马铃薯羟丙基羧甲基淀粉颗粒及分子结构变化

对马铃薯原淀粉、马铃薯羟丙基淀粉、马铃薯羧甲基淀粉、马铃薯羟丙基羧甲基淀粉分别利用红外光谱分析(FT-IR),证实了马铃薯羟丙基羧甲基淀粉的结构变化;利用X-射线衍射分析(X-RD),证实了马铃薯羟丙基羧甲基淀粉的结晶度变化,随着无序化程度降低,导致其结晶度增加;利用扫描电子显微镜(SEM)观察了复合变性前后淀粉的表观形貌变化,证实了淀粉羟丙基羧甲基化其反应不仅发生在淀粉颗粒表面,也发生在淀粉颗粒内部,同时该反应首先发生在淀粉颗粒中结构较薄弱的非结晶区。     

羟丙基马铃薯淀粉的羧甲基化影响因素研究

在环氧丙烷制备羟丙基马铃薯淀粉的基础上,再利用乙醇溶剂法对羟丙基马铃薯淀粉进行二次变性制得羟丙基羧甲基马铃薯淀粉。文中讨论氯乙酸用量、NaOH用量、反应时间、反应温度对羟丙基羧甲基马铃薯淀粉的取代度(DS)的影响,结果表明:羟丙基马铃薯淀粉羧甲基化的最佳条件为反应温度60℃,反应时间4 h,NaOH用量75%,氯乙酸用量65%。     

复配变性淀粉的性质及其在面团中的应用

将冻融稳定性较好的醋酸酯淀粉、羟丙基二淀粉磷酸酯和透明度、黏度较高的羧甲基淀粉进行复配,对比三种变性淀粉和复配变性淀粉的性质,研究其在面团中的应用。结果表明,复配变性淀粉可以综合各变性淀粉的优点,比单一变性淀粉的性质更加全面,其中1∶2∶1(醋酸酯大米淀粉∶羧甲基淀粉∶羟丙基二淀粉磷酸酯)组表现最优异,透明度、凝沉性、冻融稳定性、糊化特性、流变性等性质优于其他组。在面团的应用研究中,添加复配变性淀粉可有效改善面团的持水性和质构特性,提高熟面坯的感官品质。复配变性淀粉添加量为5%～7.5%时最好。     

复配变性淀粉的性质及在面团中的应用

将冻融稳定性较好的醋酸酯淀粉、羟丙基二淀粉磷酸酯和透明度、黏度较高的羧甲基淀粉进行复配,对比三种变性淀粉和复配变性淀粉的性质,研究其在面团中的应用。结果表明,复配变性淀粉可以综合各变性淀粉的优点,比单一变性淀粉的性质更加全面,其中1:2:1（醋酸酯大米淀粉:羧甲基淀粉:羟丙基二淀粉磷酸酯）组表现最优异,透明度、凝沉性、冻融稳定性、糊化特性、流变性等性质优于其他组。在面团的应用研究中,添加复配变性淀粉可有效改善面团的持水性和质构特性,提高熟面坯的感官品质。复配变性淀粉添加量为5%～7.5%时最好。     

三种变性淀粉浆料性能对比研究

对比玉米、小麦、木薯变性淀粉的浆料性能。以玉米、小麦及木薯原淀粉为原料,分别制备了各自的氧化淀粉、羧甲基淀粉及羟丙基淀粉等浆料,并对其浆膜性能及黏附性进行对比。研究结果表明:氧化淀粉、羧甲基淀粉及羟丙基淀粉浆液黏度较原淀粉有明显降低,黏度热稳定性显著提高;以木薯淀粉为原料制备的三种变性淀粉的浆膜断裂强度、浆膜断裂伸长率及对棉纱黏附力好于相应的玉米和小麦变性淀粉;同一种原淀粉制备的变性淀粉中羟丙基淀粉浆膜断裂强度、浆膜断裂伸长率及对棉纱黏附力略优于羧甲基淀粉,而氧化淀粉的浆膜断裂强度、浆膜断裂伸长率及对棉纱黏附力等性能则明显低于另外两种变性淀粉。认为:在三种原料的不同变性淀粉中,木薯羟丙基淀粉较适宜纯棉产品上浆。     

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。     

玉米淀粉与玉米变性淀粉性质比较研究

测定了玉米淀粉、羟丙基淀粉、羧甲基淀粉、淀粉磷酸酯的冻融稳定性、透光率、膨胀度、粘度、糊化特性等主要物理性质并进行了比较。试验结果表明：变性淀粉与玉米淀粉的性质不同，由于变性淀粉引进了羟丙基、羧甲基、磷酸基团等亲水性基团，使淀粉极性增强，亲水能力增大，使其都具有较强的冻融稳定性、抗凝沉性，较高的膨胀度、透明度，因此变性淀粉具有更广阔的应用性。     

交联羟丙基羧甲基复合改性玉米淀粉的性能研究

以玉米淀粉为原料,利用乙醇溶剂法进行羟丙基醚化改性,再采用环氧氯丙烷交联剂和一氯乙酸进行处理而制得复合改性淀粉。采用傅里叶变换红外谱仪、X射线衍射仪和扫描电镜等对玉米原淀粉、羟丙基淀粉、交联羟丙基淀粉、羟丙基羧甲基淀粉和交联羟丙基羧甲基淀粉的微观结构进行了表征。红外分析表明改性淀粉在1287 cm-1处出现羟丙基的吸收峰,同时在1328~1603 cm-1处出现了-COO-吸收峰,说明原淀粉已接入了羟丙基和羧甲基基团。利用X-射线衍射分析改性淀粉仍属A型衍射图,证实了反应主要发生在无定形区。复合变性前后淀粉的表观形貌变化,证实了淀粉其反应不仅发生在淀粉颗粒表面,也发生在淀粉颗粒内部。讨论了改性淀粉的理化性质,结果表明交联羟丙基羧甲基淀粉具有良好的透明性、冻融稳定性、流变性。     

几种不同品种淀粉及羟丙基产物糊液性质比较研究

以薯类淀粉(木薯,马铃薯)及禾谷类淀粉(普通玉米、蜡质玉米、高直链玉米及糯米)为原料,以环氧丙烷为醚化剂。制备了羟丙基变性淀粉。反应条件:淀粉乳质量分数40%、反应温度40℃、无水Na_2SO_4添加量12%(以淀粉干基计)、NaOH添加量1.2%、环氧丙烷添加量12%、反应时间18h。分别对原淀粉及在相同的反应条件下制备的羟丙基变性淀粉糊性质做了对比研究。不同品种淀粉糊性质存在很大差别。经过羟丙基改性。淀粉糊液粘度性质、冻融稳定性、透光率、都有不同程度的改善,但凝沉性质不能准确反映羟丙基化对蜡质玉米淀粉和糯米淀粉糊液性质的改善。     

变性淀粉对面条品质的改良研究

以交联淀粉、醋酸酯淀粉和羟丙基淀粉为面粉改良剂,通过正交实验研究了单一变性淀粉和复合变性淀粉对新鲜面和冷冻面条的改良效果。结果表明:添加1%的马铃薯交联羟丙基淀粉∶1%醋酸酯淀粉∶1.5%磷酸酯淀粉和0.5%的谷朊粉对面条的改良效果最佳。     

嗜热酸性生淀粉α-淀粉酶Gt-amy中结构域C的环化重排及其对Gt-amy催化性能的影响

为确定嗜热酸性生淀粉α-淀粉酶Gt-amy中结构域C对其催化性能的影响,本研究采用基于蛋白质分子结构的环化重排方法对Gt-amy的结构域C进行分子改造,获得Gt-amy环化重排突变体,并比较了突变体的生淀粉吸附率、生淀粉降解率、酶比活力以及动力学常数。与Gt-amy相比,生淀粉吸附能力提高的Gt-amy环化重排突变体,其生淀粉降解能力也得到提高;生淀粉吸附能力降低的Gt-amy环化重排突变体,其生淀粉降解能力也降低。即Gt-amy的生淀粉降解能力和生淀粉吸附能力之间存在正相关性。其中,环化重排突变体Gt-amy-S498的生淀粉吸附率由78.86%提高至93.14%,生淀粉降解率由65.80%提高至90.93%。本研究证实环化重排突变可以作为一种工程学手段改变蛋白质的结构与功能,为提高酶类蛋白质的催化性能提供了思路。     

Mechanism of Hydrolysis of the Treated Sago Starch Granules by Raw Starch Digesting Amylase from Penicillium brunneum

We have prepared raw starch digesting amylase from Penicillium brunneum, which is similar to other raw starch digesting enzymes, and is effective in hydrolyzing raw cereal starches, but not effective for raw sago starch and raw root starches. Treatment of sago starch granules before incubation with the enzyme by heating to below gelatinization temperature at low pH condition was effective in improving the hydrolysis. Observation by scanning electron microscope showed that structure of treated sago starch granules at 60°C pH 2.0 for 2h was not changed. Observation under polarized light showed the birefringence clearly was preserved. However, viscosity of treated sago starch granules decreased. After incubation with the enzyme, untreated starch granules corroded and several holes were seen on the surface of granule. Enzyme action on the treated starch granules resulted in much higher intensity of degradation and the holes deepened into the interior of granules. Analysis of the product of this process showed that mainly glucose was produced from the hydrolysis of treated or untreated sago starch granules by crude enzyme. But on gelatinized sago starch other types of sugars were formed during enzyme reaction.     

微孔淀粉制备的预处理工艺研究

改进了微孔淀粉的制备工艺。在酶法制备微孔淀粉的基础上进行了原淀粉的预处理工作，包括原淀粉的预糊化和超声波预处理。结果表明微孔淀粉的吸油率从原工艺的61％提高到97％，具有很好的效果。     

Short-chain fatty acid content and pH in caecum of rats fed various sources of starch

Caecal pH and contents of short-chain fatty acids (SCFA) were registered in rats fed three potential sources of resistant starch (RS); raw pea starch, raw potato starch, and an RS-enriched preparation obtained from wheat starch by autoclaving and enzymatic incubation. Small intestinal digestibility and delivery of RS to the hind-gut in the case of raw starches were determined by analysis of faecal starch in animals treated with antibiotics to prevent hind-gut fermentation. RS content in the RS-enriched preparation was determined as total starch remaining in an enzymatic gravimetric dietary fibre residue. The fermentability of RS was estimated from the faecal recovery of starch in normal animals with intact hind-gut microflora. Approximately 35 g per 100 g and 32 g per 100 g were RS in the case of raw potato starch and the RS-enriched preparation, respectively, versus only 1 g per 100 g in the case of raw pea starch. The caecal pH decreased with all test diets, being most significant with raw potato starch. SCFA production and faecal bulking were negligible with raw pea starch, whereas both raw potato starch and the RS-enriched preparation significantly increased these parameters. The fermentability of RS in raw potato starch and the RS-enriched preparation was similar, or about 60–70%. If calculated on basis of fermented amount, RS in raw potato starch was more potent in generating SCFA (49 μmol g^?1) than in the RS-enriched preparation (19 μmol g^?1). RS in raw potato starch also displayed the highest faecal bulking capacity. In fact, the faecal dry weight increased more than expected merely from delivery of RS. The relative proportion in caecal contents of acetic-, propionic- and butyric acid was 70, 17 and 8%, respectively, with no significant differences between the three sources of RS.     

Change in Digestibility of Raw Starch by Gamma-Irradiation

Irradiation effect on digestion of raw starch by glucoamylase has been investigated as a basic research for application of radiosterilization on uncooked starch fermentation. The digestibility of raw tapioca starch decreased with an increase in dose while that of other starches such as wheat, corn, sweet potato and potato were little changed by irradiation. Tapioca starch granules coagulated by irradiation and were sedimented rapidly in suspension. The coagulation of irradiated tapioca starch granules can be dispersed completely by ultrasonic treatment. These results show that the decrease in digestion of raw tapioca starch depends on the coagulation of starch granules but other factors also contribute because the recovery of digestibility by ultrasonic treatment was not complete.     

海洋生淀粉酶菌株发酵条件响应面优化

生淀粉酶是催化淀粉直接水解的酶类,其可广泛应用于食品、工业、医学等领域。该研究首先利用单因素试验研究发酵时间、发酵温度,发酵初始pH、装液量、接种量对生淀粉酶活的影响,并在此基础上利用响应面法设计试验,优化了海洋生淀粉酶菌株ZXS-1的发酵条件。结果表明,其最佳发酵条件为发酵时间38 h,发酵温度25 ℃,初始pH 7。在此最佳发酵条件下,生淀粉酶酶活可达445.2 U/mL,较优化前提高25.6%。     

淀粉原料生料发酵法生产酒精概述

该文介绍生料发酵概念,回顾生料糖化及发酵历史,对生料酒精发酵工艺与传统蒸煮双酶法发酵工艺进行比较,总结生料发酵优势,认为生料发酵作为一种低能耗、工艺简单及糖醇转化率高的酒精生产工艺应得到大力推广。     

Modification of granular corn starch with 4-alpha-glucanotransferase from Thermotoga maritima: effects on structural and physical properties

ABSTRACT:  Corn starch was converted using α-1,4-glucanotransferase from Thermotoga maritima (TmαGT), a hyperthermophilic bacterium, without inducing gelatinization, and the structural changes and physical properties of the modified starches were investigated. Enzyme modification was induced at 65 °C for 8, 16, or 24 h, and the morphology of the modified starches was observed with light and scanning electron microscopy. Granule integrity was mostly maintained after enzyme treatment, although some granules were partially fragmented as evidenced by enlarged surface pores and some cracks. The modified starches had lower apparent amylose levels than raw starch. The molecular weights of amylose and amylopectin molecules in the treated starches were lower than those of raw starch, and the amount of branched molecules, which had much lower molecular weights, also increased in the treated starches. The chain-length distribution of amylopectin showed an increased number of shorter branched chains. The modified starches showed a wider melting temperature range and a lower melting enthalpy than that of raw starch. The X-ray diffraction pattern of the modified starches showed typical A-type starch peaks, but the relative crystallinities were lower than that of raw starch. The solubility and paste clarity of the modified starches were much higher than those of raw starch. The modified starch gels maintained their rigidity over the whole frequency range tested and showed thermoreversibility between 4 and 75 °C. These results suggest that TmαGT can be used to produce granular corn starch, which contains amylose and amylopectin having lower molecular weights and a thermoreversible gelation property.     

Glucose Production from Treated Sago Starch Granules by Raw Starch Digesting Amylase from Penicillium brunneum

Several microorganisms have been found to produce raw starch digesting amylase. We have isolated Penicillium brunneum from sago palm tree at a sago processing site, which was used as a source of starch digesting amylase. All the raw starch digesting enzymes were effective for cereal starches, but root starches and sago starch were resistant to the enzyme reaction. Treatment of sago starch by heating to temperature below gelatinization temperature at lower pHs resulted in an increase in the ability of enzyme to digest sago starch granules. Heating to 60°C at pH 2.0 resulted in a conversion rate of sago starch granules to glucose near to the conversion rate of raw corn starch to glucose. At higher concentration, the degree of hydrolysis of treated sago starch granules was about 275% as compared to that of untreated sago starch granules. Addition of the enzyme in large amount or small portion at various time intervals was found effective in the hydrolysis of treated sago starch granules.