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.     

Effect of the Extent of Conversion and Retrogradation on the Digestibility of Potato Starch

The effect of starch conversion on the susceptibility of potato granules to α‐amylase was studied by direct sampling at different pasting times corresponding to different points on the RVA profile of a 6.4% (w/w) suspension of starch in distilled water. Native granules showed high resistance to α‐amylase with 8.6 ± 0.4% digestibility for a 6 h incubation period with the enzyme. When the suspension was heated to 60 °C, the digestibility increased to 53.5 ± 0.7% although, at this temperature, there was still no noticeable increase in the measured viscosity (≤0.040 Pa · s). The material sampled after a pasting time corresponding to the RVA peak viscosity showed a digestibility of 88.4 ± 0.5%. This suggested, owing to the expected retrogradation of amylose on cooling, the quasi‐total susceptibility of amylopectin to enzymatic digestion at this pasting stage. The effect of ions on the swelling of potato starch was used to assess whether the decrease of the swelling of the granules in the presence of NaCl was paralleled by an increase in resistance to α‐amylase. A small (∼6.1%) but significant decrease in the digestibility of pasted starch was observed in the presence of salt. Finally, the effect of the retrogradation of the amylopectin fraction on its digestibility was assessed in extruded potato starch ribbons containing 35% (w/w) water and stored at different temperatures. After 14 days of storage, the digestibility decreased from 77.0 ± 0.9% in the freshly extruded samples to between 28.0 ± 1.7% and 42.1 ± 0.3%, depending on the storage temperature. This suggested a measurable difference in the α‐amylase susceptibility between the A and B polymorphs of retrograded amylopectin.     

High Carbonyl Content Oxidized Starch Prepared by Hydrogen Peroxide and Its Thermoplastic Application

Hydrogen peroxide was used to oxidize gelatinized starch to oxidized starch (OS) with degree of oxidation (DO) ranging from 0.096 to 0.554 depending on the H₂O₂/starch molar ratios used. Then glycerol was added to OS to produce thermoplastic oxidized starches (TPOS). Titrimetric determination of carboxyl and carbonyl groups, FT‐IR, ¹H‐NMR and ¹³C‐NMR confirmed that at H₂O₂/starch molar ratios < 0.7, oxidized starch contained much more aldehyde than carboxyl groups, while at molar ratios up to 2.0, peroxide oxidation produced mainly carboxyl groups. Scanning electron microscopy (SEM) revealed that the oxidized starch particles (at DO 0.385) obtained a porous structure. The effect of DO on the structure and properties of OS, as well as mechanical properties and moisture resistance of TPOS was studied, respectively. With an increase in DO, the crystallinity, intrinsic viscosity and thermal stability of OS decreased markedly, the ability of OS to take up water decreased at low DO and increased at higher DO. These observations show that hydrogen peroxide can be used to oxidize starch in a controlled way. TPOS with DO 0.385 showed the best mechanical properties, its tensile strength was 6.1 MPa after placing in 100% relative humidity for 15 days.     

Visual Observation of Hydrolyzed Potato Starch Granules by α‐Amylase with Confocal Laser Scanning Microscopy

Porous starch was produced by digestion of freeze‐dried potato starch with α‐amylase from Bacillus sp. The surface structure of the granules became perforated and in the interior of the granules a capsule‐like cavity was formed, i.e. the hydrolyzed starch can be used as an encapsulant. The structure change of the granules was observed with confocal laser scanning microscopy and scanning electron microscopy. The degree of starch hydrolysis could be correlated with the Avrami equation. The activation energy of starch hydrolysis by α‐amylase was 83 kJ/mol.     

Preparation and Characterization of Annealed‐Enzymatically Hydrolyzed Tapioca Starch and the Utilization in Tableting

Tapioca starch was annealed at 60°C for 90 min followed by hydrolysis with α‐amylase at 60°C at various lengths of time (30, 60 and 120 min) to obtain high‐crystalline starches. The reaction products were subjected to spray drying to obtain annealed–enzymatically hydrolyzed–spray dried tapioca starch (SANET) in the form of spherical agglomerated granules. The properties of SANET were compared with those of annealed–spray dried tapioca starch without enzymatic treatment (SANT) and native–spray dried tapioca starch (SNT). Scanning electron micrographs of the starch samples were used to study the morphological changes and to suggest the mode of enzyme attack during hydrolysis. The á‐amylase preferentially attacked the interior of the starch granules, leaving a deep round hole on the starch granule surface. It was found by X‐ray diffraction that both annealing and amylolysis did not alter the A type diffraction pattern. The% relative crystallinity of SANET was raised with increasing hydrolysis time and with decreasing amylose content. High performance size exclusion chromatography (HPSEC) demonstrated the decrease of the degree of polymerization (DP) of the amylose fraction of SANET after prolonged hydrolysis. For the utilization of SANET as tablet filler, it was directly compressed by a tablet compression machine at 4 kN to obtain tablets. The increased relative crystallinity of starch resulted in increased crushing strength and disintegration time, but in a decreased tablet friability.     

Physicochemical,structural, and digestibility properties of enzymatic modified plantain and mango starches

The effect of two enzymatic treatments (increasing the branch density of starch and shortening of AP and amylose chains) on the fraction of slowly digestible starch (SDS) and resistant starch (RS) of plantain (Musa paradisiaca L.) and mango (Mangifera indica L.) starches was investigated. The enzymatic modifications were carried out using β‐amylase (β‐AMY) and β‐amylase‐transglucosidase (β‐AMY‐TGs), in gelatinized starches. Plantain starch showed an increase from 10.9 to 18.5% of SDS, when it was modified by β‐AMY‐TGs, while the treatment with β‐AMY alone showed reduction from 10.9 to 7.1% in SDS. RS content increased with both treatments. On the other hand, mango starch showed an increase in SDS from 6.3 to 22.3% using β‐AMY treatment and from 6.3 to 11.7% using β‐AMY‐TGs treatment. The latter treatment also increased RS content. The enzyme modified starches showed a reduction in the values of molar mass and gyration radius compared with the native starch. The content of short chains of AP, particularly in the DP range 5–12, increased, the percentage of crystallinity decreased in treated starches, and ¹H NMR spectra showed a significant increase of α‐(1 → 6) linkages in the starches modified with β‐AMY‐TGs. These characteristics were related to an increase in the slow and resistant digestion properties of plantain and mango starches.     

A more Efficient Starch Degradation by the Combination of Hydrolase and Transferase Activities of α‐Amylase and Cyclomaltodextrin Glucanotransferase

α‐Amylases catalyze the hydrolysis of internal α‐(1→4) linkages of glucose polymers as their main reaction; however, some α‐amylases catalyze transfer reactions in addition to hydrolysis. It has been observed that those α‐amylases capable of transferring glycoside residues are also those that generate low molecular weight products from their action on starch (i.e. saccharifying α‐amylases). In this paper the product profiles of a liquefying α‐amylase, a cyclomaltodextrin glucanotransferase and both enzymes acting together on starch and maltodextrins are compared. The increase in glucose and maltose concentration, when both enzymes act together, is due to the combined action of the transfer and hydrolytic activity of CGTase and the liquefying α‐amylase, respectively.     

Kinetics of Granular Starch Hydrolysis in Corn Dry‐Grind Process

A promising modification to the dry grind process is the use of granular starch hydrolyzing enzymes (GSHE) for corn fractionation and ethanol production. Modeling the kinetics of granular starch hydrolysis in the corn dry‐grind process is challenging given the heterogeneity of the substrate and the combined activities of α‐amylase and glucoamylase. By measuring reducing sugars, the hydrolysis progress in dry‐grind corn slurry treated with a commercial GSHE was monitored during 3 h of reaction. Progress curves consisted initially of a rapid product formation phase (<15 min), followed by a longer range kinetics characterized by relatively slower product formation. The initial product from the accelerated kinetics was proportional to the adsorbed GSHE concentration, after accounting for the contribution of dissolved starch hydrolysis. The long range kinetics was modeled by an empirical equation that yielded two parameters: a which stood for the asymptotic limit of the product concentration, and ln (b) which was the time required to reach a product concentration of a/2. In response to increasing GSHE concentration, a increased and ln (b) decreased towards a saturation limit. In response to decreasing corn particle size (geometric mean diameter), a increased and ln (b) decreased linearly. These behaviors indicated both parameters were controlled by the concentration of accessible substrates in the starch granules. The findings have implications on the optimal usage of GSHE in dry‐grind processes.     

Formation of Resistant Starch in Corn Starch and Estimation of its Content from Physicochemical Properties

The effect of autoclaving temperatures (100‐120°C) on yields of enzyme‐resistant starch (RS) from normal corn starch and the physicochemical properties of autoclaved‐cooled starches were studied. The RS content increased linearly with increasing autoclaving temperature (R² = 0.993) and the number of autoclaving‐cooling cycles at an autoclaving temperature of 120°C. The effect of the number of autoclaving‐cooling cycles was more pronounced than that of temperature. The swollen starch weight measured at 60°C slightly increased as the RS content increased, and then drastically decreased with the continous increase of the RS content (R² = ‐0.969). As the RS content increased, all parameters of Rapid Visco Analyser (RVA) viscosity except breakdown decreased. Log RVA peak viscosity showed a negative correlation with the RS content (R² = ‐0.986). The enthalpy in the differential scanning calorimetry (DSC) endotherm corresponding to the transitions of RS linearly increased as the RS content increased (R² = 0.988). The RS content of the heat‐treated starch estimated from the relationship between RS content and swollen starch weight at 60°C, log RVA peak viscosity or DSC enthalpy was in good agreement with that determined with the standard method.     

Production of isomalto‐oligosaccharide syrup from rice starch using an one‐step conversion method

Isomalto‐oligosaccharides (IMO) belong to a group of prebiotics that can significantly increase the number of protective gut microflora. A one‐step method using neopullulanase (NPN) in conjunction with saccharifying α‐amylase (SAA) for the bioconversion of rice starch into IMO was investigated. Purified rice starch slurry (30% w/w) was mixed with NPN (3.5 U g^?1 starch substrate) and SAA (6.5 U g^?1 starch substrate) and the slurry was incubated at 57 °C for 92 h under constant stirring. The carbohydrate composition of the resulting syrup was analysed by high performance liquid chromatography (HPLC) and the dextrose equivalent (DE) determined by titration. The amount of IMO in the syrup reached maximum (59.2%, dry basis) after 72 h of bioconversion. The concentration of glucose and maltose, which were the main carbohydrate residues of the IMO syrup, was 25.5% while the concentration of other oligosaccharide residues was about 1.0%. The results demonstrate that rice starch is a suitable matrix for producing IMO syrup and the one‐step conversion procedure appears to be an efficient method for converting starch into IMO syrup.     

Combination of acid‐demineralization and enzymatic desizing of cotton fabrics by using industrial acid stable glucoamylases and α‐amylases

In this study, the possibility of simultaneous acid‐demineralization and enzymatic desizing of cotton fabric in acidic conditions (pH 2) by using industrial acid stable enzymes has been investigated. Acid‐demineralization is necessary to remove undesired cationic metals and earth alkalis. Our experiments showed that by use of a mixture of two appropriate enzymes, a glucoamylase (Multifect GA 10L) and an α‐amylase (Optisize Next) in a solution of citric acid and presence of a chelating agent, enzymatic desizing, and acid‐demineralization can be successfully carried out at the same time. Therefore, two processes of pretreatment were integrated into a single process, which can effectively reduce time and costs for textile industry.     

山西谷子全粉淀粉指标间相关性及消化特性研究

本文主要研究了77个山西谷子全粉样品中淀粉组分的相关性以及淀粉消化特性。分别测定了谷子金粉中淀粉、直链淀粉和抗性淀粉(RS)含量。制备谷子淀粉并分析了淀粉中快速消化淀粉(RDS)、慢速消化淀粉(SDS)、RS的含量以及淀粉消化指数(SDI)和持续消化淀粉(LS)。结果表明:各品种间RS含量差异性较大;全谷物以及制备得到的淀粉所测定的备指标间相关性较强。其中。谷子中RS与直链淀粉相关性最强(r=0.885),对谷子中RS聚类分析后发现。RS与直链淀粉近似呈线性相关(r=0.954)。对谷子淀粉体外消化研究表明:黄谷(2010)等品种中SDS舍量较高,晋谷21号(2010)等品种中RS含量较高,而陇谷10号(2012)等品种中LS含量相对较高,这些品种适用于糖尿病等人群食用或有助于开发相关降糖产品。     

Impacts of Starch and the Interactions Between Starch and Other Macromolecules on Wheat Falling Number

Wheat with a low falling number (FN) has been particularly prevalent in recent years and has resulted in a loss of more than $140 million in a single year in the wheat industry in the Pacific Northwest of the United States. FN measurement is a standard method for the evaluation of grain α‐amylase activity, and a low FN indicates a reduction in hot wholemeal paste viscosity due to sprouting damage. Recent studies show that a low FN may result from a developmental change of starch and adverse effects of non‐α‐amylase macromolecules on wheat. In this review, we describe the principles of FN measurement and the relationship between FN and α‐amylase. We also discuss the isozymes, locations, and inhibitors of wheat α‐amylase. The effects of various aspects of starch, which is the substrate of α‐amylase, on wheat FN are also discussed, including starch structural characteristics (for example, starch granule architecture), starch susceptibility to α‐amylase, and the interaction between starch and nonstarch macromolecules (for example, lipids). Studies on the effects of planting environments (for example, temperature) and agronomic practices (for example, irrigation and fertilization) on both starch paste viscosity and FN are also reviewed. This paper highlights the importance of considering the impacts of starch and the interactions of starch and other macromolecules, including wheat α‐amylase, on wheat FN, which is important for developing strategies to solve the low FN problem.     

Synthesis and in vitro digestion of resistant starch type III from enzymatically hydrolysed cassava starch

Resistant starch type III (RS III) was synthesised from cassava starch by autoclaving followed by debranching with pullulanase, at varied concentrations (0.4–12 U g^?1) and times (2–8 h), and recrystallisation (?18 to 90 °C for 1–16 h). The highest RS III yield (22 g/100 g) was obtained at an enzyme concentration of 4 U g^?1 after 8 h incubation, followed by recrystallisation at 25 °C for 16 h. Varying the recrystallisation conditions indicated that higher RS III yields (30–35 g/100 g) could be obtained at 90 °C within 2 h. Thinning cassava starch using α‐amylase prior to debranching using pullulanase did not further increase the RS III content. In vitro digestion data showed that whereas 44% RS III was digested after 6 h, the corresponding value for cassava starch was 89%.     

酶预处理和酸水解制备糯玉米淀粉纳米晶及其表征

采用糖化酶对糯玉米原淀粉进行预处理,通过X射线衍射(XRD)确定糖化酶预处理的最佳用量,再对酶预处理淀粉进行硫酸酸水解,制备糯玉米淀粉纳米晶,采用傅里叶变换红外光谱（FT-IR）、扫描电子显微镜(SEM)、粒径测量和Zeta电位分析等对淀粉纳米晶进行表征。结果表明,用1000U/(g淀粉)活性的糖化酶对糯玉米原淀粉处理2h,再结合酸水解2天,得到粒径约100nm、分散性好、产率为24.1%的糯玉米淀粉纳米晶;相较于仅硫酸酸水解处理,酶预处理结合酸水解法制备糯玉米淀粉纳米晶的反应时间缩短了3天,产率提高了70.9%,淀粉纳米晶的Zeta电位达-22.3 mV。     

Batter rheology and bread texture of sorghum‐based gluten‐free formulations modified with native or pregelatinised cassava starch and α‐amylase

The influence of α‐amylase (0–0.3 U g^?1) on the crumb properties of gluten‐free sorghum batter and bread, respectively, was investigated. The formulations were modified using native or pregelatinised cassava starch (i.e. batter A – 17% pregelatinised starch, 83% sorghum, 100% water fwb; batter B – 17% native starch, 83% sorghum, 100% water fwb; and batter C – 30% native starch, 70% sorghum, 80% water fwb). The batters had solid viscoelastic character with the storage modulus predominant over the loss modulus. Storage moduli of batter A decreased with increasing angular frequency, whereas the moduli of batters B and C were independent from the angular frequency. Increasing enzyme concentration did not affect the loss factors of the batters. Batters’ resistance to deformation, from highest to lowest, followed the order C > A > B. Increasing enzyme concentration decreased crumb firmness, cohesiveness, springiness, resilience and chewiness but increased adhesiveness. Overall, breads containing native starch had better crumb properties (i.e. springier and less firm, chewy and adhesive) than breads containing pregelatinised starch.     

Characteristics of raw starch degrading α‐amylase from Bacillus aquimaris MKSC 6.2 associated with soft coral Sinularia sp.

Partially purified α‐amylase from Bacillus aquimaris MKSC 6.2, a bacterium isolated from a soft coral Sinularia sp., Merak Kecil Island, West Java, Indonesia, showed an ability to degrade raw corn, rice, sago, cassava, and potato starches with adsorption percentage in the range of 65–93%. Corn has the highest degree of hydrolysis followed by cassaca, sago potato and rice, consecutively. The end products of starch hydrolysis were a mixture of maltose, maltotriose, maltotetraose, maltopentaose, maltohexaose, and small amount of glucose.