Rheological Properties of Calcium Treated Hydroxypropyl Rice Starches

Unisolated rice starch was used for hydroxypropylation and calcium complexation. Viscosity was measured at different starch concentrations, temperatures, and shear rates. The viscosity decreased with increase of calcium concentrations and shear rates. Temperature, starch concentrations and levels of Molar Substitution (MS) enhanced the viscosity. Hysteresis behaviour was markedly influenced by levels of calcium and MS. Higher viscosity was observed in hydroxypropyl starch. It is assumed that starch molecules exist in an expanded and/or extended forms which may result in higher viscosity. Calcium treated starch shows lower viscosity. Calcium ions possibly squeezed the starch molecules into a tighter configuration and/or calcium may compete with starch for water causing the limitation of water thus resulting in reduction of viscosity. Higher viscosity was observed at higher temperatures. Higher temperature cause the starch granules swelling thus produce higher frictional forces responsible for higher viscosity.     

不同品种大米淀粉的流变学特性研究

以不同品种大米淀粉为材料,研究淀粉糊的流变学特性,温度、淀粉糊浓度对黏度系数、流变指数的影响,为淀粉质食品的原料选择和加工提供参数。结果表明,大米淀粉糊呈假塑性流体的特性。不同品种大米淀粉湖的流变特性有较大差异,金优和放心米的热稳定性较差,大米淀粉糊的黏度系数为0.1~11。黏度系数和流变指数对温度和浓度对有较大的依赖性。大米淀粉的流动能约为1.66×106J/mol~20.53×106J/mol。     

3种大米淀粉脱支前后结构及流变特性

通过普鲁兰酶处理糯米、粳米和籼米淀粉,研究酶水解对3 种大米淀粉结构和流变特性的影响。结果表明,经普鲁兰酶处理后3 种大米淀粉的结晶度降低,无定型区域增加;链长分布结果表明3 种大米淀粉的精细结构相似,水解反应对较短的侧链更有效,糯米淀粉更易被酶解;脱支淀粉和天然大米淀粉的傅里叶变换红外光谱没有明显差异,—OH的伸缩振动吸收峰相对增强;添加普鲁兰酶后,淀粉糊黏度急剧下降,糯米淀粉黏度下降最快,较容易被水解;流变学特性表明淀粉颗粒分子间缔合、排列松散,运动性增强,溶解度和持水力有所增强。糯米淀粉对普鲁兰酶处理较其他两种大米淀粉更为敏感。结论：脱支处理改善了淀粉凝胶性能,增强了淀粉的流动性。     

Effect of Modified Starches on Rheological Properties of Ketchup

The aim of this work was to study the effect of commercial modified starches of different origin on rheological properties of ketchup. The following starches were used to produce the ketchup samples: chemically modified potato (acetylated distarch adipate from potato starch), waxy maize (acetylated distarch adipate from waxy maize starch and hydroxypropyl distarch phosphate from waxy maize starch), and cassava (acetylated distarch adipate from cassava starch) starches and physically modified cassava and waxy maize starches (physically modified cassava starch and physically modified waxy maize starch). The SEM microphotographs revealed that swollen or disrupted starch granules were present in the ketchup samples. As was evaluated by particle size distribution analysis, two peaks characteristic for different starch granule sizes were observed, the first peak at about 100 μm for ketchup thickened with potato starch and the second one at about 50 μm for the rest of the samples. Ketchups showed non-Newtonian, shear-thinning flow with tendency to yield stress. Values of the rheological parameters describing the flow curves significantly correlated with Bostwick consistency. Ketchup samples exhibited different susceptibility for temperature changes, while values of flow activation energy were from 4.18 to 9.00 kJ/mol. On the basis of mechanical spectra, it is noted that values of G′ were higher than these of G″ showing that elastic properties dominated over the viscous ones. Ketchup samples exhibited properties of weak gels which were estimated from the values of G′ and G″ moduli and their relation and from values of tangent of phase angle (tan δ = 0.14???0.37). Principal component analysis revealed both similarities and differences in rheological behavior of the examined ketchup samples thickened with different modified starches.     

Oxidation of Maize and Rice Starches Using Sodium Chlorite Along with Formaldehyde

Maize and rice starches were independently oxidized with sodium chlorite in absence and presence of formaldehyde. The treatment was carried out under different conditions including sodium chlorite and formaldehyde concentrations and duration. Since the treatment involves degradation of starch via oxidation, the treated starch samples were monitored for carboxyl and carbonyl contents as well as apparent viscosity at different rates of shear. Results obtained indicated that with both starches the percent chlorite decomposed increases as the formaldehyde concentration increases within the range studied (0.0–0.3 g/100 starch). The same holds true for the duration of oxidation (15–90min). The apparent viscosity of starch before and after oxidation decreases as the rate of shear increases. Maize starch is more susceptible to oxidation than rice starch. When applied as sizing agents for cotton textiles oxidized starches derived from maize and rice starch display better performance than the unoxidized starch but with the superiority of the sizeability and desizeability of oxidized maize starch.     

Crystallinity and Rheological Properties of Pregelatinized Rice Starches Differing in Amylose Content

Three rice starches with different amylose contents (Glutinous: 1.4%, Jasmine: 15.0% and Chiang: 20.2%) were pregelatinized in a double drum dryer at 110, 117 and 123°C. Starch crystallinity was determined by X‐ray diffractometry and Fourier transform infrared (FTIR) spectrometry. Rheological properties were assessed by a Rapid Visco Analyser (RVA) and rheometer. Pregelatinized starches obtained from Glutinous (PGS) and Jasmine rice (PJS) gave an RVA pasting profile with cold peak viscosity. At drum temperature 110°C, PGS and PJS showed X‐ray patterns that were indicative of amorphous structures. However, pregelatinized Chiang rice starch (PCS) exhibited RVA hot peak viscosity and the presence of an amylose‐lipid complex with remaining granule structure. The PCS had a lower water absorption index (WAI) and water solubility index (WSI) than PJS and PGS. After pregelatinization at increased drum temperature (117, 123°C), the PGS had a lower WAI, whereas PCS showed an opposite trend indicating lower degree of granule disruption. In addition, the cold peak viscosity of PGS and PJS decreased with increasing drum temperature. For all drum temperatures, the apparent viscosity at 25°C for PGS and PJS decreased with increasing shear rate, indicating shear‐thinning behavior.     

超声处理对玉米淀粉颗粒性质的影响

研究超声处理前后玉米淀粉颗粒性质的变化。采用超声波对70%水分含量的玉米淀粉进行处理。结果表明超声处理后淀粉颗粒的偏光结构、形状和大小没有变化,但颗粒表面出现小孔。超声处理也没有改变淀粉的X-射线衍射曲线。     

麦芽糖对糯性谷物淀粉糊化和流变性质的影响

以大黄米、糯米、糯玉米淀粉为原料,通过快速黏度分析仪、流变仪、差示扫描量热仪以及低场强核磁研究不同添加量的(2％、6％和10％)麦芽糖对糯性谷物淀粉糊化和流变性质的影响.结果表明:麦芽糖能够提高3种糯性谷物淀粉的成糊温度,显著降低3种淀粉的峰值黏度、终值黏度和回生值;随着麦芽糖添加量的增加,3种淀粉糊的剪切应力逐渐降低...     

超声处理对玉米淀粉热性质的影响

研究超声处理前后玉米淀粉热性质的变化。采用超声波对70%水分含量的玉米淀粉进行处理。结果表明超声处理提高了糊化转变温度、膨胀度和溶解度,降低了析水率、焓值以及转变温度范围。玉米淀粉经处理后粘度降低,但其粘度曲线不改变。以上数据表明超声处理优先降解无定形区,且直链淀粉比支链淀粉更容易被降解。     

Characterization of the Pasting,Flow and Rheological Properties of Native and Phosphorylated Rice Starches

Phosphorylation of rice starch and its effects on the physiochemical properties of the starch were investigated. Phosphorylation was conducted using the oven heating method by heating mixtures of rice starch and monosodium dihydrogenphosphate at 120‐150°C for 0.5‐2 h, and the pasting, flow and rheological properties of the resulting starch phosphates were analyzed. Phosphorylation with substitution degrees of up to 0.12 was achieved by raising the reaction temperature to 140°C, but further increase in the temperature to 150°C caused a marked reduction in the degree of substitution. Phosphorylation resulted in significant declines in pasting temperature and setback, but increases in peak viscosity and breakdown. Suspensions of rice native starch and starch phosphates were shown to be non‐Newtonian, pseudoplastic fluids, exhibiting typical shear thinning. They also exhibited yield stress, the magnitude of which increased with the degree of phosphate substitution. Dynamic testing showed that phosphorylation resulted in a decrease in the temperature at which storage and loss moduli (G′ and G″) reached a peak during heating and a reduction in G′ during cooling. These results appeared to indicate that phosphorylation improved the shear stability of rice starch pastes and enhanced swelling of starch granules, but impeded starch retrogradation.     

Rheological and Breadmaking Properties of Wheat Flours Supplemented with Octenyl Succinic Anhydride-Modified Waxy Maize Starches

The feasibility of emulsifying starches as bread improvers was investigated by incorporating starch sodium octenyl succinate (OSA-st), pre-gelatinized OSA-st and hydrolysed spray-dried OSA-st at 2.5, 5 and 10 % into wheat flour. Dough rheological properties (creep and recovery measurements; Mixolab, Alveograph) and bread quality parameters (specific loaf volume, crust and crumb colour, crumb moisture, crumb grain features, texture) were evaluated. The substituted flours, except hydrolysed OSA-st, significantly increased water absorption measured by Mixolab. The study on the rheological behaviour of doughs containing emulsifying starches, performed using a rheometer and an Alveograph, showed that OSA-st incorporation yielded strengthened dough, whereas pre-gelatinized and hydrolysed OSA-st addition led to more extensible dough. With regard to the thermal behaviour, investigated in water-limited systems by Mixolab, doughs prepared from pre-gelatinized OSA-st and hydrolysed OSA-st exhibited lower maximum peak torque, whilst all three examined starches increased cooking stability and decreased the setback value. Specific volumes of loaves baked from the substituted flours increased, and the highest effect was observed with pre-gelatinized OSA-st, which consequently produced bread crumbs with the largest mean gas cell area. The bread crumbs baked with octenyl succinate starches were whiter and softer. Although upon 1 day of storage no significant moisture retention capacity of emulsifying starches was noticed, the firmness values of OSA-st and pre-gelatinized OSA-st-supplemented bread crumbs, after 24 h of storage, were similar to or significantly lower than those of the control determined 2 h after baking. The obtained results indicate a requirement for further optimization of the octenyl succinate starch-supplemented doughs in terms of the combination of different types and levels of modified starches in order to obtain maximum bread quality.     

酸解时间对大米淀粉结构性质的影响

以4种不同直链淀粉含量的大米淀粉(0%的优糯3号、10.90%的稻花灿、21.03%的聚两优、28.46%的华优香占)为原料,酸解处理不同时间,以酸解大米淀粉的酸解率、颗粒形貌、结晶性质、溶解度的变化为指标衡量不同酸解时间对大米淀粉结构及性质的影响。结果表明,不同直链淀粉含量的大米淀粉具有不同的耐酸性,酸解时间对不同直链淀粉含量大米淀粉的结构和性质有着不同的影响。大米淀粉酸解率与直链淀粉含量成反比,优糯3号为50%而华优香占仅为30%;所有淀粉颗粒在酸解后均产生一定程度的破碎,偏光十字变形直至消失,酸解相同时间,直链淀粉含量高的大米淀粉破碎率低;酸解未改变淀粉的晶型,仍为A晶型;随着酸解时间的延长相对结晶度增加;淀粉的溶解度随着酸解时间的增加而增大。     

氧化对肌原纤维蛋白流变学特性及结构的影响

以鸡肉肌原纤维蛋白(myofibrillar protein,MP)作为研究对象,利用脂肪氧化酶-亚油酸体系研究了蛋白质氧化对MP加热过程中的流变性质、凝胶状态下的二级结构和疏水相互作用的影响,并探讨了加热过程中的流变性质、凝胶状态下蛋白质的二级结构与疏水相互作用的内在联系。研究表明,与其他亚油酸浓度处理的样品相比,亚油酸浓度为2 mmol/L的MP样品的G'值(>68 ℃)最大。随着亚油酸的加入,α-螺旋含量从未氧化时的48.31%一直降低到亚油酸10 mmol/L时的最低值29.57%,而β-折叠含量则从14.75%缓慢升高到22.14%,β-转角含量也随着氧化程度的升高,从16.28%增加到21.88%,无规则卷曲的含量总体呈现升高的趋势。随着氧化程度的升高,MP凝胶的疏水相互作用先增加后降低,在2 mmol/L达到最大值,同时G'值(>68 ℃)在2 mmol/L时达到最大,这表明疏水相互作用的变化与MP凝胶中蛋白质二级结构的变化具有密切的相关性。     

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。     

湿热处理对大米淀粉流变特性的影响

本文通过测定湿热处理前后大米淀粉的流变学特性,旨在研究湿热处理对大米淀粉稳态流变、动态流变及温度流变学行为的变化。结果表明,湿热处理后大米淀粉均呈现剪切稀化的现象,且湿热处理增强了大米淀粉的凝胶强度;在动态流变测定中发现,所有大米淀粉样品的弹性模量（G'）都大于黏性模量（G″）,且湿热处理后大米淀粉的弹性模量（G'）和黏性模量（G″）均增加,损耗角正切值tan δ降低,表明大米淀粉的凝胶强度增强;在温度流变测定中发现,湿热处理大米淀粉的糊化温度升高,弹性模量（G'）的峰值温度增加,表明湿热处理增强了淀粉分子链之间的相互作用,从而使大米淀粉凝胶具有较强的凝胶强度。     

脂肪酸对稻米淀粉流变性的影响

为了解脂肪酸对稻米淀粉糊流变特性的影响,利用旋转黏度仪测定了月桂酸、豆蔻酸、棕榈酸和硬脂酸与稻米淀粉结合形成复合物后淀粉糊的流变特性。结果表明,分别将1.0%、2.0%和3.0%的脂肪酸添加到稻米淀粉中,在95℃下蒸煮5、10和15 min,复合指数随脂肪酸量的增加而增加,随碳链增加而降低;黏度系数随复合物的增加而增加,而流变指数则随复合物的增加而降低;在4种脂肪酸中月桂酸与淀粉形成复合物的能力最强,对稻米淀粉的流变性影响最显著。     

Rheological Properties of Acidified and UV‐Irradiated Starches

This study evaluated the effect of added lactic acid and/or UV irradiation on the depolymerization and rheological properties of cassava and corn starches. Combination of lactic acid addition and UV irradiation decreased the intrinsic viscosity of corn and cassava starches. Lactic acid addition alone also decreased paste viscosity in both starches. The paste viscosity of cassava (but not corn) starch was also reduced after UV irradiation. Acidification and UV irradiation increased expansion volume during the baking of cassava (but not corn) starch dough. The baking expansion of cassava starch may be due to its high swelling capacity and solubility resulting from molecular degradation after acidification and irradiation. For corn starch, its high gelatinization temperature and internal lipids content could interfere in starch leaching and thus delay the decrease in viscosity and inhibit dough expansion.     

Effect of Ultrasonic Treatment on the Physicochemical Properties of Maize Starches Differing in Amylose Content

Normal maize, waxy maize and amylomaize V starches were treated at a moisture content of 70% by ultrasonic treatment. The results showed that the surface of normal and waxy maize starches was porous after treatment and a fissure could be clearly observed in the surface of amylomaize V starch. Ultrasonic treatment did not change the X‐ray pattern of the three maize starches. The swelling power (amylomaize V (B‐type) > normal maize > waxy maize (A‐type)) and solubility (amylomaize V > normal maize > waxy maize), the syneresis of amylomaize V starch and the gelatinization transition temperatures of the three starches increased on this treatment. Ultrasonic treatment decreased the syneresis of normal and waxy maize starches, the enthalpy of gelatinization (amylomaize V > waxy maize ≈︂ normal maize) and the gelatinization temperature range (amylomaize V > normal maize ≈︂ waxy maize) of all starches. A drop in viscosity of all three starches was observed and the viscosity patterns of three starches remained unchanged after ultrasonic treatment. The data showed that ultrasonic treatment degraded preferentially the amorphous regions and more easily attacked linear amylose than highly branched amylopectin.     

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。