The impact of coupled acid or pullulanase debranching on the formation of resistant starch from maize starch with autoclaving–cooling cycles

Maize starch was treated by autoclaving–cooling cycles, coupled with acid or pullulanase hydrolysis to prepare resistant starch (RS). Debranching of retrograded or gelatinized maize starch with acid or pullulanase was studied to show the corresponding impact on RS formation. When maize starch was treated with three autoclaving–cooling cycles and retrograded maize starch was hydrolyzed at room temperature, with 0.1 mol L⁻¹ citric acid for 12 h, analysis results showed that debranching of citric acid was helpful in RS formation for RS yield increased from 8.5 to 11%. Debranching of gelatinized or retrograded maize starch at 60 °C with pullulanase at addition level of 3 PUN g⁻¹ starch showed a more favorable effect on RS formation. When gelatinized maize starch was hydrolyzed by pullulanase for 12 h and then treated with two autoclaving–cooling cycles, RS yield increased to 23.5%. If retrograded maize starch subjected to one autoclaving–cooling cycle was hydrolyzed by pullulanase for 10 h and then followed by two autoclaving–cooling cycles, RS yield elevated to 32.4%. The debranching effect of pullulanase on retrograded maize starch to help RS formation is obvious and most effective, indicating this treatment is applicable in RS preparation to increase the RS yield.     

Effect of debranching and storage condition on crystallinity and functional properties of cassava and potato starches

Debranching starch by pullulanase is considered to improve the RS content of starch which is widely used to produce the starch‐based foods with high‐health benefit impacts. In this study, the cassava and potato starches were debranched by pullulanase, followed by an autoclave treatment and storage at −18°C, 4°C, or 25°C to investigate their crystallinity and functional properties. After debranching, the potato starch contained significantly higher CL (35.4 glucose units) than did the cassava starch (32.4 glucose units). The debranched cassava and potato starches after retrogradation at the storage temperatures had a typical B‐type crystalline structure although the native cassava and potato starches exhibited the different crystalline forms (A‐ and B‐type, respectively). The RS contents of the debranched cassava and potato starches significantly improved with higher RS content of the debranched potato starch than that of the debranched cassava starch at the same storage condition. The storage temperature significantly affected the RS formation of the debranched starches with the highest RS content at storage temperature of −18°C (35 and 48% for the debranched cassava and potato starches, respectively). The debranched starches had significantly lower viscosities and paste clarities but higher solubilities than did the native starches. As a result, the debranched cassava and potato starches can be considered for use not only in functional foods with enhanced health benefits but also in pharmaceutical and cosmetic industries.     

Structural characterizations and digestibility of debranched high-amylose maize starch complexed with lauric acid

Structural characterizations and digestibility of debranched high-amylose maize starch complexed with lauric acid (LA) were studied. The cooked starch was debranched by using pullulanase and then complexed. Light microscopy showed that the lipids complexed starches had irregularly-shaped particles with strong birefringence. Gel-permeation chromatograms revealed that amylopectin degraded to smaller molecules during increasing debranching time, and the debranch reaction was completed at 12 h. Debranching pretreatment and prolonged debranching time (from 2 h to 24 h) could improve the formation of starch lipids complex. X-ray diffraction pattern of the amylose–lipid complexes changed from V-type to a mixture of B- and V-type polymorphs and relative crystallinity increased as the debranching time increased from 0 to 24 h. In DSC thermograms, complexes from debranched starch displayed three separated endotherms: the melting of the free lauric acid, starch–lipid complexes and retrograded amylose, respectively. The melting temperature and enthalpy changes of starch–lipid complex were gradually enhanced with the increasing of debranching time. However, no significant enthalpy changes were observed from retrograded amylose during the starch–lipid complex formation. Rapidly digestible starch (RDS) content decreased and resistant starch (RS) content increased with the increasing of debranching time, while the highest slowly digestible starch (SDS) content was founded at less debranching time of 2 h. The crystalline structures with dense aggregation of helices from amylose-LA complex and retrograded amylose could be RS, while SDS mostly consisted of imperfect packing of helices between amylopectin residue and amylose or LA.     

Production of resistant starch from acid-modified amylotype starches with enhanced functional properties

Amylotype corn starches, Hylon V and Hylon VII, were acid-hydrolyzed followed by autoclaving-storing cycles and drying in an oven or freeze-dryer. Molecular weights of the samples decreased with increasing hydrolysis time. Resistant starch (RS) contents of acid-hydrolyzed samples did not differ from those of native starches. RS contents of oven-dried samples were higher than those of freeze-dried samples. Onset (T_O) and peak (T_P) transition temperatures of hydrolysates were lower than those of respective native starches. Autoclaving-storing increased in T_O and T_P and decreased in ΔH values as compared to acid-hydrolyzed starches. Water binding and solubility values of hydrolysates were higher than those of respective native starches. Autoclaved-stored samples had higher water binding and solubility values than those of respective acid-hydrolyzed samples. Acid-hydrolyzed and autoclaved-stored samples increased the emulsion capacity and stability values of albumin. The RVA viscosity values of the autoclaved-stored samples were higher than those of the hydrolysates.     

Resistant Starch Made from Banana Starch by Autoclaving and Debranching

Resistant starches (RS) were prepared from banana starch by debranching with pullulanase for different times and after autoclaving treatment. The different treatments produced seven RS products, which were tested with respect to available starch (AS), RS and in vitro hydrolysis rate. The control sample (without debranching) had the highest AS (80.5%) and the lowest RS content (9.1%). The samples debranched for 5 h and longer did not show significant differences (α = 0.05) in AS (approximately 72%) and RS (approximately 18%). The RS values obtained in the samples prepared were twice as high as that of the control sample. However, the sample debranched for the longest time had the highest hydrolysis rate, demonstrating that this product has a high digestion rate. Banana starch is a good source for RS preparation by autoclaving due to its high RS content and can be an alternative source in developing countries for obtaining a nutraceutic ingredient for functional food preparation.     

Resistant starch prepared from high-amylose maize starch with citric acid hydrolysis and its simulated fermentation in vitro

Resistant starch (RS) was prepared from high-amylose maize starch through two autoclaving–cooling cycles and then acid hydrolysis of retrograded starch. Experimental results showed that hydrolysis of retrograded high-amylose maize starch with 0.1 mol L⁻¹ citric acid at room temperature for 12 h would increase RS yield to 39%. At simulated conditions of large intestine (anaerobic and 37 °C), the prepared RS product was fermented in culture by fresh feces extract from healthy adult or healthy infant to produce short chain fatty acids. Formic, acetic, propionic and butyric acid produced in culture were analyzed by GC with capillary column. The GC analysis results showed that as the increase of fermentation time and the addition level of RS in culture, the production of short chain fatty acids was increased. However, the production of short chain fatty acids (especially butyric acid) in culture fermented by healthy infant feces extract was much higher than that fermented by healthy adult feces extract. It suggested that the production of short chain fatty acids from RS in simulated intestinal conditions might be affected by the intestinal microflora.     

Effect of Pullulanase Debranching of Sago (Metroxylon sagu) Starch at Subgelatinization Temperature on the Yield of Resistant Starch

The effects of pullulanase debranching of sago (Metroxylon sagu) starch in the granular state and subsequent physical treatments on the formation and yield of type III resistant starch (RS 3) have been investigated. Sago starch was enzymatically debranched with pullulanase at 60°C and at pH 5.0 using different enzyme concentrations (24, 30, 40, 50 PUN/g dry starch) which was added to 20% (w/v) starch slurry and incubated for 0 to 48 h. Optimum enzyme concentration of 40 PUN/g dry starch and three debranching times (8, 16 and 24 h) have been selected for subsequent preparation of RS. Granule morphology and molecular weight distribution (MWD) of the debranched and resistant starch were examined. Debranched starch samples showed blurred birefringence patterns, a decrease in amylopectin fraction, an increase in low molecular weight fraction and a broadening of MWD. Debranched starch samples with a maximum RS yield of 7% were obtained at 8 h debranching time. Temperature cycling and incubation at certain temperature and storage time enhanced the formation of RS. Under the conditions used in this study, the optimum conditions to obtain the highest RS yield (11.6%) were 8 h of debranching time, followed by incubation at 80°C for seven days. The MWD analysis showed that RS consisted of material with relatively low degree of polymerization. This study showed that pullulanase treatment of starch in the granular state resulted in limited debranching of amylopectin but the subsequent physical treatments (incubation time/temperature) can be manipulated to promote crystallization and enhance formation of RS 3.     

The influence of time and storage temperature on resistant starch formation from autoclaved debranched banana starch

Debranching and autoclaving processes of banana starch were carried out for obtaining a resistant starch-rich powder with functional characteristics. Debranching was carried out using pullulanase for 24 h and the autoclaving was done at 121 °C for 30 min, the samples were then cooled down and stored between 24 and 48 h, and temperatures between 4 and 60 °C. The resistant starch level increased due to the debranching and autoclaving processes. The water absorption index values decreased when the storage time increased, pattern that agrees with the higher RS content. The water solubility index (WSI) was affected by the storage temperature but not by the storage time. The autoclaved sample was hydrolyzed to a lesser extent than native starch. The RS-rich powder presented also crystallinity because the process of autoclaving and storage induced starch retrogradation. The procedure proposed might be used for production of a RS-rich powder from banana starch with high RS level and functional properties.     

Determination of Optimum Conditions for Enzymatic Debranching of Cassava Starch and Synthesis of Resistant Starch Type III using Central Composite Rotatable Design

Cassava starch was debranched by treatment with isoamylase and pullulanase and the yield of resistant starch type III (RS III) optimized with respect to starch solids concentration (7.5‐15%, w/v), incubation time (8‐24 h) and enzyme concentration using central composite rotatable design. Higher concentrations of pullulanase (10‐35 U/g starch) compared to isoamylase (30–90 mU/g starch) were required to give a similar degree of starch hydrolysis within the experimental domain. A clear debranching end‐point was identifiable by following the reducing value, blue value and β‐hydrolysis limit of cassava starches debranched using isoamylase. It was difficult to define a debranching endpoint of pullulanase treatment by these parameters due to contaminating α‐D ‐(1→4) activity. The yield of RS III was significantly higher in isoamylolysates and increased steadily with increasing degree of hydrolysis to peak at 57.3%. Purification of the debranched material further increased the RS III yield to 64.1%. Prolonged (24 h) hydrolysis of cassava starch with high concentration of pullulanase (35 U/g) gave lower RS III contents in the purified (34.2%) and unpurified (36.2%) hydrolysates compared to 49.5 and 62.4%, respectively, at moderate pullulanase concentration (22.5 U/g) and incubation time (16 h).     

豌豆抗性淀粉的酶法制备及其性质研究

以豌豆淀粉为原料,经糊化、普鲁兰酶脱支和凝沉处理,使其分子结构发生改变,制备出高含量的抗性淀粉,并研究了其理化性质。结果表明,在加酶量为300 ASPU/g,脱支时间12 h,凝沉时间24 h时,抗性淀粉含量达到最高52.66%;经糊化、脱支和凝沉处理后的样品结晶结构由C型变为B+V型;随着抗性淀粉含量的增加,其溶解度逐渐降低且均高于原淀粉,但膨胀度均低于原淀粉;消化产物随抗性淀粉含量的增加而降低。     

Impacts of acid-methanol treatment and annealing on the enzymatic resistance of corn starches

Normal corn, Hylon V and Hylon VII starches were acid-methanol-treated at 25 °C for 1–30 days in methanol containing 0.36% HCl, and then annealing at 50 °C for 72 h in excess water. The rapid digestible starch (RDS), slow digestible starch (SDS) and resistant starch (RS) contents of starch before and after treatments were determined. The molecular structure, thermal properties, double helix content and relative crystallinity of starch were observed for elucidating the impacts of acid-methanol treatment and annealing, as well as the molecular structure, on the enzymatic resistance of starch. Results showed that the weight-average degree of polymerization of acid-methanol-treated corn starches ranged from 884 × 10³ to 404, 778 × 10³ to 299 and 337 × 10³ to 250 anhydrous glucose units for normal corn, Hylon V and Hylon VII starches, respectively. Annealing increased the RS content of starch, and the increment of RS increased with decreasing molecular size of starch. Furthermore, the change in RS content after treatments depended on the content and weight-average chain length of amylose fraction of starch. The RS content of starch after treatments increased from 19.2 to 56.2%, 69.9 to 86.1%, and 73.1 to 89.1% for normal corn, Hylon V and Hylon VII starches, respectively. The gelatinization peak temperature and double helix content of starch increased after acid-methanol treatment or annealing. Results demonstrate that the degradation of starch, causing by acid-methanol treatment, enhances the mobility and realignment of starch chains in molecules during treatments and further increases the enzymatic resistance of starch granules.     

Production and physicochemical properties of resistant starch from hydrolysed wrinkled pea starch

The content and physicochemical properties of resistant starches (RS) from wrinkled pea starch obtained by different molecular mass reduction processes were evaluated. Native and gelatinised starches were submitted to acid hydrolysis (2 m HCl for 2.5 h) or enzymic hydrolysis (pullulanase, 40 U g^?1 for 10 h), followed by hydrothermal treatment (autoclaving at 121 °C for 30 min), refrigeration (4 °C for 24 h) and lyophilisation. Native starch showed RS and total dietary fibre contents of 39.8% and 14.3%, respectively, while processed ones showed values from 38.5% to 54.6% and from 22.9% to 37.1%, respectively. From these, the highest contents were among acid‐modified starches. Processed starches showed endotherms between 144 and 166 °C, owing to the amylose retrogradation. Native and processed starches showed low viscosity, which is inversely proportional to the RS concentration in samples. The heat treatment promoted an increase in the water absorption index. The pea starch is a good source for obtaining resistant starch by acid hydrolysis.     

Application of enzyme-treated corn starches in breakfast cereal coating

Presently ready-to-eat cereals are coated with high levels of sugar coating to extend the bowl life. Because of health concerns of added sugar, there is a need to identify alternative coating materials. This study was designed to test the efficacy of debranched corn starches with varying amylose contents as a cereal coating. Hylon VII (70% amylose), common, and waxy corn starches were gelatinized and debranched, and then sprayed onto ready-to-eat breakfast cereal flakes. The surface morphology, milk absorption, texture, and digestibility of coated cereals were determined. A starch film with a thickness of 50 to 130 μm was observed with scanning electron microscopy on the surface of the cereals coated with Hylon VII. All starch-coated cereals had a lower milk absorption value than the uncoated and glucose-coated controls. Among starch coatings, common corn starch and Hylon VII resulted in lower milk absorption than did waxy corn starch. After soaking in milk for 3 min, the peak force and work to peak of the cereals coated with corn starches were higher than those of the glucose control and uncoated reference. The cereals coated with Hylon VII were found to have an increase in dietary fiber content. The results suggest that debranched amylose-containing corn starches could extend the bowl-life of ready-to-eat cereals. Practical Application: Currently, many cereals are coated with sugar to keep them from becoming soggy in milk. However, added sugar has been linked to obesity, hyperactivity, and dental caries. This has led to the investigation of alternative coating materials. This study employed the film-forming properties of enzyme-treated corn starch to function as a coating material in breakfast cereal flakes. In addition, the enzyme-treated high amylose corn starch also increased the dietary fiber content of the cereal flakes.     

Molecular structure and physicochemical properties of Hylon V and Hylon VII starches illuminated with linearly polarised visible light

Aqueous suspensions (30 g/100 g) of Hylon V and Hylon VII high amylose corn starches were illuminated with linearly polarized visible light for 5, 15, 25 and 50 h. For each native and illuminated starch sample, weight average molecular weight, M_w, and hydrodynamic radius, R_g, of starch polysaccharide molecules were measured by high pressure size exclusion chromatography coupled with multiangle laser light scattering and refractometric detectors (HPSEC-MALLS-RI). Additionally, X-ray diffraction patterns, intrinsic viscosity, kinetic of alpha-amylolysis together with iodine binding properties and distribution of amylopectin structural units were established for each starch sample. Changes in molecular weight M_w of starch polysaccharide chains eluted under whole polysaccharide peaks and values of intrinsic viscosity of corresponding starch samples observed in the course of illumination indicated that illumination of both starches studied, with linearly polarized visible light (LPVL), induced first depolymerysation followed by repolymerisation reaction of starch polysaccharide chains. Illumination induced rearrangements of the molecular structure of polysaccharide chains of illuminated Hylon V and Hylon VII starches led to significant changes of their physicochemical properties as compared with native starches.     

Prediction of the Glass Transition Temperature on Extruded Waxy Maize and Rice Starches in Presence of Glycerol

Polymer science approach has shown to be useful to understand the structural complexity of food systems. This work looks at the effect of glycerol (5%, 10%, and 20% (dry weight basis)) on the glass transition temperature (Tg) of a starchy matrix determined by DSC and its prediction using Ten-Brinke–Karasz equation. Waxy maize starch (WMS) and rice starch (RS) systems were prepared by thermomechanical extrusion. A decrease in Tg, from ∼170 to ∼25 °C, was detected for both starches (0% glycerol) when the moisture increased from 5% to 25% (wet weight basis (wb)). When glycerol was added, a further decrease in Tg was obtained. Tg was reduced from 120 to 60 °C and 45 °C for 10% and 20% glycerol, respectively, at a moisture content of 10% (wb). A direct comparison between starches with similar composition showed equal Tg (P > 0.05). The modeling for the control samples (0% glycerol) gave a ΔCp ∼ 0.4 Jg⁻¹ K⁻¹ for WMS and RS and ∼1.9 Jg⁻¹ K⁻¹ for water. These values can be explained by the well-known Tg dependence on degree of polymerization and molecular weight. When the glycerol concentration was increased, an increase was observed, ΔCp ∼ 0.6 Jg⁻¹ K^−1, for both starches and ∼2.8 Jg⁻¹ K⁻¹ for water. This behavior would indicate an overestimation in the plasticizing effect of glycerol due to the possible occurrence of polyol-rich fractions in the extruded samples.     

Comparison of structural features and in vitro digestibility of purple yam (<Emphasis Type="Italic">Dioscorea alata</Emphasis> L.) resistant starches by autoclaving and multi-enzyme hydrolysis

Resistant starches (RS) were prepared from purple yam by dual autoclaving-retrogradation (DAS), and pullulanase debranching treatment (PDS). DAS and PDS were then hydrolyzed by α-amylase and amyloglucosidase to obtain DAS.H and PDS.H. Differences in structural characteristics and in vitro digestibility among the four samples were investigated. The results showed that granules of RS had a rough surface and irregular shape. DAS had the lowest amylose content (29.52%), whereas PDS.H had the highest amylose content (41.96%). The order of crystallinity of the RS was: PDS.H (31.23%) > DAS.H (30.16%) > PDS (21.23%) > DAS (15.30%). Analysis by in vitro digestibility indicated a decreased hydrolysis index and glycemic index due to lower swelling power and water-binding capacity, and a well-ordered double helix structure and more crystallization in PDS.H than in the other RS samples. These results suggest that pullulanase debranching combined with α-amylase and amyloglucosidase hydrolysis may produce better RS with improved crystalline structure and higher digestion resistibility.     

Development and Physicochemical Characterization of New Resistant Citrate Starch from Different Corn Starches

Resistant starch has drawn broad interest for both potential health benefits and functional properties. In this study, a technology was developed to increase resistant starch content of corn starch using esterification with citric acid at elevated temperature. Waxy corn, normal corn and high‐amylose corn starches were used as model starches. Citric acid (40% of starch dry weight) was reacted with corn starch at different temperatures (120–150°C) for different reaction times (3–9 h). The effect of reaction conditions on resistant starch content in the citrate corn starch was investigated. When conducting the reaction at 140°C for 7 h, the highest resistant starch content was found in waxy corn citrate starch (87.5%) with the highest degree of substitution (DS, 0.16) of all starches. High‐amylose corn starch had 86.4% resistant starch content and 0.14 DS, and normal corn starch had 78.8% resistant starch and 0.12 DS. The physicochemical properties of these citrate starches were characterized using various analytical techniques. In the presence of excess water upon heating, citrate starch made from waxy corn starch had no peak in the DSC thermogram, and small peaks were found for normal corn starch (0.4 J/g) and Hylon VII starch (3.0 J/g) in the thermograms. This indicates that citrate substitution changes granule properties. There are no retrogradation peaks in the thermograms when starch was reheated after 2 weeks storage at 5°C. All the citrate starches showed no peaks in RVA pasting curves, indicating citrate substitution changes the pasting properties of corn starch as well. Moreover, citrate starch from waxy corn is more thermally stable than the other citrate starches.     

Physicochemical properties and in vitro digestibility of resistant starch from mung bean (Phaseolus radiatus) starch

RS from mung bean starch was prepared by autoclaving, pullulanase debranching, and retrogradation. Physicochemical properties, crystalline structure, and in vitro digestibility of selected RS samples with different RS content were investigated. Compared to native starch, AAM content of RS increased but MW decreased greatly. SEM clearly showed RS samples exhibited irregular shaped fragments with compact structure. XRD pattern indicated that RS samples had typical B‐type pattern with sharp peaks at 17.0°, 22.2°, and 23.9° 2θ. The relative crystallinity, gelatinization temperatures, and enthalpy increased with increasing RS content. The α‐amylase digestibility of RS was lower than that of native starch. The results suggested that the decrease in enzymatic digestion of RS might due to compact and ordered crystalline structures after debranching and recrystallization.     

Effect of gelatinisation on slowly digestible starch and resistant starch of heat-moisture treated and chemically modified canna starches

The effects of gelatinisation on slowly digestible (SDS) and resistant starch (RS) of native and modified canna starches were investigated. Starch slurries (10% w/w) were gelatinised at 100 °C for 5, 10, 20 and 40 min using a rapid visco analyzer (RVA). Significant change in the degree of gelatinisation (DG) values of all starch samples was observed during the initial 10 min of gelatinisation; after that the DG values increased gradually with gelatinisation time. The RS contents in all gelatinised starches decreased with increasing gelatinisation time, while the SDS values fluctuated. Chemical modification affected DG values as well as RS/SDS contents. The RS contents in 10% (w/w) acetylated, hydroxypropylated, octenyl succinylated and cross-linked canna starches gelatinised at 100 °C for 40 min were 26.6%, 32.0%, 45.3% and 19.8%, respectively, which were higher than that of the native starch (12.4%). Canna starch modified by crosslinking had the highest SDS content when gelatinised for 20-40 min. Modification of canna starch by heat-moisture treatment resulted in a lower content of RS for all treated samples. However, the Vt-HMT25 (canna starch containing moisture content of 25% during heat treatment) when gelatinised for 5-20 min contained a higher amount of SDS, compared to unmodified starch. The most effective modification method for RS and SDS formation was octenyl succinylation, where the sum of RS and SDS approached that of Novelose260.     

Quantification of Resistant Starch in Several Starch Sources Treated Thermally

The purpose of the research was to determine the effect of heat-moisture treatment at different phases and temperatures on resistance starch (RS) level on native starches samples of several botanical sources and to evaluate the thermal stability of different granules. Samples of potato, cassava, wheat, and corn starches were moisturized up to 30% wet basis and then treated in a convection oven at 80, 100, and 120°C during 40 and 60 minutes. RS was determined gravimetrically by a modification of Method 991.43 of the AOAC for the determination of total dietary fibre. All samples were submitted to different thermal analysis in a range from 40 to 180°C at 10°C/min. Overall, in the treated samples an increase of RS was observed, being the corn starch sample treated at 120°C and 60 minutes – the one that presented the highest content of RS (4.2%). Other treated samples showed a decrease in the gelatinization enthalpies with the presence of granular fusion, indicating internal re-arrangement, an increase in the gelatinization temperature and the thermo stability below 95°C.