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。     

Pasting Properties of Ohmically Heated Rice Starch and Rice Flours

ABSTRACT:  Pasting characteristics were examined for conventionally or ohmically heated rice starch and rice flours. Brown rice flour showed the greatest cooking stability and least retrogradation potential. Brown rice flour also showed the greatest pasting temperature and lowest peak viscosity, whereas commercial starch had the lowest pasting temperature. Nonstarch components of the brown rice flour, such as fat and protein, may have acted as stabilizers delaying water access into the granules and reducing swelling of the starch. Ohmic heating reduced pasting temperature for commercial rice starch, resulting in a starch that swelled faster. Furthermore, ohmic heating produced better cooking stability in white rice flour 1 and 2 than in the native sample, and caused white rice flour 2 to have less potential for retrogradation than the conventionally heated sample. At lower electric field strength (20 V/cm), ohmic heating resulted in the greatest cooking stable starches compared to higher voltages (40 and 70 V/cm) because more starch granules were disrupted from a longer cooking time, so there were fewer intact granules for pasting. Ohmic heating has been shown to alter rice starch and flour pasting characteristics with an added influence of lipids, proteins, and amylose contents.     

Effects of cationization on DSC thermal profiles,pasting and emulsifying properties of sago starch

Cationic sago starches were prepared using an aqueous alkaline process with different levels of cationic reagent 3‐chloro‐2‐hydroxypropyltrimethylammonium chloride (0.01–0.10 M ), sodium hydroxide (0.03–0.86 M ) and reaction temperature (30–62 °C). The degree of substitution (DS), reaction efficiency, thermal and pasting properties of cationic sago starches were analysed. Emulsifying and fat binding properties of native sago starch, cationized sago starch and commercial chitosan were compared at two different pH values (4 and 7). Degree of substitution increased with an increase in concentration of cationic reagent or NaOH, or reaction temperature. The reaction efficiency was proportional to the concentration of NaOH and reaction temperature but inversely proportional to the cationic reagent concentration. The highest DS and reaction efficiency achieved was 0.06 and 79%, respectively. The pasting temperature and gelatinization enthalpy of cationic starch (DS 0.06) were lower compared with native sago starch. Cationization increased the peak viscosity and breakdown of the starch paste but decreased the setback. The presence of cationic groups significantly increased emulsion stability, emulsion viscosity and fat binding capacity of sago starch. However, the cationic sago starch was still inferior to chitosan, which showed the highest emulsion stability, emulsion viscosity and fat binding capacity. There was no significant difference between the surface tension values of native and cationic sago starch and chitosan. The influence of pH on emulsifying properties was not significant. The emulsion stability of the cationic sago starch improved due to an increase in viscosity and fat binding capacity but not its surface active property. Copyright © 2004 Society of Chemical Industry     

西米淀粉的物化性质研究

研究了西米淀粉的组成、颗粒形貌及糊化、透明度、老化方面的性质,并与木薯和马铃薯进行了比较。结果表明,西米淀粉的蛋白质含量为0.21%,直链淀粉含量为28%,颗粒为椭圆形,西米淀粉的起糊温度为70.3℃,热糊稳定性高,凝沉性比薯类淀粉弱,西米淀粉的透明度为57.5%,比薯类淀粉易老化。为进一步了解西米淀粉的特性及应用开发提供了一定的理论依据。     

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.     

Pasting,swelling and solubility properties of UV initiated starch-graft-poly(AA)

UV-initiated graft copolymerization of sago starch with acrylic acid (AA) at low level (2.5%, 5%, 7.5% and 10% w/w) was investigated. The UV curing technique and procedure was found to successfully produce starch-graft-poly(acrylic acid) [S-g-poly(AA)]. The carboxyl group content was found to increase with increasing % of monomer. Rapid visco-analyzer (RVA) pasting profile, swelling and solubility of the samples were studied. UV irradiation of sago starch (control) results in high pasting temperature, high peak viscosity and high setback, besides retarding swelling and solubility as compared to the native untreated starch (p<0.05). Pasting temperature was decreased after grafting as compared to the control. S-g-poly(AA) showed higher peak viscosity, peak time and setback than native untreated starch (p<0.05). Breakdown was retarded at 2.5% S-g-poly(AA) but increased at 10%. S-g-poly(AA) exhibited lower swelling power and solubility than the native sample (p<0.05).     

大米淀粉磷酸酯的制备及其理化性质研究

为合理地利用丰富的大米淀粉资源,以大米淀粉为原料,尿素为催化剂,正磷酸盐为酯化剂,采用响应曲面法确定了制备大米淀粉磷酸酯的最佳工艺条件:磷酸盐用量为淀粉质量的46.61%,催化剂用量为淀粉质量的4.03%,反应pH为5.5,反应时间为4.6 h。在此条件下制得的磷酸酯淀粉的取代度为0.020 34。并用扫描电镜(SEM)对反应前后淀粉颗粒的形貌进行了观察,结果表明,磷酸酯化后,部分淀粉颗粒受到侵蚀。同时研究了大米淀粉磷酸酯的理化性质,包括溶解度、膨胀度、糊化特性、凝沉性、冻融稳定性及黏弹特性。结果表明,相对于原淀粉,磷酸酯淀粉的溶解度、膨胀度、黏度有所提高,糊化温度、凝沉性、凝胶硬度和强度则下降。     

Physicochemical properties of potato and cassava starches and their mutants in relation to their structural properties

Physicochemical properties [swelling power (SP), pasting behaviour and retrogradation] of five wild type (wt), five amylose free (amf), four high-amylose (ha) potato starches (ps) and one wt and amf cassava starch (cs) were investigated. While swelling of wtps occurred in two phases, amfps showed a very fast swelling and no gel of swollen granules was observed at higher temperatures (>90 °C). Haps underwent only restricted swelling. SP of cassava starches were lower than those of potato starches. Wtps leached mainly amylose (AM) during heating at low temperatures. Molecules of higher molecular weight (MW) leached out at higher temperatures. Longer amylopectin (AP) chains [degree of polymerisation (DP) > 18] inhibited swelling while short chains (DP < 14) favoured swelling. Starch pasting behaviour of 5.0 and 8.0% starch suspensions was studied using Rapid Visco Analyser (RVA). For 5.0% suspensions, increased levels of high-MW AP and decreased levels of AM molecules led to higher peak viscosity. Longer AP chains (DP > 18) depressed peak viscosity, while short chains (DP < 14) increased peak viscosity for both concentrations. At 8.0%, peak viscosity increased with starch granule size. After 1 day of storage of gelatinised starch suspensions, wtps and especially amfps showed only limited AP retrogradation. In contrast, the high enthalpies of retrograded AP (ΔH_retro) and peak and conclusion temperatures of retrogradation (T_p,retro and T_c,retro) of haps suggested partial cocrystallisation between AM and AP. Chains with DP 18–25 seemed to be more liable to AP retrogradation. Wtcs and amfcs did not retrograde at room temperature.     

Effect of the Extent of Conversion and Retrogradation on the Digestibility of Potato Starch

The effect of starch conversion on the susceptibility of potato granules to α‐amylase was studied by direct sampling at different pasting times corresponding to different points on the RVA profile of a 6.4% (w/w) suspension of starch in distilled water. Native granules showed high resistance to α‐amylase with 8.6 ± 0.4% digestibility for a 6 h incubation period with the enzyme. When the suspension was heated to 60 °C, the digestibility increased to 53.5 ± 0.7% although, at this temperature, there was still no noticeable increase in the measured viscosity (≤0.040 Pa · s). The material sampled after a pasting time corresponding to the RVA peak viscosity showed a digestibility of 88.4 ± 0.5%. This suggested, owing to the expected retrogradation of amylose on cooling, the quasi‐total susceptibility of amylopectin to enzymatic digestion at this pasting stage. The effect of ions on the swelling of potato starch was used to assess whether the decrease of the swelling of the granules in the presence of NaCl was paralleled by an increase in resistance to α‐amylase. A small (∼6.1%) but significant decrease in the digestibility of pasted starch was observed in the presence of salt. Finally, the effect of the retrogradation of the amylopectin fraction on its digestibility was assessed in extruded potato starch ribbons containing 35% (w/w) water and stored at different temperatures. After 14 days of storage, the digestibility decreased from 77.0 ± 0.9% in the freshly extruded samples to between 28.0 ± 1.7% and 42.1 ± 0.3%, depending on the storage temperature. This suggested a measurable difference in the α‐amylase susceptibility between the A and B polymorphs of retrograded amylopectin.     

Pasting Properties of Potato Starch and Waxy Maize Starch Mixtures

The pasting viscosity, morphological properties, and swelling properties of potato starch and waxy maize starch mixtures at different ratios were investigated. Pasting analysis of the starch mixtures (7% solids in water, w/w) using a Rapid Visco Analyser showed linear changes in peak viscosity and pasting temperature according to the mixing ratios of both starches, but not in breakdown and setback. The pasting profile revealed that the starches rendered mutual effects during pasting, more significantly when the amounts of potato and waxy maize starches were similar. The volume fraction of swollen granules and the presence of amylose appeared to be important parameters in the mutual effects of both starched during pasting. Under a light microscope, the swelling of potato starch granules was delayed by the presence of waxy maize starch. Overall results indicate that new pasting properties can be generated by mixing starches of different botanical sources.     

长山山药淀粉的制备及性能

以长山山药为原料,采用碱法工艺提取山药中的淀粉。对山药淀粉的颗粒特性、理化特性、糊化动力学、结晶类型等进行研究和分析。扫描电子显微镜观察发现长山山药淀粉的颗粒大都呈圆形或椭圆形,表面光滑;粒径分析结果显示山药淀粉颗粒的粒径分布主要呈单峰曲线变化,峰值粒径为48.57μm、中位径为22.72μm;偏光显微镜观察发现山药淀粉颗粒有明显的偏光十字;山药淀粉溶液在95℃时溶解力为16.78%,膨润力为33.55%;淀粉糊化之后的透明度为23.2%;淀粉糊凝沉稳定性为6 h;淀粉糊析水率为48.20%;差示扫描量热仪测定结果显示淀粉糊化起始温度为72.50℃,终止温度为85.40℃;糊化动力学结果表明山药淀粉糊化属于一级反应;快速黏度分析仪测出山药淀粉的峰值黏度为6 220 cP,最低黏度为3 902 cP,最终黏度为5 702 cP,衰减值为2 318 cP,回生值为1 800 cP;X射线衍射结果表明山药淀粉的结晶类型为C型。     

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.     

Effect of deproteinization on degree of oxidation of ozonated starch

Effects of deproteinization on the degree of oxidation of ozonated starch (corn, sago, and tapioca) were investigated. Starch in dry powder form was exposed to ozone for 10 min at different ozone generation times (OGTs: 1, 3, 5, 10 min), and then native starches (NS) and deproteinized starches (DPS) were analyzed for protein content. Deproteinization caused a significant reduction in protein content for corn (∼21%) and sago (∼16%) starches relative to NS. Carbonyl and carboxyl contents increased significantly in all ozonated deproteinized starches (ODPS) with increasing OGT. Carbonyl and carboxyl contents of ODPS ranged from 0.03 to 0.13% and 0.14 to 0.28%, respectively. The carboxyl content for all ODPS was significantly higher than that of ozonated native starches (ONS). A Rapid Visco Analyser was used to analyze pasting properties of all starches. Deproteinization increased the pasting viscosities of corn and sago starches compared to their native forms. Generally, pasting viscosity of all ODPS decreased drastically as OGT increased. At the highest oxidation level (10 min OGT), all ODPS exhibited the lowest pasting viscosities compared to their ozonated native form, except for peak viscosity, breakdown viscosity, and setback viscosity for ozonated deproteinized corn starch. In conclusion, deproteinization as a pretreatment prior to starch ozonation successfully increased the degree of oxidation in the three types of starch studied. However, the extent of starch oxidation varied among the different starches, possibly due to differences in rates of degradation on amorphous and crystalline lamellae and in rates of oxidation of carbonyl and carboxyl groups.     

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.     

Wheat starch production,structure, functionality and applications—a review

Starch is the main component of wheat having a number of food and industrial applications. Thousands of cultivars/varieties of different wheat types and species differing in starch functionality (thermal, retrogradation, pasting and nutritional properties) are grown throughout the world. These properties are related to starch composition, morphology and structure, which vary with genetics, agronomic and environmental conditions. Starches from soft wheat contain high amounts of surface lipids and proteins and exhibit lower paste viscosity, whereas that from hard cultivars contain high proportion of small granules and amylose content but lower gelatinization temperature and enthalpy. Waxy starches exhibit higher‐percentage crystallinity, gelatinization temperatures, swelling power, paste viscosities and digestibility, but lower‐setback viscosity, rate of retrogradation and levels of starch lipids and proteins than normal and high‐amylose starches. Starches with high levels of lipids are less susceptible towards gelatinization, swelling and retrogradation and are good source of resistant starch, while that with high proportion of long amylopectin chains are more crystalline, gelatinize at high temperatures, increase paste viscosity, retrograde to a greater extent and decrease starch digestibility (high resistant and slowly digestible starch and low rapidly digestible starch).     

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。     

淮山药淀粉及其抗性淀粉理化性质的比较

分析比较了淮山药淀粉及压热法制备的淮山药抗性淀粉的理化性质。结果表明:淮山药淀粉颗粒呈圆形或卵圆形,属C型淀粉;抗性淀粉颗粒为不规则形、多角形,尺寸较原淀粉有所减小。2种淀粉的化学结构相似,与原淀粉相比,抗性淀粉没有生成新的基团。抗性淀粉的溶解度、膨润度、透明度均低于原淀粉,而持水性、乳化性优于原淀粉;糊化温度较原淀粉高,热稳定性和冷稳定性更好。原淀粉糊和抗性淀粉糊均为屈服-假塑性流体,原淀粉糊易剪切稀化,抗性淀粉糊耐机械力的性能好。     

Physicochemical properties of Pinhão (Araucaria angustifolia, Bert, O. Ktze) starch phosphates

Physicochemical properties of pinhão (seeds of Paraná pine) starch phosphates were evaluated and compared to corn starch phosphates. The phosphorylation process used yielded starch phosphates with three different degrees of substitution (DS): low (0.015), medium (0.07) and high (?0.12). Medium and high DS starch phosphates had higher cold water binding capacity, swelling power, and paste clarity, but lower paste syneresis (at 5 °C and after freeze-thaw cycles) than native starches (P<0.05). Low, medium, and high DS corn starches had higher solubility than native starches (3.8-, 8-, and 6-fold higher; P<0.05), but the solubility of pinhão starch increased only in medium DS starch phosphates (3-fold higher; P<0.05). Low DS starch phosphates had viscosity curves similar to native starches. In contrast, medium and high DS starch pastes had peak viscosity at room temperature, reached the minimum viscosity when heated to 95 °C, and had low setback.     

颗粒冷水可溶亲脂性玉米淀粉的制备及性质研究

该研究以玉米淀粉为原料,首先利用酒精-碱法对其α-化,在此基础上,以辛烯基琥珀酸酐(octenyl succinic anhydride,OSA)为酯化剂,在干法条件下制备出颗粒冷水可溶亲脂性淀粉,所得产品取代度最高可达0.0192。通过分析试验制备的颗粒冷水可溶玉米淀粉和颗粒冷水可溶亲脂性玉米淀粉的透明度、冻融稳定性、凝沉性、黏度、流变学特性,并进一步探索这些特性与产品取代度之间的关系。结果表明:这两种淀粉的性质比原淀粉有显著的改善,后者又比前者具有良好的性质,随着取代度的增大,颗粒冷水可溶亲脂性玉米淀粉的透明度增强,冻融稳定性提高,凝沉性降低,表观黏度增加;流变学分析显示两种淀粉呈现出假塑性流体的性质,表观黏度随着剪切速率的增加而降低。     

G4淀粉酶抑制小麦淀粉老化研究

测定G4淀粉酶处理小麦淀粉相关理化性质,如凝沉性、冻融稳定性、糊化特性、质构性、溶胀度和可溶指数等,研究G4酶对小麦淀粉抗老化性。实验结果表明:经G4淀粉酶处理后,小麦淀粉凝沉体积提高57.5%,析水率和粘度均有所降低;随温度升高,两种小麦淀粉溶胀度和可溶指数均呈现上升趋势;但G4酶处理小麦淀粉溶胀度和可溶指数明显高于原小麦淀粉,小麦淀粉凝胶硬度显著降低,G4淀粉酶具有抑制小麦淀粉老化作用。