Effect of raw and heat–moisture‐treated high‐amylose corn starches on the process of digestion in the rat digestive tract

High‐amylose corn starch (HAS) is widely known as a resistant starch foodstuff. We developed heat–moisture‐treated high‐amylose corn starch (HMT‐HAS) that was more resistant to enzymatic hydrolysis. Resistant starch contents of HAS and HMT‐HAS using the enzymatic–gravimetric method were found to be 30% and 65% respectively. Rats were given 10% ordinary corn starch (CS), HAS or HMT‐HAS by meal feeding for 10 days. The caecum contents increased and the caecal pH was lower after their diets were supplemented with HAS and HMT‐HAS. Starch contents increased in the upper and the lower small intestine with HAS and HMT‐HAS. Caecal starch with HAS and HMT‐HAS was more than that with CS. Particularly, caecal starch with HMT‐HAS was seven times more than that with HAS. There were no differences in starch content in the large bowel between CS and HAS, but the content increased with HMT‐HAS. These results suggested that HAS and HMT‐HAS were resistant to digestion and absorption in the small intestine, and any indigestible starches reached the caecum. In the caecum, HAS was hydrolysed almost completely by intestinal bacteria; however, some HMT‐HAS escaped bacterial hydrolysis. This escaped HMT‐HAS reached the large bowel and was excreted in the faeces. © 1999 Society of Chemical Industry     

Impact of mild acid hydrolysis on structure and digestion properties of waxy maize starch

In this study, the molecular structure of acid-treated waxy maize starch residues was investigated, and the in vitro digestibility of the residues with 2.2 N HCl at 35 °C for different time periods, was assessed. The granular appearance of waxy maize starch was destroyed and small fractions formed aggregates. A change in chain-length distribution profiles occurred with the degradation of shortest A chains and long B chains in amylopectin. The rise in the ratio of absorbance height at 1047 cm⁻¹ to the height at 1022 cm⁻¹, the intensities of major peaks, X_c, T_p, T_c, and ΔH were observed during mild acid hydrolysis, but the X-ray diffraction patterns displayed A-type for all starches. The amount of rapidly digestible starch increased, whereas the amounts of slowly digestible and resistant starch decreased. These results demonstrate that the amorphous regions of starch granules, including the shortest A chains and long B chains, are preferentially hydrolysed and affect the slow digestion and resistance properties of waxy maize starch.     

A comparison of native and acid thinned normal and waxy corn starches: Physicochemical, thermal, morphological and pasting properties

The starches isolated from normal and waxy corn varieties were hydrolyzed with hydrochloric acid (0.14 mol equivalent/L) and evaluated for physicochemical and functional properties. Acid thinning decreased the amylose content and swelling power but increased the solubility. The light transmittance of acid thinned (AT) starch pastes was higher than those of their native starches after similar storage intervals. The scanning electron microscopic observation demonstrated that the acid thinning did not cause any disruption of the granular crystalline structure. Native normal corn starches showed lower onset temperature (T_o) and peak temperature (T_p) as compared to their counterpart AT starches, whereas the reverse was observed for waxy corn starch. Enthalpy of gelatinization (ΔH_gel) was lower in AT normal and waxy starches as compared to their native starches. The percentage of retrogradation (%R) was significantly higher for native corn starches as compared to their AT starches. A significant reduction in peak—(P_V), trough—(T_V), breakdown—(B_V), final—(F_V), and setback viscosity (S_V) was observed by acid thinning, and the reduction was more pronounced in AT waxy starches. Among AT starches, AT waxy starch showed the lowest values of P_V, T_V, B_V, F_V and S_V.     

Microstructural and physicochemical properties of heat-moisture treated waxy and normal starches

Starches from normal rice (21.72% amylose), waxy rice (1.64% amylose), normal corn (25.19% amylose), waxy corn (2.06% amylose), normal potato (28.97% amylose) and waxy potato (3.92% amylose) were heat-treated at 100 °C for 16 h at a moisture content of 25%. The effect of heat-moisture treatment (HMT) on morphology, structure, and physicochemical properties of those starches was investigated. The HMT did not change the size, shape, and surface characteristics of corn and potato starch granules, while surface change/partial gelatinization was found on the granules of rice starches. The X-ray diffraction pattern of normal and waxy potato starches was shifted from B- to C-type by HMT. The crystallinity of the starch samples, except waxy potato starch decreased on HMT. The viscosity profiles changed significantly with HMT. The treated starches, except the waxy potato starch, had higher pasting temperature and lower viscosity. The differences in viscosity values before and after HMT were more pronounced in normal starches than in waxy starches, whereas changes in the pasting temperature showed the reverse (waxy > normal). Shifts of the gelatinization temperature to higher values and gelatinization enthalpy to lower values as well as biphasic endotherms were found in treated starches. HMT increased enzyme digestibility of treated starches (except waxy corn starch); i.e., rapidly and slowly digestible starches increased, but resistant starch decreased. Although there was no absolute consistency on the data obtained from the three pairs of waxy and normal starches, in most cases the effects of HMT on normal starches were more pronounced than the corresponding waxy starches.     

A comparison of native and oxidized normal and waxy corn starches: Physicochemical, thermal, morphological and pasting properties

The effect of sodium hypochlorite on the physicochemical and functional properties of normal and waxy corn starches was investigated in this study. It was found that both carboxyl and carbonyl contents of oxidized starches from normal corn were higher than those of waxy corn. The introduction of carboxyl and carbonyl groups resulted in lower amylose content and swelling power. Both amylose and amylopectin were oxidized and degraded during oxidation but amylose was more susceptible to oxidation. Studies conducted on paste clarity revealed that the percentage transmittance increased after oxidation. The morphology of the starches was not altered after oxidation. Thermal properties measured by differential scanning calorimeter, showed that oxidation reduced transition temperatures (onset temperature, T_o; peak temperature, T_p; and conclusion temperature, T_c), gelatinization and retrogradation enthalpies of both normal and waxy corn starches. The retrogradation tendency was reduced after oxidation both in normal and waxy corn starches. Oxidation produced waxy starch with significantly higher peak (P_V), trough (T_V), breakdown (B_V), final (F_V), and setback viscosity (S_V) as demonstrated by using a rapid visco analyzer. Oxidation reduced the pasting temperature of both normal and waxy corn starches. Also, the principal component analysis (PCA) study was conducted to find the overall variations among the oxidized starches studied. Together, the first two components represent 88.7 g/100 g of the total variability.     

Effect of acid–methanol treatment on the molecular structure and physicochemical properties of lentil (Lens culinaris Medik) starch

The effect of acid–methanol treatment using 0.36% HCl in methanol at 25 °C for 4–216 h on molecular structure and physicochemical properties of lentil starch was investigated. The recoveries for modified starch granules were quite high (91.9–95.6%). Upon modification, the starch granules showed formation of cavities, surface roughness and development of protuberances. The solubility of lentil starch increased, while swelling power, pasting viscosity and gel strength decreased with increase in treatment duration. These changes were found to be due to preferential degradation of amylose and amylopectin long chains in acid–alcohol treatment, which was confirmed by studies conducted on high-performance size-exclusion chromatography (HPSEC). Data obtained from HPSEC was also used to develop an exponential model to illustrate the degradation kinetics of acid–methanol-treated lentil starch.     

Influence of molecular structural characteristics on pasting and thermal properties of acid-methanol-treated rice starches

Rice starches from TKW1, TNG67 and TCS17 varieties, differing widely in amylose contents (0.1, 18.3 and 29.2%) were treated at 45 °C for 1 h in methanol containing various amounts of HCl. The recovery, pasting properties, thermal behaviors, molecular size and chain length distribution of starch were observed. Starches exhibited widely different pasting and thermal behavior upon acid-methanol treated (AMT). Degradation of starches upon AMT affected the leaching extent and chain length of amylose. No obvious changes were found on chain length and content of chain fractions of amylopectin. The pasting viscosity of rice starch decreased with increasing concentration of HCl, and the pasting profiles depended on the variety of rice. The pasting profile of AMT-TNG67 starch showed a two-step increasing pattern during heating, while TKW1 and TCS17 starches showed smoothly increasing pasting curves. The relationship between pasting patterns of AMT-TNG67 starches with amylose leaching and two stages of swelling behavior of starch granules was investigated. Results indicated that the pasting of starch granules depend on the amount, as well as the chain length, of amylose in granules.     

Effect of heat-moisture treatment on the structure and physicochemical properties of legume starches

Native green arrow pea (GAP), eston lentil (EL), othello pinto bean (PB), black bean (BB) and express field pea (FP) starches were heat-treated at 100 °C for 16 h at a moisture content of 30%. The heat treatment did not change granule size and shape. The surfaces of GAP and EL were modified after heat treatment. Heat treatment decreased amylose leaching (GAP > FP˜EL > BB˜PB) and the swelling factor (EL ˜ FP > GAP > BB ˜ PB). The X-ray diffraction intensities increased in GAP starch, but decreased in the other starches (FP > BB > PB > EL). However, the X-ray pattern of all starches remained unchanged after heat treatment. Differential scanning calorimetry of the heat-treated samples showed a broadening of the gelatinization temperature range and a shifting of the endothermal transition towards a higher temperature (EL-EP>BB-PB). However, the gelatinization enthalpy (ΔH) of all starches remained unchanged. The susceptibility towards hydrolysis by porcine pancreatic -amylase increased on heat treatment (BB > EL > FP > PB > GAP). The action of -amylase on the starches decreased ΔH in EL and FP. However, ΔH decreased only marginally in PB and BB. Acid hydrolysis (2.2 N HCl) increased on heat treatment (BB>FP˜EL˜PB>GAP). The results showed that bonding forces within the amorphous regions of the granule, crystallite orientation and the granule surface (in GAP and EL) are altered during heat treatment, the magnitude of these changes being dependent upon the starch source.     

Effects of mucilage on the thermal and pasting properties of yam, taro, and sweet potato starches

This study investigates the effects of water-soluble mucilages (0, 2.5, and 5 g/100 g; w/w, dry basis) on the thermal and pasting properties of isolated starches from three root and tuber crops. The results show that yam tuber presents the greatest level of mucilage and also possess the largest amylose content of the three isolated starches. The addition of mucilage caused a remarkable increase in the temperature of gelatinization for the three tested starches due to the competition for water during starch gelatinization. Furthermore, adding mucilage increased the phase transition temperature range (Tc-To) of starches but decreased enthalpy (ΔH). However, although the pasting temperature increased with the addition of mucilage into tuber starches, it did not change that of taro starch. The peak viscosity of taro and sweet potato starches decreased significantly as their mucilages were added into each starch suspension system (p < 0.05). However, the addition of mucilage slightly increased the viscosity of yam starch. Furthermore, the addition of mucilage slightly increased the swelling power of yam and taro starches, but did not change that of sweet potato starch.     

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。     

Multi‐scale structural and digestion properties of wheat starches with different amylose contents

The physicochemical and digestion properties of three wheat starches with different amylose contents were studied. Scanning electron microscopy (SEM) showed they displayed a spherical disc‐like form, a lenticular shape and an irregular morphology, respectively. Compared with waxy and normal wheat starches, high‐amylose wheat starch (HAWS) was characterised by the presence of lower molecular weight amylose fraction, and its granules demonstrated the highest resistance to the cooking. The changes in the IR ratio 1022/999–1047/1022 cm^?1 following the gel storage suggested the molecules of HAWS are more readily to re‐associate and re‐organise into a more organised status than other two starches. The determination of glucose release showed that HAWS had the lowest digestion kinetics (P < 0.001), and this difference in the digestion properties between HAWS and the other two starches might imply that starch molecular structure, in particular amylose structure is another key factor for manipulating starch digestion property rather than amylose content alone.     

Effect of annealing on the semicrystalline structure of normal and waxy corn starches

The influence of amylose and amylopectin on structural reorganization occurred during annealing was studied for normal and waxy corn starches. Annealing caused an increase in crystallinity in the waxy corn starch, whereas the number of pores on the granule surface, observed by SEM, increased especially for normal corn starch. Amylose and amylopectin chains of the annealed normal corn starch were degraded to greater extension during enzymatic hydrolysis than those of the native starch. On contrary, the annealing caused a protective effect on waxy corn starch amylopectin toward the enzymatic reaction suggesting that this treatment promoted a better interaction between amylopectin chains of waxy corn starch. The amylose molecules of normal corn starch may have impaired the mobility of amylopectin molecules and restricted the reorganization of the crystalline structure during the annealing. The major increase in pores number on the granule surface of annealed normal corn starch, resulted of the endogenous amylase action during annealing, could facilitate the exogenous enzymes’ role in the degradation of the starch granules’ amorphous area.     

Enhanced thermal and antibacterial properties of cross‐linked waxy maize starch granules by chitosan via dry heat treatment

Cross‐linked starch was synthesised using chitosan as cross‐linking agent via a dry heating method. Thermal properties measured by DSC showed transition temperatures increased as compared with that of native starch (P < 0.001), which might indicate the starch and chitosan molecules interacted with each other. XRD demonstrated that the crystalline pattern of the starch remained the same, but there was slight change in the crystallinity degree after the cross‐links. The significant reduction of solubility, swelling power and transparency (P < 0.001) indicated that the cross‐links restricted the starch granules swelling and molecules leaching. Agar diffusion test showed that chitosan‐cross‐linked starch had excellent bacterial growth inhibition, and its antibacterial activity was stronger against Gram‐negative bacteria than against Gram‐positive bacteria. Its antibacterial activity was further confirmed using liquid broth method. Thus, the cross‐linked starch may be directly used in the food formula for protecting food as a natural antimicrobial ingredient.     

Impact of annealing on the molecular structure and physicochemical properties of normal,waxy and high amylose bread wheat starches

Starch from normal (CDC teal), high amylose (line 11132) and waxy (99 WAX 27) bread wheat cultivars was isolated and its morphology, composition, structure and properties were studied before and after annealing. Granule diameters, total phosphorus, total amylose, lipid complexed amylose chains, crystallinity, gelatinization temperature range, gelatinization enthalpy, swelling factor (at 90 °C), and amylose leaching (at 90 °C), in the above starches ranged from 2–38 μm, 0.007–0.058%, 26.9–32.3%, 13.4–18.7%, 28.6–42.8%, 12.7–14.3 °C, 11.3–13.3 J/g, 27.6–72.2 and 22.2–26.2%, respectively. Peak viscosity, thermal stability, set-back and susceptibility towards acid hydrolysis followed the order: 99WAX27 > CDC teal > 11132, 11132 > CDC teal > 99WAX27, CDC teal > 99 WAX 27 > 11132, and 99WAX27 > 11132 > CDC teal, respectively. Susceptibility towards α-amylase hydrolysis followed the order: 99 WAX 27 > 11132 > CDC teal (<24 h) and 11132 > CDC teal > 99WAX27 (>24 h). The extent of retrogradation measured by spectroscopy and differential scanning calorimetry followed the order: 11132 > CDC teal > 99WAX27 and 99WAX27 > CDC teal > 11132, respectively. In all starches, concentration of amylose, lipid complexed amylose chains, gelatinization temperature range, swelling factor, amylose leaching, peak viscosity, final viscosity, set-back, light transmission, susceptibility towards α-amylase and acid hydrolysis and the proportion of small (2–8 μm) B-type granules decreased on annealing. Thermal stability and crystallinity increased on annealing. In all starches, gelatinization, enthalpy, retrogradation rate and amylopectin chain length distribution remained unchanged on annealing. Pores and indentations were formed on the granule surfaces of CDC teal and 99WAX27 starches on annealing.     

Ozonation of corn and potato starch in aqueous solution: effects on the thermal,pasting and structural properties

Starch–water suspensions were exposed to ozone gas for 1 h at 5 °C. The concentration of dissolved ozone gas in the suspension was kept at 4.2 mg ozone/L^?1 water. Polarised light and scanning electron microscope (SEM) were used to examine the birefringence and surface characteristics of the samples, respectively. A differential scanning calorimeter (DSC) was used to measure the gelatinisation properties, while a rapid visco analyser (RVA) was used to examine pasting properties. The structure of corn and potato starch showed very little change after treatment with ozonated water. The DSC gelatinisation temperatures (i.e. onset, peak and conclusion) of starch samples increased as a result of ozonation. However, a decrease in gelatinisation enthalpies was observed for ozonated starch samples. A dramatic decrease in the RVA viscosities of ozonated starch samples was observed after ozonation, which are explained by the partial cleavage of the glycosidic linkages in the starch granules during ozonation.     

羟丙基糯玉米淀粉的制备及其性质的研究

以糯玉米淀粉为原料,环氧丙烷为醚化剂,在碱性条件下对羟丙基淀粉的制备工艺及其性质进行了研究.考察了醚化剂、膨胀抑制剂、pH、反应温度、反应时间对羟丙基淀粉取代度和反应效率的影响.实验结果表明,随着pH的增大,羟丙基淀粉的取代度和反应效率都增大;提高反应温度,羟丙基淀粉的取代度和反应效率都增加;增加环氧丙烷的用量,羟丙基淀粉的取代度随之增加,但反应效率呈下降的趋势;延长反应时间,淀粉的取代度和反应效率都呈上升趋势;增加硫酸钠的用量,羟丙基淀粉的取代度和反应效率都先增大,当硫酸钠用量超过12g时,随着硫酸钠用量的增加取代度和反应效率都降低.并且确定出最佳的反应条件:淀粉用量为100g时,pH为11.5,膨胀抑制剂12g,环氧丙烷10mL,反应温度50℃,反应时间20h.随着羟丙基糯玉米淀粉取代度的增加,其冻融稳定性、透明度、耐酸性、黏度热稳定性都增加.     

Gelatinization of waxy starches under high pressure as influenced by pH and osmolarity: Gelatinization kinetics, final structure and pasting properties

We investigated the influence of pH and osmolarity on the high-pressure-induced gelatinization of waxy corn and waxy rice starches in salt solutions, and the properties of the resulting gels. Gelatinization kinetics, the gel swelling power of starches, their structure and their rheological properties were studied for starch suspensions treated at 500 MPa. Gelatinization took place mostly in the first 15 min of the pressure treatment and both the gelatinization speed and the maximal level of gelatinized starch decreased with increasing osmolarity. pH had a minor influence on gelatinization kinetics differing from one starch to another. The resulting gels appeared as a mix of a gel and starch granules with a higher proportion of native granules with increasing osmolarity. Gel strength and swelling were positively correlated to their proportion of gelatinized starch. Thus, gels with different structures and gelatinization levels can be obtained under pressure depending on pH and osmolarity.     

Influence of moisture content on the degradation of waxy and normal corn starches acid-treated in methanol

Waxy and normal corn starches with different moisture contents, 5.1-16.9% and 4.8-15.9%, respectively, were prepared and treated in methanol containing 0.36% HCl at 45 °C for 1 h. Recovery of all the treated starches was found to be above 90%. Peak viscosity, gelatinization temperature and enthalpy change of gelatinization of waxy and normal corn starches decreased after treatment and this decrement was found to be more in treated starches having lower initial moisture content. The weight-average degree of polymerization and chain length (CL) of waxy and normal corn starches decreased upon acid-methanol treatment. The decrement ratio of molecular weight of modified starches was found to be negatively correlated with the initial moisture content of the starches. The decrement ratio of normal corn starch was higher than waxy corn starch with similar moisture content of starch. The content and CL of long chain fraction of amylopectin for waxy corn starch slightly decreased after treatment, while no obvious trend was found among starches with different moisture contents. CL of amylose for acid-methanol-treated normal corn starch decreased and this change was found to be higher in starches with lower initial moisture contents. Results demonstrated that the initial moisture content of starch granules strongly influenced the functional properties and degradation of starch treated by acid in methanol.     

蜡质玉米淀粉对糯米粉及速冻汤圆品质的影响

将蜡质玉米淀粉添加于糯米粉中制作速冻汤圆,考察蜡质玉米淀粉对糯米粉及速冻汤圆品质的影响.结果显示:蜡质玉米淀粉的添加能提高糯米粉的透明度,升高沉降值,同时降低糯米粉的峰值黏度和崩解值.蜡质玉米淀粉添加于糯米粉中制作速冻汤圆,使汤圆的高径比有所降低,冷冻失水率上升.加有蜡质玉米淀粉的速冻汤圆煮制后汤的透明度提高,质构特性...     

Effect of ionic gums and dry heating on physicochemical,morphological, thermal and pasting properties of water chestnut starch

Starch from water chestnuts (Trapa natans) was isolated and modified by dry heating and hydrocolloids [carboxy methyl cellulose (CMC) and sodium alginate]. Native and modified starches were evaluated for their physicochemical, pasting, thermal and morphological properties. Pasting and thermal properties were studied using Rapid Visco Analyzer (RVA) and Differential Scanning Calorimeter (DSC) respectively. Morphological properties were studied by Scanning Electron Microscopy (SEM). Modification of the starch by dry heating with and without gums reduced paste clarity and increased the water and oil binding capacity; solubility and swelling power decreased. Dry heating of native starch increased peak viscosity; however, with addition of CMC, peak viscosity decreased. Starch modified with CMC and 4 h heating exhibited lowest gelatinization temperature (T₀). Pasting characteristics of native water chestnut starch were largely affected by the addition of gums and/or heat treatment. Overall onset gelatinization temperature reduced with heat treatment and addition of gums. Morphological studies revealed no significant variation in starch granule size. Starch granules were seen agglomerated because of leaching of amylose and granule interspacing decreased with addition of gums.