Isolation and Characterization of Starch-Iodine Positive Material Formed During Saccharification of Corn Starch

The increasing sophistication of customers has put pressure on corn wet-millers to improve product quality. One quality requirement is that glucose and corn syrups be free of material stained blue or green by iodine, i.e. free starch. Observations from a number of corn wet milling plants indicate that liquified corn starch may test negative for free starch but yield a positive iodine test after saccharification. Such dextrose hydrolyzates are difficult to process into product and often fail to meet customer specifications. The problem has been traced to small (0.2 to 1.0 μm) particles which are present in the starch supply. The particles exhibit an iodine spectrum similar to that of gelatinized corn starch. Enzymatic degradation of the particles was compared to that of gelatinized and non-gelatinized starch, and lipid-amylose complexes; the behavior of the particles most closely resembled nongelatinized starch. Extended liquefaction reduces, but does not eliminate the problem. Cellulase, hemicellulase, amylase, and proteasewere tested as adjuncts to normal glucoamylase products; none of these were effective in assisting hydrolsis of the particles under saccharification conditions. The particles can be completely eliminated by microporous filtration of liquefact or dextrose hydrolyzate.     

小麦B淀粉的糖化工艺

以谷朊粉生产过程中的副产物B淀粉为原料,通过测定反应液DE值得变化,分析糖化时间、糖化酶添加量、普鲁兰酶添加量以及糖化酶和普鲁兰酶协同作用对糖化过程的影响规律,找出最佳糖化工艺,为B淀粉的进一步发酵利用奠定基础。结果显示:反应时间为120 min,糖化酶和普鲁兰酶协同作用添加量为25 U/g(以B淀粉干基计),DE值达到93.8%。     

Progress in the Enzymatic Saccharification of Wheat Starch

Problems were noticed when trying to include wheat starch to the normal liquefaction and saccharification lines because of the formation of precipitations which are difficult to filter. The effects of different side activities of Aspergillus niger glucoamylases on the filterability of wheat syrups are demonstrated. In order to speed up filtration, viscosity has to be decreased by degradation of arabinoxylanes with present pentosanes. A new enzyme has been discovered which is able to split partially the lysophospholipids contained in wheat starch and let the insoluble components flocculate to big particles. This enzyme splits the phospholipids into free fatty acids and glycerophophorylcholines. The properties of this enzyme present in a novel glucoamylase preparation for the wheat starch processing are demonstrated by using an HPLC method, showing the degradation of wheat lipids as well as synthetic lysophopholipids.     

Enzymatic Starch Saccharification in an Ultrafiltration Membrane Reactor

Enzymatic hydrolysis of starch has traditionally been performed in large volume batch reactors using soluble enzyme during long time. Introduction of the membrane bioreactor brings possibility of continuous operation in lower volume reactors in shorter reaction time. Studies on the simultaneous enzyme action of glucoamylase and pullulanase on liquefied potato starch in a continuous membrane reactor were made with the application of the various cut-off and transmembrane pressure of membranes. Influence of different reaction conditions namely enzyme concentration, substrate: enzyme ratio and residence time on glucose content were measured. Membrane reactor with 3.000 Da produced almost pure glucose at residence time of 3–4 h.     

Formation of Resistant Starch During Processing and Storage of Instant Noodles

Instant noodle was prepared in a commercial noodle plant using varying steaming and frying conditions. Wheat flour had very low amount of resistant starch (RS) as 0.26 g/100 g dry solids. Dough was formed by mixing wheat flour with other adjuncts for 15–20 min, cut into about 0.5 mm strands and steamed in a tunnel for 90 to 240 s. Steaming of dough increased RS content from 0.22 to 0.49 g/100 g dry solids in 90 s and to 1.4 g/100 g dry solids in 240 s. Frying of steamed noodles at temperatures ranging from 145–170°C for 60–160 s resulted in sudden decrease in moisture content from 42.9–49.6 to 0.6–1.6 g/100 g dry solids and increase in oil content up to about 20 g/100 g dry solids. Frying of steamed noodle strands resulted in only slight increase in RS content (up to 1.2 times), depending on steaming time and temperature. Storage of instant noodles showed up to 1.4 times increase in RS content but refrigerated storage did not increase the RS content.     

三种淀粉质原料糖化工艺的优化

以薏苡仁、马铃薯以及大米为原料,以葡萄糖当量值(DE值)为评价指标,对薏苡仁、马铃薯以及大米淀粉糖化工艺的条件进行优化,为酿造食醋提供基础数据。考察原料破碎度、液化酶添加量及液化时间对DE值的影响,并通过正交试验确定淀粉质原料的糖化工艺。最优糖化工艺条件为:原料破碎度60~80目,液化酶用量为4μl/g,液化时间为40 min。此条件下,大米、薏苡仁和马铃薯的DE值分别为:80.21%、80.99%和73.17%。     

Studies on the Application of Pullulanase in Starch Saccharification Process

Pullulanase belongs to direct debranching enzymes which separate α-1,6-links directly by splitting side chains of various length. In connention with the enzyme research a specific trade product of thermostable, acidophilic pullulanase of Bacillus species was investigated. Investigations have been carried out with the aim of improving saccharification of liquified potato starch by simultaneous application of glucoamylase and pullulanase. The results of the investigations carried out until now can be summarized by increasing the effectiveness of saccharification process, reduction of reaction time and increasing of substrate concentration.     

竹芋淀粉液化及糖化条件的优化

以竹芋淀粉为原料,以葡萄糖当量值(DE)为评价指标,对竹芋淀粉液化及糖化工艺进行研究,考察酶添加量、温度、时间对DE值的影响。通过单因素试验和正交试验确定了竹芋淀粉最佳的液化及糖化工艺。结果表明:最优的液化工艺条件为酶添加量1.5%,液化时间2.5 h,液化温度75℃;糖化的最优条件为酶添加量1.5%、糖化时间2.5 h、糖化温度55℃。在此条件下,最终水解液的DE值为76.36%。     

马铃薯淀粉糖化动力学的研究

进行了马铃淀粉应用黑曲糖化酶糖化的动力学研究。导出了包括底物浓度，酶剂浓度，反应温度等因素在内的糖化动力学模型。统计分析表明：米氏方程当作模拟模型，应用Ｌｉｎｅｗｅａｖｅｒ－Ｂｕｒｋ和Ｗｉｌｋｉｎｓｏｎ法进行数学回归，以及最终动力学模型的导出都是很有价值的。     

机械活化木薯淀粉无液化直接糖化的研究

对机械活化木薯淀粉进行酶解研究,探讨了机械活化对淀粉无液化直接糖化的影响规律。试验采用搅拌球磨机对木薯淀粉进行机械活化,以不同活化时间的木薯淀粉为原料,直接以糖化酶为糖化试剂,分别考察机械活化时间、糊化温度、反应时间、淀粉酶用量、pH值、反应温度等因素对糖化DE值的影响。结果表明,机械活化淀粉水解DE值明显比原淀粉高,淀粉经机械活化后对糊化温度、反应温度的依赖性降低。说明机械活化能有效破坏淀粉紧密的颗粒表面和结晶结构,降低结晶度,提高糖化酶水解的反应活性,加快酶解速度,缩短酶解时间。淀粉经机械活化处理后甚至可不经糊化直接进行酶水解。     

Saccharification of Tapioca Starch Residue with a Multienzyme Preparation of Aspergillus ustus

Enzyme preparation obtained cultivating Aspergillus ustus on rice straw-wheat bran mixture (7:3) possessed cellulase, D -xylanase, β-D -glucosidase, α-amylase, amyloglucosidase and pectinase activities. Used at 2% level with tapioca starch residue (TSR) slurry gelatinized at 80°C or pressure cooked, it yielded 45–60% reducing sugar and degraded 52–65% of the fiber material. Enhanced saccharification (72%), fiber degradation (75%) could be achieved by pretreating the substrate with mineral acid. Fermentation of the hydrolysates with Saccharomyces cerevisiae produced 29–36 ml alcohol per 100 g of sun dried TSR. Data on TSR hydrolysis by α-amylase and amyloglucosidase, A. ustus enzyme preparation individually and in combination with amyloglucosidase, in acid pretreated or untreated TSR are presented.     

Comparison of Enzymic Saccharification of Starch and Cellulose from Technological and Economic Aspects

Enzymatic saccharification of starch in the case of both pure starch and starchy raw materials is a long adopted technology successfully applied on industrial scale for many years. On the other hand, a feasible procedure for enzymatic saccharification of the other glucose polymer, cellulose, has been realized so far only on pilot-plant scale. A particularly difficult problem is the enzymatic saccharification of cellulosic substances encrusted with lignin. The first step in starch and cellulose saccharification is pretreatment and digestion of the raw material. In the case of starch, this is solved by liquefaction in the presence of thermostable alpha-amylase in a jet cooker. As a result, starch undergoes partial degradation and liquefaction. In the case of cellulose, the most economical method of pretreatment seems to be “steam-explosion”, although this does not involve liquefaction either, i. e., saccharification proceeds still in heterogeneous phase. Comparison is made of the energy requirements of digestion of the raw materials and costs of enzymatic saccharification for both substrates.     

新型青稞酒发酵前淀粉液化及糖化条件的优化研究

以青稞和贡米为酿酒原料,以葡萄糖当量值(DE值)为指标,对新型青稞酒发酵前淀粉液化和糖化工艺优化进行研究,主要研究不同因素对青稞和贡米混合料中的淀粉液化及糖化过程的影响。结果表明,最优液化条件为:温度65℃,时间5h,α-淀粉酶添加量4U/g,p H值6.0;最优糖化条件为:时间45h,温度60℃,p H值5.5,糖化酶添加量100U/g。在此工艺条件下水解液中还原糖的含量和DE值达到最大。     

淀粉分子结构对形成抗性淀粉的影响

考察了几种大米淀粉和土豆淀粉形成抗生淀粉的能力,用分子排阻色谱的方法研究其分子结构。认为土豆淀粉比大米淀粉更适用来生产抗性淀粉。     

薏米酒发酵前淀粉液化及糖化条件的优化

以薏米为原料,以葡萄糖当量值(DE值)为评价指标,对薏米酒微生物发酵前淀粉液化及糖化工艺进行研究,考察酶添加量、pH值、温度、时间对DE值的影响。结果表明,最优的液化工艺条件为α-淀粉酶添加量2.0%、pH6.5、液化温度60℃、液化时间3.0h;糖化最优工艺条件为糖化温度55℃、pH4.5、糖化酶添加量2.5%、糖化时间2.5h。在此条件下,最终水解液的还原糖含量和DE值分别达到6.87g/100mL和76.4%。     

Role of Starch in Bread Formation

Characteristics of starch grains from wheat, potato, tapioca, rice, maize, waxy maize, and high-amylose maize were assessed for their effects on the properties of a “synthetic” wheat gluten-starch bread system. Statistically significant negative correlations existed between amylose content and fractional volume increase, crumb penetration (tenderness), and crumb hydration capacity. Significant positive correlations were found between fractional volume increase and crumb penetration and between crumb hydration capacity and crumb soluble amylose. Gelatinized wheat starch was most uniformly oriented in fibrous strands of crumb and in films about the walls of gas cells.     

Shear Induced Starch Conversion During Extrusion

Using a capillary rheometer and a singlerscrew extruder, waxy corn starch was extruded at a relatively low temperature range. Notable conversions induced by shear energy were obtained in very short residence times (from several sec to 1 min). Conversions up to > 70% were also achieved. Kinetic studies showed that conversion caused by shear energy was more efficient than that by thermal energy. The shear rate constant, k, was an exponential function of shear stress and a linear function of shear rate. The minimum shear stress required to cause starch conversion was from 10⁴ to 10⁶ N/m² for 100°C to 21°C. In such “shear” experiments, the maximum temperature rise due to viscous thermal dissipation, measured experimentally and calculated theoretically, was too low to cause any significant thermal cooking of starch. The shear converted starch extrudates were unpuffed and had shapes of traditional pasta.     

Starch Hydrolysis During Sorghum Beer Brewing

Samples were taken at different stages of sorghum beer brewing and the starch isolated. The physico-chemical properties of the starch were determined to establish what changes occurred at the molecular level of the starch during brewing. Complete hydrolysis of the starch to fermentable sugars is never the aim of mashing during sorghum beer brewing. A certain amount of starch in the beer is required to give it its characteristic viscosity and body. This residual starch was found to be much reduced in amylose content as well as in molecular size compared with the starch in the raw materials. Debranching with isoamylase followed by gel filtration chromatography indicated that the amylopectin side chains were reduced in length by approximately half.     

多孔淀粉的形成过程

从两个方面研究了多孔淀粉的形成过程，其中扫描电子显微镜照片形象、直观地展现了糖化酶和α-淀粉酶协同作用原淀粉颗粒的宏观效果；水解不同时间后残留物的直链淀粉含量、吸热焓的变化说明了复合酶水解的优先次序，二者从不同角度说明了酶水解原淀粉得到多孔淀粉这一过程．