木薯粉液化醪过滤液酒精发酵的研究

在木薯粉浓醪酒精发酵中,为了降低醪液的粘度并提高连续发酵液的流动性,按不同料水比对木薯粉进行调浆,液化后将液化醪进行过滤,并洗涤滤渣,测定过滤前后的粘度变化及糖回收率,再对滤液进行酒精发酵试验.结果表明,过滤后醪液粘度大幅度降低;料水比为1:2.9时的糖回收率最高,达99.3％;滤液发酵效率比全渣发酵效率平均提高4.4％.     

木薯酒精浓醪发酵中液化条件的优化

利用木薯进行酒精浓醪发酵,对其中液化过程中的条件进行了优化,得出最佳液化条件为:液化pH值5.0～6.0,液化酶加入量为10U/g木薯粉,液化温度和时间分别为105℃、2h。     

木薯粉酒精浓醪发酵条件的优化

以木薯粉为原料进行浓醪酒精发酵,在前期优化液化糖化条件的基础上,分析了培养基成分以及温度,pH值等条件对发酵的影响。实验结果表明,在优化的液化糖化条件下进行木薯粉浓醪酒精发酵,氮源和无机盐的最适添加量为尿素0.25%(w/w),MgSO4·7H2O0.45g/L,KH2PO41.50g/L,CaCl20.20g/L,发酵最适温度为33℃,最适初始pH4.5,酵母接种量10%(v/v),发酵时间48h。在此条件下发酵成熟醪酒精浓度高达17.2%(v/v),淀粉利用率达91%。     

木薯粉酒精浓醪发酵条件的优化

以木薯粉为原料进行浓醪酒精发酵,在前期优化液化糖化条件的基础上,分析了培养基成分以及温度,pH值等条件对发酵的影响.实验结果表明,在优化的液化糖化条件下进行木薯粉浓醪酒精发酵,氮源和无机盐的最适添加量为尿素0.25%(w/w),MgSO4·7H2O 0.45g/L,KH2PO4 1.50g/L,CaCl2 0.20g/L,发酵最适温度为33℃,最适初始pH4.5,酵母接种量100,6(v/v),发酵时间48h.在此条件下发酵成熟醪酒精浓度高达17.2%(v/v),淀粉利用率达91%.     

酵母菌与糖化酶共固定化木薯酒精连续发酵工艺研究

采用聚乙烯醇(PVA)为载体共固定化酵母菌细胞和糖化酶制剂,并以木薯为原料进行酒精连续 发酵工艺研究。实验结果表明,木薯酒精连续发酵的最佳工艺条件为:硫酸铵添加量为原料量的0.5%,α-淀 粉酶用量为5u/g,糖化酶的用量为150u/g,适宜pH值4.5,酵母菌细胞与糖化酶制剂共固定化凝胶颗粒填装 量为50%。在稀释速率为0.155h$C1、糖化醪总糖为119.8g·L-1、还原糖为80.33g·L-1、醪液在反应器中 停留时间为3.1h时,发酵醪酒精浓度为12.3%,成熟发酵醪残余总糖为2.72g·L-1,残余还原糖为0.6g· L-1,总糖利用率达96.91%。     

微波预处理木薯发酵酒精的研究

利用微波预处理木薯代替传统酒精发酵生产中的蒸煮液化工艺,并对微波预处理后的木薯进行无蒸煮发酵工艺的研究。通过正交试验,得出微波处理后的木薯最佳发酵条件为：料水质量比1:2.8,糖化酶添加量180U/g,活性干酵母添加量为原料质量的0.3%,氮源用量为原料质量的0.3%,30℃发酵72h,发酵醪液的酒精体积分数达到12.7%。通过与传统蒸煮液化工艺进行能耗对比,至少节省30.8% 的能耗。     

高浓度木薯粉浆糊化液化粘度的研究

为了更好地利用高浓度木薯醪液进行酒精发酵,应用旋转粘度计时高浓度木薯粉浆的糊化液化粘度进行研究.实验结果表明:木薯粉浆的糊化曲线符合典型的淀粉糊化曲线;其糊化液化粘度随着粉浆浓度的增加而上升;在淀粉含量相同的条件下,木薯淀粉浆比木薯粉浆起糊快且峰值粘度较高;糊化前加入液化酶可以大幅度降低峰值粘度,加入10u/g木薯粉耐高温α-淀粉酶,10%(vol)酒精度对应木薯粉浆的液化峰值粘度仅为不加酶时的3.26%,15%(vol)酒精度对应物料的液化峰值粘度仅为10%(vol)酒精度对应物料在不加酶时的6.52%.     

连续微通氧浓醪乙醇发酵研究

为了提高浓醪酒精发酵效率,以高浓度木薯粉浆液化滤液为原料,对微通氧浓醪酒精发酵过程进行了研究。在搅拌式5 L发酵罐中,通过对连续通风速率分别为0、0.04、0.08、0.16、0.24、0.35 L/min的高浓度液化滤液酒精分批发酵过程分析表明,最佳通风策略为:以通风速率0.08 L/min进行酒精发酵,酵母细胞密度达到5.40×108个/m L,发酵效率为90.00%,与未通风发酵相比分别提高了56.52%和2.45%。总之,在浓醪酒精发酵过程中微通氧能够提高酵母细胞活性,进而提高发酵效率。     

新鲜木薯直接转化生产乙醇

介绍了利用新鲜木薯生产乙醇的新工艺:用真菌α淀粉酶和降粘酶预处理新鲜木薯醪液,后加入颗粒淀粉水解酶STARGENTM进行酵母酒精发酵.该工艺可直接利用新鲜木薯进行酒精发酵;相比传统高温工艺,该发酵新工艺过程中新鲜木薯醪液粘度显著降低,有更多可发酵性糖被利用,并且最终发酵效率显著提高.     

芭蕉芋原料清液酒精发酵工艺初步研究

以芭蕉芋粉为原料,考察了芭蕉芋原料清液酒精生产工艺,对料水比、液化、糖化、温度、接种量等条件进行初步研究.结果表明,芭蕉芋酒精清液生产最佳工艺为:料水比1∶3.0,拌料水温是60℃,拌料时间为30 min,液化酶用量为6 U/g,液化时间为50 min,糖化酶用量150 U/g,糖化时间30 min,发酵pH 4.2,发酵温度30℃,接种量0.17%(v/v),在此发酵工艺条件下,芭蕉芋发酵醪液的酒精含量达8.8%vol,淀粉利用率为72.14%,原料出酒率达到20.2%.     

Some flavouring constituents of cassava and of processed cassava products

Flavouring constituents of cassava, gari and farine were analysed and compared. The characteristic compounds of gari were identified as pyrazines and lactic acid. Farine, which is either unfermented or fermented for a much shorter time than gari, was qualitatively similar but had fewer volatiles, present in small amounts. Pyrazines and lactic acid were absent from cassava, the flavouring constituents of which were fewer and qualitatively different from those of gari and farine. The characteristic flavour of gari and farine was largely due to the fermentation and roasting processes.     

生长期对不同品种(系)木薯淀粉特性的影响

研究生长期对3个品种(SC、E和C)木薯淀粉冻融稳定性、凝沉稳定性和粒径的影响.结果表明,生长期为6个月时,淀粉具有较好的冻融稳定性、较差的凝沉稳定性、较高的体积平均粒径以及较小的表面积平均粒径.相关性分析表明,3个品种木薯淀粉的凝沉稳定性与淀粉表面积平均粒径呈显著正相关,品种SC的淀粉凝沉稳定性与体积平均粒径显著正相关,品种E的冻融稳定性与淀粉表面积平均粒径呈极显著负相关.     

Physiological deterioration of cassava roots

Rapid post-harvest physiological deterioration of cassava roots (Manihot esculenta Crantz) appears to be due essentially to wound responses, comparable to those observed in other plant storage organs. The wound responses observed include: increased activity of phenylalanine ammonia lyase, an enzyme associated with phenol biosynthesis; increased activity of peroxidase and polyphenol oxidase; formation of phenols/polyphenols including leucoanthocyanidins, catechins, sco-poletin and condensed tannins, and often the formation of a wound periderm. In cassava, the responses did not remain localised at wound surfaces in roots when held at low storage humidity but spread through the roots causing a discolouration of the vascular tissue and storage parenchyma. Roots stored at high humidity showed a more typical wound response with localised production of phenols and periderm formation.     

木薯淀粉黄原酸酯制备

以木薯淀粉为原料,研究环氧氯丙烷用量、二硫化碳用量、反应时间、硫酸镁用量等因素对淀粉黄原酸酯吸附银离子能力影响。通过正交试验,确定对木薯淀粉黄原酸酯吸附性能影响能力大小依次为:环氧氯丙烷>反应时间>二硫化碳>硫酸镁;且最优制备工艺制得木薯淀粉黄原酸酯对银离子吸附率可达97.9%。     

Preparation of linamarase solution from cassava latex for use in the cassava cyanide kit

A simple method is described for the preparation of linamarase from cassava latex (sap). Latex, obtained from the end of the petiole (stalk) of cassava leaves, is mixed with water and the solution filtered to give a crude solution of enzyme. This solution may be stored indefinitely in the deep freeze. It may be used without any purification in kits for determination of cyanogens in cassava tubers and cassava products (flour, gari, etc). Immobilisation of linamarase in filter paper discs in the presence of a stabiliser (gelatin/PVP-10) reduces its activity to 25% and in the absence of stabiliser to only 4%.     

Preparation of linamarin from cassava leaves for use in a cassava cyanide kit

A simple method is described for the preparation, from very young cassava leaves, of a dilute hydrochloric acid solution of linamarin. Linamarin extraction from the leaves is virtually quantitative. The linamarin solution is used in the preparation of standard linamarin filter paper discs that are needed to monitor the performance of picrate kits for determination of the total cyanide content of cassava roots and cassava products. These standard discs are stable indefinitely if stored in the refrigerator, but very slowly lose linamarin activity if stored for more than one month at room temperature.     

Physical properties of cassava mash

Sorption and thermophysical properties (desorption curves, density and specific heat) of native and gelatinized cassava mash and of cassava starch were determined, in order to gain a better understanding of the heat and mass-transfer phenomena involved in gari cooking and drying.
Desorption isotherms of native cassava mash are given at four temperatures from 40 to 90°C; the experimental data were described using the GAB model with a maximum root mean square error (RMS) of 5%.
The net desorption enthalpy, calculated from the desorption data, decreases from 902.0 to 80.2 kJ/kg when the moisture content increases from 0.04 to 0.24 kg of water/kg dry matter. Desorption curves are not significantly affected by the degree of gelatinization of the starch, but at constant water activity, native cassava mash has a higher equilibrium moisture content than the other samples.
The density of cassava mash increases from 1239 to 1509 kg/m³ when it is dehydrated from 51.8 to 6% (wet basis), and the specific heats of dry cassava starch and dry cassava mash, determined by differential scanning calorimetry, vary linearly over the temperature range -20°C to 96°C from 1.128 to 1.760 and from 0.979 to 1.591 kJ/kgxK.     

Techno-economic feasibility of ethanol production from fresh cassava tubers in comparison to dry cassava chips

The use of unpeeled and peeled fresh cassava tubers for the production of ethanol indicated that the extent of liquefaction and saccharification is comparable to that of dry chips. However, the fermentation efficiencies were lower by about 13 and 2% with the use of fresh unpeeled and peeled tubers respectively. The use of unpeeled tubers can be ruled out due to viscous mass formation after saccharification and consequent resistance in solid-liquid separation. The viscosity of the hydrolysed slurry of peeled tubers was nearly the double and the recovery of hydrolysate was lower by 5% as compared to those with dry chips. Additional machinery, land and building are also essential for processing fresh tubers in harvest season. These will involve heavy depreciation and financial expenses due to idling over eight months when the plant will have to depend on dry chips. The studies establish that the gain obtainable due to differences in the cost of fresh tubers and dry chips is surpassed by various techno-economic factors.     

Detoxification of cassava during gari preparation

Gari, a fermented cassava product, is widely consumed in many West African countries. The present study was undertaken to investigate the detoxification of cassava during the preparation of gari. The most important processing stages, with regard to elimination of cyanide, were the initial grating of the cassava and the final roasting of the product. The breakdown of linamarin was dependent primarily on the presence of endogenous linamarase and the lactic acid bacteria present during the fermentation were not directly involved in its hydrolysis.