Structural and physicochemical characterization of RS prepared using hydrolysis and heat treatments of chickpea starch

The aim of this study was to evaluate the production and the structural and physicochemical properties of RS obtained by molecular mass reduction (enzyme or acid) and hydrothermal treatment of chickpea starch. Native and gelatinized starch were submitted to acid (2 M HCl for 2.5 h) or enzymatic hydrolysis (pullulanase, 40 U/g per 10 h), autoclaved (121°C/30 min), stored under refrigeration (4°C/24 h), and lyophilized. The hydrolysis of starch increased the RS content from 16% to values between 20 and 32%, and the enzymatic treatment of the gelatinized starch was the most efficient. RS showed an increase in water absorption and water solubility indexes due to hydrolytic and thermal process. The processes for obtaining RS changed the crystallinity pattern from C to B. Hydrolysis treatments caused an increase in relative crystallinity due to the greater retrogradation caused by the reduction in MW. RS obtained from hydrolysis showed a reduction in viscosity, indicating the rupture of molecules. The viscosity seemed to be inversely proportional to the RS content in the sample.     

Production and characterization of digestion‐resistant starch by the reaction of Neisseria polysaccharea amylosucrase

Recombinant amylosucrase (200 U/mL) from Neisseria polysaccharea was used to produce digestion‐resistant starch (RS) using 1–3% (w/v) corn starches and 0.1–0.5 M sucrose incubated at 35°C for 24 h. Characterization of the obtained enzyme‐modified starches was investigated. Results show that the yields of the enzyme‐modified starches were inversely proportional to the original amylose contents of corn starches. After enzymatic reaction, insoluble RS contents increased by 22.3 and 20.7% from 6.9% of waxy and 7.7% of normal corn starches, respectively, using 3.0% starch as acceptor and 0.3 M sucrose as donor, while amylomaize VII showed the lowest increase (8.5%) in RS content. The crystalline polymorph of these enzyme‐modified starches resulted in the B‐type immediately after enzymatic reaction. The enzyme‐modified starches displayed higher melting peak temperatures (85.6–100.6°C) compared to their native starch counterparts (70.1–78.4°C). After enzymatic reaction, pasting temperature increased in waxy (71.9 → 77.6°C) and normal corn starches (75.3 → 80.6°C), and the peak viscosity of waxy corn starches increased from 264 to 349 RVU, whereas that of normal corn starches decreased from 235 to 66 RVU.     

Effects of Cooking Methods and Starch Structures on Starch Hydrolysis Rates of Rice

This study aimed to understand effects of different cooking methods, including steamed, pilaf, and traditional stir‐fried, on starch hydrolysis rates of rice. Rice grains of 3 varieties, japonica, indica, and waxy, were used for the study. Rice starch was isolated from the grain and characterized. Amylose contents of starches from japonica, indica, and waxy rice were 13.5%, 18.0%, and 0.9%, respectively. The onset gelatinization temperature of indica starch (71.6 °C) was higher than that of the japonica and waxy starch (56.0 and 56.8 °C, respectively). The difference was attributed to longer amylopectin branch chains of the indica starch. Starch hydrolysis rates and resistant starch (RS) contents of the rice varieties differed after they were cooked using different methods. Stir‐fried rice displayed the least starch hydrolysis rate followed by pilaf rice and steamed rice for each rice variety. RS contents of freshly steamed japonica, indica, and waxy rice were 0.7%, 6.6%, and 1.3%, respectively; those of rice pilaf were 12.1%, 13.2%, and 3.4%, respectively; and the stir‐fried rice displayed the largest RS contents of 15.8%, 16.6%, and 12.1%, respectively. Mechanisms of the large RS contents of the stir‐fried rice were studied. With the least starch hydrolysis rate and the largest RS content, stir‐fried rice would be a desirable way of preparing rice for food to reduce postprandial blood glucose and insulin responses and to improve colon health of humans.     

The effects of annealing and acid hydrolysis on resistant starch level and the properties of cross‐linked RS4 rice starch

The effects of ANN prior to cross‐linking of non‐wx rice starches on a RS level and granular shape were investigated to apply them for a fat replacer with RS in a liquid food system. Acid hydrolysis and sonication were also evaluated to improve RS quality. The RS level was also compared with AOAC and P/G methods. The RS levels of CRS analyzed with the AOAC method were higher than those analyzed with the P/G method, but the differences in the RS level of CRS affected an ANN condition and starch content during cross‐linking. When ANN was conducted at 50°C for 12 h using the AOAC method, and starch content (40%) used in cross‐linking was at 45°C for 3 h, the highest RS level of CRS treated with ANN was 69.4% compared to 38.3% RS level of CRS without ANN. The 1 h acid hydrolysis (pH 4.0) of CRS treated ANN increased 114.5% of the RS level (79.4% compared to 69.4% in CRS treated ANN), regardless of which analytical methods were used. CRS granules remained the same as native ones with a polygonal shape and A type crystallinity even after being treated with ANN, and acid hydrolysis. The sonication before cross‐linking reaction increased the RS level and prevented increase in size from aggregating CRS granules.     

Mild hydrolysis of resistant starch from maize

To investigate structural changes of resistant starch (RS) caused by mild-acid treatment, native maize starch, retrograded (RS3), and cross-linked (RS4) resistant starches, prepared from maize starch, were hydrolyzed with 0.1 M HCl at 35 °C for 30 days. The hydrolysis rate of RS3 was shown to be the highest, at 44.1% after 30 days of the hydrolysis. The hydrolysis rapidly progressed upto 10 days but gradually changed after that. Native starch and RS4 showed less than 5% of hydrolysis during the period of hydrolysis. As for the RS level of the residue after the hydrolysis, RS4 did not show any significant change, but RS3 exhibited an increase of up to 25.9% after 30 days, which led to 88% increase in comparison with 13.8% at the initial stage. As a result of examining the molecular weight (MW) of RS3 by the SEC-MALLS-RI system, the non-hydrolyzed RS3 exhibited three peaks, having MW 53.4 × 10⁶, 7.4 × 10⁶, and 0.8 × 10⁶, respectively, but the MW of the molecules decreased to 4.9 × 10⁶ and 0.6 × 10⁶ after 7 days of hydrolysis. It was difficult to verify the MW of RS4 because this was not dispersed in 1 M NaOH. The crystallinity of native starches, RS3 and RS4, by X-ray diffractometry of the residue hydrolyzed with 0.1 M HCl was equal to that of the non-hydrolyzed starch. The peak intensity at 2θ = 17° of RS3 increased sharply after hydrolysis.     

In vitro availability of starch in heat‐treated potatoes as related to genotype,weight and storage time

The objective of the study was to determine the influence of potato variety, weight and storage time after lifting on the glycaemic index (GI) and resistant starch (RS) content predicted from measurement of the rate and extent of in vitro starch hydrolysis, respectively. The potatoes were either boiled, or boiled and subjected to different heat‐cycling conditions selected to promote retrogradation of amylose or amylopectin, respectively. The hydrolysis indices (HI) and predicted GIs of all 19 potato products were high and fell within narrow ranges of 122–144 and 118–138, respectively. No correlation between average weight of the potato tuber and HI was found. Furthermore, there was no difference in HI between potatoes stored for 1–3 or 8–10 months, nor between varieties of new potato and winter potato. However, the HI was significantly lowered by temperature cycling at conditions known to promote retrogradation of amylopectin (6 °C, 48 h) compared with 6 °C for 24 h followed by 70 °C for 24 h. RS content was already substantial in boiled potatoes, 4.5 g 100 g^?1 (starch basis), and could be increased further by temperature cycling, the highest yield obtained, 9.8 g 100 g^?1 (starch basis), following heat treatment at 6 °C for 24 h followed by 70 °C for 24 h; that is at conditions known to favour amylose retrogradation. Copyright © 2004 Society of Chemical Industry     

Effect of heat-moisture treatment on the formation and physicochemical properties of resistant starch from mung bean (Phaseolus radiatus) starch

Mung bean starch was subjected to a range of heat-moisture treatments (HMT) based on different moisture contents (15%, 20%, 25%, 30%, and 35%) all heated at 120 °C for 12 h. The impact on the yields of resistant starch (RS), and the microstructure, physicochemical and functional properties of RS was investigated. Compared to raw starch, the RS content of HMT starch increased significantly, with the starch treated at 20% moisture having the highest RS content. After HMT, birefringence remained at the periphery of the granules and was absent at the center of some granules. The shape and integrity of HMT starch granules did not change but concavity was observed under scanning electronic microscopy. Apparent amylose contents of HMT starch increased and the HMT starch was dominated by high molecular weight fraction. Both the native and HMT starches showed A-type X-ray diffraction pattern. Relative crystallinity increased after HMT. The gelatinization temperatures (To, Tp, and Tc), gelatinization temperature range (Tc–To) and enthalpies of gelatinization (ΔH) increased significantly in HMT starch compared to native starch. The solubility increased but swelling power decreased in HMT starches. This study clearly shows that the HMT exhibited thermal stability and resistance to enzymatic hydrolysis owing to stronger interactions of starch chains in granule.     

Effect of storage on resistant starch content and in vitro starch digestibility of some pressure‐cooked cereals and legumes commonly used in India

Resistant starch (RS) is that fraction of starch, which escapes enzymic hydrolysis in the small intestine and passes in the colon. Effect of storage time (12 and 24 h) and temperature (4 °C and 25 °C) was studied on RS content of the pressure‐cooked cereal and legume grains/seeds and their flours. RS content was observed to increase in the stored cereals and legumes, with more enhanced increase in the flour samples stored at refrigeration temperature for longer duration (41.4% in wheat flour and 85.4% in pea flour). Significant positive correlations were observed between RS content (4 °C, 24 h) and amylose (y = 0.388 × –5.948, r = 0.840, P ≤ 0.05, n = 7) as well as between % increase in insoluble dietary fibre content (4 °⁰C, 24 h) and amylose (y = 2.257 × –27.724, r = 0.971, P ≤ 0.05, n = 7). Reduced in vitro starch digestibility of the cooked/stored samples (4 °C, 24 h) was observed when compared to freshly cooked samples.     

Resistant starch production from mango starch using a single‐screw extruder

Resistant starches were prepared from mango starch by extrusion. An experimental design with independent variables temperature, screw speed and moisture content produced 20 samples that were studied to determine the effect of these variables on resistant starch (RS) content, water absorption index (WAI) and water solubility index (WSI). RS content was affected by moisture content and temperature. Screw speed and temperature also influenced RS content, the highest level (97 g kg⁻¹) being obtained at low screw speed and high temperature, this pattern can be associated with a longer residence time, which gives rise to more opportunity for amylose chain association. The regression model fitted to the RS experimental results showed a good correlation coefficient (0.80). When moisture content and temperature decreased, WAI increased (105–142 g kg⁻¹), but low WAI values (70–77 g kg⁻¹) were obtained at moisture contents between 200 and 300 g kg⁻¹ and high temperatures (140–150 °C). When moisture content and temperature increased, WSI increased (222–332 g kg⁻¹), but at high temperature value (120 °C) assayed and the lowest moisture content (150 g kg⁻¹), WSI also increased. In the range of moisture contents tested and at low temperatures, only partial gelatinisation occurred and low solubility was obtained. Copyright © 2005 Society of Chemical Industry     

Short-chain fatty acid content and pH in caecum of rats fed various sources of starch

Caecal pH and contents of short-chain fatty acids (SCFA) were registered in rats fed three potential sources of resistant starch (RS); raw pea starch, raw potato starch, and an RS-enriched preparation obtained from wheat starch by autoclaving and enzymatic incubation. Small intestinal digestibility and delivery of RS to the hind-gut in the case of raw starches were determined by analysis of faecal starch in animals treated with antibiotics to prevent hind-gut fermentation. RS content in the RS-enriched preparation was determined as total starch remaining in an enzymatic gravimetric dietary fibre residue. The fermentability of RS was estimated from the faecal recovery of starch in normal animals with intact hind-gut microflora. Approximately 35 g per 100 g and 32 g per 100 g were RS in the case of raw potato starch and the RS-enriched preparation, respectively, versus only 1 g per 100 g in the case of raw pea starch. The caecal pH decreased with all test diets, being most significant with raw potato starch. SCFA production and faecal bulking were negligible with raw pea starch, whereas both raw potato starch and the RS-enriched preparation significantly increased these parameters. The fermentability of RS in raw potato starch and the RS-enriched preparation was similar, or about 60–70%. If calculated on basis of fermented amount, RS in raw potato starch was more potent in generating SCFA (49 μmol g^?1) than in the RS-enriched preparation (19 μmol g^?1). RS in raw potato starch also displayed the highest faecal bulking capacity. In fact, the faecal dry weight increased more than expected merely from delivery of RS. The relative proportion in caecal contents of acetic-, propionic- and butyric acid was 70, 17 and 8%, respectively, with no significant differences between the three sources of RS.     

Enhancement of Resistant Starch (RS3) in Amylomaize,Barley, Field Pea and Lentil Starches

Native starches isolated from amylomaize. Glacier high amylose barley, field peas and lentils contained 3–5% (w/w) resistant starch (RS3). Retrograded gels that were prepared from these starches had higher RS3 (6–9%) contents. The effects of gel concentration (% starch), storage temperature and time on the RS3 content of the retrograded gels were investigated; the optimum RS3 content was determined in gels prepared at = 10% (w/v) starch concentration and stored under = 20°C for = 5 days. Annealing of the retrograded starch gels by heating and cooling cycles, further enhanced RS3 content to 9–19%; the effect of annealing temperature and number of heat-cool cycles on the RS3 content of the annealed gel were studied. The hydrolysis of retrograded starch gels by pulanase enzyme or acid (2.2 N HCl), prior to annealing, enhanced the RS3 formation during annealing; the enzyme or acid treatment increased RS3 content of the annealed gel to 15–24% or 17–24%, respectively. The potential molecular mechanism that is responsible for the RS3 increase is discussed.     

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.     

豌豆抗性淀粉制备工艺优化及理化性质研究

采用压热-普鲁兰酶酶解豌豆淀粉制备豌豆抗性淀粉,并测定豌豆抗性淀粉理化性质。以3,5-二硝基水杨酸测得抗性淀粉产率为参考指标,在单因素试验基础上进行响应面试验优化豌豆抗性淀粉制备工艺,并测定最佳条件下豌豆抗性淀粉的理化性质。结果表明,最佳制备工艺条件为：酶解pH 5.4、酶添加量17.3 U/mL、酶解温度53 ℃、老化时间23 h。在此优化条件下,豌豆抗性淀粉产率为27.51%。理化性质分析结果表明,与豌豆淀粉相比,豌豆抗性淀粉贮藏稳定性（透光率：1.48%～2.31%）、溶解度（0.064～0.524）均有所增大,冻融稳定性（析水率：0.549～0.679）、膨润度、平均聚合度（吸光度峰：波长612.0 nm～583.5 nm）均有所降低。     

Effect of acid treatments and drying processes on physico-chemical and functional properties of cassava starch

The effects of acid treatments (HCl or organic acids) and drying processes (oven or sun) on the physico-chemical and functional properties of cassava starch have been studied. The objective was to obtain modified starches with expansion properties similar to those of sun dried fermented cassava starch (polvilho azedo) as produced by an empirical process. Expansion was evaluated using a baking test. Independent of the drying method, organic acid-hydrolysed cassava starch presented the same X-ray diffraction patterns (changes from C to A) and similar intrinsic viscosity values. SEM observations showed no differences between granule surfaces of sun dried and oven dried samples. However sun dried organic acid-hydrolysed starches presented lower paste consistency values at 30°C when compared with oven dried ones. HCl-modified cassava starches were oven or sun dried, giving biscuits with low specific volumes (2·5–3·1 ml g⁻¹). Similar behaviour was obtained using oven dried organic acid modified cassava starches. When submitted to sun drying, organic acid modified starches showed great improvements in biscuit expansion (5–10 ml g⁻¹). The highest average specific volumes were obtained using lactic acid modified starches. © 1998 SCI.     

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%.     

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.     

Physicochemical properties,resistant starch content and enzymatic digestibility of unripe banana,edible canna,taro flours and their rice noodle products

Unripe banana, edible canna and taro flours, which have been reported to contain significant amounts of fibre, were investigated for their physicochemical properties, resistant starch (RS) content and in vitro starch digestibility, and compared with commercial high‐fibre‐modified starches from corn and tapioca. Differential scanning calorimetry showed a single endothermic peak located around 70–83 °C for the samples except the modified starches, which exhibited no transition enthalpy. The samples showed different pasting behaviours in the Rapid Visco‐Analyser (RVA) ranging from full to restricted swelling. The RS content varied from 1–26 g per 100 g dry sample, and the estimated glycaemic indices (GIs) of the samples were from 67% to 99%. Generally, samples with high RS were low in GI values. The starches produced acceptable rice noodles but with reduced rate of starch digestion and GI. The effects of the unripe banana, edible canna and taro flours on starch digestibility were either comparable or better than the commercial modified starches. These flours can substitute commercial modified starches to lower GIs of noodles and identical foods.     

紫山药抗消化淀粉的制备及水解特性*

以酶解-压热法制备紫山药抗消化淀粉,考察了淀粉乳浓度、普鲁兰酶用量、酶解时间、压热时间对制备淀粉中抗消化淀粉含量的影响,通过正交试验和方差分析明确影响因素的重要性并优化工艺条件;比较分析了糊化淀粉、压热淀粉以及酶解-压热法制备淀粉的水解动力学。结果表明:酶解-压热法制备紫山药抗消化淀粉的含量随各因素水平的增加呈先增加后减小的趋势,优化的条件为:淀粉乳质量分数20%、普鲁兰酶用量8 U/g、酶解12 h、以120℃压热处理40 min 2次时,制备抗消化淀粉样品纯度为96.67%,其中抗消化淀粉含量为47.85%;水解特性研究表明:与糊化、压热法相比,酶解-压热法制备抗消化淀粉的水解率、水解指数与血糖指数均显著降低,具有更好的抗消化性。     

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 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.