大米醋酸酯淀粉乙酰基含量影响因素的研究

以优质大米为原料,用醋酸酐交联酯化制备大米醋酸酯淀粉。通过研究,得到了影响大米醋酸酯淀粉乙酰基含量的因素分别为:米浆浓度、反应温度、反应pH值、醋酸酐添加量,符合产品应用要求的最佳工艺参数分别为米浆质量分数为40%,反应温度为20℃,反应pH值为8.5,醋酸酐最经济的添加量为3%。     

大米抗性淀粉压热处理制备工艺的研究

抗性淀粉以其显著优点及特殊的生理功能,成为食品营养学的一个研究热点。以大米淀粉为原料,制备大米抗性淀粉对大米的深加工具有重要的经济意义。以抗性淀粉得率为评价指标,通过单因素及正交试验研究了压热法制备抗性淀粉的最佳工艺参数。结果表明,对大米淀粉进行压热处理时,影响抗性淀粉得率的主次因素为:热处理温度热处理时间淀粉乳质量分数,最佳工艺条件为:热处理温度120℃,热处理时间70 min,淀粉乳质量分数30%。采用此组合进行验证性试验得抗性淀粉产率为9.54%。     

压热冷却循环处理制备青稞抗性淀粉的工艺优化及其特性研究

以青稞淀粉为原料,探讨压热冷却循环法制备青稞抗性淀粉的过程中淀粉溶液质量分数、冷藏时间、循环次数对抗性淀粉含量的影响,利用单因素和正交实验优化工艺。结果表明,最佳工艺条件为:青稞淀粉溶液质量分数10%、冷藏24 h、4次压热冷却循环,所得抗性淀粉含量最高,为(8.57±0.10)%。对最佳工艺条件下所制备的青稞抗性淀粉的理化性质进行表征,结果表明,经过压热冷却循环处理后,快消化淀粉(RDS)和慢消化淀粉(SDS)含量均减少,抗性淀粉含量增加至(8.57±0.10)%。颗粒形态由扁球状变成形状不规则的块状且表面形成大量沟壑,晶型由A型变为V型,峰值黏度和最终黏度显著降低。     

挤压法制备大米抗性淀粉中系统参数控制与目标参数的关系

采用正交试验,进行挤压法制备大米抗性淀粉的研究,得到了挤压法制备大米抗性淀粉的最佳工艺条件:大米粉水分含量40%,挤压机腔体170℃,螺杆挤压频率35Hz,储藏时间7d,储藏温度4℃,喂料机喂料频率20Hz。在此工艺下,抗性淀粉得率8.77%,与原料相比,抗性淀粉含量提高了近7倍。在正交试验的基础上,建立了反映挤压法制备大米抗性淀粉中系统参数控制与目标参数关系的回归方程:Yi=-4.1408 0.1655XA 0.0402XB 0.0069XC-0.0299XD 0.0586XE 0.0911XF     

压热法制备荞麦抗性淀粉的研究

以荞麦淀粉为原料,通过单因素及正交试验研究了压热法制备抗性淀粉的最佳工艺参数.结果表明:淀粉乳质量分数为20%,调节pH值为7.O,120℃压热处理90 min,4℃放置24 h.按此工艺参数制备荞麦抗性淀粉,其得率可达到15.54%.     

大米抗性辛烯基琥珀酸淀粉酯的制备及特性分析

为探究抗性淀粉制备新途径,提高大米特别是碎米资源的利用价值,以大米淀粉为原料,水相法制备大米辛烯基琥珀酸淀粉酯（OSA淀粉）,以取代度DS和反应效率RE为考察指标,探讨反应温度、反应pH、酸酐滴加时间和淀粉浆浓度对DS和RE的影响。对OSA淀粉进行湿热处理,探究湿热处理时间对抗性淀粉含量和理化特性的影响,并进行体外消化试验。结果表明:制备OSA淀粉适合的工艺条件为反应温度40 ℃、反应pH为9.0、酸酐滴加时间为4 h、淀粉乳浓度30%,此条件下得到的OSA淀粉DS为1.3915,RE为78.2%。将此条件获得的OSA淀粉湿热处理18 h,抗性淀粉含量从25.2%增加至42.2%。在模拟胃肠道中消化水解率为58.8%。     

鲜米粉加工专用原料的选择研究

本研究对21种籼米进行了品质测定,并对其制备的鲜米粉进行感官评价,通过相关性及聚类分析确定主要评价指标,为鲜米粉生产过程中专用大米原料的筛选提供理论依据。研究结果表明,大米品质特性的部分指标对鲜米粉的感官特性有显著(P<0.05)的影响,其中灰分与口感、总分呈显著负相关(P<0.05);总淀粉含量与除气味外的其他感官指标呈显著正相关(P<0.05);直链淀粉含量与组织形态之间存在显著正相关性(P<0.05)。考虑实际生产中的可操作性并结合品种的聚类分析,选择蛋白质、直链淀粉含量作为大米品种品质评价的核心指标,当大米蛋白质质量分数在6.0%~7.0%、直链淀粉质量分数在21.0%~25.0%时,加工的鲜米粉柔软顺滑、口感较好,鲜米粉生产过程中可据此筛选大米品种。     

响应面优化高抗性淀粉速食粥加工工艺

以水稻精米为加工原料,经过加水浸泡、高压蒸煮和预冷冻处理,最后利用真空冷冻干燥法制备速食粥。通过单因素试验,确定加水比例(加水体积mL与大米质量g的比例)、蒸煮时间和冷冻温度3个加工条件为自变量。以速食粥中抗性淀粉含量作为响应值,根据中心组合(BoxBenhnken)试验设计原理,利用Design Expert8.0.4软件对3个自变量的3个水平进行响应面分析,得到高抗性淀粉速食米粥最佳工艺条件:加水比例5(mL/g)、高压蒸煮时间20 min、冷冻温度-5℃。在此工艺条件下加工获得的速食粥抗性淀粉含量为8.72%,比原料大米抗性淀粉含量提高了22.64%。     

木薯醋酸酯淀粉的制备及性能研究

以木薯淀粉为原料,醋酸酐为酯化剂,研究获得制备木薯醋酸淀粉的最佳工艺条件为:醋酸酐量为7％(对干基),pH8.5,反应时间60min,反应温度25℃.所制得的淀粉乙酰基含量为2.09％,反应效率为77.2％.对不同取代度(DS)醋酸酯淀粉的黏度、透明度、冻融稳定性等特性进行了研究.     

鲜米粉加工专用原料的选择

本研究对21种籼米进行了品质测定,并对其制备的鲜米粉进行感官评价,通过相关性及聚类分析确定主要评价指标,为鲜米粉生产过程中专用大米原料的筛选提供理论依据。研究结果表明,大米品质特性的部分指标对鲜米粉的感官特性有显著(P0.05)的影响,其中灰分与口感、总分呈显著负相关(P0.05);总淀粉含量与除气味外的其他感官指标呈显著正相关(P0.05);直链淀粉含量与组织形态之间存在显著正相关性(P0.05)。考虑实际生产中的可操作性并结合品种的聚类分析,选择蛋白质、直链淀粉含量作为大米品种品质评价的核心指标,当大米蛋白质质量分数在6.0%~7.0%、直链淀粉质量分数在21.0%~25.0%时,加工的鲜米粉柔软顺滑、口感较好,鲜米粉生产过程中可据此筛选大米品种。     

Synthesis and Characterization of Hypochlorite Oxidized Starches

Egyptian rice and maize starches were treated with sodium hypochlorite at different concentrations. The oxidized starches so obtained were monitored for carboxyl content and rheological properties. In addition, the extent and rate of the oxidation reaction was assessed by investigating the chlorine consumption. Results indicated that the extent and rate of oxidation of rice starch, expressed as chlorine consumption, are much higher than those of maize starch. The opposite holds true for the carboxyl content. Pastes of rice and maize starches before and after oxidation exhibit non-Newtonian thixotropic behaviour but their apparent viscosity decreases by increasing the hypochlorite concentration. At any event, however, the apparent viscosity of rice starch is substantially higher than that of maize starch. Storing the pastes for 24 h adversely affect the apparent viscosity particularly with oxidized starches prepared using higher hypochlorite concentrations.     

籼米多孔淀粉的研制

试验以籼米淀粉为原料,通过α-淀粉酶水解籼米淀粉制备籼米多孔淀粉,探讨并获得了酶水解法制备籼米多孔淀粉的较优工艺：酶解反应温度为35℃,酶解反应时间为12 h,加酶量为酶解40%淀粉量,酶解体系pH值为4.0。并利用砂芯漏斗测定淀粉对液体的吸附能力,观察到大米多孔淀粉对液体的吸附能力大大强于大米原淀粉。     

含水量对机械活化大米淀粉理化特性的影响

采用籼米、粳米和糯米三种类型大米淀粉为原料,研究淀粉含水量对机械活化大米淀粉理化特性的影响,得到利于机械活化的淀粉含水量范围,从而提高机械活化效果,缩短机械活化时间。研究表明,随着机械活化时间的延长,三种大米淀粉的糊化度、冷水溶解率、糊透明度和还原力均增大,而碘兰值(BV)均减小。籼米淀粉在含水量为6.02%时最易发生分子链断裂,粳米淀粉和糯米淀粉均在含水量为8.50%左右时最易断链。对糊化度和冷水溶解率而言,籼米淀粉以含水量为6.02%时最大,粳米淀粉和糯米淀粉以含水量为8.50%左右最大;对糊透明度而言,三种大米淀粉均在含水量为8.50%左右时最大;而对于还原力和BV而言,籼米淀粉含水量为3.50%时变化最快;对粳米淀粉和糯米淀粉均以含水量为6.00%左右时变化最快。由此可知,淀粉含水量对大米淀粉的机械活化具有一定影响,得到适宜的机械活化大米淀粉的含水量范围为6.00%~8.50%左右。     

冷冻球磨稻米淀粉理化特性及反应活性研究

稻米淀粉于高频振动式冷冻球磨机中处理一定时间制备不同球磨程度的稻米淀粉,采用布拉班德黏度仪和化学分析技术等测试方法,研究了冷冻球磨的处理方法对稻米淀粉理化性质和反应活性的影响规律。结果表明,稻米淀粉经过长时间的冷冻球磨后,淀粉颗粒的糊化性质发生了显著的改变,成为非糊化的淀粉颗粒;同时淀粉的吸附能力以及与水的结合能力增强,吸湿性、溶解度和膨润度提高;淀粉的反应活性增强,酶解速度加快;淀粉碘结合能力下降,蓝值逐渐变小。     

加热时间对大米淀粉特性及抗性淀粉含量的影响

采用不同的加热时间对大米进行处理,并从加热处理过的大米中提取淀粉,采用电镜扫描仪、差示扫描量热仪、质构仪、流变仪等检测仪器研究加热时间对大米淀粉的颗粒形貌、热力学性质、凝胶特性、流变等性质的影响,采用酶解法测定加热处理过的大米中抗性淀粉的含量。结果表明：随着加热时间的延长,淀粉的膨润力与溶解度先增大后减小;加热时间在0～10min 时,抗性淀粉含量减少,其范围为18.01%～8.10%;淀粉颗粒由单个独立的颗粒逐渐膨胀至相互粘连,糊化焓值降低;硬度、延伸性等都有不同程度的变化;淀粉糊的剪切稳定性降低。     

Structural changes induced by high speed jet on in vitro digestibility and hydroxypropylation of rice starch

Influences of high speed jet (HSJ) at different pressures (0, 80, 160, 250 MPa) on digestibility and hydroxypropylation of rice starch were evaluated. HSJ treatment increased the content of rapidly digestible starch and slowly digestible starch and decreased the content of resistant starch with increasing of the treatment pressure in native starch. The degree and the reaction efficiency of hydroxypropylation of rice starch increased with an increase in treatment pressure. Scanning electron microscopy and X‐ray diffraction analysis showed that both the crystalline structure and the overall granular structure were partially destroyed. Meanwhile, HSJ treatment led to degradation of starch molecules. The results suggested that the changes of starch structure resulted in decreasing gelatinisation enthalpy of rice starch and might be response for the changes of reactivity and its digestibility to some extent.     

Effects of acetic acid on the rice gelatinization and pasting properties of rice starch during cooking

The mechanism of the textural changes such as increase in stickiness of rice cooked with acetic acid was studied focusing on the gelatinization and rheological properties of both rice starch and rice flour. The results of swelling power and solubility of rice starch indicated that acetic acid promoted water absorption of amylopectin in rice starch. It was shown by DSC measurements that rice starch heated with acetic acid was easy to gelatinize compared to that without acetic acid. The pasting properties measured by an RVA and rotational viscometer suggested that the structure of rice starch became more fluid by addition of acetic acid. Biochemical analysis using α-amylase indicated that the spaces which allowed the enzyme reaction were formed more in the structure of rice starch cooked with acetic acid. It was suggested that these changes in rice starch contributed to the textural properties of rice cooked with acetic acid.     

Structural characterization of rice starch in rice cake modified by Thermus scotoductus 4-alpha-glucanotransferase (TS alpha GTase)

ABSTRACT:  Rice cake was produced with a thermostable 4-α-glucanotransferase from Thermus scotoductus (TSαGTase). Starch molecular fine structure, texture, and retrogradation for the enzymatically prepared rice cake were investigated and compared to those for control rice cake. The amylose content in TSαGTase-treated rice cakes decreased, whereas branched and linear malto-oligosaccharides ranging from maltose to maltoheptaose increased slightly. The average molecular weight of the enzyme-treated rice starch in rice cake decreased as amylopectin macromolecules were cleaved and reorganized into small amylopectin clusters. The number of shorter side chains (degree of polymerization [DP] < 9) increased, whereas the number of longer side chains (DP > 10) decreased through the disproportionation reaction of TSαGTase. After 24 h of storage at 4 °C, the enzyme-treated samples demonstrated significantly lower melting enthalpy of retrograded starch (0.4 mJ/mg) compared to that of the control (1.4 mJ/mg). The results indicated that TSαGTase treatment effectively inhibited starch retrogradation in rice cakes. It is suggested that the reduction of amylose content, the rearrangement of amylopectin, and the production of malto-oligosaccharides caused by TSαGTase treatment are responsible for the ineffective molecular reassociation of rice starch in rice cake.     

Effect of amylose content and rice type on dynamic viscoelasticity of a composite rice starch gel

Amylose content is an important indicator to determine the utility of raw milled rice. Indica type rice with high amylose content is usually used for manufacturing rice noodles, while Japonica rice may be mixed partially to adjust the noodle texture. The effect of amylose and rice type on dynamic viscoelasticity of rice starch gel was investigated using a model starch composite in this study. The information will be helpful to control and obtain the required noodle texture by combination of different rice types. The results show that nonwaxy Indica and waxy Japonica rice starches in a composite mixture were incompatible and demonstrated their individual gelatinization behavior during heating. High amylose starch showed higher moduli and lower loss tangent values, as well as higher retrogradation rate. The starch gel made from Japonica rice starch showed a slow retrogradation rate even containing a similar amount of amylose to Indica starch. The storage modulus of the gel made from higher amylose rice was shown to be more independent of frequency. Not only amylose content but also chain length distribution in amylopectin affected the dynamic viscoelasticity of rice gel. Japonica rice starch, with fewer super-long chains in amylopectin, retrograded slower after gelatinization than Indica rice, thus the paste is too sticky for production of rice noodles.