Partial Gelatinization Research Articles

Effects of partial gelatinization on structure and thermal properties of corn starch after spray drying

Partially gelatinized starch was prepared by gelatinizing corn starch at 64–72°C followed by spray drying (inlet temperature, feed flow rate, air flow rate of 200°C, 7.2ml/min and 0.375m3/h, respectively). The morphology, granule size, crystalline fraction, swelling power and gelatinizing properties of partially gelatinized starch were investigated and compared with those of native starch. The surface morphology of partially gelatinized starch granules was shriveled with multiple surface folds. The granule size of partially gelatinized starch was smaller than that of native corn starch. There was either complete absence of crystalline fraction in partially gelatinized starch or the extent of crystalline fraction was greatly reduced. The swelling power of partially gelatinized starch was higher than that of the native starch below 60°C, while it was lower than that of native starch above 60°C. There was an increase in gelatinization temperature and a decrease in gelatinization enthalpy in partially gelatinized starch compared to that of native starch.

Effect of Partial Gelatinization during Precooking Operation on the Viscosity of Retort Curry

製造工程中に起きるデンプンの部分糊化が，レトルトカレーの最終粘度に及ぼす影響を調べた．レトルトカレーの粘度は，煮込みとそれに続くレトルト殺菌工程で，原料中のデンプンが糊化することで上昇する．しかし，煮込み工程前の原料混合工程の温度が高過ぎると，最終粘度が十分に上昇しないことが経験的にわかっている．そこで，原料混合工程の温度とデンプンの糊化状態をアミロース溶出度，膨潤度，動的粘弾性および示差走査熱量分析から調べ，最終粘度との関係を考察した．その結果，原料混合工程の温度が65℃以上であると，デンプンの部分糊化が起こるため，その後の煮込み工程と殺菌工程での粘度上昇は抑制されることがわかった．

Starch particles for food based Pickering emulsions

Intact starch granules are a new source of particles for stabilizing emulsions, so called Pickering emulsions. Small (1-2μm) and uni-modal starch granules at various concentrations have been used in this study to investigate the stability of the emulsions, the drop size dependence of the starch concentration and the barrier properties of the stabilizing starch layer upon heating. The granules were modified with octenyl succinic anhydride (OSA) to increase the hydrophobicity. The drops in the emulsions prepared in this study were in the 10-100μm range depending on the starch concentration, and the drop size decreased with an increased amount of added starch granules. During the 8 week storage, the emulsion drops were stable to coalescence and the volume occluded by the emulsion phase was unaffected or even increased. In order to increase the barrier properties at the oil-water interface the emulsions were gently heated, which induced a partial gelatinization of the starch granules. The efficiency of the barrier was characterized by a lipolysis experiment where the activity of lipase was measured. The activity of lipase was decreased with nearly 70% compared to an unheated starch stabilized emulsion, which will be useful in applications where a controlled release of specific substances in the gastro intestinal tract is desirable.

Effect of acid‐ethanol treatment followed by ball milling on structural and physicochemical characteristics of cassava starch

AbstractStructural and physicochemical characteristics of cassava starch treated with 0.36% HCl in anhydrous ethanol during 1 and 12 h at 30, 40, and 50°C followed by ball milling for 1 h were analyzed. Average yield of acid‐ethanol starches reached 98% independent of the treatment conditions. Solubility of acid‐ethanol starches increased with reaction temperature and time, but it did not change after ball milling. Granule average size reduced with chemical treatment from 25.2 to 20.0 µm after 12 h at 50°C. Ball milling decreased the granule average diameter of the native starch and those chemically treated at 30°C/1 h or 40°C/1 h, but it did not alter the starches treated for 12 h, independent of temperature. From scanning electron microscopy (SEM), starch granules presented round shape and after modification at 50°C/12 h, before and after ball milling, showed a rough and exfoliated surface. Some granules were deformed, suggesting partial gelatinization that was more intense after milling. Starch crystallinity increased as temperature and time of chemical treatment were increased, while amylose content, intrinsic, and pasting viscosities decreased. Gelatinization temperatures increased for all chemical starches. The findings can be related to the preferential destruction of amorphous areas in the granules, which are composed of amylose and amylopectin. After ball milling, the starch crystallinity decreased, amylose content, intrinsic, and pasting viscosities kept unchanged and gelatinization temperatures and enthalpy reduced. Ball milling on native and chemical starches caused the increase of amorphous areas with consequent weakening and decreasing of crystalline areas by breaking of hydrogen bonds within the granules.

Study of DIC hydrothermal treatment effect on rheological properties of standard maize (SMS), waxy maize (WMS), wheat (WTS) and potato (PTS) starches

Standard maize (SMS), waxy maize (WMS), wheat (WTS) and potato (PTS) starches were hydrothermally treated by Instantaneous Controlled Pressure Drop (DIC) process at different pressure levels (1, 2 and 3 bar) corresponding to the temperatures of 100, 122 and 136 °C, respectively. The rheological properties and particle size of treated starches under various conditions were compared to the native ones. The results showed for all starches, except for WTS, a reduction of the consistency coefficient and the yield stress ( τ 0) with increased intensity of the hydrothermal treatment conditions. Furthermore, τ 0 vanished for severe treatment conditions. The DIC treatment yielded an increased fluidity and a loss of the conservative modulus of the pastes, as a result of partial gelatinization of starch granules. The extent of the observed effect depended on the botanical origin. Wheat starch exhibited a different behaviour: the consistency coefficient and the conservative modulus being higher for DIC treated starch except for the most severe conditions.

Crystallinity and structure of starch using wide angle X-ray scattering

Wide angle X-ray diffraction was used to evaluate the crystalline fraction of a variety of starches, using preliminary smoothing then an iterative smoothing algorithm to estimate amorphous background scattering. This methodology was then used to determine initial crystallinity and monitor gelation and retrogradation of high amylose thermoplastic starch used to produce film. Retrogradation was monitored over a 5-day period. It was found that the starch film retrograded rapidly over the first 12 h with the film displaying both B-type crystallinity and long range amorphous ordering that were separately quantitatively calculated. Changes in starch films, including complete or partial gelatinization, retrogradation and crystallinity, were all determined through wide angle X-ray diffraction.

INFLUENCE OF HYDROXYPROPYL METHYLCELLULOSE ON THE RHEOLOGICAL AND MICROSTRUCTURAL CHARACTERISTICS OF WHOLE WHEAT FLOUR DOUGH AND QUALITY OF PURI

ABSTRACTPuri is a traditional unleavened fried product prepared from whole wheat flour. Hydroxypropyl methylcellulose (HPMC) was used to study its effect on rheological characteristics of whole wheat flour dough and puri making quality. Addition of HPMC at 0.5 and 1.0% w/w increased the water absorption and dough stability whereas the resistance to extension and extensibility decreased. Pasting temperature, peak viscosity and cold paste viscosity gradually decreased. The moisture and fat contents of puri increased marginally. Quality parameters and sensory acceptability were monitored after 0 and 8 h of storage. Addition of 0.5% HPMC gave higher sensory scores. Microscopic observations during puri processing showed that the starch granules in the control dough were clearly visible in the protein matrix, which reduced on frying due to partial gelatinization. Microstructure of puri with HPMC showed higher gelatinization of starch. It also helped in moisture retention and hence, resulted in highly pliable and soft‐textured puri.PRACTICAL APPLICATIONS Puri is a traditional unleavened fried product that is prepared by mixing whole wheat flour and water, sheeted to a desirable thickness and fried. Use of hydroxypropyl methylcellulose (HPMC) affected the whole wheat flour dough and puri making quality. It helped in moisture retention and hence, resulted in highly pliable and soft‐textured puri. Microstructure of puri with HPMC showed higher gelatinization of starch.

Properties of Starch Subjected to Partial Gelatinization and β-Amylolysis

The overall objective of this research is to understand the impact of partial gelatinization and beta-amylase hydrolysis (beta-amylolysis) on the physicochemical properties of starch. Three starches (normal corn, waxy corn, and wheat) were chosen as test examples and thermally treated at 40% moisture content to up to 95 degrees C and then subjected to beta-amylolysis. The enzyme treatment resulted in over 10% maltose yield. Subsequent debranching analysis showed the production of chain stubs as short as having the degree of polymerization of 2 and 3, suggesting a thorough beta-amylolysis at certain branch locations. For starch samples subjected to partial gelatinization, polarized light microscopy shows reduced intensity of birefringence and differential scanning calorimetry shows reduced enthalpy change associated with gelatinization. Both indicate the reduced chain organization due to the treatment. Further, a substantial transformation of initial A-type crystalline structure to B- and V-types upon treatments is noticed from X-ray powder diffraction measurements. In addition, the rapid viscosity analysis (RVA) indicated a drastic viscosity reduction, increased peak temperature, and improved stability of pasting behavior due to hydrothermal treatments and beta-amylolysis. Overall, our results point out the possibility of obtaining modified starches having desirable stable pasting behavior by using a combined partial gelatinization and beta-amylolysis approach.

Analysis of aged gelatin by AFlFFF-MALS: Identification of high molar mass components and their influence on solubility

Gelatin is an important product for several industries and its solubility dramatically influences its functional properties. In order to be able to predict the gelatin behaviour, a new technique for its analysis has been developed with an Asymmetrical Flow Field-Flow Fractionation coupled to a multi-angle light scattering. The AFlFFF-MALS analysis showed the gelatin molar mass ranging from 5 × 10 4 to 2 × 10 7 g mol −1. This technique also permitted to follow aggregation of gelatin samples after process in an oven at 75 °C. Between 0 and 4 days, some huge aggregates appeared. Their size and density increased without changing gelatin solubility. From 8 to 30 days, the molar mass and density of these aggregates increased leading to partial gelatin insolubilisation in water. This phenomenon is supposed to be due to cross-linking of the gelatin macromolecules.

Maize-Based Gluten-Free Bread: Influence of Processing Parameters on Sensory and Instrumental Quality

The performance of maize bread with spongy texture is still a technological challenge due to the absence of a natural network required for holding the carbon dioxide released during the fermentation process. The objective of this research was to investigate the influence of different maize varieties (regional and hybrid), milling process (electric and water mill), formulation and processing variables on the sensory and instrumental (specific volume, texture and colour) quality attributes of corn bread. For that purpose, the traditional breadmaking process applied to the development of the ethnic Portuguese bread (broa) obtained from composite maize–rye–wheat flour was modified to produce gluten-free broa. Significant differences (P < 0.05) between regional and hybrid maize were detected in terms of protein, amylose, and maximum, minimum and final viscosities as evaluated by Rapid Visco Analyser. Concerning the effect of milling process, the grinding in a water mill occurs at slower rate than it does in the electrical mill, in consequence the flour from water milling had lower ash content and higher maximum, minimum and final viscosities than the one obtained from electrical milling. An important point in the breadmaking process was the flour blanching that resulted in doughs with higher consistency, adhesiveness, springiness and stickiness as measured by texture analyser, due to the partial gelatinisation of the corn starch. Baking assays demonstrated sensory preference for regional in detriment of hybrid maize varieties for traditional broa production. Breadmaking technology could be satisfactorily applied to produce gluten-free broa.

Study of Structural and Thermal Changes in Endosperm of Quality Protein Maize During Traditional Nixtamalization Process

ABSTRACTThis work presents the study of the structural changes of the endosperm of Quality Protein Maize (QPM H‐368C), modified by alkaline cooking at two different temperatures (72 and 92°C) and steeping time of 0–7 hr. Structural changes in the outermost 10% layers, the subsequent 10%, and the remaining 80% of the endosperm as a function of the steeping time were studied using scanning electron microscopy (SEM), X‐ray diffraction, and differential scanning calorimetry (DSC) techniques. SEM images revealed that soft and hard endosperm have different shapes and packing factors. The X‐ray diffraction patterns of the hard and soft endosperm from raw corn suggest that the hard endosperm consists mainly of amylopectin and has a bigger relative crystallinity quality than the soft endosperm. Samples cooked at 72 and 92°C with and without the (Ca(OH)2 and steeped for 0, 3, and 7 hr, showed structural changes, X‐ray diffraction patterns from the outermost 10% layers and subsequent 10% of the endosperm were completely amorphous. This fact is related to the total or partial gelatinization of the starch. The crystallinity in the internal layers of endosperm (remaining 80%) did not have significant changes after the treatments and exhibited the characteristic patterns of crystalline amylose and amylopectin. DSC measurements in the outermost layers of the endosperm did not exhibit the characteristic endothermic peak of starch (from 64 to 81°C) compared with the raw sample, while the endotherm peak for 80% of the endosperm internal layers appears in all cases (72 and 92°C). According to these results, a new definition of the nixtamalization process can be developed as follows. During the nixtamalization process there is a total gelatinization of the starch granules from the most external layers, and a partial gelatinization of the innermost internal layers of the endosperm.

Influence of alkali concentration on the deproteinization and/or gelatinization of rice starch

Starch was extracted from BR-IRGA110 rice flour using solutions of NaOH at concentrations varying between 0.06% and 0.30% (w/v). The efficiency in protein removal was evaluated using intrinsic fluorescence. In parallel, the morphological changes in starch granules and their partial gelatinization were observed using scanning electron microscopy. The starch crystallinity was monitored by X-ray diffraction and the gelatinization properties were analyzed using differential scanning calorimetry. It was found that the granular organization was significantly altered when the alkaline extraction was conducted with NaOH solutions at concentrations higher than 0.24% (w/v).

State diagram of potato starch–water mixtures treated with high hydrostatic pressure

Potato starch–water mixture was treated with high hydrostatic pressure (HHP) of up to 1.2 GPa, and effect of starch content (10–70% (w/w)) on HHP-gelatinization was investigated by differential scanning calorimetry (DSC). Depending on the treatment pressure and potato starch content, DSC thermograms showed decrease in enthalpy change of heat gelatinization reflecting the progress of HHP-gelatinization and increase in enthalpy change of re-gelatinization of retrograded starch. From the viewpoint of the enthalpy changes, physically modified state of HHP-treated potato starch–water mixtures was classified as follows: no change, partial gelatinization, complete gelatinization, partial gelatinization and retrogradation, and complete gelatinization and retrogradation. A state diagram of potato starch–water mixtures (treatment pressure vs. starch content) was presented.

Thermal and rheological properties of nixtamalized maize starch

The effect of nixtamalization process on thermal and rheological characteristics of corn starch was studied. Starch of raw sample had higher gelatinization temperature than its raw counterpart, because, the Ca 2+ ions stabilize starch structure of nixtamalized sample; however, the enthalpy values were not different in both samples. The temperature of the phase transition of the retrograded starches (raw and nixtamalized) were not different at the storage times assessed, but the enthalpy values of the above mentioned transition was different, indicating a lower reorganization of the starch structure in the nixtamalized sample. The viscoamylographic profile showed differences between both starches, since raw starch had higher peak viscosity than the nixtamalized sample due to partial gelatinization of some granules during this heat treatment. Rheological test showed that at low temperature (25 °C) the raw and nixtamalized starches presented different behaviour; however, the elastic characteristic was more important in the starch gel structure. The nixtamalization process produced changes in thermal and rheological characteristics becoming important in those products elaborated from nixtamalized maize.

Effect of partial gelatinization and retrogradation on the enzymatic digestion of waxy rice starch

The effect of partial gelatinization and retrogradation on in vitro enzymatic digestibility of waxy rice starch was investigated, and the relationship between the residual crystallinity and digestibility measured. An aqueous dispersion of starch (5%, dry weight basis) was partially gelatinized by heating at different temperatures (60, 65, or 70 °C for 5 min). The relative melting enthalpy values of the starch samples, based on the melting enthalpy of native starch, were 69.0, 36.7, and 8.5%, respectively. Retrograded starch samples were also prepared by storing a fully gelatinized starch paste (5% starch) at 4 °C for 2, 4, or 7 d, and the relative melting enthalpy values for the starch samples were 36.7, 67.2, and 79.9%, respectively. The partial gelatinization and retrogradation changed the enzymatic digestion behavior of the waxy rice starch samples, and the changes were significant in the initial stage of digestion. The digestion rate was reduced as the melting enthalpy increased. The amounts of slowly digestible starch (SDS) and resistant starch (RS) correlated positively with the relative melting enthalpy of the partially gelatinized or retrograded starch samples. The glycemic index (GI) estimated using an in vitro digestion test correlated negatively with the relative melting enthalpy. At similar melting enthalpy levels, the partially gelatinized starch samples were more resistant to enzymatic digestion than the retrograded starch samples, indicating that the thermal history and the crystalline morphology affected the enzymatic digestion behavior of starch.

Effect of Annealing Temperature on Gelatinization of Rice Starch Suspension As Studied by Rheological and Thermal Measurements

The effect of annealing temperature (Ta) on the rheological behavior of 10 wt % rice starch suspension was investigated by the dynamic viscoelasticity, the differential scanning calorimetry (DSC), and the amount of leached out amylose and the swelling ratio of starch suspension. The rheological behaviors of the annealed samples are classified into three types in terms of Ta: Ta1, 48 and 55 degrees C, which are much lower than the gelatinization temperature, Tgel (=62 degrees C); Ta2, 58, 60, and 62 degrees C, which are almost the same as Tgel; and Ta3, 65, 68, 70, and 73 degrees C, which are much higher than Tgel. For the samples annealed at Ta2, the onset temperature of the storage and the loss moduli, G' and G'', increased with increasing T(a), and G' and G" in the temperature range from 65 to 90 degrees C gradually increased though smaller than those for the nonannealed sample, the control. This can be understood by the partial gelatinization; i.e., the leached out amylose prevents further amylose from leaching out. The rheological property of the samples annealed at Ta1 is not so different from that of the control, and the samples annealed at Ta3 are almost gelatinized. The rheological behavior of starch suspension can be controlled by Ta.

Resistant starch production from mango starch using a single‐screw extruder

AbstractResistant starches were prepared from mango starch by extrusion. An experimental design with independent variables temperature, screw speed and moisture content produced 20 samples that were studied to determine the effect of these variables on resistant starch (RS) content, water absorption index (WAI) and water solubility index (WSI). RS content was affected by moisture content and temperature. Screw speed and temperature also influenced RS content, the highest level (97 g kg−1) being obtained at low screw speed and high temperature, this pattern can be associated with a longer residence time, which gives rise to more opportunity for amylose chain association. The regression model fitted to the RS experimental results showed a good correlation coefficient (0.80). When moisture content and temperature decreased, WAI increased (105–142 g kg−1), but low WAI values (70–77 g kg−1) were obtained at moisture contents between 200 and 300 g kg−1 and high temperatures (140–150 °C). When moisture content and temperature increased, WSI increased (222–332 g kg−1), but at high temperature value (120 °C) assayed and the lowest moisture content (150 g kg−1), WSI also increased. In the range of moisture contents tested and at low temperatures, only partial gelatinisation occurred and low solubility was obtained. Copyright © 2005 Society of Chemical Industry

Effect of hydrothermal treatment on the physical and rheological properties of maize starches

Standard maize (SMS) and waxy maize starch (WMS) were hydrothermally treated at their residual moisture level (∼12%) by Instantaneous Controlled Pressure Drop process in order to obtain pre-gelatinised starches in a single step. The effects of two parameters of this process, namely the steam pressure level and processing time, on the structural and rheological properties of the native maize starches were described. The occurrence of partial gelatinization for DIC treated starches was clearly attested by the increase of the median volume diameter in cold water, the decrease of the gelatinization enthalpy and a loss of birefringence under polarized light. This was more prominent for the highest pressure and longest time: 2.7–3 bar for 200–300 s. Sensitivity of starches to the process was also dependent on their origin, SMS being more affected than WMS.

Modification of Gelatinization Properties of Rice Flour by Heat-Treatment

The effects of autoclave and oven treatments on gelatinization properties of rice flour and on crystallite structures of rice starch in rice flour were studied using dynamic oscillatory measurement, differential scanning calorimetry (DSC), X-ray diffractometry, and scanning electron microscopy (SEM). Autoclave-treated rice flour (ATR) and oven-treated rice flour (OTR) were prepared using an autoclave at 120 °C for 60 min and oven at 160 °C for 60 min. Dynamic oscillatory and DSC measurements demonstrated that autoclave treatment modified the gelatinization properties that delayed gelatinization temperature (TG' and To) and decreased in peak storage modulus (G'p). Autoclave treatment caused formation of amylose-lipid complexes and partial gelatinization of starch granules in ATR studied by DSC and X-ray diffractometry. Autoclave-treatment engendered formation of amylose-lipid complexes and partial gelatinization of starch granules in ATR studied by DSC and X-ray diffractometry. Alteration of gelatinization properties of ATR flour is attributed to changes in rigidity of starch granules during treatment. Similarly to ATR, oven treatment was effective for gelatinization properties. Nevertheless, it was insufficient for rearrangement of starch chains in OTR flour.

Effect of Aminated Gelatin on the Nasal Absorption of Insulin in Rats

Absorption enhancers, which increase the permeability of drugs through epithelial membranes without damaging them, are especially useful for intranasal administration of peptide drugs. In this study, aminated gelatins, candidate enhancers, having different numbers of amino groups were prepared from gelatin (H-gelatin, isoelectric point = 9.0, MW 100 kDa) and a partial gelatin hydrolysate (L-gelatin, isoelectric point = 8.0, MW 5 kDa), and the enhancing effects on the nasal absorption of insulin, used as a model peptide drug, and 5(6)-carboxyfluorescein (CF), a paracellular marker, were examined in rats. The enhancing effect on insulin and CF depends on the MW and number of amino groups. A high correlation between the enhancing effects on insulin and CF was observed and this suggests that an increase in the paracellular permeability is the mechanism governing the nasal absorption-enhancement of aminated gelatins, at least as far as insulin and CF are concerned. The enhancing mechanism might be shared with other cationic polymers having absorption-enhancing effects.