酸预处理对蜡质玉米乙酰化淀粉性质的影响

以蜡质玉米淀粉为原料,采用先酸顸处理再进行乙酰化改性的方法制备酸解乙酰化复合改性淀粉,研究了酸预处理对淀粉黏度、透明度、膨胀度等理化性质的影响并用傅里叶变换红外光谱仪和X射线衍射仪对改性淀粉的结构进行分析。结果表明：酸预处理后,改性淀粉的黏度显著降低,起始糊化温度高于乙酰化淀粉但低于酸解淀粉,冷、热糊稳定性与糊的抗凝沉性增强;酸预处理降低了复合改性淀粉的膨胀度,提高了透明度,溶解度显著增加且随着酸浓度的增加而增加;低浓度酸处理对改性淀粉的冻融稳定性影响较小,高浓度降低改性淀粉的冻融稳定性：酸预处理对改性淀粉的结晶结构影响较小,没有破坏改性淀粉的基本结构。     

马铃薯淀粉及其7种变性淀粉糊液特性的比较研究

通过对马铃薯淀粉(PS)及其7种变性淀粉(醋酸酯淀粉、羟丙基淀粉、磷酸酯双淀粉、乙酰化二淀粉磷酸酯、羟丙基二淀粉磷酸酯、氧化淀粉、氧化羟丙基淀粉)在糊化温度、峰值黏度、热稳定性、凝胶性、抗剪切、耐酸性、冻融稳定性和透明度等性能差异的研究,探讨了不同改性方式对马铃薯淀粉糊特性的影响。结果表明:⑴羟丙基和醋酸酯改性均可降低马铃薯淀粉的糊化温度,提高淀粉峰值黏度,增加糊液透明度和冻融稳定性,但淀粉糊的热稳定性和凝胶性差;⑵交联改性提高了马铃薯淀粉的糊化温度和凝胶性,增强了糊液热稳定性和耐酸性,但透明度降低;⑶氧化处理降低了马铃薯淀粉的糊化温度和峰值黏度,提高淀粉糊透明度;(4)双重改性处理的复合变性淀粉同时兼有二种单一变性淀粉的共同特性,其中:氧化羟丙基淀粉的透明度最好,羟丙基二淀粉磷酸酯的冻融稳定性最好。     

茶叶籽淀粉理化性质研究

研究茶叶籽淀粉颗粒形貌、大小和糊化温度,测定其溶解度和膨胀度、透明度、冻融稳定性、凝沉性及黏度等理化性质,并与玉米淀粉进行比较。结果表明：茶叶籽淀粉颗粒表面光滑,呈椭圆形或球形;不易发生糊化;溶解度与膨胀度随温度变化程度不大;与玉米淀粉相比,透明度与冻融稳定性不及玉米淀粉糊,但抗老化性稍强,黏度也高于玉米淀粉。     

鹰嘴豆、饭豆、绿豆淀粉性质的比较

以鹰嘴豆、饭豆、绿豆淀粉为对象,研究了不同豆类淀粉的糊化性、膨胀度、溶解度、淀粉-碘复合物的可见光谱、淀粉糊的透明度、冻融稳定性、凝沉性以及沉降体积等性质。结果表明:绿豆淀粉的成糊温度和峰黏度最高,而鹰嘴豆淀粉的热糊稳定性和冷糊稳定性最好;3种淀粉的膨胀度和溶解度均随温度的升高而增加,并且淀粉碘复合物可见光光谱的最大吸收波长都在620 nm左右。绿豆淀粉糊的透明度、冻融稳定性和凝沉性最好,沉降体积最大。     

苦荞淀粉颗粒及淀粉糊性质研究

为明确苦荞籽粒淀粉理化特性,以7个苦荞品种为材料,分析了其淀粉颗粒表面结构及其淀粉糊的透明度、冻融稳定性、凝沉性、糊化特性、热焓特性。结果表明,苦荞淀粉颗粒多为不规则多面体球形,颗粒大小平均为6.8μm;苦荞淀粉糊的透明度平均为7.68%,低于玉米淀粉糊;苦荞淀粉糊凝沉性、冻融稳定性均强于玉米淀粉糊;苦荞淀粉的峰值黏度、谷值黏度、最终冷黏度、破损值及回生值均高于玉米淀粉;苦荞淀粉糊具有较强的热黏度稳定性、冷黏度稳定性和凝胶形成能力;苦荞淀粉糊的平均糊化温度范围为65.87℃到78.41℃,峰值温度为70.88℃,均低于玉米淀粉糊。     

乙酰化羟丙基复合改性玉米淀粉物化特性研究

为揭示乙酰化、羟丙基化及复合改性对玉米淀粉物化特性的影响,通过扫描电子显微镜、X射线衍射仪、红外光谱及差示扫描量热仪研究淀粉的颗粒特性、结晶特性、热焓特性及糊的性质。结果表明:随着取代度的提高,改性淀粉糊的透明度、凝沉性、冻融稳定性均有不同程度的改善;红外结果表明,经过乙酰化羟丙基复合改性后,淀粉分子内引入新的基团,证实了酯化及醚化反应的发生;XRD结果表明,复合改性主要发生在淀粉颗粒的不定形区,改性后淀粉仍为A型结晶结构;从DSC参数可以看出,与原淀粉相比,改性淀粉的糊化起始温度、峰值温度、终止温度及糊化焓均有所降低,表明改性可能会部分破坏淀粉的双螺旋结构,淀粉更易糊化。     

不同取代度板栗淀粉磷酸酯理化特性研究

通过改变板栗淀粉酯化反应的时间,制得不同取代度的板栗淀粉磷酸酯,对其理化性质进行研究。结果表明:原板栗淀粉颗粒表面光滑,可见椭圆形、三角形、梨形等;改性后,淀粉颗粒出现不同程度凹陷、破损和裂痕。同时,随着取代度的增加,其透明度、溶解度、膨胀度增加,冻融稳定性提高。质构分析显示,改性后,其凝胶的硬度、脆裂性、胶黏性和咀嚼性降低,内聚性和黏附性增大。差示扫描量热分析显示,改性后,其糊化初始温度、吸热高峰温度和糊化最终温度降低,糊化热焓值显著变小。糊化特性显示,改性后的淀粉糊黏度提高,糊化温度降低,黏度稳定性较好。     

凉薯淀粉的理化性质研究

以玉米淀粉、木薯淀粉和马铃薯淀粉为对照,分析了凉薯淀粉的颗粒形貌及大小、溶解度、膨胀度和糊化特性等理化性质。结果表明:凉薯淀粉颗粒形状多为不规则多边形,少数为圆形,粒径范围为3~11μm,平均粒径为8μm,小于其他三种淀粉;溶解度和膨胀度比木薯淀粉和玉米淀粉高,比马铃薯淀粉低,且随温度升高,溶解度和膨胀度显著增大;糊化温度为80℃,高于其他三种淀粉,峰值黏度小于木薯、马铃薯淀粉,高于玉米淀粉,糊化热稳定性比其他三种淀粉强,回生能力比玉米、马铃薯淀粉强,比木薯淀粉弱;透明度较低,易凝沉,表观黏度较小,表现出剪切稀释现象,冻融稳定性较差;凝胶硬度、咀嚼性、黏聚性、黏附性远低于马铃薯、木薯淀粉,高于玉米淀粉,且凝胶弹性最低。     

食用醋酸酯甘薯淀粉性质的研究

以甘薯淀粉为原料,醋酸酐为酯化剂,以乙酰基含量和取代度为指标,制备出不同取代度系列醋酸酯甘薯淀粉。研究了不同乙酰基含量醋酸酯甘薯淀粉的性质,包括颗粒形态、膨胀度、溶解度、淀粉糊黏度、透明度、凝沉性和冻融稳定性等,为其在食品中的应用提供依据。实验结果表明,随着醋酸酯淀粉取代度的增加,淀粉糊的峰值黏度不断提高,起糊温度不断降低。乙酰化作用提高了淀粉的膨胀度和溶解度以及淀粉糊的透明度和冻融稳定性;降低了淀粉糊的凝沉性。     

脱脂对3种豆类淀粉理化性质的影响

为研究脂类物质对豆类淀粉理化性质的影响,以红豆、鹰嘴豆、蚕豆为材料,采用湿法分离淀粉并做脱脂处理,分析了脱脂前后3种豆类淀粉颗粒特性、热特性、淀粉糊特性存在的差别。结果表明:脱脂后3种淀粉的溶解度、膨胀度和糊透明度升高,热焓值降低,冻融稳定性变差,颗粒形貌、偏光十字、淀粉晶型、起糊温度、峰值黏度、终值黏度、破损值、回生值和凝沉性无明显变化。脱脂处理使3种豆类淀粉的溶解度、膨胀度、糊透明度得到改善。     

低取代度乙酰化绿豆淀粉的性质

以绿豆淀粉为原料,冰醋酸为乙酰化剂,制备低取代度的乙酰化绿豆淀粉。对乙酰化绿豆淀粉的膨润力、溶解度、凝沉性、透明度、黏性、质构特性等进行研究。结果表明：与原淀粉相比,经过乙酰化处理的绿豆淀粉透明度、膨润力、溶解度均比原淀粉有所增加,糊化温度降低,谷值黏度、末值黏度有所升高,而峰值黏度、衰减值则降低,绿豆淀粉乙酰化后凝胶特性也有所改善。     

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.     

Physical Properties of Cross-linked and Acetylated Normal and Waxy Rice Starch

Waxy and normal starches present wide biological diversity in their structure. The objective of this study was to investigate the effect of chemical modification on the physical properties of cross-linked and acetylated normal (NR) and waxy (WR) rice starch. Cross-linking increased shear stability and decreased swelling power and solubility of NR and WR, but increased viscosity, pasting temperature, and heat of gelatinization of WR, and decreased pasting temperature and heat of gelatinization of NR. Acetylation increased viscosity and solubility of NR and WR, while it increased the swelling power of NR, and decreased the swelling power of WR. Cross-linking increased hardness and adhesiveness of NR and WR gels, while acetylation increased hardness but decreased adhesiveness of the gels. Freeze-thaw stability results showed that both acetylation and cross-linking decreased retrogradation of NR, but increased it in WR.     

Functional properties and retrogradation behaviour of native and chemically modified starch of mucuna bean (Mucuna pruriens)

Mucuna bean (Mucuna pruriens) starch was isolated and subjected to chemical modification by oxidation and acetylation. The proximate analysis of the non‐starch components of the native starch on a dry weight basis was 92 g kg^?1 moisture, 5 g kg^?1 ash, 2 g kg^?1 fat, 7 g kg^?1 crude fibre and 19 g kg^?1 protein. Chemical modification reduced the values for all the non‐starch components except the moisture level. For all the samples, swelling power and solubility increased as the temperature increased in the range 50–90 °C. The swelling power of mucuna native starch (MNS) and mucuna acetylated starch (MAS) increased with increasing acidity and alkalinity, while that of mucuna oxidised starch (MOS) only increased with increasing pH in the acidic range. The maximal solubility of all the starches was observed at pH 12. All the starch samples absorbed more oil than water. The lowest gelation concentration followed the trend MAS < MNS < MOS. Chemical modification reduced the gelatinisation temperature (Tp), while peak viscosity (Pv), hot paste viscosity (Hv) and cold paste viscosity (Cv) decreased after oxidation but increased following acetylation. The setback tendency of the native starch was reduced significantly after chemical modification. However, the breakdown value of MNS, 65 BU (Brabender units), was lower than that of MOS (78 BU) but higher than that of MAS (40 BU). Differential scanning calorimetry studies of gelatinisation and retrogradation revealed that chemical modification reduced the onset temperature (T_o), peak temperature (T_p) and conclusion temperature (T_c). Oxidation and acetylation reduced the gelatinisation and retrogradation enthalpies of the native starch. The enthalpy of retrogradation of the starches increased as the length of storage increased. Copyright © 2003 Society of Chemical Industry     

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 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.     

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.     

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.     

Physicochemical,morphological, thermal,pasting, and textural properties of starch acetates

Acetylated starches are a commercially important group of modified starch known for their reduced retrogradation tendency, high clarity, low viscosity, high swelling power, and lower gelatinization temperature and time. Due to these remarkable properties, acetylation is a commonly used chemical modification for preparing stabilized starches. This review summarizes the methods used for preparation of starch acetates and corresponding effects of acetylation on morphological, thermal, pasting, digestibility, textural, and other functional characteristics of starches isolated from various botanical sources. Starch acetates are also useful as packaging material, as wall material for encapsulating active ingredients, and to improve the storage stability of different products.     

Effect of reagent type on the acetylation of barley and maize starches

The objective of this work was to study the effect of reagent type on properties of acetylated barley starch (BS) and maize starch (MS) after modification with acetic anhydride (AA) and vinyl acetate (VA) at similar molar concentration for mole of glucose of both reagents. Degree of substitution (DS), morphological characteristics and granule size distribution, gelatinization and retrogradation, pasting properties, and X‐ray diffraction pattern were evaluated. Acetylation disturbs the short and long range order, and the effect was higher with AA than VA, and for BS than MS. This is due to the higher DS determined in AA–BS. In the pasting profile, acetylated starch showed the maximum peak viscosity at lower temperature, this effect was strongest for BS and anhydride acetic‐acetylation. Differential scanning calorimetry showed decrease in gelatinization parameters in acetylated starches (temperatures and enthalpy), and retrogradation was suppressed by acetylation. This effect was stronger in starches acetylated with AA despite their higher DS. This pattern can be explained from the occurrence of surface effects in acetylation with AA.