Mechanochemical degradation of potato starch paste under ultrasonic irradiation

In the paper, changes in the molecular weight, the intrinsic viscosity and the polydispersity (molecular mass distribution) of treated potato starch paste were studied under different ultrasonic conditions which include irradiation time, ultrasonic intensity, potato starch paste concentration, and distance from probe tip on the degradation of potato starch paste. Intrinsic viscosity of potato starch paste was determined following the ASTM (American Society for Testing and Materials) standard practice for dilute solution viscosity of polymers. Molecular mass and polydispersity of potato starch paste were measured on GPC (Gel Permeation Chromatography). The results showed that the average molecular mass and the intrinsic viscosity of starch strongly depended on irradiation time. Degradation increased with prolonged ultrasonic irradiation time, and the increase of ultrasonic intensity could accelerate the degradation, resulting in a faster degradation rate, a lower limiting value and a higher degradation extent. Starch samples were degraded faster in dilute solutions than in concentrated solutions. The molecular mass and the intrinsic viscosity of starch increased with the increase of distance from probe tip. Our results also showed that the polydispersity decreased with ultrasonic irradiation under all ultrasonic conditions. Ultrasonic degradation of potato starch paste occured based on the mechanism of molecular relaxation of starch paste. In the initial stage, ultrasonic degradation of potato starch paste was a random process, and the molecular mass distribution was broad. After that, ultrasonic degradation of potato starch paste changed to a nonrandom process, and the molecular mass distribution became narrower. Finally, molecular mass distribution tended toward a saturation value.

Rheological properties of sweet potato starch before and after denaturalization

Based on the sweet potato starch,cationic starch,acetic starch and cationic-acetic compoundedly modified starch were made through chemical denaturalization.The above three kinds of static rheological parameter and dynamic rheological parameter were measured,respectively.The experimental result reveals that the thermal stability of starchy viscosity increases after chemical denaturalization.Under the condition of identical shearing rate,the shear stress of cationic-acetic ester compoundedly modified sweet potato starch paste is the largest among these kinds of sweet potato starch.This attributes to a phenomenon of shearing thinning.Furthermore,raw sweet potato starch has a larger gel intensity than that of modified starch.

RVA and Farinograph Properties Study on Blends of Resistant Starch and Wheat Flour

Resistant starch （RS） is the undigested starch that passes through the small intestine to the large intestine. As a functional low calorie additive, it has special applications in the food industry. Rapid visco analysis （RVA） and the Brabender farinograph were used to study the pasting properties and the viscoelasticity of blends of RS （RS3 and RS2） and three wheat flours. The wheat flours represented strong gluten wheat （SGW）, intermediate gluten wheat （IGW）, and weak gluten wheat （WGW） flours, at different levels of RS substitution （0, 5, 10, 15, and 20%）. The influence of RS3 on the control wheat flours and RS-wheat flour blends were consistent with those of RS2. The peak, trough, and final viscosities of RS3-wheat flour blends were higher than those of the corresponding RS2-wheat flour blends. The peak, trough, breakdown, final, and setback viscosities ofwheat-RS blends decreased with an increase in resistant starch contents from 0 to 20% in the blends. The 0-20% RS-wheat flour blends were all able to form doughs. The dough development times, dough stabilities, dough breakdown times, and farinograph quality numbers for the RS-wheat flour blends decreased as the RS proportion in the blends increased. The values for RS-SGW flour blends were the highest, followed by RS-IGW and then RS-WGW flour blends. The water absorption values for RS-wheat flour blends and the mixing tolerance index for RS-WGW flour blends were found to increase significantly with an increasing proportion of RS from 0 to 20%, but the mixing tolerance index for RS-SGW and RS-IGW flour blends showed no significant differences amongst the different ratios. Correlation analysis showed that the Farinograph quality number was highly positively correlated with dough breakdown time, dough stability, and dough development time （r= 1.000, 0.958, 0.894）, and highly negatively correlated with the mixing tolerance index （r =-0.890）. Data from this study can be used for the development of dough-based products. It also provides a basis for RS-wheat flour blends and quality evaluation in the food industry.

Effect of Cultivar on Quality Attributes of Sweet Potato Fries and Crisps

Effect of cultivar differences on physical and proximate composition, and sensory attributes of sweet potato fries and crisps were determined. Physicochemical and colour characteristics of sweet potato flours and starches were evaluated using Rapid Visco Analyser and Hunter L a b, respectively. Chroma, colour intensity and hue angle were calculated. Objective and sensory parameters of sweet potato fries and crisps were evaluated. Proximate and pasting properties were typical of sweet potato tubers, flour and starches. Maltose (0.05% - 0.08%), sucrose (0.05% - 1.60%) contents of sweet potato were significantly different (p < 0.05). Amylose and amylopectin contents of sweet potato starches were 19.5% - 24.6% and 75.4% - 80.5%, respectively. Swelling power and solubility were 2.42 - 2.88 and 0.11 - 0.32, 5.01 and 0.02 - 3.00 for flours and starches, respectively. Lovers name fries showed significantly better appearance, while Big Red and Black Vine fries showed similar sensory scores. No significant difference occurred in all the sensory attributes of crisps of the sweet potato cultivars.

瓜尔胶和黄原胶对马铃薯淀粉及其变性淀粉糊化和流变性质的影响

研究瓜尔胶和黄原胶对马铃薯淀粉、马铃薯磷酸酯淀粉和马铃薯阳离子淀粉糊化和流变性质的影响。糊化性质实验表明瓜尔胶增加了3种淀粉的峰值黏度和成糊温度,降低了淀粉糊的热稳定性。黄原胶降低了马铃薯淀粉和马铃薯磷酸酯淀粉的峰值黏度并提高了糊的热稳定性和成糊温度,但对马铃薯阳离子淀粉起相反作用。动态流变实验表明加入黄原胶显著提高了3种淀粉的G′、G′′值,降低了损耗角正切值tanδ,黄原胶对马铃薯阳离子淀粉动态流变学性质的影响最大,瓜尔胶对3种淀粉的动态流变学性质的影响不显著。静态流变实验表明加入瓜尔胶和黄原胶后的淀粉糊仍为假塑性流体,滞后环面积减少,稳定性提高,两种胶对马铃薯淀粉和马铃薯磷酸酯淀粉的作用比对马铃薯阳离子淀粉作用明显,并且黄原胶比瓜尔胶对淀粉作用更为显著。研究发现胶体与淀粉之间的电荷相互作用对复配体系的糊化性质和流变学性质起重要的作用。

黄原胶对绿豆淀粉糊化和流变特性的影响

研究黄原胶(XG)对绿豆淀粉(MBS)的糊化和流变学性质的影响,并与目前应用较多的玉米淀粉(CS)、马铃薯淀粉(PS)进行比较分析。快速黏度分析仪(RVA)曲线表明黄原胶可增加绿豆淀粉的峰值黏度和起始糊化温度,降低崩解值和回生值。动态流变学实验表明黄原胶能够提高绿豆淀粉的储能模量和损耗模量(G’、G")值,体系表现出更为优越的黏弹性。静态流变学实验表明绿豆淀粉与黄原胶体系的稠度系数K增加,流体指数n降低,滞后环面积减少,稳定性提高。与玉米淀粉+黄原胶体系、马铃薯淀粉+黄原胶体系相比较而言,玉米淀粉呈现出与绿豆淀粉相类似的性质,而马铃薯由于其带电荷的差异性,表现为混合体系的峰值黏度降低,稠度系数减少。

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。

超声波处理下马铃薯淀粉糊的流变学特性

为了对马铃薯淀粉进行物理化学改性,利用超声波处理马铃薯淀粉,采用Brookfield旋转粘度计研究了不同处理时间下马铃薯淀粉糊的流变特性.结果表明:不同超声波处理时间下的马铃薯淀粉样品均呈假塑性流体特征,符合幂定律;超声波处理时间越长,马铃薯淀粉糊的表观粘度越低,触变性相应减弱;超声波处理后,马铃薯淀粉糊的剪切稀化程度随马铃薯淀粉含量的增大而加深.

马铃薯淀粉糊的黏度性质

采用Viscograph-E型Brabender黏度仪,测定了不同品牌马铃薯淀粉糊及马铃薯淀粉糊在不同质量浓度、pH、食盐、蔗糖、明矾、磷酸盐和魔芋葡甘露聚糖条件下的黏度曲线,研究了淀粉糊黏度性质及其影响因素。结果表明,淀粉乳质量浓度、pH和添加食盐、蔗糖、明矾、磷酸盐及魔芋葡甘露聚糖对淀粉糊黏度性质均有影响,其中蔗糖、魔芋葡甘露聚糖对淀粉糊热稳定性、凝胶性、凝沉性影响较小。

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。

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。

甘薯淀粉糊性质的研究

甘薯淀粉是重要的粮食、饲料和工业原料。淀粉的应用主要是应用淀粉糊,因此糊的性质至关重要。本文采用Brabender连续粘度计测定了甘薯淀粉在不同浓度、pH、食糖、盐和硬脂酸条件下对甘薯淀粉糊粘度曲线的影响;并对甘薯淀粉糊的透明度、凝沉性和冻融稳定性等进行了测试,为进一步开发甘薯淀粉的应用提供基础。

超声处理对马铃薯淀粉糊流体性质和表观黏度的影响

利用超声波处理马铃薯淀粉糊,研究超声场下马铃薯淀粉糊流体性质及表观黏度性质变化规律。采用超声波设备处理马铃薯淀粉糊样品,用流变仪测定马铃薯淀粉糊剪切力和表观黏度,运用幂函数定律建立超声场马铃薯淀粉糊流动模型。结果表明:超声作用改变了马铃薯淀粉糊的流体性质,从假塑性流体趋于符合牛顿流体特征;作用时间和声强对马铃薯淀粉糊表观黏度影响较大,成正相关;随着超声作用时间的延长,马铃薯淀粉糊质量分数对表观黏度的影响呈现先增大后减小的趋势。因此,增加超声时间和声强可以降低马铃薯淀粉糊表观黏度,改变淀粉糊流动性。

亚麻多糖对木薯淀粉和红薯淀粉糊物理性质的影响

采用快速黏度分析法、质构分析法、离心法、冻融循环法,研究了自然条件下及在NaCl、蔗糖、葡萄糖或酸碱环境中,亚麻多糖对木薯淀粉、红薯淀粉糊化温度、峰值黏度、末值黏度、衰减值、凝胶硬度、凝胶析水率等物理性质的影响。结果表明:自然条件下,亚麻多糖能增强木薯淀粉、红薯淀粉的膨胀力,降低热稳定性、凝胶硬度、冻融稳定性。在盐、糖环境中,亚麻多糖均能增强木薯淀粉、红薯淀粉的膨胀力和冻融稳定性,降低热稳定性。在低pH条件下,亚麻多糖能降低红薯淀粉的冻融稳定性和热稳定性;高pH条件下提高木薯淀粉的冻融稳定性和膨胀力。

大米淀粉的流变性质和质构特性

以大米淀粉为原料,考察了淀粉糊质量分数、温度、pH值、蔗糖、盐等对大米淀粉糊流变性质和质构特性的影响,可为大米淀粉食品的加工提供基本参数和依据。对大米淀粉糊流变性质研究结果表明:大米淀粉糊黏度随着淀粉质量分数的增加而增加;随温度的增加而减小,在pH值2～4和8～10的范围,大米淀粉糊黏度急剧降低;大米淀粉糊黏度随蔗糖添加量的增加而增大;随NaCl添加量的增加而降低,CaCl2对大米淀粉糊黏度的影响较小。采用质构仪对大米淀粉糊质构特性分析发现:淀粉质量分数、pH值对大米淀粉糊的凝胶强度影响较大,其硬度随淀粉质量分数的增加而增加;在pH值2～10范围内,硬度随pH值的增加而显著增大;蔗糖、NaCl和CaCl2对大米淀粉糊硬度影响较小。

羧甲基化对马铃薯淀粉糊性质的影响

羧甲基化对改善马铃薯淀粉糊的性质具有重要作用。本文对马铃薯羧甲基淀粉糊的糊性质进行了详细研究 ,包括糊的冷热粘度稳定性、冻融稳定性、透明度、pH值和介质 (蔗糖、氯化钠 )对糊粘度性质的影响。结果表明 ,马铃薯淀粉经过羧甲基化后 ,糊的热粘度稳定性及冷粘度稳定性均有所降低 ,在pH为 6 5～ 8 5范围内 ,羧甲基淀粉糊有最大的粘度。蔗糖对羧甲基淀粉糊粘度有一定影响 ,氯化钠对羧甲基淀粉糊粘度有显著影响。马铃薯羧甲基淀粉具有易糊化、粘度大、糊凝沉性低。

甘薯淀粉糊的流变特性

通过考察甘薯淀粉糊在不同甘薯淀粉浓度和不同温度下的流变特性,结果表明甘薯淀粉糊是典型的非牛顿型、剪切变稀的和触变性流体,温度越高,浓度越低,甘薯淀粉糊的滞后性越小;同时用幂律方程和Cross方程来描述糊的流变特性,发现Cross方程比幂律方程拟合精度更高。而浓度很低的情况下(如2%),甘薯淀粉糊的触变特性与其他浓度不同,表现为下行线在上行线之上,更适合用Herschel-Bulkley方程来描述它的流变行为。甘薯淀粉糊的动态流变行为则表现为在将开始糊化时,储能模量G'、损耗模量G"和tanδ都急剧上升,在到达糊化顶峰时急剧下降,而在降温过程中G'和G"都呈上升趋势,tanδ则是在100～50℃时下降,50～20℃时上升。

蜡质马铃薯淀粉性质的研究

研究了蜡质马铃薯淀粉的品质特性,结果表明:蜡质马铃薯淀粉糊液的黏度比马铃薯淀粉高,蜡质马铃薯淀粉糊化后不易老化,其糊液抗凝沉、透光度都优于蜡质玉米淀粉和糯米淀粉。用RVA测定了蜡质马铃薯淀粉糊在不同介质中黏度曲线的变化情况。

无添加马铃薯粉条老化工艺及贮藏品质

以马铃薯淀粉为原料,对粉条的定型时间、老化时间、低温老化温度进行单因素试验和正交试验,以感官评分为标准,确定最佳的粉条制作工艺,并利用差示扫描量热仪和快速黏度分析仪测试不同老化时间和老化温度下粉条热力学特性和糊化特性,利用质构仪分析贮藏期间粉条的弹性、剪切力、断条率、硬度等品质指标的变化。结果表明:马铃薯粉条生产工艺条件为定型时间60 s、室温老化时间90 min、低温老化温度-2 ℃,在此条件下粉条的感官品质较好,硬度适中,弹性好,断条率低。室温老化和低温老化均对马铃薯粉条的热力学参数和黏度参数有一定的影响。贮藏期间粉条的弹性、剪切力、断条率、硬度、膨润度和糊汤率均随着贮藏时间的延长而增加。综上,马铃薯淀粉的老化对粉条的品质影响较大,并且贮藏过程中粉条的品质也产生较大变化,甚至产生过度老化。

乙酰化己二酸交联蜡质马铃薯淀粉糊的黏度性质

采用Brabender黏度仪、旋转黏度计等现代分析仪器,研究了乙酰化己二酸交联蜡质马铃薯淀粉糊的流变、黏度性质,以及耐酸性和耐盐性等.结果表明:蜡质马铃薯淀粉经乙酰化己二酸交联后,淀粉糊的起糊温度由64.7℃升至67.3℃,峰值黏度从919 BU下降为652 BU,相对破裂强度从76.4%降至27.6%;糊的黏度稳定性、抗剪切稳定性、凝沉性都得到改善.此外,经乙酰化己二酸交联改性后的淀粉糊的耐酸性和耐盐性均有不同程度的提高.