Gelatinization Of Starch Granules Research Articles

Fabrication and Characterization of Native and Oxidized Potato Starch Biodegradable Films

The need to replace conventional polymers due to environmental pollution caused by them has led to increased production of biodegradable polymers such as starch. Thus, the application possibilities of starch have increased. In this study, we produced and characterized biodegradable films derived from native and oxidized potato starch. The film-forming solution was prepared with different concentrations of extracted starch (native or oxidized) and a plasticizer (glycerol or sorbitol). Then, the mechanical, barrier, morphological, and structural properties of the films were characterized. The moisture content of the films varied from 15.35 ± 1.31 to 21.78 ± 0.49%. The elastic modulus of the films ranged from 219 ± 14.97 to 2299 ± 62.91 MPa. The film of oxidized starch plasticized with sorbitol in the lowest content was the most resistant and flexible; moreover, this film also presented lower water vapor permeability and low solubility in water. Fourier-transform infrared spectroscopic analysis of the biodegradable films indicated the presence of same functional groups as those of starch with bands in the same regions. The film thickness was lower for the films plasticized with glycerol whereas the color variation (ΔΈ) was lower for the ones plasticized with sorbitol. In case of both plasticizers, the increase in their content decreased the ΔΈ value. All the biodegradable films presented stability against water absorption owing to their low solubility in water. Morphological evaluation revealed the presence of partially gelatinized starch granules in the films. The roughness parameter (Rq) of the films varied from 3.39 to 10.9 nm, indicating that their surfaces are smooth. X-ray diffraction studies showed a B-type pattern for the starches, which is representative of tubers. Further, the films present higher relative crystallinity (RC) compared to the starches. The biodegradable starch films are uniform, transparent and with low solubility in water. The oxidation of starch and use of sorbitol as a plasticizer resulted in improved properties of the starch films, which is suitable for application.

Effects of cooking temperature and time on the color, morphology, crystallinity, thermal properties, starch-lipid complexes formation and rheological properties of roux

Roux is an equal part mixture of flour and clarified butter cooked for a few minutes, and is the basic recipe for producing sauces. There is a lack of systematic studies regarding the effects of cooking temperature and time on the characteristics of roux. To this end, roux pasta (50:50 of wheat flour and clarified butter) was prepared to assess the effects of cooking time (1, 2 and 4 min) and temperature (80 and 100 °C) on physicochemical and morphological properties. Viscosity and viscoelastic moduli increased with both temperature and cooking time, an effect ascribed to partial gelatinization of starch granules. XRD analysis showed that starch granules underwent crystallinity reduction (∼20–60%) with both cooking temperature and time. Deconvoluted FTIR indicated gradual reduction of short-range ordering with time caused by leaching out of amylose chains from starch granules, leading to the formation of amylose-lipid inclusion complexes as corroborated by DSC measurements. Also, it was found that the secondary structure of proteins was affected by cooking, with the fraction of β-sheet aggregates increasing (∼35%) upon cooking time. Overall, the above results provided a basis for understanding the very complex physicochemical changes occurring during roux manufacture.

Effect of extrusion cooking of sorghum flour on rheology, morphology and heating rate of sorghum–wheat composite dough

Addition of a gluten-free flour such as sorghum has negative impact on the quality of wheat dough for bread making. One of the methods which can be used to promote the quality of sorghum-wheat composite dough is to extrude the sorghum flour before incorporation. In this regard, to produce a dough with appropriate bakery properties sorghum flour was extruded at 110 °C and 160 °C die temperature with 10%, 14% and 18% feed moisture. The effect of extruded sorghum flour incorporation (10%) on rheological (farinography and stress relaxation behavior), morphological and temperature profile of sorghum-wheat composite dough were evaluated. Extrusion cooking altered the sorghum-wheat composite dough properties through partial gelatinization of starch granules. Addition of extruded sorghum flour increased the water absorption and dough development time but it decreased the dough stability. Native sorghum-wheat composite dough showed viscoelastic liquid-like behavior whereas addition of sorghum flour extrudate changed dough to a more viscoelastic solid-like structure. Maxwell model was more appropriate than Peleg model to describe the viscoelasticity of the sorghum-wheat composite dough. Extrusion cooking decreased composite dough elasticity and viscosity. Sorghum extrudate increased the heating rate of composite dough crumb during baking. Addition of extruded sorghum flour formed a non-uniform and less compact dough structure. As a result, dough containing extruded sorghum flour had a good potential for producing a high-yielding bread in a short time of baking.

Effect of pressure with shear stress on gelatinization of starches with different amylose/amylopectin ratios

Effect of pressure with shear stress on the gelatinization of cornstarch with different amylose/amylopectin ratios (waxy 0/100; maze 23/77; G50 50/50; G80 80/20) was systematically investigated using a high-pressure rheometer. Onset and peak temperature of starch gelatinization as well as the peak viscosity were used to discuss the influence of pressure together with shear stress on the gelatinization of starch granules. The results showed that without shear stress, pressure could resist the gelatinization process due to weak swelling of starch granules and lower quantity of amylose released. However, the shear stress can simply counteract the influence of the pressure since its impact is much high on gelatinization. Under certain pressure and shear stress, both onset and peak temperatures of gelatinization were increased with increasing amylose content, which is in correspondence with the results from differential scanning calorimeter measurement, while the overall viscosity was lower when starches with a higher amylose content was used because part of its granular was not fully dissolved during the measurement. SAXS measurements were used to study the gel structure and stability of starch suspensions. It was found that the scattering intensity of starches in the measured range (0.1–1.0 nm−1) is G80 > waxy, indicating the amount of ordered semi-crystalline structures in amylose is higher. Peak values, q = 0.4 nm−1 and q = 0.2 nm−1, detected for waxy starch under different shear rates, indicates that higher shear stress which plays a dominant role compared with pressure, resulted in more degradation in amylopectin, inhibiting the formation of aggregate structure.

Effect of blanching and drying temperatures on starch-related physicochemical properties, bioactive components and antioxidant activities of yam flours

The effects of blanching (in boiling water for 1min) and different hot air drying temperatures (40 °C, 60 °C and 80 °C) on the polyphenol oxidase (PPO), peroxidase (POD) and antioxidant activities, main bioactive components, as well as the starch-related physicochemical properties of yam flours were studied. The results of PPO and POD activities, and total flavone and total soluble polyphenol contents showed that blanching was effective to inhibiting enzymatic browning of yams, and the substrate of enzymatic browning reaction may be mainly flavonoid ingredients. The sample of H-40 had higher allantoin and total soluble polyphenol content, stronger DPPH scavenging activity and reducing power. From the results of scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR), the blanching yams was found contain partly gelatinized starch granules, and had lower crystallinity. The H-40 and H-80 samples had higher RS contents and lower GI values. Furthermore, the protein and soluble amylose contents, solubility and swelling power at 90 °C of the blanching yams were lower than those of the yams without blanching. We can effectively apply these flours in various products based on their characteristics.

Inclusion of poultry based food ingredients in the formulation of noodles and their effects on noodle quality characteristics

Incorporating exogenous proteins into food products is a better practice for improving nutritional attributes of food commodities. In the search for a way to improve the product and nutritional quality of noodles, this study was aimed to evaluate the impact of the incorporation of poultry based ingredients egg yolk powder (EYP) and chicken mincemeat (CMM) in noodles at different levels (5, 10 and 15%, w/w). The incorporated noodles were subjected to evaluation of the cooking, texture, colour, sensory and microstructure properties. The results showed that the incorporation of poultry based food ingredient types and amount influence the nutritional content of noodles. Simultaneously, poultry based ingredients incorporated noodles showed the acceptable firmness and colour charatertistics. Scanning electron micrograph of the incorporated noodles showed the gelatinized starch granules enveloped by protein matrix, and also indicating a better structure as compared to the control. The sensory profile of incorporated noodles was showed significant (p ≤ 0.05) high overall quality. The result of this study showed that 10% (w/w) EYP and 15% (w/w) CMM incorporated noodles showed a better overall noodles quality attributes (texture, colour, sensory and microstructure). The results also provide ideas about the inclusion of the appropriate levels of poultry based ingredients (EYP and CMM) with a better sensory and nutritional profile. Therefore, this study may be useful in the food industry for the production of poultry based ingredients noodles with enhanced quality characteristics.

THE INFLUENCE OF GLUTEN - FREE FLOURS ON THE QUALITY INDICATORS OF BISCUIT SEMI - FINISHED PRODUCTS

The article is devoted to the research of applicability of gluten-free flours from cereal crops and from by-products of cereal crop processing - ground crumbs sifted out in a process of flake production from rice, corn and millet during the production of biscuit semi-finished products. Taking into account that viscosity is an important technological characteristic of foam-like biscuit dough, as it determines foam strength and dispersed medium stability, the influence of gluten-free flours on the structural and rheological properties of biscuit dough was studied. It is determined that the substitution of wheat flour for cereal flours leads to viscosity reduction of the dough as a consequence of absence of gluten-forming proteins in them. A comparative analysis of changes in viscous properties of biscuit dough based on flour from flakes crumb while warming it up to 60°C with dough based on cereal flours and dough based on wheat flour was held. It is shown that the presence of partially gelatinized starch granules in flour from flake crumb, as a result of technological peculiarities of their extraction, promotes greater demonstration of thickening properties already at the initial stage of baking than in cereal flours. This leads to an increase of dough viscosity and formation of desired rheological characteristics, which provide the porous structure of finished products. To provide the high quality of gluten-free biscuit semi-finished products, the recipe composition of gluten-free biscuit semi-finished product, based on flour mixture from millet flakes crumb, corn and rice flour, was optimized by using the method of mathematical design of experiments. The porosity indicator was chosen as the criteria for the evaluation of influence of proportion of gluten-free flours on the quality of biscuit semi-finished products. The response surfaces of dependency of biscuit porosity from mass ratio of recipe components in the composite mixture were obtained. It was confirmed experimentally that the use of pre-gelatinized acetylated modified starches during the production of gluten-free biscuit semi-finished products, facilitates the stabilization of the structural and rheological properties of foam structure - viscosity growth of biscuit dough because of foam-stabilizing property, which is particular to them. It was demonstrated that the obtained gluten-free biscuit semi-finished products based on flour composite mixtures with addition of modified starches, had high quality indicators. Based on the results of the research conducted, the recipe was formulated, technological parameters of production of new types of gluten-free biscuit semi-finished products were determined. Key

Effects of drying processes on starch-related physicochemical properties, bioactive components and antioxidant properties of yam flours.

The effects of five different drying processes, air drying (AD), sulphur fumigation drying (SFD), hot air drying (HAD), freeze drying (FD) and microwave drying (MWD) for yams in terms of starch-related properties and antioxidant activity were studied. From the results of scanning electron microscopy (SEM), polarized optical microscopy (POM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR), the MWD sample was found to contain gelatinized starch granules. The FD yam had more slow digestible (SDS) and resistant starches (RS) compared with those processed with other modern drying methods. The bioactive components and the reducing power of the dried yams, were lower than those of fresh yam. When five dried samples were compared by principal component analysis, the HAD and SFD samples were observed to have the highest comprehensive principal component values. Based on our results, HAD would be a better method for yam drying than the more traditional SFD.

High pressure processing (HPP) of pea starch: Effect on the gelatinization properties

High pressure processing (HPP), an emerging technology, can be used to promote gelatinization of starch granules. This phenomenon is highly dependent on the source of starch, pressure level, time and temperature applied as well as the dispersion medium. This work evaluated the effect of HPP (up to 600MPa/15 min/25 °C) on particle size distribution, optical microscopy, differential scanning calorimetry and pasting properties of pea starch. Results showed no difference between control samples and processed ones up to 400 MPa (water dispersion) or all samples dispersed in ethanol, except for the thermal properties at 400 MPa that showed 31% of gelatinization in water dispersion. Samples processed at pressures higher than 500 MPa showed changes on particle size and distribution (increase at 500 MPa and a slight reduction at 600 MPa), and no detected gelatinization enthalpy at DSC. The optical microscopy observation indicated that HPP (>400 MPa) caused the loss of birefringence. Regarding the pasting properties, the initial viscosity increased from 8 cP at 0 MPa to 34 cP at 600 MPa. All results indicated that HPP can be used to promote “cold gelatinization” on pea starch water dispersion, achieving a specific technological profile and possibly leading to new ingredients.

Effect of starch source on gel properties of kappa-carrageenan-starch dispersions

Eight different starches (2%, w/w) were incorporated into dispersions containing various amount of kappa-carrageenan (0.2%, 0.6% and 1.0%, w/w), and the properties including morphology, rheology, texture and syneresis of gel from carrageenan and carrageenan-starch dispersions were examined and compared for elucidating the effect of starch source on gel properties of the dispersions. Results showed that the swelling of starch granules in carrageenan dispersions decreased with increasing concentration of carrageenan. Carrageenan dispersions incorporated with starch possessed high granule rigidity or low swelling power had high values of storage modulus and gel firmness. The presence of starch reduced the syneresis of carrageenan gels, and this was more profound for dispersions containing starch with high amylose content. At each concentration of carrageenan, swelling power of starch showed significant correlations with the storage modulus (r2 ≥ 0.590, p < 0.05) and firmness (r2 ≥ 0.890, p < 0.05) of carrageenan-starch dispersions. Results indicate that the presence of starch in carrageenan dispersion improves the gel strength and reduces the syneresis of carrageenan. Moreover, the amylose content of starch and the rigidity of gelatinized starch granules play important roles on gel properties of carrageenan-starch dispersions.

Influence of water chestnut (Trapa natans) on chemical, rheological, sensory and nutritional characteristics of muffins

Water chestnut flour (WCF) was utilized in the formulation of muffins. Blends were prepared by replacing 25, 35, 45 and 55 % of wheat flour with WCF. Farinograph characteristics of the blends showed that with increase in the level of WCF there was a decrease in the dough stability and increase in mixing tolerance index, indicating weakening of the dough in comparison to control. Pasting characteristics indicated increase in gelatinization temperature and peak viscosity of the blends. Micrographs of muffin crumb prepared by incorporating WCF showed gelatinized starch granules embedded in the disrupted protein matrix. The lightness value of muffin crumb and sensory scores for crust color, shape, crumb color, grain and texture decreased with increase in the level of WCF in muffins when compared to control. However the 55 % WCF incorporated muffins received significantly lower scores for overall quality. Incorporation of WCF at 45 % level produced muffins of acceptable quality.

Starch Consolidation Casting of Cordierite Precursor Mixtures—Rheological Behavior and Green Body Properties

The rheology of suspensions and mechanical properties of green bodies with cordierite composition (raw materials 37 wt% kaolin, 41 wt% talc, 22 wt% alumina, resulting in 46.6 wt% SiO2, 38.1 wt% Al2O3, 13.6 wt% MgO) and two types of starch (corn or potato) are investigated. Rotational viscometry of suspensions with solids loading 50, 60, and 70 wt% without starch showed that all tend to be shear‐thinning with a small degree of thixotropy. Suspensions with a total solids loading of 60 wt% with 25 wt% replaced by starch exhibited higher viscosity and thixotropy, but the viscometric behavior is almost identical for the two starch types (apparent viscosities 130–50 mPa·s). Oscillatory rheometry shows that for suspensions with potato starch the onset temperature for gelatinization is 61°C–63°C, that is, lower than for corn starch (72°C–73°C). Maximum storage moduli and phase shift values after gelatinization are similar for both systems. The mechanical properties of green disks, measured via diametral compression tests, reveal clear differences between materials prepared with corn and potato starch, with the latter showing higher elastic modulus, higher strength, and higher deformation at fracture, obviously because of incompletely gelatinized starch granules in the green bodies prepared with corn starch.

FLOCCULATION/DISPERSION OF HEMATITE WITH CAUSTIC DIGESTED STARCH

Selective flocculation of hematite with starch is a process well-known in practice. However, the separation of hematite from other minerals depends strongly on the methods of starch digestion performed either as heating-digestion or alkali-digestion (different type and dosage of alkali). The purpose of this study is to identify possible influence of the alkali-digested starch on flocculation of ultra- fine hematite when the starch was digested at different concentrations of sodium hydroxide at room temperature. Adsorption of starch digested with sodium hydroxide at different concentration on hematite was investigated by abstraction and co-precipitation tests. Turbidities tests, settling rates, flocculation/dispersion measurement and Fourier transform infrared spectroscopic analysis (FTIR) have also been conducted. Based on the results of the above mentioned tests it is suggested that the flocculating power of caustic digested starch towards fine particles may be significantly weakened, while its dispersing ability starts to play a role instead, if the concentration of sodium hydroxide is high enough in starch digestion. When the weight ratio of NaOH /starch is lower than 2, incomplete gelatinization of starch granules may lead to coagulation of fine particles of hematite mostly due to non-selective electrostatic attraction. The weight ratio of NaOH /starch from 2 to 4 helps to flocculate mineral surfaces selectively and efficiently, assuring a complete digestion of starch granules and a small amount of acidic functional products on the starch chain. However, much smaller and homogenous short-chain granules resulting from higher concentration of sodium hydroxide (the weight ratio of NaOH /starch is more than 4) used to digest starch may weaken the flocculating capacity of the caustized starch for hematite and lead to its dispersion.

Polishing and parboiling effect on the nutritional and technological properties of pigmented rice

This study aims to evaluate the effects of polishing and parboiling on proximate composition, structure, phenolic compounds, antioxidant activity, cooking time and hardness of IAC-600 black rice cultivar and MPB-10 red rice lineage. Proximate analysis and light micrographs revealed higher migration of red rice proteins than black rice proteins to the endosperm as a result of parboiling. Parboiling reduced the ash content of red rice while no difference was determined in black rice. Gelatinized starch granules from both genotypes showed similar appearance. There was a decrease in relative crystallinity on both black and red rice subjected to parboiling, which was an indicative of crystallites disruption. Polishing removed more than 90% of free phenolics for both genotypes, while parboiling allowed the partial preservation of free phenolics content in polished rice. Parboiling induced an increase in the cooking time of red rice, but a decrease in the cooking time of black rice.

Evaluation of rheological, bioactives and baking characteristics of mango ginger (curcuma amada) enriched soup sticks.

Wheat flour was replaced with mango ginger powder (MGP) at 0, 5, 10 and 15%. Influence of MGP on rheological and baking characteristics was studied. Farinograph was used to study the mixing profile of wheat flour-MGP blend. Pasting profile of the blends namely gelatinization and retrogradation were carried out using micro-visco-amylograph. Test baking was done to obtain the optimum level of replacement and processing conditions. Sensory attributes consisting texture, taste, overall quality and breaking strength were assessed. Nutritional characterization of the soup sticks in terms of protein and starch in vitro digestibility, dietary fiber, minerals, polyphenols and antioxidant activity were determined using standard methods. With the increasing levels of MGP from 0 to 15%, the farinograph water absorption increased from 60 to 66.7%. A marginal increase in the gelatinization temperature from 65.4 to 66.2°C was observed. Retrogradation of gelatinized starch granules decreased with the addition of MGP. The results indicated that the soup stick with 10% MG had acceptable sensory attributes. The soup stick showed further improvement in terms of texture and breaking strength with the addition of gluten powder, potassium bromate and glycerol monostearate. The total dietary fiber and antioxidant activity of the soup sticks having 10% MGP increased from 3.31 to 8.64% and 26.83 to 48.06% respectively as compared to the control soup sticks. MGP in soup sticks improved the nutritional profile.

Pasting investigation, SEM observation and the possible interaction study on rice starch–pullulan combination

The pasting properties of rice starch (RS) with high concentration (10%, w/w) were investigated in the presence or absence of pullulan (PUL) using a rapid visco-analyzer (RVA). Addition of pullulan resulted in the reduction of peak viscosity, trough viscosity, final viscosity, and setback value of RS. Furthermore, an interesting phenomenon, i.e. a small viscosity peak appeared in the RVA curves of RS–PUL mixtures, was observed. It indicated that addition of pullulan might suppress the gelatinization of starch granules by maintaining the integration of some granules. The scanning electron microscope (SEM) observation of samples suggested that starch granules could be wrapped by a thin membrane composed of pullulan and/or pullulan-amylose associations. The coating ability of pullulan and/or the possible molecular interactions between pullulan and amylose could be responsible for these results.

Study of Thermal and Structural Properties of Starch Granules from Different Maize Genotypes

The thermal and structural properties of starch granules of four maize genotypes (Palomero Toluqueno native maize, HS-2 commercial hybrid, L3-Q2 M09 experimental hybrid and Cacahuacintle native maize) were studied. By using adiabatic scanning calorimetry (ASC), the specific heat capacity (cp(T)) of these samples was obtained. Also, by integration of the area under the cp(T) curves, the enthalpy for the starch gelatinization was determined, from which the percentage of gelatinized starch granules was obtained as a function of the temperature. From the X-ray diffraction patterns of the starch granules, the degree of crystallinity of the samples was derived. The average size of the starch granules, for the different maize genotypes, was calculated from the images obtained by Scanning Electron Microscopy (SEM). We found a correlation between the enthalpy of gelatinization and the average size of starch granules, and also between the degree of crystallinity and the average size of the starch granules.

Physical and Molecular Characterization of Millet Starches

ABSTRACTThis study investigated the physical and molecular starch characteristics of four Canadian‐grown millet species: pearl, foxtail, proso, and finger millet. The millet starch granules ranged from about 2.5 to 24 μm in size and were mainly polygonal with a few spherical ones. Their amylose contents ranged from 28.6 to 33.9%, with finger and pearl millets having much more of long amylose chains than short amylose chains compared with foxtail and proso millets. Starches also differed in the molecular structure of their branched amylose, with finger and pearl millets having longer glucan chains between branch points. The enthalpy of gelatinization of starch granules ranged from 11.8 to 13.2 J/g, and the enthalpy of melting of the retrograded starches ranged from 2.2 to 5.9 J/g. The onset temperature of gelatinization (To) of the starches ranged from 62.8 to 70.6°C. Addition of iodine vapor to the granular starches showed significant (P &lt; 0.05) differences in the ratio of the absorbance to scattering coefficient (K/S) values, indicating differences in the rigidity of the glucan chains present in the granules. Starches with short amylose chains exhibited higher K/S values. Iodine vapor addition resulted in altered X‐ray diffractogram peak intensities. The study suggested differences in the structure and granular architecture of the millet starches.

Physicochemical characterization and in vitro assessment of the nutritive value of starch yield from corn dried at different temperatures

To assess modifications induced in starch granules during high temperature drying of corn grain and their effect on the nutritive value of corn-starch, physicochemical and structural characteristics of starch granules from corn grains dried at different temperatures have been determined. Additionally, their in vitro digestibility and fermentation patterns were investigated, using a two steps in vitro model of the pig digestive tract. High drying temperatures induced a partial gelatinization of starch granules and produced a very favorable substrate for porcine pancreatic amylase and led to an altered physical structure which affected the rate and extent of starch granules digestion by gastric and pancreatic enzymes. Starch micrographs showed that granules extracted from corn dried at 130°C were less angular, bigger, and had smoother surface than granules extracted from corn dried at lower temperature. High-temperature drying increased the digestibility of wet-milled starch granules, while the residues of starch from corn dried at lower temperature produced higher volume of gas during their in vitro fermentation, despite their more pronounced crystalline characteristic. The residues from pepsin–pancreatic digestion of overall samples analyzed showed highly degraded and pitted granules or fragmented external shells, starch from corn dried at 130°C being the most degraded. Aforementioned changes of nutritional attributes of starch granules are discussed according to the restructuration occurring within both their amorphous and crystalline phase, as well as to the changes of the granules size and purity.

Pasting and rheological properties of rice starch as affected by pullulan

Effect of pullulan (PUL) on the pasting, rheological properties of rice starch (RS) was investigated. The swelling power, amylose leaching, and confocal laser scanning microscopy (CLSM) observation of the samples were also conducted to explore the possible interaction between starch and pullulan. Rapid visco-analysis (RVA) showed that PUL significantly changed viscosity parameters of rice starch–pullulan (RS–PUL) mixtures. Dynamic rheological measurements revealed that the modulus (G′, G″) of the mixtures increased with the increase of pullulan concentration from 0.01% to 0.07%, but then decreased with the increase of pullulan concentration from 0.07% to 0.50%. The pasting and rheological properties of samples indicated that pullulan could blend well with rice starch and promote the gelatinization of starch granules at low concentration of pullulan, but suppress the gelatinization of starch granules at high concentration of pullulan. The results of swelling power, leached amylose and CLSM observation of samples further suggest that the interaction between starch and pullulan occurred in the RS–PUL system and the interaction was hypothesized to be responsible for these results.