Some Aspects of the Continuous Production of Low-acetylated Potato Starch

Experiments are carried out on the acetylation of potato starch by vinylacetate in suspension in various types of continuous flow reactors. The reactors used were a cascade of four mixing vessels, each of equal size, a cascade of 4 mixers of increasing size, and a tubular reactor. The percentage of the vinylacetate which is bound to the starch under optimum conditions varies with the reactor type used. The product quality, as measured by the variation in viscosity of a starch acetate solution with time, is found to be lower for the starch acetates produced in the cascade reactors than for batchwise produced material of the same DS. This is shown to be due to the variation in DS of the individual starch granules. Starch acetates produced in the tubular reactor have a quality comparable to the acetates produced batch-wise. An approximate design for a commercial acetylation plant is presented.     

Production of Low Substituted Cassava Starch Acetates and Citrates

Starch acetates and citrates were prepared by treating starch with sodium hydroxide at room temperature with and without 1% concentrated sulphuric acid (per dry weight of starch) as catalyst. Starch acetates were obtained by varying the reaction time (2h, 4h, 6h and 8h) while starch citrates were obtained using citric acid monohydrate conentrations of 5, 10, 15 and 20% (per dry weight of starch). The yields of acetylated starches were greater than those of the starch citrates. Use of catalyst significantly increased the rate and extent of acetylation. Also there were progressive increases in the acetyl values of the catalysed reaction with time. Citrate substitution in catalysed and uncatalysed reactions were not significantly different at citric acid concentrations higher than 10%.     

Effect of Acetylation on Some Properties of Corn and Potato Starches

Corn starch and starches separated from different potato cultivars were acetylated to evaluate the effect of plant source on the physicochemical, morphological, thermal, rheological, textural and retrogradation properties of the starches. Corn starch showed a lower degree of acetylation than potato starches under similar experimental conditions. The degree of acetylation for different potato starches also differed significantly. Morphological examination revealed that the granules of acetylated Kufri Chandermukhi and Kufri Sindhuri starches tended to appear as fused and less smooth than native starch granules. Acetylation of corn and potato starches decreased the transition temperatures and enthalpy of gelatinization and increased swelling power and light transmittance. However, the change in these was greater in the potato starches with higher percentage of small sized granules. Acetylated starches showed higher peak G', G'' and lower tan δ than their counterpart native starches during heating. Among the starches from different cultivars, the change in the rheological parameters after acetylation differed to a significant extent. The retrogradation was observed to be negligible in the acetylated cooked starch pastes. Results implied that the change in functional properties of starches with acetylation depends on source and granule morphology of native starch.     

乙酰化对红薯淀粉性质的影响

以红薯淀粉为原料,醋酸酐为乙酰化剂,制备低取代的乙酰化红薯淀粉.通过制备不同取代度乙酰化淀粉(DS 0.044～0.096),与红薯原淀粉进行比较,对乙酰化淀粉的透明度、凝沉性、溶解度、溶胀度、黏度和质构特性等进行深入研究.结果表明,与原淀粉相比,红薯淀粉经乙酰化作用后,凝沉性明显减弱,乙酰化红薯淀粉透明度、溶解度和溶胀度都随着取代度的增加而增加,且明显高于原淀粉.乙酰化红薯淀粉的糊化温度降低6～10℃,最终黏度和回生值显著降低,硬度显著降低.     

Physicochemical and Functional Properties of Low DS Cassava Starch Acetates and Citrates

Physicochemical and functional properties of low degree of substitution (DS) cassava starch citrates and acetates were compared with properties of native cassava starch. Substituted starches have lower ash content and pH, but the solubility in water at room temperature was not significantly different from that of the native starch. Swelling power of the substituted starches was dependent on the extent of substitution. Apparent viscosities were generally lower in starch acetates and citrates than the native starch. The substituted starches had better cooking properties in terms of lower setback viscosity, reduced gelatinization time and better stability at low pHs. Substituted starches also have better colour, improved freeze-thaw stability and better storage characteristics at room temperature compared to native starch.     

Influence of prior acid treatment on physicochemical and structural properties of acetylated sorghum starch

Influence of prior acid treatment on acetylation of starch isolated from an Indian sorghum cultivar was investigated. The starch was acid thinned (AT) using 0.1, 0.5, and 1 M HCl for 1.5 h and then acetylated (Ac) with acetic anhydride (8% w/w). The acid thinning and subsequent acetylation appeared to reduce the percentage acetylation as indicated by degree of substitution. Ac‐AT starches exhibited significantly different physicochemical, thermal, pasting, and gel textural properties from those of AT and Ac starches. Starches after dual modification showed higher solubility, lower AM content, gelatinization temperatures, retrogradation, peak viscosity, and gel hardness than native starch. Enthalpy and range of gelatinization were observed to be higher in dual modified starches than native starch. However, no significant changes in granule morphology or crystalline pattern of Ac‐AT starches were observed compared with native starch.     

Influence of acetylation on physicochemical, functional and thermal properties of potato and cassava starches

Starches were isolated from cassava (Manihot esculenta) and potato (Solanum tuberosum) tubers. They were further modified by acetylation. The physicochemical, functional and thermal properties of native and modified starches, prepared using acetic anhydride at different times (10 and 20 min) were compared. Potato starch (Sipiera/20) showed higher acetyl percentage and degree of substitution values than cassava (2425/20) starch when acetylated for 20 min. Proximate analysis revealed that the acetylated starches retained more moisture than the native ones. Above 75 °C, acetylation improved the water binding capacity of the native cassava starch; the same trend was observed for potato starch from 60 to 90 °C after acetylation. The X-ray powder diffraction patterns derived from acetylated potato starches were similar to its native form, which was expected as B-type pattern; the same trend was observed for modified cassava starch. However the modified starches showed increased crystalline index.     

Morphological,physicochemical, and pasting properties of modified water chestnut (Trapabispinosa) starch

Selected physicochemical properties of native and modified water chestnut starch (Trapabispinosa) were studied. Single- and dual-modifications were carried out by pregelatinization, acetylation and acid-thinning methods. Chemical modification created unevenness on the surface of starch granule. Swelling power, solubility, and water retention capacity were improved by all modification techniques used. The peak viscosity was reduced in all modified starches as compared to native water chestnut starch. The setback value which is an indication of retrogradation (re-association of starch molecules) tendency in the starch paste was reduced after pregelatinization and acid-thinning but increased by acetylation.     

Preparation and Characterization of Starch Acetate

Acetylation of native hydrolyzed and oxidized, maize starch has been studied. The different factors affecting acetylation process were investigated. These factors include liquor ratio, acetic anhydride, perchloric acid concentration, reaction time and temperature. Also investigated were characterization and application of the acetylated starches in textile warp sizing. The acetyl content increases to reach a maximum and then decreases on increasing either liquor ratio or perchloric acid concentration. Also it increases with increasing acetic anhydride concentration within the range examined whereas the actylation reaction efficiency % decreases. Hydrolysis of starch prior acetylation inhances the susceptibility of the starch towards acetylation whereas oxidation do the reverse. The solubility of acetylated starches derived from hydrolyzed or oxidized starches increases more than that of acetylated native starch. The solubility depends on the extent of acetylation and of the modification prior acetylation. Acetylation of starch improves its sizeability of cotton yarns.     

Facile Preparation of Starch Triacetates

Commercial high-amylose corn, ordinary corn and potato starches were fully acetylated by reacting the starches at 123°C for 5 h in fourfold quantities of acetic anhydride to which 11% (w/w starch) of sodium hydroxide catalyst had been added as 50% aqueous solution. Intrinsic viscosities of the starches regenerated from their esters were slightly lower than the values for the corresponding unreacted starches and indicated that only minor degradation hat occurred during acetylation. Amylose obtained by the butanol fractionation of corn starch was also readily acetylated by this procedure. However, commercial potato amylose required removal of the small amount of magnesium sulfate present to achieve both full acetylation (44.8% acetyl) and minimum depolymerization of the starch.     

Physicochemical properties of acetylated starches from some Indian kidney bean (Phaseolus vulgaris L.) cultivars

Starches separated from four kidney bean cultivars were modified by acetylation to reduce retrogradation and increase gel stability and compared with respective native starches (data of native starch reported by Wani et al., 2010 ). Acetylation was carried out by treating starches with 0.04 and 0.08 g of acetic anhydride per gram of starch dry weight basis (dwb) at 25 °C and pH between 8.0 and 8.5. The extent of acetylation increased proportionally with the concentration of acetic anhydride used. The pasting curves of 10.7% starch determined by Rapid Visco Analyzer at 160 rpm showed that acetylation decreased the setback viscosity values by 0.64–34.58% and pasting temperature by 4.4–9.2 °C when compared with the native starch. Differential scanning calorimetry observations also revealed significant (P ≤ 0.05) decrease in gelatinisation temperature of acetylated starches than the corresponding native starches. Hardness of starch gels varied between 14.3 and 44.0 g, which was significantly (P ≤ 0.05) lower than the corresponding native starch gels.     

Functional Properties of Modified Black Gram (Phaseolus mungo L.) Starch

Black gram (Phaseolus mungo L.) starch was modified by heat and moisture treatments, acetylation, oxidation, cross-linking, and adding free fatty acids (palmitic, stearic, and linoleic). Heat and low moisture treatment, acetylation, oxidation, and cross-linking lowered the starch gelatinization temperature by 1–6°C, while adding fatty acids and the high moisture-heat treatment raised it by 1–4°C. All modifications caused an increase in least gelation concentration of starch. High moisture-heat treatment increased both water and oil absorption of starch. At 95°C, heat-moisture treated, acetylated, and oxidized starches were more soluble, while fatty acid treated and cross-linked starches were less soluble compared to raw starch. The modified starches had greater swelling capacity and solubility at pH 2.0 and 10.0. Heat-moisture treated and chemically modified starches had lower swelling capacity (at 95°C) than that of isolated starch, whereas addition of fatty acids increased it.     

VISCOELASTIC BEHAVIOUR DURING THE GELATINIZATION OF STARCH I. COMPARISON OF WHEAT, MAIZE, POTATO and WAXY-BARLEY STARCHES

Dynamic measurements were used to characterize the viscoelastic behavior during gelatinization of wheat, maize, potato and waxy-barley starches. During the experimental conditions used the curves of storage modulus (G') and loss modulus (G") versus temperature showed an initial peak for all starches, followed by a second peak at 90–95° C in the case of wheat and maize starches. Wheat starch gave a more viscous response than the other starches. The changes in G' and G" were correlated to the changes in gel volume and amylose leaching during the heating. The results were interpreted using a composite material as a model for the starch gel.     

Effect of hydroxypropyl β-cyclodextrin on physical properties and transition parameters of amylose–lipid complexes of native and acetylated starches

The effect of hydroxpropyl β-cyclodextrin (HPβ-CD) on physical properties and digestibility of wheat, potato, waxy maize and high-amylose maize starches before and after acetylation was studied. Effect of HPβ-CD on amylose–lipid complexes in native and acetylated potato starches synthesized using α-lysophosphatidylcholine was also studied. Acetylation increased swelling factor, amylose leaching, peak viscosity and susceptibility to α-amylase hydrolysis, but decreased gelatinization temperature and enthalpy and gel hardness in all starches. HPβ-CD markedly increased swelling factor and amylose leaching in native and acetylated wheat starches but had little or no impact on other starches. Wheat starch gelatinization enthalpy decreased in the presence of HPβ-CD but gelatinization temperature of all the starches was slightly increased. HPβ-CD had no influence on enzymatic hydrolysis. Melting enthalpy of amylose–lipid complex in both native and acetylated wheat starches was decreased by HPβ-CD. Acetylation also decreased the melting enthalpy of amylose–lipid complex in wheat starch. Similar trend of thermal transitions was observed in the presence of HPβ-CD for the amylose–lipid complexes synthesized in potato starch. Acetylation reduces the complex formation ability of the amylose polymer. Similar to gelatinization, acetylation widened the melting temperature range of amylose–lipid complexes while shifting it to a lower temperature. Higher swelling and amylose leaching, and decreased gelatinization temperature and enthalpy resulting from acetylation of wheat starch is consistent with its influence on starch hydration. Similar effects resulting from the inclusion of HPβ-CD were consistent with the disruption of amylose–lipid complex by HPβ-CD which promotes granular hydration.     

Characterization of Acetylated Waxy Maize Starches Prepared under Catalysis by Different Alkali and Alkaline‐Earth Hydroxides

The effects of the catalyst used in acetylation, including sodium hydroxide (NaOH), potassium hydroxide (KOH), and calcium hydroxide (Ca(OH)₂), on the chemical and physicochemical properties of acetylated waxy maize starch were investigated. The Ca(OH)₂‐catalyzed acetylated starch exhibited a slightly higher pasting temperature and a lower β‐amylolysis limit compared with acetylated starch prepared under NaOH or KOH catalysis, but no difference was observed for their thermal properties. The carbohydrate profiles of isoamylase‐debranched acetylated starches and their β‐limit dextrins were characterized by high‐performance size‐exclusion chromatography. The Ca(OH)₂‐catalyzed acetylated starch showed a elution profile that was different from those of the other two acetylated starches with a greater proportion of saccharides eluted at a longer retention time. However, the differences in pasting temperature, β‐amylolysis limit, and carbohydrate profile among the acetylated starches diminished when ethylenediaminetetraacetic acid (EDTA) was added. The results suggest that calcium might induce intermolecular crosslinking through chelation with oxygen of the anhydroglucose units and this type of crosslinking was promoted in acetylation catalyzed by Ca(OH)₂.     

Eigenschaften der Triticalestärke am Beispiel polnischer Triticalesorten

Properties of Triticale Starch Refered to Polish Triticale Varieties. A high content of starch in triticale grains makes us suppose that this cereal may also be a good raw material for starch industry. To be able to answer this question studies were conducted on many Polish lines and varieties with respect to more important physico-chemical properties of their starches, such as graininess, water binding capacity, solubility in water and pasting characteristics. Studies have shown that starches of many investigated lines and varieties of triticale are characterized by properties of interest for starch industry. Compared to wheat triticale seems to be a good raw material for food industry and particularly for starch industry. This view finds support in high yields of grain and starch as well as good graininess, viscosity of starch and high degree of purity.     

Characteristics of menthone encapsulated complex by mungbean,tapioca, and rice starches

In order to use commercial starch for flavor encapsulation, three starches (mungbean, rice, and tapioca) were selected to determine their ability to form inclusion complex with menthone. Mungbean starch had the highest amylose content, followed by rice starch and tapioca starch, respectively. After complexation, appearance and microstructure changes were observed for all starches. Mungbean and tapioca complexes with well-organized V7 crystalline pattern gave similar menthone entrapment (around 4%) which was higher than that of the rice sample (<1%). Molecular size distribution of the complexes revealed the role of amylose fractions for both mungbean and tapioca complexes. According to differential scanning calorimetric analysis, menthone complexes formation was confirmed by a thermoreversible event. Regarding the high yield of starch precipitate and menthone entrapment, mungbean starch is considered a more suitable material for menthone encapsulation rather than tapioca and rice starches.     

食用型化学变性淀粉性质研究

该文综述常见化学变性如乙酰化、羟丙基化和交联处理对淀粉物理化学、形态学、热力学等性质影响;且探讨影响淀粉变性效率因素,如淀粉种类、颗粒结构、变性试剂类型和用量等,通过选择合适变性试剂和淀粉原料可生产出具有良好应用效果食品用变性淀粉。     

A Study of Native and Chemically Modified Potato Starch. Part II: Digestibility in the Rat Intestinal Tract

The in vivo digestibility of the following chemically modified potato starch derivatives was evaluated in rats; distarch phosphate (DSP), acetyl di-starch phosphate (ADSP) and hydroxypropyl di-starch phosphate (HPDSP). Unmodified potato starch was used as reference. The starches were studied raw and after gelatinization by drum-drying. The extent of in vivo digestion was evaluated through balance experiments in normal rats (apparent digestibility) and in rats treated with an antibiotic drug to suppress hind-gut fermentation (true digestibility). Starch digestibility was calculated from direct measurement of starch in feed and faeces. Three different methods for starch analysis were compared. The apparent digestibility of raw potato starches was low, ranging from 50 (HPDSP) to 84% (ADSP). The true digestibility of gelatinized unmodified potato starch was essentially complete and was not affected to any appreciable extent as a result of cross-linking or acetylation. In contrast, etherification with hydroxypropyl significantly reduced the extent of digestion and absorption to a low level, about 50%, which was not significantly different from that with the corresponding raw material. Thus, the digestibility of the HPDSP derivative was not improved by gelatinization. The maldigested hydroxypropylated starch fraction was only metabolized to a limited degree by the hind-gut microorganisms.     

Gelatinization and Thermal Properties of Modified Cassava Starches

The thermal properties of seven commercial modified cassava starches, including oxidized, acetylated, cross‐linked, and combined acetylated and cross‐linked starches were studied by differential scanning calorimetry (DSC) in the glassy and rubbery states. Increase in gel hardness in the rubbery state during storage was also monitored, as well as gelatinization behavior. The modified starches were prepared from granular starch and had a degree of substitution in the range 0–0.053. The glass transition temperatures (T_g) of the modified starches were 3–6°C significantly lower than that of the non‐modified starch. The physical aging peak temperatures were also significantly reduced by 2–3°C, compared to the non‐modified starch, while aging enthalpies increased. Starch modifications did not decrease amylopectin retrogradation significantly. During storage, the oxidized starch gel became significantly harder than the non‐modified starch gel, while the hardness of the acetylated and/or cross‐linked starch gels was significantly reduced, which confirmed that acetylation or cross‐linking can decrease hardness, even when the extent of modification is limited. Different modifications controlled different properties of the starch system, with cross‐linking and acetylation influencing the gelatinization behavior and the changes in starch gel texture during storage, respectively.