Gelatinization Endotherm Research Articles

Assessing the occurrence of barley starch annealing under heat, moisture and time conditions relevant for kilning: An experimental design approach

In this work, the possible occurrence of barley starch annealing under kilning conditions was investigated. Using an I-optimal response surface methodology, the impact of temperature (45–55 °C), moisture content (30–50%) and time (1–5h) on the gelatinisation behaviour of starch in green malt was studied. An increase in onset (0.5–4.3 °C) and peak temperature (0.5–2.7 °C) and a change in peak width (+0.5 to - 3.2 °C) of the starch gelatinisation endotherm showed the extent of annealing that occurred within an industrially relevant design space. Temperature was the main driver behind the observed changes, but also interaction effects between temperature, moisture content and time contributed. Combined with increasingly high starch gelatinisation temperatures in barley, the observed increases in peak gelatinisation temperature due to annealing could hamper fermentable sugar production during brewing.

Changes in physico-chemical properties and water status of durum wheat constituents in pasta due to processing and cooking

Pasta is simply made from durum wheat semolina and water, through a succession of unitary operations. The changes of the interactions between durum wheat constituents and water molecules under different water content conditions provide information on the mechanisms involving wheat constituents and induced by the successive unitary operations. The objective of the present work is to describe the interactions between durum wheat constituents and water molecules in durum wheat semolina, dry pasta, and cooked pasta under different water content conditions using complementary analytical methods at different observation scales. Selected products were investigated by measurements of gelatinization endotherms by DSC, viscosity curves of a suspension by RVA, proton mobility by NMR, and molecular interactions by ATR-FTIR spectroscopy. The measured values describing the interactions between wheat constituents and water molecules are sensitive to changes induced by the process. These results contribute to a better understanding of the modifications induced by the succession of unitary operations on durum wheat constituents, from native semolina to cooked pasta.

Preparation and physicochemical properties of Cyperus esculentus starch from its tubers using ultrasound-assisted alkali method

Cyperus esculentus tubers are rich in starch, oil, protein, dietary fiber, and other nutrients. Ultrasonic treatment can reduce the combination of starch, protein, and dietary fiber in C. esculentus tubers during extraction of C. esculentus starch, thereby improving the extraction yield and shortening of the extraction time. In this study, the extraction yield of C. esculentus starch was 92.2% using ultrasound-assisted alkali method. The microstructure analysis showed that the granule characteristics of C. esculentus starch and other starches were similar. X-ray diffraction analysis showed that C. esculentus starch possessed an A-type crystal structure. The onset temperature of gelatinization endotherm and peak temperature of gelatinization of C. esculentus starch were only lower than those of sweet potato starch, and higher than other starches, which is 67.9 °C. The content of resistance starch (RS) (11.0%) in C. esculentus starch was the highest among the six starches. As an underutilized resource, C. esculentus is a new crop with high quality, high yield, and high comprehensive utilization value. Its aerial parts can be used as feed, green manure, and its underground parts can be edible and oily. C. esculentus starch can be a valuable source to develop into new functional food.

Physicochemical properties and viscoelastic behavior of rice–mung bean composite flour systems as potential ingredients for plant‐based foods

AbstractBackground and ObjectivesComposite flour (CF) from cereals and legumes has been used to formulate plant‐based and/or gluten‐free food products. Fundamental knowledge regarding the properties of CF is required to formulate food products with desirable qualities. This study aimed to investigate the pasting properties, thermal properties, and viscoelastic behavior of CF, containing rice flour (RF), mung bean flour (MF), and mung bean protein concentrate (MPC). The protein contents of the CF were 17.6%‐23.6% on a wet basis.FindingsThe CF containing the highest proportion of RF had the highest pasting temperature, peak viscosity, breakdown, setback, and melting enthalpy of retrograded amylopectin. The deconvoluted thermogram from differential scanning calorimetry (DSC) clearly distinguished the endotherms that arose from starch gelatinization, protein denaturation, and melting of the amylose−lipid complex. The gelatinization endotherm of CF was mainly governed by RF. CF containing a higher proportion of RF and MPC had stronger elastic behavior.ConclusionsThe type and composition of the flour greatly affected the physicochemical and viscoelastic properties of the CF. RF played an important role in the pasting and thermal properties of the CF samples. Combining RF and MPC could be used to enhance the elastic behavior of dough from CF systems.Significance and NoveltyDeconvoluted DSC peaks provided insight into the multiple thermal transitions that occurred during the processing of CF‐based foods. The overall results from this study could help in the formulation of food containing rice−mung bean CF in excess water or in a dough system.

Effect of different extrusion methods on physicochemical properties and qualities of noodles based on rice flour.

Rice noodles have been manufactured in the food industry using different extrusion methods, such as traditional and modern extrusions, which affect the noodle structure and qualities. Therefore, the effects of the extrusion process on qualities of rice noodles using the same blend of rice flour and crosslinked starch were evaluated. In this study, a capillary rheometer was used as an alternative approach to simulate the traditional extrusion method in which the noodles are obtained by continuously pressing the pregelatinized noodle dough through a die. For modern extrusion, a twin-screw extruder was employed to obtain the noodles in a one-step process. The optimal range of moisture content used in the formulation was studied. Upon cooking, the noodles showed a decrease in cooking time and cooking loss with increasing moisture content in the formulation. All cooked noodles showed comparable tensile strength, but those extruded by a twin-screw extruder had substantially greater elongation. Scanning electron micrographs revealed that the noodles prepared using the extruder had a denser starch matrix, while those obtained from a capillary rheometer showed the aggregation of starch fragments relevant to the existence of starch gelatinization endotherm from differential scanning calorimetry. This indicated that the extrusion process using the twin-screw extruder provided a more uniform starch transformation, i.e., more starch granule disruption and gelatinization, thus giving the noodles a more coherent structure and better extensibility after cooking. The obtained results suggested that different thermomechanical processes used in the noodle industry gave the extruded rice noodles different qualities respective to their different microstructures.

Gelatinization behavior of starch: Reflecting beyond the endotherm measured by differential scanning calorimetry

In this study, the gelatinization behavior of wheat starch was investigated using starch-water mixtures that were heated under different conditions. Heating starch-water mixtures at 50 °C, a temperature below onset temperature (To) of starch gelatinization, resulted in disruption of long- and short-range ordered structure, as measured by differential scanning calorimetry, X-ray diffraction and laser confocal micro-Raman spectroscopy, and the extent of disruption was greater when starch was heated at higher water content. At low water content (23–44%), heating duration had little effect on gelatinization behavior of starch, whereas at higher water content (54–75%), longer duration of heating resulted in greater disruption of multiscale structure of starch. From this study, we concluded that the gelatinization endotherm of starch does not represent the complete gelatinization behavior, and starch gelatinization initiates earlier than To. Longer duration of heating caused a greater disruption of starch structure at high water content than at low water content.

Structure, Physicochemical Properties, and In Vitro Starch Digestibility of Yellow Pea Flour Modified with Different Organic Acids

The objective of this study was to produce a pea flour ingredient with higher slowly digestible (SDS) and resistant (RS) starch fractions for functional food applications. Heat‐moisture treated flour (HMTF) in the presence of citric, gallic, or vanillic acids and esterified flour (EF) with citric acid were prepared and analyzed for structure and functionality using in vitro starch digestibility, differential scanning calorimetry, Rapid Visco Analyzer, swelling factor (SF), amylose leaching (AML), optical microscopy, and Fourier transform infrared (FT‐IR) spectroscopy. Significant (P < 0.05) increases in SDS and RS content of HMTF and EF were observed. Whereas the granule integrity and the birefringence were not affected by modification, the degree of crystalline order, which was determined by FT‐IR 1,047/1,022 cm−1 peak ratio, was decreased. Gelatinization enthalpies of modified flour were lower than that of native flour, whereas the gelatinization endotherms of HMTF were shifted to higher temperatures and those of EF to lower temperatures. Pasting properties were also affected greatly by both treatments. HMTF demonstrated reduced SF and AML, whereas EF had reduced SF and increased AML. Further, the extent of changes in the structure and functionality of HMTF depended on the type of acid utilized. Overall, heat‐moisture treatment with an organic acid and esterification were effective modifications to produce a pea flour ingredient with enhanced SDS and RS content.

Preparation and Evaluation of Alcohol-Alkaline-Treated Rice Starch as a Tablet Disintegrant

Purpose: To prepare and characterize alcohol-alkaline modified rice starch (MRS) as a disintegrant for tablets. Methods: The preparation of MRS was carried out using 3 M NaOH and 40 % ethanol solution. Characterization carried out for MRS include morphology, swelling capacity, thermal and pasting properties. Direct-compressed tablets (DCT) containing either propranolol hydrochloride (PPNL) or hydrochlorothiazide (HCTZ) were evaluated for hardness, friability, disintegration time and drug release. Results: The microstructure of MRS was different in shape and dimension from that of rice starch (RS). The absence of gelatinization endotherm and FT-IR spectral peak for MRS correlated with change in MRS structure and arrangement. MRS showed significantly higher swelling capacity (p < 0.05) than RS, and also proved to be a disintegrant in DCT. The disintegration time of the tablets containing MRS was lower in the presence of large particles (3.55 ± 0.56 min); high content of MRS (1.03 ± 0.06 min); low content of lubricant (3.16 ± 0.44 min); water soluble filler (1.55 ± 0.16 min for Super-tab®); and model drug (0.84 ± 0.09 min for HCTZ) (p < 0.05). Conclusion: MRS exhibits improved water solubility and swelling capacity compared with RS, and is thus a good disintegrant for direct-compressed tablet formulations, especially in the presence of water insoluble fillers. Keywords: Rice starch, Alcohol-alkaline treatment, Disintegrant, Directly compressed tablet, Insoluble fillers

Supramolecular structural evolutions of maize starch hydrothermally treated in excess water

Supramolecular structural changes of maize starch as affected by hydrothermal treatment in excess water were investigated. At a temperature slightly higher than the onset (To) of gelatinization endotherm (G), an increase in the size of the cavity at the granule core and a sharp decrease in the ordering degree of the semi‐crystalline lamellae occurred, together with the scattering objects apparently becoming looser. When the temperature approached close to the peak temperature (Tp) of endotherm G (70°C), the semi‐crystalline lamellae disappeared, accompanied by the emergence of a dual fractal structure. This suggests that the molecules of swollen maize starch displayed inhomogeneity on nanoscale, with a mass fractal structure at a higher scale level constituted by the scattering objects at a lower scale level. Additionally, it is proposed that a reduction in starch crystallites could enhance the degree of mixing between the crystalline and amorphous materials. The results enable a better understanding of starch supramolecular structural evolutions during the hydrothermal treatment in excess water.

Thermal Characterization of the Gelatinization of Corn Starch Suspensions with Added Sodium Hydroxide or Urea as a Main Component of Corrugating Adhesives.

The effects of sodium hydroxide and urea on the gelatinization of corn starch suspensions, a main component of corrugating starch adhesives, were studied using differential scanning calorimetry (DSC). Sodium hydroxide and urea decreased the gelatinization starting temperature (Ts1), peak temperature, conclusion temperature, enthalpy of gelatinization (DSCΔH), apparent activation energy (ApEa), and van’t Hoff enthalpy change (ΔHvHº). DSC analysis showed the gelatinization endotherm, the melting endotherm of starch−lipid complexes, and an exotherm attributable to the alkali-decomposition of starch. This exotherm was only observed in the first scan for sodium hydroxide additions of more than 3.8 mol%. The existence of the starch−lipid complexes was also suggested by the reappearance of the corresponding endotherm in the second DSC scan. The increases in the gelatinization rate constants caused by the two additives were deduced from the Arrhenius equation using ApEa. The relationship between the temperature corresponding to the half gelatinization transition (Tm) and DSCΔH, and that between Tmand ApEa quantitatively agreed for the two additives, suggesting that gelatinization might be stimulated by a similar mechanism involving breaking intermolecular hydrogen bonds in starch. Only sodium hydroxide caused a significant decrease of Ts1 and broadening of the gelatinization peak. Therefore, ΔHvHºand the size of the gelatinizing cooperative unit estimated from the ΔHvHº/DSCΔH ratio were decreased more by sodium hydroxide than by urea, indicating that sodium hydroxide facilitated the mobility of starch molecules more effectively during gelatinization.

The role of ingredients on thermal and rheological properties of cake batters and the impact on microcake texture

Starch is the major ingredient in cakes which are composed from flour, eggs, fat and sugar. Starch gelatinization plays an important role – together with the protein network – in defining the structure and quality of the final product. Rheology, texture and batter thermal and pasting properties were used to determine the effect of ingredients on batter and microcake (cake without bubbles) properties. The rheology of the batter was controlled by the water content which governed the phase transitions of the batter constituents. Differential scanning calorimetry clearly attested that ingredients addition shifted the gelatinization endotherm to higher temperatures. This was in agreement with the MicroViscoAmyloGraph (MVAG) measurements, where the batter ingredients addition to flour increased the pasting temperature and the peak viscosity. When 20% of the flour was replaced by the pregelatinized wheat or maize starch, a decrease in the peak viscosity and setback was observed which could explain the texture improvement. The association of these different techniques helped to better understand the effects of the different ingredients of the batter on starch properties that are important for improving the quality of these high sugar and fat content cakes.

Effects of Fatty Acid Addition on the Physicochemical Properties of Corn Starch

The effect of addition of six fatty acids (stearic, palmitic, myristic, oleic, palmitoleic, and myristoleic acid) on the gelatinization, glass transition, and retrogradation properties of corn starch as well as their complexing abilities with amylose were determined. Differential scanning calorimeter studies reflected that addition of fatty acids caused a 73–89% decrease in the gelatinization enthalpy compared to that of the native starch. Besides amylose-lipid formation, exotherm was determined at the same temperature range with the gelatinization endotherm. As a result, it was suggested that fatty acids complexed with amylose during gelatinization. Fatty acid addition significantly increased the glass transition temperature of starch gel. This was attributed to two reasons: the first is due to the physical cross-linking action of amylose–lipid complexes in starch-water system; the second may be due to the effect of uncomplexed fatty acids on water distribution in the gel structure as a result of their amphiphilic character. Thermal properties of amylose-lipid complexes were compared in order to determine the effect of fatty acid properties. It was found that the shorter chain length and unsaturation favored the complex formation but the complexes formed by longer and saturated fatty acids were more heat stable. Addition of fatty acids resulted in 73–90% and 47–71% reduction in the retrogradation enthalpy compared to native starch gels at 5°C and 21°C, respectively. The reduction in the retrogradation enthalpy was inversely related to the amylose-lipid complexing abilities of the fatty acids and it might be explained by the hindrance effect of uncomplexed fatty acids to the water distribution in the starch gel matrix.

Devitrification of the amorphous fractions of starch during gelatinisation

Gelatinisation of waxy maize starch (WMS) in excess glycerol was investigated by a temperature modulated DSC in quasi-isothermal and non-isothermal mode. By using the measured specific heat capacities (cp) at different stages of gelatinisation and the hypothetical enthalpy of melting for 100% crystalline amylopectin, a method was developed to reveal the amorphous fraction which remains glassy in the presence of excess glycerol what can be called “rigid amorphous”. It was suggested that the amorphous part of starch was plasticised at around 40°C whereas, rigid amorphous fraction underwent a second stage glass transition which showed itself by an increase in cp under the gelatinisation endotherm. It was also shown that holding WMS in excess glycerol at 100°C (10°C above the gelatinisation onset temperature) for 10 days was not enough to gelatinise the whole WMS implicating that the most stable crystals did not melt before the required threshold temperature was reached.

Gelatinization and retrogradation of thermoplastic starch characterized using modulated temperature differential scanning calorimetry

Starches with varying amylose content, one hydroxypropylated high amylose starch and two thermoplastic starches (pre-gelatinized and with V type crystals) were gelatinized in the presence of added water. Gelatinization was characterized using wide-angle X-ray scattering and modulated temperature differential scanning calorimetry (mT-DSC) with a heat-cool temperature profile. The gelatinization endotherms were recorded in total heat capacity curves that were resolved into storage (reversing) and loss heat capacities, and non-reversing heat capacity curve. The endotherms were mainly of non-reversing nature, with a small contribution from the reversing component. Starch melting is a plasticizer-assisted disruption of crystals and other structures such as starch–lipid complexes and granules. Reversibility was limited since the native amylopectin crystals are rarely recrystallized and starch–lipid complexes do not reform. Recrystallization is predominantly due to subsequent slow formation of V type amylose crystals, with some B type due to recrystallization of amylopectin.

Gelatinization and Retrogradation of Hydroxypropylated Cornstarch

Gelatinization and retrogradation of a high amylose cornstarch modified by hydroxypropylation were studied by DSC. It was found that the gelatinization temperature of the starch was decreased and a narrow gelatinization range was measured by DSC after hydroxypropylation. The decreasing of the gelatinization temperature is explained by disrupting inter- and intra-molecular hydrogen bonds, while the narrowing of the gelatinization endotherm is explained by destroying the amylose-lipid complex. Morphologies of the starch granules with and without iodine treatment were studied under microscopy with normal and polarized lights. Brightness and birefringence decreased with increasing molar substitution since crystal structure in starch granular was partly destroyed. Weaker retrogradation was observed for the hydroxpropylated starch, ascribed not only to steric effects imposed by the bulky hydroxypropyl groups in amylopectin, but also to the removing of amylose-lipid complexes during alkaline treatment.

Effect of storage temperature on rice thermal properties

Abstract Study on the gelatinization kinetics of rice showed that gelatinization process was divided into two steps: swelling of the amorphous region and disruption of the crystalline region. Higher temperature storage (37 °C) resulted in an increase in the breaking point temperature suggesting that energy for the disorder of these two regions of starch in rice stored at 37 °C was higher than the rice stored at 4 °C. Storage-induced changes in rice led to significant increases in DSC peak temperature ( p p 0.01) for rice stored at 37 °C compared to rice stored at 4 °C. As the peak temperature of rice stored at 37 °C was not influenced by the “annealing” treatment in contrast with the increased peak temperature of rice stored at 4 °C after the “annealing” treatment, the results indicate that the ageing process (37 °C storage) has already re-ordered the rice grain structure and that the annealing process under these conditions has no further effect on starch thermal properties. Because starches isolated from rice grain stored at 4 °C and 37 °C had similar thermal properties, this implies that the effects of storage on thermal properties are associated with the interactions between starch and non-starch components following storage. The gelatinization endotherm shifted to a lower temperature ( p

Effect of instantaneous controlled pressure drop (DIC) on physicochemical properties of wheat, waxy and standard maize starches

Standard maize starch (SMS), waxy maize starch (WMS) and wheat starch (WTS) were hydrothermally treated by the Instantaneous Controlled Pressure Drop (DIC) process. This process consists in a short pressurisation obtained by the injection of saturated steam at fixed pressure during a predetermined time followed by a sudden pressure drop towards vacuum. The effects of DIC conditions on thermal characteristics, enzyme susceptibility, pasting (Brabender) and rheological properties of treated starches were investigated. For treated starches, an increase of transition temperatures ( T o and T p), a narrowing of the width of gelatinization endotherms and a decrease of the gelatinization enthalpies (Δ H) were observed as the severity of processing conditions increased. WMS, SMS and WTS showed a significant increase in enzymatic hydrolysis after treatment. The saccharification yield showed an increase from 19% (native) to 44%, 21% (native) to 59% and 55% (native) to 79% for SMS, WMS and WTS, respectively. The study suggests that the structural modifications due to the previous DIC treatment influence the in-vitro hydrolysis and the access to the ultrastructure of starch granules; the susceptibility to hydrolysis increases from SMS to WMS and WTS. For all treated starches, the decrease in peak viscosity and in apparent viscosity was related to the processing conditions.

Pasting properties of a heat-moisture treated canna starch in relation to its structural characteristics

Native and moistened canna starches (moisture contents of 15%, 18%, 20%, 22%, and 25%) were heat treated at 100 °C for 16 h. Heat-moisture treatment (HMT) did not alter the shape or size of starch granules. Heat-treated starches showed lower paste viscosity, more stable paste (with no breakdown) and noticeable decrease in setback value compared to untreated native starch. These changes were more obvious when the starch samples contained more moisture. Starch gel morphology investigated by I 2 staining revealed that the granules of untreated native canna starch were completely ruptured, whereas those of HMT22% and HMT25% samples remained in granular form. These gel morphologies were correlated and provided the information to explain the pasting behaviors of treated and untreated canna starches. Shifts of gelatinization endotherms towards higher temperatures (1–8 °C) with broadened peaks following the moisture contents in starch samples were found after HMT. Amylose leaching of treated samples tended to be lower when the moisture content of the samples increased. HMT did not alter crystalline type of canna starch (B-type), but with increase of the moisture, slight reduction of a peak at 5.7° and a fusion of doublet at 22° and 24° were observed.

Effect of Sodium Dodecyl Sulphate on the Physicochemical, Thermal and Pasting Properties of Cassava Starch

AbstractThe effect of different concentrations of sodium dodecyl sulphate (SDS) on cassava starch properties after complexation and in situ addition were studied. The swelling volume of the starch‐SDS complexes increased to a maximum of 100 mL/g with increase in concentration of SDS (even at 0.004 mol SDS) with a corresponding decrease in solubility. During in situ addition also, a similar but gradual behaviour was observed for swelling volume and solubility. The apparent and total amylose contents showed an irregular trend. The soluble amylose content decreased with increase in concentration of SDS. In vitro enzyme digestibility of starch‐SDS complexes was significantly lowered compared to that of native starch. The water‐binding capacity showed an initial decrease followed by a significant increase at higher concentrations of SDS. DSC studies showed that in addition to the gelatinisation endotherm, a peak corresponding to the melting of the starch‐SDS complex was obtained in the case of in situ addition of the surfactant. The peak viscosity of starch during in situ addition of SDS exhibited a rapid increase except at the highest concentration. The peak viscosity of starch‐SDS complexes underwent an initial reduction followed by a gradual increase at higher concentrations. The breakdown, setback and pasting temperature were also affected.

Retrogradation of corn starch after thermal treatment at different temperatures

Multi-endotherms of the gelatinization of corn starch, such as G, M1, M2, and Z endotherms, have been detected by DSC. The retrogradation of corn starch after initial thermal treatment at different temperatures was studied by DSC; in particular, the effect of thermal treatment before and after each endotherm of gelatinization on retrogradation was determined as a function of annealing time. The effect of thermal treatment at a certain temperature on the residual gelatinization endotherm at a higher temperature is also discussed. It was found that the higher temperature of thermal treatment always removed all the endotherms below that temperature. However, a certain thermal treatment temperature could affect the residual endotherm above this treatment temperature. The time-dependent retrogradation of corn starch is mainly due to G and M1 endotherms. The temperature and enthalpy of the melting of amylose–lipid complexes M2 and nonlipid complex amylose Z were not affected by aging time. The final enthalpy of retrogradation was found to be lower than that of gelatinization.