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.     

Structural characterizations of waxy maize starch residue following in vitro pancreatin and amyloglucosidase synergistic hydrolysis

The objective of this work was to determine if in vitro digestion altered the molecular structure and slow digestion property of waxy maize starch. The Englyst testing on partially hydrolysis residual starches showed an increase of RDS accompanied a reduction of RS with increasing time of digestion, while SDS was almost constant. Scanning electron micrographs showed that the pattern of enzymatic hydrolysis was inside-out layer-by-layer digestion. A threefold decrease in the average molecular weight of starch components was observed after α-amylolysis for 120 min. There were increases in the onset temperature, peak temperature and ratio of absorbance 1047/1022 cm⁻¹, while the enthalpy of gelatinization, crystal structure, and crystallinity invaried. These changes suggest simultaneously enzymatic hydrolysis of both crystalline and amorphous regions of starch granule during in vitro digestion. SDS of starch residue also may consists of layered structure of amorphous and crystallite regions and located periphery of starch granules.     

Effect of controlled gelatinization in excess water on digestibility of waxy maize starch

An aqueous dispersion of waxy maize starch (5%, w/w) was controlled gelatinized by heating at various temperatures for 5 min. The treated samples were analysed using in vitro Englyst assay, light microscopy, differential scanning calorimetry, X-ray diffraction, and Fourier-transform infrared spectroscopy. When heated, SDS and RS levels were decreased inversely with RDS. A high SDS content (>40%) was kept prior to the visible morphological and structural changes (before 60 °C). Swelling factor began to increase slightly at 50–60 °C and continued to maximum value at 80 °C. A large decrease in ΔH, crystallinity, and ratio of 1047/1022 cm⁻¹ attributed to partially dissociation of crystalline clusters and double helices occurred at 65–80 °C. These changes showed that controlled gelatinized starch with slow digestion property occurred in the molecular rearrangement process before granule breakdown and SDS mainly consists of amorphous regions and a small portion of less perfect crystallites.     

Characterization of modified high-amylose maize starch-α-naphthol complexes and their influence on rheological properties of wheat starch

Amylose can form inclusion complexes with diverse small molecules. Modified starch has different and unique properties compared with its native counterpart. In this study, chemically/enzymatically modified high-amylose maize starches were used to make inclusion complexes with α-naphthol, and the physical properties of complexes and their influences on the rheology of wheat starch were characterized. The results showed that modification of starch had little influence on the wide angle X-ray diffraction pattern of complex (eightfold single helix), but did so on the complexation index and precipitation yield. Inclusion complexes with chemically modified starch showed a lower range of thermostability and recrystallization temperatures. Addition of complex considerably influenced the rheological properties of wheat starch, and the effect was dependent on the type of modified starch used. It may be concluded that starch inclusion complexes, with a range of properties and potential food applications, may be feasibly prepared by using diverse modified high-amylose maize starches.     

Effect of debranching and heat treatments on formation and functional properties of resistant starch from high-amylose corn starches

High-amylose corn starches [(Hylon V (H5) and Hylon VII (H7)] were debranched with pullulanase, followed by autoclaving–storing cycles and drying in an oven (at 50 °C) or freeze-dryer. The samples were autoclaved at 123 and 133 °C and stored at 4 and 95 °C. Molecular weights of the samples decreased and resistant starch (RS) contents increased with increased debranching time. RS contents of H7 samples were higher than those of H5 samples. RS contents of oven-dried samples were higher than those of freeze-dried samples. Debranching caused decreases in DSC peak temperature (T _p) and increases in enthalpy (ΔH) values of H5 and H7. Autoclaving at 133 °C caused higher ΔH values as compared to autoclaving at 123 °C. The solubility and water-binding values of autoclaved-only (control) and autoclaved–debranched (3–48 h) samples and the samples treated with autoclaving–storing cycles after debranching of both H5 and H7 were higher than those of their respective native starches. Debranching of starch samples affected the emulsion capacity of albumin adversely, but improved the emulsion stability of albumin. Cold viscosity values of freeze-dried samples were higher than those of oven-dried samples. Autoclaving–storing cycles after debranching caused decreases in peak, breakdown and final viscosity values.     

Effects of alkaline treatment on the structure of phosphorylated wheat starch and its digestibility

Phosphorylated wheat starch (PWS) was prepared with sodium trimetaphosphate and sodium tripolyphosphate (99/1, w/w), and the modified starch gave 88.8% total dietary fibre by the Prosky method and 68.7% resistant starch (RS) by the Englyst method. The stability of the phosphate esters in aqueous sodium hydroxide was investigated and related to total dietary fibre and RS contents. The phosphorylated starch was slurried (40%, w/w) at 40 °C for 4 h at pH 9.0, 10.0, 11.0, and 12.0. The phosphorus content of the PWS decreased from 0.37% to 0.29% after treatment at pH 12.0, whereas only a slight decrease in phosphorus content occurred after treatments at pH 9.0–11.0. Despite the 22% decrease in total phosphorus content, total dietary fibre content and RS content of the alkali-treated PWS changed only slightly. ³¹P nuclear magnetic resonance spectroscopy showed that after the alkali treatment at pH 12.0, cyclic monostarch monophosphate and monostarch diphosphate were not detectable and that the level of total monostarch monophosphate decreased from 0.077% to 0.067%. Conversely, distarch monophosphate increased from 0.17% to 0.20%, of ≈18%. The increase in distarch monophosphate (cross-linking) content after alkali treatment at pH 12.0 probably explained the retention of total dietary fibre and RS contents in the alkali-treated PWS.     

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.     

Effect of high-pressure homogenization on microstructure and rheological properties of alkali-treated high-amylose maize starch

The effect of high-pressure homogenization (HPH) on the microstructure, rheological properties, paste clarity, as well as gel retrogradation behavior of alkali-gelatinized high-amylose maize starch (HMS) was investigated. The alkali-treated HMS pastes were subjected to HPH at homogenizing pressures of 25, 50, 75, 100, and 125 MPa. After HPH treatment, the uniformity in the microstructure of HMS pastes was greatly increased. At homogenizing pressures greater than 100 MPa, starch ghost particles were found to completely disappear. The apparent viscosity of the HMS pastes was found to decrease significantly due to the application of HPH. The paste clarity of the HMS pastes increased when HPH treatment was applied. After storing at 4 °C for 7 days, HMS pastes homogenized at 50 and 100 MPa displayed weaker viscoelastic behavior than their corresponding unhomogenized pastes. This indicated that HPH treatment is capable of inhibiting starch retrogradation in gels.     

Effect of Cooling,and Freezing on the Digestibility of Debranched Rice Starch and Physical Properties of the Resulting Material

Ten percent non‐waxy and waxy starch suspensions were debranched with pullulanase followed by heating and cooling (1 °C) to crystallize and/or gel. Products with a range of textures can be made depending on the type (waxy and non‐waxy) of starch used. The water holding capacity was 35% and 84% for waxy and non‐waxy cooled debranched starch, respectively, at 4 h of cooling and did not change. The hardness of the debranched waxy and non‐waxy starch continued to increase beyond 24 h up to 45 g and 245 g of force, respectively. The particle size of precipitates of non‐waxy and waxy debranched starch was 45 μm and 4 μm after 4 h of cooling and did not change. Cooling of debranched non‐waxy starch at 1 °C for 12 h without agitation decreased digestibility by 59%; with stirring digestibility decreased by 42% after 24 h of cooling. Freezing of debranched cooled waxy and non‐waxy starch does not effect the decreases in digestibility. Particle size of debranched, cooled/freeze‐thawed, dried, and milled starch affects digestibility.     

Effect of pre-gelatinised high-amylose maize starch combined with Ca2+ -induced setting of alginate on the physicochemical and sensory properties of rice flour noodles

This study explored the effect of pre-gelatinised high-amylose maize starch combined with Ca²⁺ -induced setting of alginate on the physicochemical and sensory properties of rice flour noodles. Rice flour noodles were prepared by partially substituting rice flour with pre-gelatinised high-amylose maize starch in ratios of 5, 10 and 15% (wt/wt), combined with sodium alginate at 1% (wt/wt). The noodles were then immersed in a calcium chloride solution to set the alginate. Results indicated that the hydrocolloids significantly (P < 0.05) increased noodle tensile strength, hardness, water absorption and optimum cooking time while cooking loss was significantly (P < 0.05) reduced. SEM micrographs showed a denser, compact noodle structure with an increase in the matrix's continuity as a result of hydrocolloids addition. Formulated noodles also scored above average (5.91) sensory acceptability on the 7 points hedonic scale. Overall, results proved promising for the preparation of rice flour noodles with enhanced properties.     

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.     

Morphology and structural properties of high-amylose rice starch residues hydrolysed by amyloglucosidase

High-amylose starches are attracting considerable attention because of their potential health benefits and industrial uses. Enzyme hydrolysis of starch is involved in many biological and industrial processes. In this paper, starches were isolated from high-amylose transgenic rice (TRS) and its wild type rice, Te-qing (TQ). The morphological and structural changes of starch residues following Aspergillus niger amyloglucosidase (AAG) hydrolysis were investigated. AAG hydrolysed TQ starch from the granule surface, and TRS starch from the granule interior. During AAG hydrolysis, the content of amorphous structure increased, the contents of ordered structure and single helix decreased, and gelatinisation enthalpy decreased in TQ and TRS starch residues. The A-type polymorph of TRS C-type starch was hydrolysed faster than the B-type polymorph. The short-range ordered structure and B-type polymorph in the peripheral region of the subgranule and the surrounding band of TRS starch increased the resistance of TRS starch to AAG hydrolysis.     

Use of the resistance effect between retrograded starch and iodine for evaluating retrogradation properties of rice starch

A resistance effect between retrograded starch and iodine and its potential use for evaluating retrogradation properties of rice starch were investigated in this study. Our results showed that the resistance effect obviously occurred during the interaction of retrograded starch and iodine ions. The extent of the resistance was selected as a parameter to explore the kinetics of starch recrystallisation, indicating that the recrystallisation data obtained were suited to the Avrami equation (all correlation coefficients R > 0.99). Furthermore, the resistance was suitably employed to clarify some properties of starch retrogradation, including the rate constant (0.11 d⁻¹ ? k ? 0.17 d⁻¹) and the Avrami exponent (1.18 ? n ? 1.29). These results suggest that the resistance extent is able to provide potential data for measuring the degree of starch retrogradation.     

Effect of maize type and extrusion‐cooking conditions on starch digestibility profiles

This study aimed at evaluating the influence of screw speed (250–600 rpm), barrel temperature (100–160 °C) and water content (16.4–22.5%) on rapidly digestible (RDS), slowly digestible (SDS) and resistant (RS) starch levels of waxy, normal and high‐amylose maize starches. In native starches, an increase in amylose content was correlated with lower SDS content. After extrusion, this trend was reversed. Both waxy and normal maize starches became rapidly digested. However, for normal maize starch, some SDS fraction remained. In contrast, the high‐amylose maize starch showed a significant increase in digestibility and an increase in SDS content from 20.4% in the native starch up to 27.5% after extrusion. This high level of SDS may be attributed to the presence of some remaining granular structures and formation of crystalline orders, which have slow digestion properties.     

普鲁兰酶加酶量对蜡质玉米抗性淀粉影响及性质研究

选用蜡质玉米淀粉为原料,高温糊化后采用普鲁兰酶脱支,产生短直链淀粉,重新结晶制备抗性淀粉。结果表明,8%(w/w)淀粉乳添加20 ASPU/g(基于淀粉干基重)普鲁兰酶在58℃反应24 h,然后在20℃凝沉24 h产生样品抗性淀粉含量最高,达到27.69%。理化性质研究表明,所有抗性淀粉样品颗粒形貌遭到破坏,形成不规则碎片;X-射线衍射图谱均有新的结晶结构出现,显示为B+V型;DSC分析结果显示,随抗性淀粉含量增加,不同样品峰值温度和糊化焓也增加。