小米粉RVA糊化特性的研究

采用快速粘度分析仪（Rapid Viscosity Analyser,RVA）测定了在不同浓度、pH及添加蔗糖、食盐、明矾、硬脂酸等条件下小米糊RVA粘度曲线的变化情况,研究了小米淀粉粘度性质及其影响因素。结果显示,浓度对小米糊粘度性质影响显著,随浓度的增高,糊化温度降低,粘度曲线中峰值粘度及最终粘度升高;pH值对小米糊粘度性质影响较大,过高或过低的pH都会导致峰值粘度降低;随蔗糖添加量的增加,糊化温度略有增高;随着氯化钠浓度的增加糊化温度升高,氯化钠可提高小米糊粘度;明矾对小米糊的峰值粘度影响较大,而对糊化温度影响不大;添加硬脂酸的小米糊的最终粘度显著提高,而峰值粘度变化较小。通过研究为进一步了解小米淀粉的粘度特性及产品开发提供理论依据。     

Gelatinisation Properties of Cassava Starch in the Presence of Salts,Acids and Oxidising Agents

The effect of various cations, anions, acids and oxidising agents on the gelatinisation properties of cassava starch was studied and wide variation was observed in the pasting and swelling properties. Sodium chloride and sodium thiosulphate slightly lowered the peak viscosity of cassava starch with increase in concentration, whereas with sodium sulphite, calcium chloride and sodium hypochlorite, a more significant decrease in the viscosity and breakdown was observed. Ferrous sulphate, alum, aluminium chloride and acids enhanced the peak viscosity at lower concentrations followed by a decrease at 1% and above. Sodium metabisulphite elevated the viscosity at 0.05 and 0.1%, while sodium hypochlorite lowered the viscosity and breakdown. DSC studies showed that aluminium chloride, sodium sulphite, and sodium thiosulphate brought about an increase in T_onset, T_end and ΔH values at higher concentrations. A decrease in swelling volume was observed from 0.05 to 1% concentration of sodium chloride and above that there was a gradual increase. With sodium sulphite, a significant increase in swelling volume was observed at 2.5 and 5% levels. With 0.05 and 0.1% aluminium chloride and sodium metabisulphite an increase in swelling volume was noticed, but at higher concentrations there was a drastic fall. Sodium chloride, sodium sulphite, sodium thiosulphate and calcium chloride brought about decrease in starch paste clarity with increase in salt concentration, whereas ferrous sulphate, aluminium chloride, sodium hypochlorite, hydrochloric acid and acetic acid improved the starch paste clarity.     

Effects of Osmotic Pressure on the Crosslinking Reaction of Tapioca Starch

Tapioca starch was crosslinked with 0.1 % sodium trimetaphosphate (STMP) in the presence of alkali and of osmotic pressure enhancing salts such as sodium sulfate and sodium chloride. The addition of various percentages of sodium sulfate to the crosslinking reaction mixture changed the pasting properties of the product starch as measured in the RVA (Rapid Visco Analyser). Peak viscosity (PV) and final viscosity (FV) are first increased with the increase in osmotic pressure followed by a decrease of the viscosities after further pressure increase. Breakdown (BD) is decreased in line with the increase of the osmotic pressure with very good correlation (R² = 0.96). These pasting characteristics are attributed to the inhibited swelling without disruption of the starch granules due to the crosslinking reaction. If sodium chloride is used as an osmotic pressure enhancer of the crosslinking reaction, both pasting properties (PV, FV) decrease linearly with the increase in osmotic pressure with very good correlation (R² = 0.98 and 0.99, respectively). The BD is dramatically decreased to zero (no breakdown) after applying the osmotic pressure and remains zero after further increase in osmotic pressure. These properties are also attributed to the pasting characteristics of the crosslinked starch. The increase in pasting temperature (PT) with increasing osmotic pressure for both sodium sulfate and sodium chloride demonstrates the increase of the gelatinization temperature of the starch granules. The enhancement of the osmotic pressure can promote the activity of the crosslinking agent.     

氯化钠对马铃薯淀粉糊化特性的影响

以马铃薯淀粉为研究对象,研究氯化钠对淀粉糊特性的影响。结果表明:随着氯化钠添加量的增加,马铃薯淀粉起始糊化温度和峰值温度升高,峰值粘度和最终粘度呈现先下降后略微上升的趋势,且淀粉糊的热稳定性提高;氯化钠使淀粉糊的透明度下降,且在添加量为2%时透明度最低;马铃薯原淀粉糊不易凝沉,氯化钠的添加使淀粉糊出现较大的凝沉现象,随着氯化钠添加量的增多凝沉现象加剧,放置时间越长凝沉现象越趋于稳定;氯化钠增大淀粉的溶解度和膨胀度,且不同质量分数的氯化钠对其的影响不同;最后,氯化钠的加入提高淀粉糊的冻融稳定性。     

A PRELIMINARY STUDY OF W/O/W EMULSIONS WITH A VIEW TO POSSIBLE FOOD APPLICATIONS

A study was made of the influence of various additives on the stability and low shear viscosity of water-in-olive oil-in-water emulsions. The additives were glucose, sucrose, acetic acid, citric acid, ascorbic acid, sodium chloride and sodium acetate, Glucose and sucrose increased viscosity for some time until a constant value was reached. With the other additives an initial increase in viscosity was followed by a decrease and a corresponding decrease in stability. These observations are explained in terms of the osmotic pressure gradient between the inner and outer water compartments, and the effect of additives on the physical state of the emulsifier films adsorbed at the interfaces between the two water compartments and the oil phase.     

不同影响因素对三元食品胶溶液粘度的影响

利用德国HAAKE公司生产RS75应力控制流变仪,考察了改变pH、添加蔗糖、氯化钠和柠檬酸钠、进行冻融处理、添加大豆多肽等因素,对三元混合胶(卡拉胶∶魔芋胶∶刺槐豆胶为2∶2∶1)溶液粘度的影响。结果表明,在强酸、强碱条件下,溶液粘度均有所下降,但是碱性条件下胶体溶液的粘度相对稳定;在一定范围内蔗糖、氯化钠和柠檬酸钠均能降低胶体溶液的粘度,而两种钠盐降低胶液粘度的幅度较大;无论是冷冻处理还是冷藏处理都可降低胶体溶液的粘度;大豆多肽的加入也会在一定程度上降低混合胶溶液的粘度,改变加料方式可以减小这种影响。     

黄秋葵果胶理化特性的研究

以商品柑橘果胶为对照,研究黄秋葵果胶的理化特性及果胶质量浓度、加热温度、pH值、蔗糖质量浓度和CaCl2质量浓度等因素对黄秋葵果胶黏度的影响。结果表明：黄秋葵果胶总半乳糖醛酸含量为86.68%,酯化度为75.45%,溶解度为82%,pH值为4.63,属于弱酸性高酯果胶;黄秋葵果胶的黏度随着加热时间的延长而下降,但其热稳定性优于商品柑橘果胶;黄秋葵果胶的黏度与其质量浓度、蔗糖质量浓度均成正相关,与加热温度成负相关,而随pH值、CaCl2质量浓度的增大呈先上升后下降的趋势,表现出一般果胶的黏度特性。黄秋葵果胶的黏度及热稳定性能优于商品柑橘果胶,是一种优质果胶。     

Effect of Temperature and Starch Concentration on the Intrinsic Viscosity and Critical Concentration of Sago Starch (Metroxylon sagu)

Intrinsic viscosity and critical concentration of sago starch dispersions were studied at different temperatures and presence of solutes (sodium chloride, glucose and sucrose). Ubbelohde capillary viscometer was used to measure relative viscosity. Intrinsic viscosity decreases with an increase in temperature but the critical concentration remained fairly constant over the range of temperature studied. Sodium chloride enhanced the intrinsic viscosity but sugars somehow reduced it. Critical concentration is defined as the point where the starch molecules start to entangle with each other and abruptly enhance viscosity. Sodium chloride enhanced the molecular entanglement and lowered the critical concentration.     

Progressive freeze concentration of whey protein–sucrose–salt mixtures

Progressive freeze concentration of whey protein solutions is evaluated. Since solutions in industry are more complex, the effect of the addition of sodium chloride and sucrose on the inclusion behaviour is studied as well. Using a progressive freeze concentrator solutions of whey protein and mixtures of whey protein and/or sucrose and/or sodium chloride were freeze concentrated. At an initial concentration of 4%(w/w), whey proteins were not included in the ice fraction. At higher concentrations the inclusions are caused by the increase in viscosity in the boundary layer, impeding mass transfer. The addition of sucrose caused a similar effect. Presence of sodium chloride causes inclusions through the occurrence of a zone where the solution is locally super-cooled and leads to the formation of dendritic ice which encapsulates pockets of solution in the ice layer. Mixtures of both sucrose and sodium chloride gave no additive effect on solute inclusion but just a concurrent effect.     

Use of the Rapid-Visco-Analyzer to Measure Starch Pasting Properties. Part I: Effect of Sugars

The Rapid Visco-Analyzer (RVA) was used to measure the effects of dextrose, sucrose, corn syrup solids and polydextrose on maize, tapioca and wheat starch pasting properties. The addition of 1 part sugar: 1 part starch tended to decrease peak viscosity, whereas peak viscosity increased at higher sugar concentrations (up to 4 parts sugar: 1 part starch). Time to onset of viscosity increase and time to peak viscosity increased as sugar concentrations increased. Dextrose, sucrose and corn syrup solids increased the maximum setback viscosity, of the starches, but polydextrose reduced setback viscosity. As the molecular weights of the sugars increased, the effects generally increased for maize and tapioca starches but not for wheat starch. Pasting property parameters measured in the RVA concurred with data obtained using other viscometers or by other techniques previously reported. The RVA is useful as an alternative tool for studying starch pasting properties and the effects of food ingredients on starch performance.     

盐对马铃薯淀粉及马铃薯淀粉-黄原胶复配体系特性的影响

研究不同种类以及不同浓度的盐对马铃薯淀粉以及马铃薯淀粉-黄原胶复配体系糊化性质以及流变学性质的影响。结果表明：盐的加入均增加了马铃薯淀粉的成糊温度和回值,降低了峰值黏度、终值黏度和崩解值,且马铃薯淀粉糊的黏度值随着盐浓度的增加先降低后升高,成糊温度随着盐浓度的增加呈现先显著升高后略微下降的趋势。对于马铃薯淀粉-黄原胶复配体系,盐的加入升高了复配体系的成糊温度、峰值黏度和崩解值,并且复配体系的黏度值随着盐浓度的增加而增加。流变学性质表明盐引起马铃薯淀粉糊的假塑性增强,并随着盐浓度的增加假塑性先增强后略有减弱,相反盐引起马铃薯淀粉/黄原胶复配体系的假塑性减弱,并与盐浓度之间没有明显的规律性。     

阿拉伯胶对马铃薯淀粉糊化及流变性质的影响

研究了阿拉伯胶对马铃薯淀粉糊化及流变性质的影响,考察了马铃薯淀粉/阿拉伯胶混合体系在盐、柠檬酸、糖等不同介质下的糊化性质.RVA结果表明在水溶液中随着阿拉伯胶含量的增加,混合体系的峰值黏度显著降低,具有更好的热稳定性,但在冷却过程中,淀粉黏度明显上升,回值略有增加.添加胶体后,马铃薯淀粉在盐溶液及柠檬酸溶液中的峰值黏度稍有降低,在糖溶液中则表现出更高的黏度.静态流变实验显示不同混合体系均表现出剪切变稀性,添加胶体后,体系假塑性增强,滞后环面积明显减小.     

Effect of Sodium Dodecyl Sulphate on the Physicochemical,Thermal and Pasting Properties of Cassava Starch

The effect of different concentrations of sodium dodecyl sulphate (SDS) on cassava starch properties after complexation and in situ addition were studied. The swelling volume of the starch‐SDS complexes increased to a maximum of 100 mL/g with increase in concentration of SDS (even at 0.004 mol SDS) with a corresponding decrease in solubility. During in situ addition also, a similar but gradual behaviour was observed for swelling volume and solubility. The apparent and total amylose contents showed an irregular trend. The soluble amylose content decreased with increase in concentration of SDS. In vitro enzyme digestibility of starch‐SDS complexes was significantly lowered compared to that of native starch. The water‐binding capacity showed an initial decrease followed by a significant increase at higher concentrations of SDS. DSC studies showed that in addition to the gelatinisation endotherm, a peak corresponding to the melting of the starch‐SDS complex was obtained in the case of in situ addition of the surfactant. The peak viscosity of starch during in situ addition of SDS exhibited a rapid increase except at the highest concentration. The peak viscosity of starch‐SDS complexes underwent an initial reduction followed by a gradual increase at higher concentrations. The breakdown, setback and pasting temperature were also affected.     

食品成分对山药淀粉老化度和冻融稳定性的影响

研究了氯化钠、蔗糖、单甘酯对山药淀粉老化度和冻融稳定性的影响,结果表明山药淀粉的老化度随氯化钠浓度的增大而有所增大,随蔗糖浓度、单甘酯浓度的增大而有所减小;山药淀粉的冻融稳定性随氯化钠浓度、蔗糖浓度、单甘酯浓度的增大而改善,氯化钠、蔗糖、单甘酯对山药淀粉的冻融稳定性有促进作用。     

Gelatinisation Characteristics of Cassava Starch Settled in the Presence of Different Chemicals

Addition of chemicals during the extraction of cassava starch for enhancing the settling rate, whiteness and compactness of the settled starch is an accepted commercial practice. The effect of addition of selected chemicals such as acids (sulphuric and hydrochloric acids), bleaching and oxidising agents (sodium metabisulphite and sodium hypochlorite) and alum during settling on the thermal and pasting properties of the cassava starch was examined. Treatment with sulphuric acid produced a noticeable increase in all DSC gelatinisation parameters, viz. onset gelatinisation temperature (T_o), temperature at peak minimum (T_p) and end temperature (T_e), with increasing concentration of acid, while only a marginal shift could be obtained even at higher concentration of hydrochloric acid. However, no major effect resulted from treatment with sodium metabisulphite, sodium hypochlorite and alum. The gelatinisation enthalpy was hardly affected by the treatments. An exception was hydrochloric acid, which brought about a perceptible decrease in enthalpy at higher concentrations indicating that starch crystallinity is influenced to a small extent by hydrochloric acid. Pasting characteristics studied using a Rapid Visco Analyser showed that sulphuric acid, even at the lowest concentration (5 mM), considerably affected the structural characteristics of cassava starch, while hydrochloric acid induced similar effect only at higher concentrations. Alum reduced the paste viscosity while the bleaching agents (sodium metabisulphite and sodium hypochlorite) were not so effective in modifying the starch viscosity characteristics.     

Buffalo Gourd Root Starch. Part II. Rheologic Behavior,Freeze-thaw Stability and Suitability for Use in Food Products

Buffalo gourd (Cucurbita foetidissima HBK) starch was examined for possible food uses through physico-chemical, rheologic, and organoleptic examination. The gelatinization and rheologic properties of this starch more closely resembled maize starch than those of other root and tuber starches. Detailed studies of pasting behavior revealed: a high initial pasting temperature, a stable gel viscosity throughout the temperature regime, increases in viscosity associated with increased starch concentration, an acid stability similar to that of maize, and substantial increases in final viscosity with the addition of other food ingredients (especially 25% sucrose). Gels subjected to freeze-thaw conditions underwent a significant degree of retrogradation, suggesting the need for chemical modification prior to acceptable use of this starch in frozen products. Organoleptic evaluations of vanilla and chocolate puddings prepared with buffalo gourd starch indicated their potential consumer acceptance.     

青稞全粉与中筋小麦粉复配体系品质特性研究

选用青稞全粉作为研究对象,与中筋小麦粉复配,检测不同添加量青稞全粉的损伤淀粉特性、粉质特性、糊化特性、溶剂保持力,并进行相关性分析。研究表明:随着青稞全粉比例增加,破损淀粉显著增加(P<0.05),且与降落数值呈显著负相关;面团的吸水率呈上升趋势,当青稞全粉添加量为85%时面团的吸水率达到最大值73.10%,吸水率、弱化度显著增加(P<0.05);不同添加量对混合粉稳定时间的影响不显著;峰值黏度、最低黏度、最终黏度、衰减值、回生值显著下降(P<0.05),降落数值与峰值黏度呈极显著正相关;乳酸溶剂保持力SRC显著减少(P<0.05),湿面筋含量和乳酸溶剂保持力SRC呈极显著正相关;碳酸钠溶剂保持力SRC、蔗糖溶剂保持力SRC、水溶剂保持力SRC显著增加(P<0.05),破损淀粉值与碳酸钠溶剂保持力SRC,蔗糖溶剂保持力SRC与吸水率、蛋白质,水溶剂保持力SRC与蛋白质均呈极显著正相关性。     

Influence of sucrose on thermal and pasting properties of tapioca starch and xanthan gum mixtures

Sugars and hydrocolloids are used in starch-based product formulations during processing for improving the final quality of foods. Effect of sucrose (0–30%) on thermal and pasting properties of 5% w/w tapioca starch (TS) – xanthan gum (Xan) mixtures was investigated using differential scanning calorimeter (DSC), rapid visco-analyser (RVA) and rheometer. Sucrose increased gelatinization temperatures and enthalpies of TS and TS/Xan dispersions. RVA pasting temperatures, peak viscosity, final viscosity, breakdown and setback values of TS/Xan mixtures increased with increasing sucrose concentration (p < 0.05). Addition of sucrose in all TS/Xan pastes increased the rate of viscosity breakdown during RVA heating under constant shear and temperature. Setback values of TS/Xan pastes increased with sucrose addition but decreased significantly with increasing Xan content. Xan enhanced thermal stability of steady shear viscosities to TS pastes with and without sucrose. Linear regression from pasting profile revealed a good relationship for predicting final viscosity. These results could facilitate the development of TS-based products with improved thermal and pasting properties.     

不同介质对玉米淀粉糊化黏度特性的影响

为研究食品添加剂对玉米淀粉糊特性的影响,采用Brabender黏度仪测定玉米淀粉在添加不同量的碳酸钠、明矾、食盐和蔗糖后的黏度曲线,结果表明:四种添加剂均使淀粉的糊化温度升高。随着碳酸钠和明矾添加量的增加,淀粉糊的峰值黏度、崩解值显著升高,消减值、回生值和最终黏度降低,淀粉糊的热稳定性、凝胶性降低,凝沉性增强;而蔗糖和食盐的加入使淀粉的崩解值降低,增强了淀粉糊的热稳定性。碳酸钠和明矾对糊化特性影响较大,蔗糖和食盐的影响较小。     

Physicochemical, pasting and thermal properties of tuber starches as modified by guar gum and locust bean gum

This study was carried out in order to compare the functional characteristics of isolated starch from five tuber crops, yam, taro, sweet potato, yam bean and potato, as well as effect of guar gum (GG) and locust bean gum (LBG) on pasting and thermal properties of tuber starches. The results showed that total amylose content of five tested starches ranged from 17.85% to 30.36%. The results of pasting behaviour showed that potato starches exhibited the highest peak viscosity and yam starch presented a stable curve with little breakdown viscosity. Addition of GG and LBG resulted in a significant increase in peak, final viscosity, breakdown and setback viscosity for all tuber starches ( P  < 0.05), but a slight decrease in pasting temperature. The gelatinisation enthalpy (Δ H ) for starches with GG and LBG was slightly lower than those of the starches alone in yam and sweet potato, but not in taro and yam bean.