Heat-treated Starch Research Articles

Hydrothermal Leaching of Amylose from Native, Oxidized and Heat-Treated Starches

The kinetics of amylose leaching in hot, excess water from native, oxidized-by-potassium permanganate and heat-treated potato starch at temperatures of 62–90 °C was investigated in isothermal conditions. For the first time, it was proposed to describe the kinetic data by the Kroger–Ziegler equation. It was found that for native starch in the range of 62–70 °C, the activation energy of the amylose leaching process is 192.3 kJ/mol, and at a temperature of 80–90 °C, it decreases to 22 kJ/mol. Similar patterns were established for modified starches. In the kinetic mode, the activation energy was 102.5 kJ/mol for oxidized starch and 44.7 and 82.5 kJ/mol for heat-treated starches at a temperature of 135 °C for 2.5 and 5 h. In the diffusion mode, it was: 18.7 kJ/mol for oxidized and 16.2 and 18.9 kJ/mol for heat-treated starches for 2.5 and 5 h, respectively. It is shown that the consideration of amylose leaching as a heterogeneous pseudochemical process makes it possible to explain the change in the activation energy with increasing temperature by the transition of the leaching process from the kinetic to the diffusion mode. As such a pseudochemical process, it is proposed to consider the breaking of multiple hydrogen bonds between amylose macromolecules. The change in the activation energies of amylose extraction from modified starches is explained by the change in the degree of amylose polymerization. Thin-layer chromatography was used to compare the molecular weight distributions of the resulting modified amylose samples. FTIR spectroscopy and thermal methods of analysis were used to study the transformations of starch during heat treatment.

The effect of heat treatment of starch on its crystal structure and dynamic viscosity of starch pastes

Analysis of literature data shows the uncertainty of a number of issues of the starch dextrinization process, namely the patterns of the change in the crystal structure of starch during heat treatment and the dependence of the viscosity of starch pastes of dextrins on the conditions of starch heat treatment. These questions were chosen as the topic of this study. A decrease in the average size of starch particles by 2.7 m and an increase in the intensity of reflexes of diffractograms in the range of 2=10–200 after its heat treatment at 1350C (the temperature at which the dextrinization process starts) are well explained by dehydration and a change in the degree of crystallization of biopolymer macromolecules due to their thermal transformations. The dependence of the dynamic viscosity of hot pastes on their shear rate was studied. The steady shear flow curves showed the presence of dilatant areas as a transition from the Newtonian flow regime to the pseudoplastic flow of starch pastes. It was found that the viscosities of heat-treated starch pastes depend on the processing conditions; the viscosities increase in the following order: starch heat-treated in the presence of an acid catalyst; native starch; starch heat-treated without a catalyst for 5 hours; and starch heat-treated without a catalyst for 2.5 hours. It was proposed to divide dextrins into two separate groups: with an increased and with a reduced degree of amylose polymerization.

The mechanism of amylose leaching from native and heat-treated starches in hot excess water

In order to determine the optimizing parameters of the process of hydrothermal leaching of amylose, kinetic studies were carried out under isothermal conditions. Native (potato and corn) and heat-treated starches were used in the experiments. The obtained kinetic data are described by the Kruger-Ziegler equation. It is shown that in the temperature range of 60–700C, the apparent activation energy is 193 kJ mol–1 and 43–83 kJ mol–1 for native and heat-treated starches, respectively. With a further increase in the temperature, the activation energy decreases to 22 kJ mol–1 and 13–14 kJ mol–1 for native and modified starches, respectively. It is proposed to consider amylose leaching as a heterogeneous pseudochemical process, in which the process of breaking numerous hydrogen bonds between amylose macromolecules acts as a chemical reaction. From this point of view, the change in activation energy with increasing temperature is explained by the transition of the leaching process from the kinetic to the diffusion mode. Changes in the activation energies of modified starches are explained by a decrease in the number of hydrogen bonds between amylose macromolecules due to a decrease in their degree of linearity and size during thermal conversion. Changes in the structure of starch during their heating were investigated by the DTA method. The values of the apparent activation energy for two stages were determined as follows: 44 kJ mol–1 and ~26 kJ mol–1 for molecular dehydration and intermolecular dehydration of native starch, respectively, which indicates that both processes occur in the kinetic mode. Considering amylose leaching as a heterogeneous pseudochemical process shows that the main optimizing factors are temperature and starch pre-milling.

Supplementing oat hulls to the diet of suckling piglets altered their intestinal tract and colonic microbiota development.

Current study evaluated the effect of a fine and coarsely ground insoluble dietary fibre source on the gastrointestinal development of suckling pigs. Oat hulls (OH) were selected as a model feedstuff, rich in cellulose, lignin, and insoluble dietary fibre. Three experimental supplemental diets were formulated: a finely ground, low fibre and nutrient dense diet served as control (CON). For the 2 high fibre diets, 15% heat-treated starch in CON was exchanged with OH, either finely (OH-f) or coarsely ground (OH-c). Litters of 10 primi- and multiparous sows (mean litter size 14.6±0.84) were used. Within a litter, experimental diets were allotted to triplets of 4 piglets. From approximately 12d of age, piglets' individual feed intakes were recorded 2 times per day when separated from their dam for 70min. Piglets could suckle with their dam for the remainder of the day. On d 24 and 25, from the total pool of 120 piglets, seven healthy well-eating piglets per treatment were selected for post-mortem evaluation, resulting in 14 replicates per treatment. Consumption of OH-c and OH-f did not impede clinical health and production performance of piglets. The full stomach weights tended to be greater for OH-c compared to OH-f whereas CON was intermediate (P=0.083). Supplementing OH significantly increased ileal villus height and caecal dry matter concentration (P<0.05). For the colon, OH increased its length, contents weight, short-chain fatty acid concentration and reduced total bacterial count as well as γ-proteobacteria count and proportion (P<0.05). The OH-c treatment specifically increased full gastrointestinal tract weight and caecum contents weight compared to piglets fed CON and OH-f. Furthermore, OH-c reduced colonic crypt depth when compared to OH-f (P=0.018). In conclusion, supplementing OH to a diet for suckling piglets exerted subtle developmental effects on gastrointestinal morphology and colonic microbial community. These effects were largely independent from the particle size of the OH.

Effects of heat-treated starch and protein from foxtail millet (Setaria italica) on type 2 diabetic mice

Foxtail millet and its components have hypoglycemic effects on mice, but the role of starch and protein in millet in these effects is unclear. The present study investigated the impact of heat-treated foxtail millet starch and protein on type 2 diabetic mice and the underlying mechanisms, including the influence of gut microbiota and serum metabolic profile. In diabetic mice, the consumption of heat-treated foxtail millet starch and protein reduced, respectively, fasting blood glucose 18.52% and 26.33% and insulin levels 12.22% and 15.96%. In addition, heat-treated foxtail millet starch and protein altered the gut microbiota composition, enriched the abundance of probiotics and short-chain fatty acids producing bacteria, reduced harmful bacteria, and increased fecal short-chain fatty acids concentration. Heat-treated foxtail millet protein had greater effects on gut microbiota composition, whereas heat-treated foxtail millet starch had greater effects on metabolic function. The hypoglycemic potential of heat-treated foxtail millet starch and protein was associated with the modulation of both gut microbiota and serum metabolic profile.

Morphology and functionality of dry heat‐treated and oxidized quinoa starches

Starch from quinoa was isolated by alkaline steeping method and isolated starch was modified by oxidation (@1%, 1.5% and 2% w/v active chlorine) and dry heat treatment (@ 150 and 200°C for 2 h). Native and treated starches were analyzed for physicochemical, functional and morphological characteristics. The yield of quinoa starch was 54.2% with 89.3% purity. The shape of starch granules was polygonal and irregular with an averagediameter of 1.13 μm. Starch modified by dry heat treatment enhanced solubility, water-binding capacity, and transmittance in comparison with native starch. The peak, trough and final viscosity were higher in the case of dry heat-treated starches at a lower temperature than samples of native starch as well as dry heat-treated at a higher temperature. Oxidized starches showed higher values of whiteness, breakdown and setback viscosity. Modification treatments lowered the pasting temperature and swelling power of quinoa starch. Novelty impact statement Studies on quinoa starch modification by dry heat treatment and oxidation are rare in literature and present work represents the effect of these treatments on quino starch properties. Data revealed that active chlorine concentration and heating conditions (time and temperature) during modification treatments altered quinoa starch functionality uniquely. The results offer a useful base for modification of quinoa starch by oxidation and dry heat treatment at different conditions to enhance its applicability in different industries.

Comparison of the molecular structure of heat and pressure-treated corn starch based on experimental data and molecular dynamics simulation

The effect of high hydrostatic pressure (HHP) and heating on the molecular structure of corn starch were firstly studied using classical experimental methods and molecular dynamics (MD) simulation. Heat-treated (HT) starches showed more amorphous content further than pressure-treated (PT) starches at similar DGs, further confirming that a higher level of gelatinization occurred after heating. Compared with PT starches, longer external B2 and B3 chains (DP > 25) degraded more into A chains (DP 6–12) in HT samples at a similar degree of gelatinization (DG). Heating increased the breakage of α-1,4-glycosidic bonds and significantly reduced molecular weights even one third of the native corn starch at 100% DG. On the other hand, MD results showed that HHP triggered a greater number of amylose-water inter-molecular hydrogen bonds which agreed well with the higher the freedom degree of water molecules in PT starches. Regarding to various energy changes, PT starches exhibited lower bonding-related energies, but higher Van der Waals and electrostatic forces than HT ones. This study adds to understanding of the different molecular features of heating and HHP gelatinization and provides a molecular tool to assist the starch industry in selecting better modification parameters.

Molecular and physico-chemical characterization of de-structured waxy potato starch

This study focuses on the physico-chemical properties of a “clean-label” modified starch (de-structured starch) as a potential food ingredient. The modified starch was obtained by the disassembly of native waxy potato starch granules into its macromolecular chains. Waxy potato starch samples were treated at elevated temperatures of 120, 130, 140, and 150 °C for 30 min at a stirring speed of 300 rpm in a high pressure reactor. Starch treated at 120 °C showed similar molar mass as its native form indicating that treatment at 120 °C had resulted in the disassembly of the starch granules into its macromolecular chains. Reduction in viscosity and particle size was observed with increased temperature from 120 to 150 °C. The reduction in viscosity and size was not only attributed to the disassembly of starch granules into its macromolecular fractions but also due to a further size reduction of amylopectin chains. De-structured starch treated at 140 and 150 °C exhibited flow behavior approaching Newtonian fluid. However, de-structured starch treated at 120 and 130 °C exhibited shear-thickening behavior above their critical shear rates at 14 and 27 s−1 respectively. Shear-induced interactions among starch macromolecular fractions appeared to have occurred within a narrow range of heat treatment (120 and 130 °C) but not in more severely heat-treated starches (140 and 150 °C).

Repeated and continuous dry heat treatments induce changes in physicochemical and digestive properties of mung bean starch

Mung bean starch was subjected to continuous and repeated dry heat treatments at 130°C for 3–18 hr. Changes in structural, physicochemical, and digestive properties of mung bean starch during treatment were investigated. The starch retained a C-type crystalline structure after continuous and repeated dry heat treatments. The dry heat treatments decreased the molecular weight, amylose content, swelling power, and viscosity of mung bean starch depending on treatment duration/cycles. Greater solubility and enthalpy values were found for the dry heated starch than those of the native ones. Additionally, the content of slowly digestible and resistant starch slightly increased during the early time/cycles of treatment. Furthermore, the dry-heated mung bean starch showed a lower glycemic index than that of the native ones. And the continuous dry heat-treated starch had the strongest changes in amylose content, solubility, swelling power, and pasting parameters compared to the repeated ones. Practical applications Starch is an important ingredient in the food industry, and it is widely utilized as an additive in many food products such as pastas, soups, sauces, confectioneries, and bakeries. However, due to the instability of native starch under heating and acidic environment, unsatisfactory starch products are obtained, which limits the practical application of starch in the food field. Therefore, modification of native starch using physical, chemical, and biological methods is necessary to promote their application in the food industry. The results obtained in this study suggest that dry heat treatment can be successfully applied for producing modified mung bean starch with good water solubility, higher thermal stability, and low glycemic index to promote its application in the food industry. Additionally, dry heat treatment is a safe starch modification method because it is chemical-free.

Influence of moisture and amylose on the physicochemical properties of rice starch during heat treatment

Moisture and amylose are important factors affecting the quality of heat-treated starches. The amylose content in heat-treated rice starch increased as moisture content (MC) increased from 8% to 30%, but decreased at MC of 70%. With the increase of MC, the paste transmittance, gelatinization temperature, and digestibility of starch increased, whereas the swelling power and enthalpy decreased. The long- and short-range molecular order and the digestive properties of starch with MC ≤ 30% changed moderately, but high MC (70%) gelatinized the starch and drastically changed the physicochemical properties. High amylose content in rice starch led to low long- and short-range molecular order, swelling power, and gelatinization temperature, but increased resistant starch. The results indicated that 30% of MC separates effects of heat treatment of starch, where low MC (≤30%) and high amylose lowers digestibility, which is beneficial for diabetics, while high MC (>30%) promotes solubility and transparency.

Phytate-mediated phosphorylation of maize, rice, and potato starches at different pH conditions

Maize, rice, and potato starches were dispersed with phytate at pH 7, 9, and 11, and were subjected to dry-heating at 130 °C for 12 h. The residual phosphorus content and structural characteristics revealed that the treatment resulted in starch phosphorylation. Further, pasting viscosity, clarity, solubility, and swelling power were analyzed to determine the physicochemical properties of the phosphorylated starch. These heat-treated starches retained phosphorus mainly in the form of monostarch monophosphate. Phosphorylation increased the peak viscosity and decreased the pasting temperature in maize and rice starches, but not in potato starch. Paste clarity, solubility, and swelling power were also increased in phosphorylated maize and rice starches. Phosphorus content, paste clarity, solubility, and swelling power were the highest at pH 7, but the maximum paste viscosity was at pH 9. These results indicate that phytate can be used for starch phosphorylation, with the reaction efficiency based on the botanical source of the starch and the reaction pH.

Measurement and comparison of multi-scale structure in heat and pressure treated corn starch granule under the same degree of gelatinization

In order to popularize the application of high hydrostatic pressure (HHP) in staple food, the different impact of HHP (from 300 to 600 MPa) and heat treatment (from 60 to 75 °C) on corn starch (80 wt%) under the same DG was investigated. Granule morphology, crystalline characteristics, short-range ordered structure and lamellae structure was examined with a combination of SEM, CLSM, XRD, ATR-FTIR, and SAXS. Results obtained demonstrated Heat-Treated starch appeared endo- and exo-corrosion with more collapses and destructiveness, whereas just endo-corrosion with a dense periphery was induced by HHP. Under the same degree of gelatinization (DG), the long-range and short-range structure sustained more ordered in Pressure-Treated starch than Heat-Treated starch. Further, Heat-Treated starch exhibited more flawed semi-crystalline lamellae. The larger DG, the thicker amorphous lamellae thickness (da) of Heat-Treated starch and Pressure-Treated starch was. Moreover, when DG up to 70%, the increase of da in Heat-Treated starch was more obvious. Heat treatment was shown to be more severe than HHP to disrupt the lamellae. The loss of semi-crystalline structure order occurs more violent than crystalline structure for corn starch. It is of value to reveal that heat and HHP treatment led to similar change trend for multi-scale structural features, whereas the change extent was quite various. This study was potential to provide a theoretical basis to improve the quality of novel starch-based food.

Use of α-amylase/silica particle suspensions to optimize cleaning in a simulated cleaning-in-place system

The activity and stability of α-amylase on silica particle suspensions were studied by analyzing the influence of time, temperature, enzyme concentration and silica particle concentration. The recovery of enzymatic activity was also explored using different centrifugation and reconstitution cycles and experimental times, comparing the results with those obtained without particles. Higher recovery of enzymatic activity was obtained by centrifugation at 60 °C and with a ratio particle concentration/enzyme concentration higher than 20. The cleaning of heat-treated starch retained in stainless steel was analyzed in a Cleaning-In-Place device (CIP) using enzymatic solutions with and without silica particles. The utilization of enzymatic solutions without microparticles enabled 36% of activity to be recovered by centrifugation. When silica particles were included in the washing solutions, the detergency recovered was up to 50%, this not being significantly affected by the storage time, nor the number of centrifugation and washing cycles.

Using heat-treated starch to modify the surface of biochar and improve the tensile properties of biochar-filled styrene–butadiene rubber composites

Heat-treated starch (HTS) is a renewable material that can be used to modify the surface chemistry of small particles. In this work, HTS was used to coat hydrophilic biochar particles in order to make them more hydrophobic. Then, when added as filler to hydrophobic styrene–butadiene rubber (SBR), the coated biochar dispersed more easily and had enhanced filler–matrix interactions, which were reflected in the tensile properties of the final composites. Biochar particles modified with 5% (weight) HTS showed increases of 59% in the ultimate tensile strength, 49% in elongation percentage, and 79% in fracture toughness of SBR composites compared to unmodified biochar particles. This shows that HTS can be used to improve the tensile properties of composites filled with biochar and potentially other hydrophilic filler materials.

New scale-down methodology from commercial to lab scale to optimize plant-derived soft gel capsule formulations on a commercial scale

A new scale-down methodology from commercial rotary die scale to laboratory scale was developed to optimize a plant-derived soft gel capsule formulation and eventually manufacture superior soft gel capsules on a commercial scale, in order to reduce the time and cost for formulation development. Animal-derived and plant-derived soft gel film sheets were prepared using an applicator on a laboratory scale and their physicochemical properties, such as tensile strength, Young’s modulus, and adhesive strength, were evaluated. The tensile strength of the animal-derived and plant-derived soft gel film sheets was 11.7 MPa and 4.41 MPa, respectively. The Young’s modulus of the animal-derived and plant-derived soft gel film sheets was 169 MPa and 17.8 MPa, respectively, and both sheets showed a similar adhesion strength of approximately 4.5–10 MPa. Using a D-optimal mixture design, plant-derived soft gel film sheets were prepared and optimized by varying their composition, including variations in the mass of κ-carrageenan, ι-carrageenan, oxidized starch and heat-treated starch. The physicochemical properties of the sheets were evaluated to determine the optimal formulation. Finally, plant-derived soft gel capsules were manufactured using the rotary die method and the prepared soft gel capsules showed equivalent or superior physical properties compared with pre-existing soft gel capsules. Therefore, we successfully developed a new scale-down methodology to optimize the formulation of plant-derived soft gel capsules on a commercial scale.

Preparation and characterization of zein thermo-modified starch films

A new method of preparing films from zein thermo-modified starch was presented. According to data of micro-visco-amylography and rheometer, dry heating with zein significantly decreased the pasting properties of waxy corn starch and distarch phosphate, the values of G′ and G″ of starches dry heated with zein decreased, while the loss tangent increased as a function of heating time. Scanning electron microscopy images showed that the surfaces of starch granules became rough after dry heating with zein, suggesting interactions between zein and the granule surface. In films made from mixtures, the starch/zein compatibility was improved through dry heating. Compared with films cast from mixtures of separately heat-treated starch and zein, films made from the starch/zein mixtures heated together possessed higher water contact angle and tensile strength. Simple dry heating with zein could thus be used as a promising modification method for improving the functionality of edible films from starches.

Interfacial and foaming characterisation of mixed protein-starch particle systems for food-foam applications

This work presents mixed protein-starch systems as effective foaming agents and stabilisers. The starch size and hydrophobicity play a dominant role in determining the levels of synergy observed. Egg White Protein (EWP) and Pea Protein Isolate (PPI) were selected at two concentrations (0.5, 1 wt. %) along with three starch species of concentrations between 0.5, 1, 3 & 5wt. %. Two commercial OSA-modified starches are compared to a native granule and its heat-treated counter part. The system's effectiveness to incorporate air (overrun) as well as its capacity to hold structure (half life) is evaluated. starch's physical properties (contact angle and size) and their effect on the nature of the Air/Water (A/W) interface (interfacial dilatation rheology, surface tension) are also explored. The effect of protein species as well as starch size and hydrophobicity on foam stability is determined and discussed. The study demonstrates that addition of OSA modified starch (0–5wt%) to (EWP) foams can enhance foam stability by up to 1200% without compromising the foaming capacity, mainly due to a hypothesised exclusion volume effect. Where as the larger heat-treated starch granule is found to increase stability of wet foams by 800%, through a combination of mechanisms.

Polymer composites prepared from heat-treated starch and styrene–butadiene latex

Thermoplastic starch/latex polymer composites were prepared using styrene–butadiene latex and heat-treated cornstarch. The composites were prepared in a compression mold at 130°C, with 20% starch content. An amylose-free cornstarch, waxy maize, was used for this research, and the heat treatment range was from ambient temperature to 170°C. The heat-treated starch (HTS) was characterized by optical microscopy, dynamic light scattering, and size exclusion chromatography. The composites were characterized by mechanical analysis (stress–strain) and by scanning electron microscopy. The mechanical tests of composites revealed a dramatic increase in the modulus and tensile strength when the gelatinized starch was incorporated. When the starch was not gelatinized, starch did not contribute to the increase in the modulus and tensile strength because of its small surface area, thus weak interaction with the matrix. The reinforcing effect of starch as filler was reduced as the heating temperature of starch was increased to higher than 120°C. The variation of reinforcement effect of HTS as filler was explained by the interaction between starch and matrix material, latex.

Ultrasound Effect on Swelling Properties and Drug Release Behaviors of Spray-Dried Tapioca Starch Tablets

Modified starches have been widely used as an excipient in matrix tablets to control drug release. A new processing method for the production of modified starch, high power ultrasonic treatment (400 W), was applied to native tapioca starch. The spray drying technique was used after modification (i.e., by ultrasonic or heat treatment). Matrix tablets were then prepared by direct compression using theophylline as a model drug. The effect of starch modification on swelling, erosion and in vitro drug release behaviors of compressed matrices was investigated in 0.1 N HCl or phosphate buffer (pH 6.8). The matrix tablets of modified tapioca starch formed a continuous gel layer while in contact with the aqueous medium undergoing a combination of swelling and erosion. The ultrasound-treated starch swelled and eroded less than the native starch and heat-treated starch, thus the drug release from matrix tablets using ultrasound-treated starch was slower. For these results, it can be concluded that the ultrasound-treated starch was a promising excipient for controlled drug release.

Effect of Ultrasonic Treatment on Physical Properties of Tapioca Starch

A new processing method for the production of modified starch, high power ultrasonic treatment (400 W), was applied to native tapioca starch. The effect of processing parameters such as ultrasound amplitude (50 and 100%) and sonication time (10, 20 and 30 minutes) on the properties of the modified starches was investigated. Starch granule morphology observed by scanning electron microscopy (SEM), swelling power, solubility and powder x-ray diffractometry (PXRD) of the obtained ultrasonically treated tapioca starch were determined and compared with native as well as heat-treated tapioca starches. The results from SEM and PXRD showed that the ultrasonic treatment of tapioca starch distorted the crystalline region in starch granules, especially at higher amplitude or sonication time. The swelling power of the tapioca starch increased after treatment with both heat and ultrasound, in which the swelling power of ultrasonically treated starch was higher than that of heat-treated starch. It was found that tapioca starch treated by ultrasound for a certain period of time has an increase in solubility. The increase in the swelling power is associated with water absorption capacity and starch granules solubility.