Pasting Properties of Various Retrograded Starches Isolated with Ethanol

The pasting properties of various retrograded starches were studied by means of RVA. Most retrograded starch pastes showed a low‐temperature peak which did not appear in the viscograms of any raw starch sample: for wheat and rice starches, both a high‐temperature peak shown in the viscogram of their raw samples and a low‐temperature peak appeared, while for other cereal starches and potato starch, only a low‐temperature peak was detected in the retrograded paste. The low‐temperature peak began to appear, when the degree of gelatinization decreased below 60—70%. The viscosity of both peaks tended to increase to a maximum value and then decrease during storage.     

几种不同品种淀粉及羟丙基产物糊液性质比较研究

以薯类淀粉(木薯,马铃薯)及禾谷类淀粉(普通玉米、蜡质玉米、高直链玉米及糯米)为原料,以环氧丙烷为醚化剂。制备了羟丙基变性淀粉。反应条件:淀粉乳质量分数40%、反应温度40℃、无水Na_2SO_4添加量12%(以淀粉干基计)、NaOH添加量1.2%、环氧丙烷添加量12%、反应时间18h。分别对原淀粉及在相同的反应条件下制备的羟丙基变性淀粉糊性质做了对比研究。不同品种淀粉糊性质存在很大差别。经过羟丙基改性。淀粉糊液粘度性质、冻融稳定性、透光率、都有不同程度的改善,但凝沉性质不能准确反映羟丙基化对蜡质玉米淀粉和糯米淀粉糊液性质的改善。     

Changes in Starch Pasting Properties Due to Sugars and Emulsifiers as Determined by Viscosity Measurement

The effects of sugars, emulsifiers, and their interactions on starch pasting properties were determined by the Rapid Visco-Analyser (RVA). Solutions of 50% sugars in water were used. The disaccharides, sucrose and lactose, delayed pasting more than did the monosaccharide, dextrose. Sugars’effects on starch pasting delay and on starch paste consistency varied with the starch. Addition of the same emulsifier (1%) to different starches did not result in the same change in paste consistency in the presence of high amounts of sugar. Both sucrose ester F-160 (SE) and polysorbate 60 (PS) reduced the hot paste consistency of starch-sugar mixtures, with SE having a greater effect than PS.     

食盐对普通玉米杂交种淀粉糊化性质的影响

采用快速粘度分析仪（RVA）研究了食盐对18种普通玉米杂交种淀粉糊化性质的影响。结果表明：食盐显著降低了所有普通玉米杂交种淀粉的峰值、破损值和回生值;提高了谷值、终粘度、出峰时间和成糊温度。但对不同的普通玉米杂交种淀粉的糊化性质的影响程度有显著差别。随着食盐溶液质量分数的增加,普通玉米杂交种淀粉的谷值、终粘度、出峰时间和成糊温度也逐渐增加,破损值和回生值则显著降低,峰值受食盐溶液质量分数的影响很小。     

Correlations of the Composition,Minerals, and RVA Pasting Properties of Various Potato Starches

Multiple linear regression equations were developed to correlate the granule size distribution, composition, and minerals content with the Rapid Visco Analyser (RVA) pasting properties of potato starches of different cultivars. From the experimental values and the values of the regression coefficients, it could be observed that a higher level of amylose resulted in a lower peak viscosity (PV) and breakdown (BD) and higher setback (SB) and peak viscosity temperature (PVT) in the potato starches. The reverse was observed when the phosphorus content was higher. Smaller granule size was associated with a decrease in the PVT, whereas larger granules demonstrated higher PV, BD, and SB values in the potato starches. A higher calcium content was associated with a decrease in PV and an increase in BD, SB, and PVT. On the other hand, higher potassium was associated with an increase in PV, BD, SB, and PVT. The sodium contents demonstrated a higher PV and SB, and the reverse was observed in the BD and PVT. It is difficult to conclude the precise role of magnesium ions to the RVA properties although as divalent cations, they may have similar effect as calcium. From the positive and negative values of the regression coefficients it was shown that the correlation is useful for determining more precise values of the RVA pasting properties using a multiple linear regression equation. The correlations were also useful for predicting the effects of the starch composition and minerals on the RVA pasting properties.     

乳化剂对面粉糊化性质的影响

通过快速黏度测定仪（RVA）研究了分子蒸馏单甘酯（DGMS）、双乙酰酒石酸单甘酯（DATEM）、硬脂酰乳酸钙钠（CSL—SSL）、蔗糖酯（SE）四种乳化剂对面粉糊化特性的影响。结果发现，不同种类的乳化剂对面粉的糊化特性影响不同。     

不同乳化剂对米粉糊化和流变性质的影响

本文以大米粉为原料,研究了三种常用乳化剂分子蒸馏单甘酯、大豆卵磷脂和蔗糖脂肪酸酯对其糊化、凝胶和流变性质的影响。结果表明：分子蒸馏单甘酯和蔗糖脂肪酸酯使大米粉的崩解值、最终黏度、回生值和糊化温度显著升高。大豆卵磷脂使大米粉的峰值黏度、谷值黏度、最终黏度、回生值和糊化温度都显著降低,崩解值显著升高。分子蒸馏单甘酯、大豆卵磷脂和0.7%的蔗糖脂肪酸酯均会降低流体特征指数n,假塑性增强;0.5%～0.7%的分子蒸馏单甘酯和0.7%的蔗糖脂肪酸酯会增大稠度系数K值。三种乳化剂均会降低经高速剪切后的米粉糊表观黏度和触变环面积。     

Cooperative Test on Amylography of Milled-Rice Flour for Pasting Viscosity and Starch Gelatinization Temperature

An ICC cooperative test on Amylograph viscosity of milled-rice flour involving 11 laboratories and 4 contrasting rice samples was undertaken to determine the reproducibility of the method. The highest contribution to total variance was from sample followed by laboratory and then sample x laboratory. Only 2 of 9 laboratories showed similar peak viscosities on the samples, only 3 of 8 laboratories had similar cooked paste final viscosities, but none of 7 laboratories had similar cooled paste final viscosities using preground flour and a common method. Use of individual mills to prepare flour for the common method and use of laboratory method with preground flours increased variance due to laboratory and reduced the contribution of sample. Final gelatinization temperature of starch may be readily estimated from the apparent temperature of 20 BU intercept of the Amylograph curve of 20% preground paste from the results of 5 laboratories with 700 g · cm cartridge.     

Amylograph Pasting Behaviour of Cereal and Tuber Starches

The pasting characteristics in terms of peak viscosity (P), hot paste viscosity (H), cold paste viscosity (C) and at the selected fixed peak viscosities, the various ratios i.e., breakdown (H/P), setback (C/P), total setback (C/H) and relative breakdown, BD_r, (P-H)/(C-H) to distinguish the starches from different species, are reported. Important differences in these characteristics among various starches have been observed. The amount of soluble amylose present in a starch, significantly affected its tendency for retrogradation. The breakdown (H/P), setback (C/P), total setback (C/H) ratios and especially the relative breakdown (BD_r) can be made use of in distinguishing the starches from different species of wheat.     

糯米淀粉的晶体性质和糊化特性

以不同产地、品种的糯米为原料,探讨糯米淀粉晶体性质和糊化特性的差异,并进行相关性分析,以期为糯米食品加工的原料选择提供参考。试验结果表明,糯米淀粉的结晶度为16.4%~25.3%,糊化温度为71.1~87.2℃,且结晶度和糊化温度均以珍珠糯最高,禾胜糯1次之,扬丰糯最低。其中,结晶性质主要取决于品种,受产地影响相对较小,而产地、品种的差异极大地影响糯米淀粉的糊化性质。相关性分析表明,糯米淀粉的碘蓝值、结晶度与糊化温度三者之间呈极显著正相关关系。因此,品种和产地对糯米淀粉的结晶性质和糊化特性均有较大影响。     

Pasting and Thermal Properties of Potato and Bean Starches

Starches from potato (Mainechip, ND651-9 and Commercial) and Navy and Pinto bean were isolated and the pasting and thermal properties examined. Analysis by Rapid Visco-Analyzer (RVA) showed potato starches had lower pasting temperatures, higher peak viscosity, and lower setback than bean starches. High intrinsic viscosity values obtained for the potato starch indicated higher average molecular weight for the potato starches compared to the bean starches. Characterization of thermal (gelatinization and retrogradation) properties of starches by Differential Scanning Calorimetry (DSC) showed that potato starches had sharp, well-defined gelatinization thermograms, while bean starches had broad, shallow thermograms with higher peak temperature (Tp). Potato starches required higher gelatinization enthalpies than bean starches. In comparison with gelatinization, the retrogradation thermograms of starches stored at three different temperatures (23,4 and −10°C) were broader and occurred at the lower temperatures. Compared to potato starches, Navy and pinto bean starches showed a higher retrogradation enthalpy at 4 and 23°C storage temperatures, but a lower enthalpy at −10°C.     

谷朊粉对不同淀粉糊化特性和质构特性的影响

研究了谷朊粉对马铃薯淀粉、红薯淀粉、玉米淀粉、绿豆淀粉、小麦淀粉、大米淀粉、大米粉的糊化特性、质构特性及回生性的影响。通过RVA数据分析表明,谷朊粉添加量为0%～25%时,淀粉的糊化温度没有显著变化,峰值黏度、低谷黏度、最终黏度、衰减值和回生值均随谷朊粉添加量的增加而升高。通过TPA分析,淀粉凝胶的弹性无显著变化,硬度均呈现下降,马铃薯淀粉、红薯淀粉、玉米淀粉、绿豆淀粉、大米淀粉、大米粉的硬度分别下降了50.45%、6.58%、5.71%、54.97%、78.26%、59.90%。添加了谷朊粉后,随着贮藏时间的延长,淀粉样品的硬度增加,回生性升高,其中绿豆淀粉、马铃薯淀粉、大米淀粉和大米粉的回生性显著升高。     

Molecular Distribution and Pasting Properties of UV-Irradiated Corn Starches

Suspension (30 %, w/w) of corn starch (25 % amylose) in water was irradiated by UV-light with wavelength greater than 250 nm at 25°C, under a stream of nitrogen or air, for time intervals ranging from 5 to 25 h. Effects of the irradiation on the transition enthalpy and temperature for melting, and the pasting viscosity profile of the irradiated starch were examined. Weight-average molecular weight (M_w) and radius of gyration (R_g) of the irradiated starch molecules were measured by high performance size exclusion chromatography coupled with multiangle laser light scattering and differential refractive index detectors (HPSEC-MALLS-RI). In the case of starch irradiated under nitrogen, the transition enthalpy (ΔH) decreased with increasing irradiation time whereas the melting temperature was not changed. Similarly, the peak paste viscosity (P_v) decreased from 97 to 56 RVU by 25 h irradiation. Average M_w and R_g of amylopectin and amylose fractions, which were 93 × 10⁶ and 144 nm, and 2.0 × 10⁶ and 104 nm, respectively, were decreased by irradiation to 32.2 × 10⁶ and 93.7 nm, and 0.7 × 10⁶ and 83.6 nm by the irradiation for 15 h under nitrogen, respectively. When the starch was irradiated with aeration, sharp drops of all measured parameters were observed in 5 h of irradiation (ΔH 11.4 J/g, P_v 53.2 RVU, amylopectin M_w 50 × 10⁶). After 15 h under air, however, all measured values increased (ΔH 16.8 J/g, P_v 65.5 RVU, amylopectin M_w 63.1 × 10⁶). Molecular size distribution profiles confirmed oxidative the photodegradation in the early stage (up to 5 h), and cross-linking reactions in the late stage (5—15 h) of irradiation under aeration.     

Influence of the Heating Rate on the Pasting Properties of Various Flours

Viscoamylographic tests were carried out on six commercial flour samples, three wheat flours (WF), two semolinas (S) and one rice flour (RF), using the Brabender Micro Visco‐Amylo‐Graph (MVA). The slurries were subjected to a definite temperature profile (30°C‐95°C, 95°C×30 min, 95°C‐50°C, 50°C×30 min), stirring at 250 min⁻¹ and using a 300 cm·g_f cartridge and recording the viscosity (in Brabender Units, BU) as a function of temperature and time. The aim of this work was to evaluate the influence of different heating rates (1.5, 3.0, 5.0, 7.5, 10.0°C/min) on the pasting properties of the various flours. The peak viscosity of WFs and Ss increased when high heating rates were applied, while the RF showed similar pasting properties independently of the heating rate. These behaviours were mainly ascribed to the different molecular organisation of the starch granules, responsible of different swelling and gelatinising extents, and also to a different kinetic of alpha‐amylase inactivation according to the heating rate applied. The key role of the alpha‐amylase activity in controlling the pasting viscosity of the different samples was demonstrated by the viscoamylographic test performed in the presence of silver nitrate as enzyme inhibitor.     

羟丙基化改性对普通玉米杂交种淀粉糊化热力学性质的影响

采用湿法在实验室条件下提取18种普通玉米杂交种淀粉,并制备了羟丙基淀粉.采用差示扫描量热仪(DSC)分析了原淀粉和羟丙基淀粉的糊化过程中的热力学性质.结果表明羟丙基化改性显著降低了所有普通玉米杂交种淀粉的热焓值、起始糊化温度、峰值糊化温度和终止糊化温度,平均降幅分别为29.6%、13.9%、12.2%和7.8%.但羟丙基化改性对不同的普通玉米杂交种淀粉热力学性质的影响程度明显不同,即热力学性质各参数的降幅在杂交种间存在显著差异,热焓值、起始糊化温度、峰值糊化温度及终止糊化温度的降幅的变化范围分别为10.95～47.15、9.1%～16.9%、8.7%～14.3%、4.8%～12.2%.     

Influence of Water on Molecular and Morphological Structure of Various Starches and Starch Derivatives

In this study the influence of water on untreated, pregelatinised, and chemical modified starches was investigated. Because of their different botanical source, the starch products contain various quantities of amylose and amylopectin. The water vapour absorption capacity of the starches was studied by sorption/desorption and thermogravimetrical measurements. Higher absorption capacities were found for potato starch and for starches containing carboxymethyl and hydroxyethyl groups. Characteristic molecular differences found by Raman spectroscopy were evaluated for untreated and modified starches. To this end, the starch raw materials were classified into groups with similar pretreatments and properties based on cluster analysis. Additionally, the gelatinisation of starch‐water mixtures (gels, powders, and films) was continuously studied using temperature‐dependent Raman spectroscopy. In comparison with powder spectra, the Raman spectra of the starch films showed shifts in band positions in the range of the CH deformation and CH stretching modes. With the exceptions of high‐amylose maize starch and carboxymethylated starch, all starches form films. Starch films differ in their surface structures, water contact angles, and rates of water drop absorption, which might be caused by the different retrogradation properties. The swelling and shrinking behaviour of starch films was investigated at the morphological level by in situ environmental scanning electron microscopy (ESEM) experiments and evaluated by grey value analysis. Films of untreated starch show stronger swelling and shrinking than films of pregelatinised products.     

磷酸酯化改性对玉米杂交种淀粉糊化过程中热力学性质的影响

采用湿法在实验室条件下提取18种玉米杂交种淀粉,并制备了磷酸酯淀粉.采用差示扫描量热仪(DSC)分析了原淀粉和羟丙基淀粉的糊化过程中的热力学性质.结果表明:磷酸酯化改性显著降低了所有玉米杂交种淀粉的热焓值,小幅度降低了起始糊化温度、峰值糊化温度和终止糊化温度,平均降幅分别为15.1%、6.3%、4.8%和1.7%.但磷酸酯化改性对不同的玉米杂交种淀粉热力学性质的影响程度明显不同,即热力学性质各参数的降幅在杂交种间存在显著差异,热焓值、起始糊化温度、峰值糊化温度及终止糊化温度的降幅的变化范围分别为0 7%～37 0%、3 3%～10 2%、2 6%～7 8%、0 2%～6 4%.     

Chemical and Enzymatic Modifications of the Pasting Properties of Legume Starches

Refined legume starches were evaluated for their Brabender Visco/Amylograph properties in their native form and after chemical and enzymatic pretreatment during incubation for 20 h at room temperature. Although exhibiting the characteristic restricted paste viscosities of legume starches, native lentil starch showed much higher viscosity parameters than navy bean starch while field pea starch had very low, stable viscosities. Pretreatments with mineral acids, alkali or enzymes failed to significantly alter the amylographs of the 8% slurries (w/v). Removal of surface lipids on the refined starch granules with propanol/water (3:1 v/v) or chloroform/methanol (2:1 v/v) increased paste viscosities substantially, as did the complexation of the starches with palmitic acid or glyceryl monopalmitate. None of the treatments resulted in complete dissolution of the starch granules and the modified starches showed no improvement in gel syneresis during storage.     

小麦原淀粉和预凝胶淀粉的糊化特性比较

选取11种河南省种植小麦和4种国外小麦,对这15种小麦淀粉进行预凝胶处理,以不同温度下,淀粉的溶解度、溶胀力和酶解率作为淀粉糊化特性评价指标进行对比研究,结果表明预凝胶化处理的淀粉具有更高的溶解度、溶胀力和酶解率,这三个指标中同一小麦品种两种淀粉的酶解率差异较小.