Cassava retting: Optimisation of a traditional fermentation by an experimental research methodology

Retting, a spontaneous and traditional fermentation of cassava roots in Central Africa, was optimised in terms of time and the quality of the end-product. Optimal conditions were achieved by using an experimental research methodology. Temperature is the most influential factor, with an optimum of 34°C for quicker retting. The roots should be peeled and soaked in water immediately after harvesting to increase the quality of cassava foods. Inoculation of water with juice from a prior retting helps in cassava detoxification but has no influence on the time or the quality of foo-foo. Foo-foo samples had the most favourable organoleptic quality when an incubation temperature of between 28 and 37°C was used. Using optimal conditions, retting time was reduced 3-fold, and foo-foo of high and constant quality could be processed.     

Dispersion—flocculation studies on a Goethite-clay system

Dispersion–flocculation studies on a Goethite–clay system using flocculants were carried out as a function of flocculant concentrations, pH of slurry, time of agitation and dispersant dosage. Also, the effects of pH and polymer concentrations on the adsorption behaviour of the system were investigated. Results show that well flocculated goethite was preferentially obtained from 4% goethite/kaolinite clay suspensions, with 50 ppm causticised starch in the slurry at pH values of 3–11·5 and with 50 ppm polyacrylamide at pH values of 3–8. Good flocs were also obtained on flocculation of the goethite suspension with 50 ppm polyacrylamide at pH values of 5–7, while the kaolinite suspension did not respond to the same dosage of causticised starch in the same pH range. Results further reveal that for the goethite/kaolinite suspension, the best results was obtained with 50 ppm polyacrylamide at pH values of 7–10. Based on the data generated in the study, it was concluded that causticised starch is a better flocculant than polyacrylamide for goethite suspensions although polyacrylamide is an excellent flocculant for kaolinite suspensions.     

Rheological behavior of reactive blending of epoxidized natural rubber with cassava starch and epoxidized natural rubber with natural rubber and cassava starch

Epoxidized natural rubbers (ENR‐25 and ENR‐45) were prepared using the performic epoxidation method. Two‐component (ENR–cassava starch) and three‐component (ENR–NR–cassava starch) blends were prepared. ENR‐25 and ENR‐45 were blended with various quantities of gelatinized cassava starch in the latex state. The pure ENR exhibited lower shear stress and shear viscosity than those of the blends with cassava starch. Furthermore, the shear stress and shear viscosity were increased with an increase in the cassava starch concentration. The chemical interaction between the epoxide groups in the ENR and the hydroxyl groups in the cassava starch molecules might be the reason for the increasing trends of the shear stress and shear viscosity. The blends are classified as compatible blends because of the strong chemical bonding between different phases. SEM micrographs were used to clarify the compatibility. Power law behavior with pluglike flow profiles was observed for all sets of ENR–NR–cassava starch blends. Very low power law index values (<0.34) and highly pseudoplastic fluid behavior were also observed. The log additive rule was applied to plots of zero shear viscosity (consistency index) and the shear viscosity versus the concentration of ENR‐25. Positive deviation blending was observed, which indicates compatible blends. © 2003 Wiley Periodicals, Inc. J Appl Polym Sci 91: 1752–1762, 2004     

不同总糖浓度木薯全渣乙醇分批发酵过程的研究

为研究不同初始总糖浓度对木薯全渣乙醇发酵过程中糖消耗、酵母细胞生长以及乙醇积累的影响,采取分批发酵方式,间隔6 h取样检测.结果表明：初始总糖浓度253.75 g/L时,发酵效率最高（88.93%）,乙醇生成速率、糖消耗速率、酵母数在初总糖浓度183.75 g/L时最大,分别为7.10 g/（L·h）,13.88 g/（L·h）,4.94×108个/mL;提高初始总糖浓度,糖消耗的终点时间、酵母生长到达最大值的时间、乙醇发酵时间延长,糖消耗速率、糖利用、酵母数、乙醇生成速率下降,乙醇发酵效率先升高后下降.     

抗性淀粉测定方法的研究

抗性淀粉的测定方法有Berry法、Englys法、Bjorck法、Champ法、Goni法等.以木薯抗性淀粉和抗性淀粉标准品为原料,通过对抗性淀粉的处理方法(AOAC法、Goni法)以及还原糖的测定方法(3,5-二硝基水杨酸法、D-葡萄糖法)进行对比,得到木薯抗性淀粉最适合的测定方法.同时也研究了样品多少对测定结果的影响.结果表明,AOAC-GOPOD法操作简单、准确性高、重复性好,酶用量充足,是测定木薯抗性淀粉的首选方法.     

巯基改性木薯秸秆吸附水体Cu(Ⅱ)和Zn(Ⅱ)特性

以废弃木薯秸秆为原料,经碱化、添加巯基官能团进行改性得到吸附剂,对其进行了表征,并研究了不同条件下吸附剂的对Cu(Ⅱ)和Zn(Ⅱ)吸附性能.结果表明,木薯秸秆成功引入巯基基团.经过巯基改性后的木薯秸秆的吸附量得到提升,吸附量随pH的升高而增大,在30 min内吸附量可迅速达到平衡,吸附动力学符合准2级动力学方程.对Cu...     

淀粉接枝丙烯酸超强吸水剂研究

本文采用正交实验讨论了淀粉接枝丙烯酸合成树脂过程中,引发剂、交联剂、丙烯酸的中和度、单体的用量等因素的影响,同时讨论了产品的耐盐性和受热保水性。     

木薯发酵制备酒精后剩余残渣的综合利用

木薯发酵制备乙醇会产生大量以淀粉和纤维素为主要成分的残渣。经实验证明,在浓硫酸(60%)、浓硝酸和催化剂共同作用下,经水解-氧化-水解可成功地将木薯渣制备成草酸。实验确定了用木薯渣制备草酸的较优条件,测定了产品的熔点,分析了剩余残渣、废水,结果表明剩余残渣和废水不会对环境造成污染,既为草酸的生产提供了新思路,又为农产品的残渣综合利用找到途径,发展前景广阔。     

超声波处理对木薯氧化淀粉性质的影响

将超声技术应用于木薯淀粉的氧化改性中,对制得的氧化淀粉的性质进行了考察,并将其与木薯原淀粉、非超声法制得的氧化淀粉的性质进行比较和分析。结果表明:与原淀粉相比,超声法制备的氧化淀粉的溶解度、透明度分别增加了4.55、3.38倍,白度增加了1.23%,凝沉性降低了99.05%;同时,氧化淀粉所成的膜性能良好、均匀有韧性,而原淀粉难以成膜;超声法制备的氧化淀粉的糊化焓与原淀粉相比降低了45.79%。其他条件相同时,采用超声处理可以使氧化淀粉的溶解度、透明度分别提高97.23%、33.68%,白度增加0.26%(在显著水平α=0.05具有显著差异),凝沉性最大可降低78.80%,糊化焓降低了24.13%。因此,超声技术可以有效地应用于木薯淀粉的氧化改性。