Sub-gelatinization Temperatures Research Articles

Simple thermal and freezing treatments to improve absorption capacity and alter digestibility of canna starch granules

Swollen canna starches (SCS) were prepared by controlled heating of unmodified and heat-moisture treated (HMT) starch suspensions at sub-gelatinization temperatures; subsequently, freezing was conducted to stabilize the structure of the SCS. Sizes of both unmodified and HMT swollen granules increased with increasing heating temperatures (up to 2.5 times), and freezing resulted in a significant reduction of granular size. The absorption capacities of the swollen starches increased up to 6 times for water and 3 times for tributyrin and palm oil compared to unmodified starch. The differences in absorption capacities of the unmodified and HMT swollen starches were small. Freezing the swollen starches tended to decrease oil and water absorptions, except for unmodified starch swollen at 70 °C, where freezing increased water absorption. Freezing significantly decreased the susceptibility of the swollen unmodified starches to amylase digestion and slowed down the digestion of the swollen HMT starches.

Impact of Particle Size on the Rheological Properties and Amylolysis Kinetics of Ungelatinized Cassava Flour Suspensions

The effect of particle size on enzymatic hydrolysis of cassava flour at subgelatinization temperature was investigated. A multiscale physical metrology was developed to study the evolution of different physical-biochemical parameters: rheology, granulometry, and biochemistry. In this study, four fractions of cassava flour based on the particle sizes under 75 µm (CR075), 75–125 µm (CR125), 125–250 µm (CR250), and 250–500 µm (CR500) were screened for enzymatic hydrolysis effect. The results showed that all cassava flour suspensions exhibited a shear-thinning behavior, and the viscosity increased drastically with the increase of particle size. During hydrolysis, the viscosity reduced slightly and the non-Newtonian behavior became negligible beyond 4 h of the process. The particles size for CR075 and CR125 increased steadily in diameter mean. The samples of CR250 and CR500 showed more fluctuation by first decreasing, followed by increasing in particle sizes during the process. The highest hydrolysis yield was found for samples with particle size under 125 µm (89.5–90.7%), suggesting that mechanical treatment of cassava can enhance the bioconversion rate.

Structural and functional characterizations of α-amylase-treated porous popcorn starch

The structures and properties of normal popcorn starch (PCS) and porous PCS were studied. In comparison with normal dent corn starch (DCS), PCS had more amylopectin chains with degree of polymerization (DP) 12–24, fewer amylopectin chains with DP > 36, and shorter amylose chains. PCS had a lower crystallinity, a more disordered lamellar structure, thicker lamellae, larger granules, a more porous granular surface, lower viscosity, and a lower gelatinization temperature than DCS. After α-amylase hydrolysis at sub-gelatinization temperatures, both PCS and DCS had more porous granular surfaces, shorter amylose and outer amylopectin chains, and higher relative crystallinities. However, as compared to DCS, PCS had a lower overall yield, larger pores, a higher percentage of hydrolyzed amylose and long amylopectin chains, smaller granules, and greater water- and oil-absorption capacities. These differences were attributed to the indentations on the granular surface of PCS as well as to its fragile structure. These results increased our understanding of the structures and properties of PCS, and provided a framework for PCS preparation. In addition, our results suggested that PCS has a high potential for porous starch applications.

Influence of enzymatic hydrolysis on the properties of red rice starch

Starch is a technologically challenging polysaccharide that arouses the global interest in its modification to increase its applicability. Thus, the objective of the present work was to study the influence of enzymatic modification on the properties of red rice starch. The enzymatic modification was performed sequentially through the actions of α-amylase enzymes and amyloglucosidase using a design of experiments where several process conditions were used at sub-gelatinization temperatures. Then the native and modified starches were characterized for its physicochemical, physical, centesimal, phytochemical, morphological, and thermal properties. The enzymatic hydrolysis of the starch granules with α-amylase resulted in 4.46% hydrolysis and more 8.63% after the action amyloglucosidase. Results revealed that surface adsorption is more limiting than diffusion. The enzymatic hydrolysis process resulted in a reduction of the amylase and amylopectin content, as well as on all phytochemicals. After hydrolysis, granules starches presented surface alterations and tendency to become spherical. Small differences on crystallinity revealed that the enzymes had more influence on the amorphous fractions of the starch granules.

Physicomechanical Behaviour of Novel Directly Compressible Starch-MCC-Povidone Composites and their Application in Ascorbic Acid Tablet Formulation

The goal of this research was to provide critical evaluation of the physicomechanical performance of Starch-MCC-Povidone (SMP) composites engineered via co-processing strategy. Aqueous dispersions of the primary excipients at predetermined combination levels were subjected to physical agglomeration at controlled subgelatinization (55 °C) temperature followed by drying at 60 °C for 48 h. Under scanning electron microscope, the materials appeared as enlarged porous composites of starch-MCC bound by solid bridges of povidone. Powder fluidity indicators suggested acceptable flow properties (Angle of repose 5 gs-1). Compact weight variation studies revealed reproducible volumetric die filling capacity. Analysis of powder compaction indices shows appreciable densification and total volume reduction in both Heckel and Kawakita models. The dilution capacity of the composites was up to 40% using L-ascorbic acid as the model drug. Analysis of post compression tablet properties indicated extensive elastic recovery at low MCC content. All the novel composites were characterised by rapid in-vitro disintegration and efficient in-vitro drug release (t50% <1 min; t80% < 2 min). In comparison to Ludipress® and Prosolv®, moderate to high MCC containing Starch-MCC-Povidone composites (SMP3 and SMP5) could be employed as alternative cost effective direct compression diluents in tablet formulation.

Application of two-phase lamellar model to study the ultrastructure of annealed canna starch: A comparison with linear correlation function

Canna starch was annealed at sub-gelatinization temperature (50°C) with different annealing time. Small angle X-ray scattering (SAXS) was used to estimate the ultrastructure of the annealed starches with the combined two-phase lamellar model and one-dimensional correlation function. The results showed that, upon annealing, water preferably swelled the amorphous regions of canna starch granules while maintained the part of crystalline region, resulted in an increase in amorphous thickness (da) and lamellar repeat distance (d). Power law plots indicates that a mass fractal (self-similar) structure was observed in canna starch, and annealing induces a less compact structure compared to native canna starch (NCS). Correlation analysis showed that no correlation was existed between annealing time and lamellar peak area, width of peak, and volume crystallinity. However, due to the initial degradation of the amorphous region, the volume crystallinity increased significantly with the increase of crystalline thickness (dc).

A chimeric α-amylase engineered from Bacillus acidicola and Geobacillus thermoleovorans with improved thermostability and catalytic efficiency.

The α-amylase (Ba-amy) of Bacillus acidicola was fused with DNA fragments encoding partial N- and C-terminal region of thermostable α-amylase gene of Geobacillus thermoleovorans (Gt-amy). The chimeric enzyme (Ba-Gt-amy) expressed in Escherichia coli displays marked increase in catalytic efficiency [K cat: 4 × 10(4) s(-1) and K cat/K m: 5 × 10(4) mL(-1) mg(-1) s(-1)] and higher thermostability than Ba-amy. The melting temperature (T m) of Ba-Gt-amy (73.8 °C) is also higher than Ba-amy (62 °C), and the CD spectrum analysis revealed the stability of the former, despite minor alteration in secondary structure. Langmuir-Hinshelwood kinetic analysis suggests that the adsorption of Ba-Gt-amy onto raw starch is more favourable than Ba-amy. Ba-Gt-amy is thus a suitable biocatalyst for raw starch saccharification at sub-gelatinization temperatures because of its acid stability, thermostability and Ca(2+) independence, and better than the other known bacterial acidic α-amylases.

Physico-chemical properties of corn starch modified with cyclodextrin glycosyltransferase

Cyclodextrin glycosyltransferase (CGTase) has been used to produce cyclodextrins (CDs) from starches, but their ability to modify starches has been barely explored. The effect of CGTase on corn starch at sub-gelatinization temperature (50°C) and at different pH conditions, pH 4.0 and pH 6.0, was evaluated. Biochemical features, thermal and structural analysis, oligosaccharides and CDs content were studied. Microscopic analysis of the granules confirmed the enzymatic modification of the starches obtaining structures with irregular surface and small pinholes. The extent of the starch modification was largely dependent on the pHs, being higher at pH 6.0. This was also confirmed by the low viscosity of the resulting pastes during a heating and cooling cycle. Thermal parameters were not affected due to enzymatic treatment. Modified starches were less susceptible to undergo α-amylase hydrolysis. CDs released were higher for samples treated at pH 4.0. Therefore, CGTase modification of corn starches at sub-gelatinization temperature offers an attractive alternative for obtaining porous starches with different properties depending on the pH conditions.

Functionality of porous starch obtained by amylase or amyloglucosidase treatments

Porous starch is attracting very much attention for its absorption and shielding ability in many food applications. The effect of two different enzymes, fungal α-amylase (AM) or amyloglucosidase (AMG), on corn starch at sub-gelatinization temperature was studied as an alternative to obtain porous starch. Biochemical features, thermal and structural analyses of treated starches were studied. Microscopic analysis of the granules confirmed the enzymatic modification of the starches obtaining porous structures with more agglomerates in the case of AMG treated starches. Several changes in thermal properties and hydrolysis kinetics were observed in enzymatically modified starches. Hydration properties were significantly affected by enzymatic modification being greater influenced by AMG activity, and the opposite trend was observed in the pasting properties. Overall, results showed that enzymatic modification at sub-gelatinization temperatures really offer an attractive alternative for obtaining porous starch granules to be used in a variety of foods applications.

Characteristics of a High Maltose-Forming, Acid-Stable, and Ca2+-Independent α-amylase of the Acidophilic Bacillus acidicola

The purified acidic α-amylase of Bacillus acidicola is a monomer of 66.0 kDa, optimally active at pH 4.0 and 60 °C. The enzyme is Ca2+ independent with T1/2 for 18 min at 80 °C. The Km, Vmax, and catalytic efficiency (kcat/Km) of the enzyme are 1.6 mg mL(−1), 23.8 μmol mg(−1) min(−1), and 981 μmol s(−1), respectively. Among detergents, Tween 20, 40, and 80 stimulated enzyme activity, whereas sodium dodecyl sulfate and Triton X-100 inhibited even at low concentration. EGTA has not affected the activity, whereas EDTA β-mercaptoethanol, iodoacetic acid, and Dithiothreitol exhibited a slight inhibitory action. Phenylmethanesulfonyl fluoride, N-bromosuccinimide, and Hg2+ strongly inhibited enzyme activity. The experimental activation energy and temperature quotient are 50.12 kJ mol(−1) and 1.37. When thermodynamic parameters (ΔH and ΔS) of the enzyme have been determined at different temperatures, ΔG is positive suggesting that the enzyme is thermostable. The enzyme hydrolyzes raw starches, and therefore, the enzyme finds application in raw starch saccharification at sub-gelatinization temperatures that saves energy needed for gelatinization of raw starch at 105 °C.

Amylolysis of amylopectin and amylose isolated from wheat, triticale, corn and barley starches

Amylopectin (AP) and amylose (AM) were isolated from normal (wheat, triticale, corn, and barley), waxy (corn and barley), and high-amylose (corn and barley) starches. The relationship between the molecular characteristics of the above starch polymers and amylolysis was studied in comparison to their native granules. Amylolysis was conducted by using granular starch hydrolyzing enzymes (a mixture of α-amylase and glucoamylase) at sub-gelatinization temperatures (<55 °C) over a period of 1 to 72 h, and the degree of hydrolysis (DH) was measured as a percentage of reducing value. At the early stages (1 h) of hydrolysis, AP and AM fractions from all starches were significantly hydrolyzed by amylases to a greater extent than native granules. Regardless of starch sources, the DH of AP and AM at 1 h hydrolysis ranged from 71.4 to 86.1 and 66.4 to 81.4%, respectively. Between 1 and 72 h of hydrolysis, the DH of AP was higher than AM in normal and high-amylose starches. Significant correlations were found between the molecular weight (Mw) or molecular size (Rz) of AP, and the DH of native granules at 1 h hydrolysis. The results suggested that a high proportion of short-chains in AP, indicated by its high Mw, high Rz and low average chain-length, were responsible for high DH of native granules. The difference in DH among native granules was mainly influenced by the difference in granular architecture resulting from variations in average chain length of AP.

The susceptibility of large and small granules of waxy, normal and high-amylose genotypes of barley and corn starches toward amylolysis at sub-gelatinization temperatures

Starches from waxy (CDC Candle), normal (CDC McGwire) and high-amylose (SH 99250) genotypes of hull-less barley were isolated and fractionated into large and small granules. The unfractionated and fractionated barley starches were then characterized toward their composition, morphology and structure, and compared with commercial corn starches of similar genotypes. The effect of starch properties on degree of hydrolysis (DH) at 55°C for 1h followed by at 30°C for 72h using granular starch hydrolyzing enzymes (mixture of α-amylase and glucoamylase) was also evaluated. Morphological changes of starches before and after hydrolysis were visualized by scanning electron microscopy (SEM) and confocal laser scanning microscopy (CLSM). The proportion (% weight) of small granules in high-amylose (HA) genotypes of barley (46.5%) and corn (32.4%) starches were higher than in the waxy (WX) and normal (NM) genotypes. Apparent amylose (AM) content of corn genotypes ranged from 1 to 1.1% (WX), 21 to 26% (NM), and 66 to 70% (HA). Whereas, the corresponding ranges for barley genotypes were 4–6% (WX), 17–24% (NM), and 35–40% (HA). HA corn starch exhibited a mixed ‘A+V’-type X-ray pattern, whereas the other genotypes of corn and barley starches exhibited an ‘A’-type X-ray pattern. The relative crystallinity (RC) of the genotypes of corn and barley starches followed the order: WX>NM>HA. The AM content and RC of small granules in corn and barley starches were lower than in large granules. Regardless of genotypes and starch sources, smaller granules had a higher gelatinization temperature range (15.5–42.8°C) and a lower enthalpy of gelatinization (9.7–21.2J/g) than those of larger granules (11.1–41.9°C and 13.4–23.9J/g, respectively). Compared to large granules, the small granules were initially hydrolyzed to a greater extent (18% higher). However after 72h, hydrolysis was 10% higher in the large granules. SEM and CLSM images revealed that the distribution of surface pores and internal channels varied between genotypes of corn and barley starches. Although small variations exist between the NM corn and NM barley starches with respect to their proximate composition and amylose content, the observed large variations in the extent of amylolysis at the initial stages of hydrolysis is indicative that the molecular architecture and granule porosity influence amylolysis.

호화점 이하에서 옴가열이 감자 전분의 열적특성에 미치는 영향

Ohmic heating uses electric resistance heat which occurs equally and rapidly inside of food when electrical current is flown into. In other study, we researched about soybean protein’s characteristic changes by ohmic heating. Nevertheless treated same temperature, denaturation of soybean protein were accelerated by ohmic heating than conventional heating. In this time, we studied thermal property change of potato starch by ohmic heating besides conventional heating. For this purpose, potato starch was heated at same subgelatinization temperature by ohmic and conventional heating. And thermal properties were tested using DSC. Annealing of starch is heat treatment method that heated at 3～4% below the gelatinization point. DSC analysis results of this study, the To, Tp, Tc of potato starch levels were increased, whereas Tc～To was narrowed. This thermal property changes appear similar to annealing’s result. It is thought the results shown in this study, because the heating from below the gelatinization point. 6, 12, 24, 72, and 120 hours heating at 55℃ for potato starch, To, Tp, Tc values ​ontinue to increased with heating time increase. The gelatinization temperature of raw potato starch was 65.9℃ and the treated starch by conventional heating at 55℃ for 120 hr was 72℃, ohmic was 76℃. The gelatinization range of conventional (72 hr) was 10℃, ohmic was 8℃. In case of 24 hours heating at 45, 50, 55, 60, 65℃ for potato starch, the result was similar to before. To, Tp, Tc values ​ontinue to increased and gelatinization range narrowed with heating temperature increase. In case of conventional heating at 60℃, the results of gelatinization temperature and range were 70.1℃ and 9.1℃. And ohmic were 74.4℃ and 7.5℃. When viewed through the results of the above, the internal structure of starch heated by ohmic heating was found that the shift to a more stable form and to increase the homology of the starch internal structure.

Biochemical and molecular characterization of recombinant acidic and thermostable raw-starch hydrolysing α-amylase from an extreme thermophile Geobacillus thermoleovorans

A gene encoding acidic, thermostable and raw starch hydrolysing α-amylase was cloned from an extreme thermophile Geobacillus thermoleovorans and expressed. The ORF of 1650 bp encodes a 515 amino acid protein (Gt-amy) with a signal peptide of 34 amino acids at the N-terminus. Seven conserved sequences of GH-13 family have been found in its sequence. The specific enzyme activity of recombinant Gt-amy is 1723 U mg−1 protein with a molecular mass of 59 kDa. It is optimally active at pH 5.0 and 80 °C with t1/2 values of 283, 184 and 56 min at 70, 80 and 90 °C, respectively. The activation energy required for its temperature deactivation is 84.96 kJ mol−1. Ca2+ strongly inhibits Gt-amy at 10 mM concentration, and inhibition kinetics with Ca2+ reveals that inhibition occurs as a result of binding to a lower affinity secondary Ca2+ binding site in the active centre in a mixed-type inhibition manner. The Km and kcat of the Gt-amy are 0.315 mg mL−1 and 2.62 × 103 s−1, respectively. Gt-amy is Ca2+-independent at the concentration used in industrial starch saccharification, and hydrolyses raw corn and wheat starches efficiently, and thus, is applicable in starch saccharification at the industrial sub-gelatinization temperatures.

Amylolysis of large and small granules of native triticale, wheat and corn starches using a mixture of α-amylase and glucoamylase

Starch granules from different sources differ in their morphology and structure, resulting in diverse amylolysis, which is closely related to bioconversion efficiency of starch to fermentable sugars during ethanol production. In this study, large and small granules were fractionated from native triticale, wheat and corn starches using a centrifugal sedimentation protocol and were hydrolyzed by a granular starch hydrolyzing enzyme at sub-gelatinization temperatures. Native triticale starches had bimodal granule size distribution with highest sizes of 14.9–15.9, 19.1–20.2, and 7.2 μm in diameter for overall, large and small granules, respectively, when compared to those of wheat and corn starches. The large granules in triticale starches contributed higher proportion of the total granules either by number (36–45%) or by weight (93–95%) than did those of wheat and corn starches. Surface pores and internal channels viewed by SEM and CLSM were more visible in large granules than in small granules of triticale, wheat, and corn starches, but corn starch generally displayed more pores and channels than triticale and wheat starches. Large granules contained significantly higher apparent amylose content and higher relative crystallinity than did small granules (23.0–28.5% vs. 12.4–21.0% and 24.9–26.8% vs. 20.8–24.4%, respectively) in all starches. Small granules were hydrolyzed significantly faster than did large granules initially (DH 9.3–18.0%, 24.7–40.3%, 17.7% higher in small granules than in large counterparts of triticale, wheat, and corn starches, respectively, at 55 °C for 1 h), however slowed down in later stage of hydrolysis. The final DH of large and small granules were similar in triticale (82.3–84.5%) and corn (80.8–83.4%) starches except wheat starches (90.8–95.1% in large and 79.6–86.2% in small granules) at 72 h hydrolysis. SEM and CLSM further revealed that the hydrolysis pattern differed between large and small starch granules and among starches, indicating diverse structure of large and small granules existed at macro, micro, and nano levels within and between species and cultivars. The study may be beneficial for precise control of liquefaction and saccharification in simultaneous hydrolysis and fermentation process of ethanol production.

Hydrolysis of Native and Heat-Treated Starches at Sub-Gelatinization Temperature Using Granular Starch Hydrolyzing Enzyme

The effect of heat treatment below the gelatinization temperature on the susceptibility of corn, mung bean, sago, and potato starches towards granular starch hydrolysis (35°C) was investigated. Starches were hydrolyzed in granular state and after heat treatment (50°C for 30min) by using granular starch hydrolyzing enzyme for 24h. Hydrolyzed heat-treated starches showed a significant increase in the percentage of dextrose equivalent compared to native starches, respectively, with corn 53% to 56%, mung bean 36% to 47%, sago 15% to 26%, and potato 12% to 15%. Scanning electron microscopy micrographs showed the presence of more porous granules and surface erosion in heat-treated starch compared to native starch. X-ray analysis showed no changes but with sharper peaks for all the starches, suggested that hydrolysis occurred on the amorphous region. The amylose content and swelling power of heat-treated starches was markedly altered after hydrolysis. Evidently, this enzyme was able to hydrolyze granular starches and heat treatment before hydrolysis significantly increased the degree of hydrolysis.

Improved cold starch hydrolysis with urea addition and heat treatment at subgelatinization temperature

We explore how the presence of urea can influence the kinetics of amylolysis, with a long-term objective of developing practical and energy efficient bioconversion protocols. In this study, triticale and corn starches were hydrolyzed by a granular starch hydrolyzing enzyme with or without addition of urea and a pre-heating treatment at subgelatinization temperature. Differential scanning calorimetry showed that the gelatinization parameters of triticale and corn starches were negatively correlated with the urea concentration in the starch suspension. Addition of urea did not significantly affect starch amylolysis by the granular starch hydrolyzing enzyme at 30 °C. However when pre-heating at a higher yet sub-gelatinization temperature (50 °C for triticale and 61 °C for corn, 5 °C below the onset of starch gelatinization) for 30 min, the presence of urea greatly facilitated the amylolysis of both tricticale and corn starches. Scanning electron microcopy revealed starch granule mophological changes to a porous structure in residual starch granules/fragments rich in resistant starch. This means that the amylolysis pattern in the presence of urea was fundamentally changed, and urea disrupts starch hydrogen bonds effectively with heating treatment at a sub-gelatinization temperature. This treatment combination increased both starch hydrolysis rate and extent. Since extra energy was not necessary to gelatinize starch, this method may benefit starch and bio-enthanol industries to reduce the costs of starch hydrolysis.

Structural changes of cassava starch granules hydrolyzed by a mixture of α-amylase and glucoamylase

The structural changes of cassava starch granules were studied by scanning electron microscope (SEM), X-ray diffraction (XRD), and differential scanning calorimeter after starch granules were hydrolyzed by a mixture of α-amylase and glucoamylase. The surface of starch granules was porous after hydrolysis treatment. Enzymatic erosion occurred mainly at the surface for cassava starch. The BET-specific surface area of hydrolyzed cassava starch improved 10.7 times compared with that of native starch. The powder XRD intensity of hydrolyzed starch was higher than that of native starch. The crystallinity in the hydrolyzed cassava starch increased due to hydrolysis. Compound enzymes could hydrolyze cassava starch granules at sub-gelatinization temperature, and could produce porous starch.

Hydrolysis of granular starch at sub-gelatinization temperature using a mixture of amylolytic enzymes

Native granular starches (corn, cassava, mung bean, and sago) were hydrolyzed using a mixture of alpha-amylase and glucoamylase at 35 °C for 24 h. Hydrolyzed starches were analyzed for the degree of hydrolysis and for physicochemical and functional properties. Corn starch showed the highest degree of hydrolysis, as evidenced by the presence of distinct pores penetrating deep into the granules. Enzymatic erosion occurred mainly at the surface for cassava, whereas isolated porous structures were observed in hydrolyzed mung bean and sago starch. The amylose content was significantly lower in all starches except for sago starch. The powder X-ray diffraction of all starches showed no significant changes after hydrolysis, but hydrolyzed starches showed a more crystalline nature. The action of enzymes caused significant changes in some pasting properties and in the swelling/solubility of starches. Evidently, enzymes were able to hydrolyze granular starches to a variable degree at sub-gelatinization temperature, and produced a relatively high degree of conversion.

Enzymatic hydrolysis of granular native and mildly heat-treated tapioca and sweet potato starches at sub-gelatinization temperature

The effect of mild heat treatment (below gelatinization temperature) towards the susceptibility of granular starch to enzymatic hydrolysis was investigated. Tapioca and sweet potato starches were subjected to enzymatic hydrolysis with a mixture of fungal α-amylase and glucoamylase at 35 °C for 24 h. Starches were hydrolyzed in native (granular) state and after heat treatment below gelatinization temperature (60 °C for 30 min). The dextrose equivalent (DE) value of heat-treated starch increased significantly compared to native starch, i.e., 36–50% and 27–34% for tapioca and sweet potato starch, respectively. Scanning electron microscopy examination showed that enzymatic erosion occurred mainly at the surface of starch granules. Hydrolyzed heat-treated starch exhibited rougher surface and porous granules compared to native starch. X-ray analysis suggested that enzymatic erosion preferentially occurred in amorphous areas of the granules. The amylose content, swelling power and solubility showed insignificant increase for both starches. Evidently, heating treatment below gelatinization temperature was effective in enhancing the degree of hydrolysis of granular starch.