose increased from 2.6 to 4.0% as the heating time increased from 0.5 to 4h. The degree of branching (DB) of pyrodextrins was increased from 8.8 to 14.4%, and the average chain length (CL) reduced from 7.2 to 4.6. The increased level of new bonds and DB combined with reduced CL during the dextrinization explained the reduced extent of retrogradation of the pyrodextrin.

Structural changes of waxy and normal maize starches modified by heat moisture treatment and their relationship with starch digestibility

In the present study, the variations in structure of waxy and normal maize starches modified by heat-moisture treatment (HMT) for different treating time (3h and 9h) were investigated. HMT caused the destruction of starch granules. The 1H NMR confirmed that glycosidic bonds were broken during HMT. The 13C NMR result suggested that HMT caused the transformation of starch granules from double and single helical components into amorphous components. Heat-moisture treated starches exhibited higher gelatinization temperature (To, Tp and Tc), narrower gelatinization temperature range (Tc-To) and lower gelatinization enthalpy (ΔH). HMT caused the rearrangement of starch molecules, degeneration of double helices and formation of new single helix. In addition, in vitro digestibility assessment indicated that the contents of rapidly digestible starch (RDS) and slowly digestible starch (SDS) were improved and resistant starch (RS) was reduced after HMT, which was related to the decrease of single and double helical components.

Formulation, characterization and antimicrobial properties of black cumin essential oil nanoemulsions stabilized by OSA starch.

Preparation of oil-in-water nanoemulsions has emerged as a subject of interest for the encapsulation of lipophilic functional ingredients to increase their stability and activity. In this study, black cumin essential oil nanoemulsions (BCO-NE) using different ratios of essential oil with canola and flax seed oils (ripening inhibitors) were formulated and stabilized with octenyl succinic anhydride (OSA) modified waxy maize starch. The nanoemulsions exhibited monomodal size distributions with mean droplet diameter below 200nm and zeta potential above -30, indicating a strong electrostatic repulsion between the dispersed oil droplets. Further, during storage (4weeks at 25°C±2) emulsions showed shear thinning phenomena and stability towards coalescence. Antimicrobial properties of nanoemulsions were determined by minimum inhibitory concentration and time-kill method against two Gram-positive bacterial (GPB) strains (Bacillus cereus and Listeria monocytogenes). Negatively charged BCO-NE showed prolonged bactericidal activities as compared to pure BCO due to better stability, controlled release and self-assembly with GPB cell membrane followed by destruction of cellular constituents. Our results suggest the application of BCO-NE may be exploited in aqueous food systems for extending the shelf life and other functional properties.

Researches regarding the assessment of heritability and phenotypic, genotypic and environmental correlations in some traits of a laying hen line

Retention (R) of ethyl acetate (EA), hexanal (HE) and R-(+)-limonene (RL) in white sauces (WS) during 10-days refrigerated storage period was analyzed quantitatively using static headspace gas chromatography-mass spectrometry in relation to: starch type (waxy maize starch, WMS; potato starch, PS), starch concentration (2–5 wt%) and rapeseed oil (RO) content (3 or 9 wt%). The Avrami's equation was implemented to determine release rate constants (k) and release mechanism parameters (n). The enthalpy (ΔH) of aroma compounds (AC) affinity was calculated using van't Hoff's model, from the variations of equilibrium partition coefficients (kg/m) of AC, determined between the air (g) and matrixes (m) at temperatures ranged from 20 to 50 °C. The R values were significantly (p < 0.05) affected by both starch type (ST) and starch concentration (SC) and generally were greater in samples stabilized with PS than WMS, most probably due to the higher amylose content. Increase of RO amount, enhanced R values, particularly regarding HE and RL. Irrespectively of the ST, the k values showed descending tendency with raising SC and were higher for EA than for more hydrophobic AC (HE, RL). In all WS, the release mechanism was found to be controlled by molecular diffusion and the n values were in ranges: 0.59–0.82 and 0.56–0.81, in WS composed of 3 and 9 wt% RO, respectively. The magnitudes of ΔH related to the energy required for partitioning of AC from WS to the headspace, were greatly dependent on both AC properties and WS composition, particularly ST and SC.

The effect of high hydrostatic pressure treatment on the molecular structure of starches with different amylose content

The effect of high hydrostatic pressure processing (650MPa/9min) on molecular mass distribution, and hydrodynamic and structural parameters of amylose (maize, sorghum, Hylon VII) and amylopectin (waxy maize, amaranth) starches was studied. The starches were characterized by high-performance size-exclusion chromatography (HPSEC) equipped with static light scattering and refractive index detectors and by Fourier Transform Infrared (FTIR) spectroscopy. Significant changes were observed in molecular mass distribution of pressurized waxy maize starch. Changes in branches/branch frequency, intrinsic viscosity, and radius of gyration were observed for all treated starches. The combination of SEC and FTIR data showed that α-1,6-glycosidic bonds are more frequently split in pressurized amaranth, Hylon VII, and waxy maize starch, while in sorghum and maize starches, the α-1,4 bonds are most commonly split. Our results show that the structural changes found for pressurized starches were more strongly determined by the starch origin than by the processing applied.