The promise of a technology revolution in cassava bioethanol: From Thai practice to the world practice

The abundance of low-cost feedstock and the cost-effective technology are of great importance for reinforcing industrialization of bioethanol for fuel use as sustainably-sourced and eco-friendly energy. This paper describes improved techniques that increase the root productivity of cassava (Manihot esculenta Crantz) and its conversion to bioethanol by the energy-saving technology being developed in Thailand. The productivity of cassava roots can be significantly increased from 22 to 60 tons/ha simply by applying yield improved varieties and good cultivation practices; important ones are soil plowing, high stake quality, weed control, good planting and harvesting period, land conservation with organic fertilizers and water irrigation. Currently, the world production of cassava is around 220 million tons per annum with the average yield of 12 tons/ha and the total acreage of 18.5 million ha. If the root productivity increases, for instance, by 5 tons/ha, around 90 million tons of roots are produced which can be converted to 15,000 ML of ethanol by Simultaneous Saccharification and Fermentation (SSF) process, a current production process of which cooked and enzymatically-liquefied cassava materials are subjected to saccharifying enzymes and yeasts in concert. The promising energy-saving technology for converting cassava chips to ethanol has also been introduced at a pilot scale by using a granular starch hydrolyzing enzyme in an uncooked process.     

影响木薯淀粉加工质量因素研究

主要研究了淀粉提取过程中，削皮，水洗，干燥温度对淀粉纯度，白度和糊化粘度的影响。研究结果表明：削皮，水洗和干燥温度影响淀粉白度，纯度和淀粉糊化粘度。在相同水洗次数（1次）和相同干燥温度（50℃）下，未削皮的淀粉样品色发灰，但具有比削皮处理高的峰值粘度，95℃最后粘度，50℃时粘度，峰值降和持久性。在已削皮和相同干燥温度（50℃）下，淀粉水洗次数增加，不但增加淀粉纯度，而且提高淀粉性能，如提高峰值粘度，95℃后粘度，50℃时粘度，持久怀和糊化温度。不同干燥温度对淀粉白度无影响，但纯度随干燥熳度的增加而稍稍增。通常高的干燥温度有高的峰值粘度，95℃最后粘度，峰值降，50℃时粘度和持久性。     

Pineapple leaf fiber reinforced thermoplastic composites: Effects of fiber length and fiber content on their characteristics

Pineapple leaf fiber (PALF) was used as a reinforcement in polyolefins. Polypropylene (PP) and low‐density polyethylene (LDPE) composites with different fiber lengths (long and short fibers) and fiber contents (0–25%) were prepared and characterized. The results showed that the tensile strength of the composites increased when the PALF contents were increased. It was observed that the composites containing long fiber PALF were stronger than the short fiber composites as determined by greater tensile strength. An SEM study on the tensile fractured surface confirmed the homogeneous dispersion of the long fibers in the polymer matrixes better than dispersion of the short fibers. The unidirectional arrangement of the long fibers provided good interfacial bonding between the PALF and polymer which was a crucial factor in achieving high strength composites. Reduction in crystallinity of the composites, as evident from XRD and DSC studies suggested that the reinforcing effect of PALF played an important role in enhancing their mechanical strength. From the rule of mixtures, the stress efficiency factors of the composite strength could be calculated. The stress efficiency factors of LDPE were greater than those of PP. This would possibly explain why the high modulus fiber (PALF) had better load transfers to the ductile matrix of LDPE than the brittle matrix of PP. © 2010 Wiley Periodicals, Inc. J Appl Polym Sci, 2011     

The Role of Reaction Parameters on the Preparation and Properties of Carboxymethyl Cassava Starch

The role of reaction variables on carboxymethylation of cassava starch was investigated using a statistically experimental design approach. The reaction was carried out in an isopropanol‐water mixture at 40°C for 3 h. The reaction parameters under investigation included water fraction in the reaction medium, the ratio of sodium hydroxide to anhydroglucose unit (AGU) and the ratio of sodium monochloroacetate (SMCA) to AGU. The dependent responses were degree of substitution (DS) of CMS and the reaction efficiency (RE) of the carboxymethylation. Carboxymethyl cassava starches with DS in the range of 0.01 to 0.86 were prepared. The result from regression analysis indicated that the most important factors in controlling the DS of CMS were sodium hydroxide and SMCA contents followed by water content. Response surface plots suggested that the optimal levels of sodium hydroxide and water content to achieve CMS with high DS were at the intermediate values. Similar effects of sodium hydroxide and water content were also observed on the RE while SMCA content had a negative effect; increasing SMCA content resulted in lower RE. The optimal conditions to achieve the highest DS and RE were found to be at a water content of 17–19% with a molar ratio of sodium hydroxide to AGU of 1.8–1.9 and a molar ratio of SMCA to AGU between 1.1–1.5. Carboxymethyl cassava starch with various DS was also prepared. The properties of CMS as affected by the degree of modification were also discussed.     

Some Physical and Chemical Properties of Starch Isolates of Cassava Genotypes

Cassava starches (Manihot esculenta Crantz) were prepared from tubers of Kaesetsart 50 (KU50), Rayong 5, Hanatee and KMUL 36‐YOO2 (YOO2) and their physicochemical properties studied using the Rapid Visco Analyser (RVA), differential scanning calorimetry (DSC) and rheometry. Amylose content was determined by iodine potentiometric titration (IPT) and gel permeation chromatography (GPC). Starch contents of the tubers varied from 34.2 to 35.1% and protein and fiber contents in the starches varied from 0.8 to 1.1% and 0.6 to 0.8%, respectively. The cassava starches contained 0.06–0.12% lipid and 0.7% to 0.9% ash. Amylose content determined by IPT (15.9 to 22.4%) had higher positive correlation with peak viscosity, breakdown and gel consistencies (R₂ = 0.835, 0.772, 0.859), respectively, whereas GPC (18.1 to 25.3%) showed high correlation with setback (R₂ = 0.923) and ΔH (R₂ = 0.579). The onset gelatinization temperatures varied from 59.7–64.4°C, and KU50 exhibited highest ΔH of 13.7 J/g. Hanatee and YOO2 formed clear gels with higher peak viscosities, setback and gel consistency viscosities attributed to their higher amylose contents. Retrogradation of KU50 and Rayong 5 tended to be more severe on cooling and formed opaque gels, showing higher resistance to shearing, properties attributed to recrystallized amylopectin fractions.     

Electrospun polylactic acid and cassava starch fiber by conjugated solvent technique

Smoothed fibers of PLA/cassava starch were prepared by single nozzle electrospinning process intended for tissue scaffold application. PLA in dichloromethane (DCM) solution was immiscible with cassava starch in dimethylsulfoxide (DMSO) solution. A conjugated solvent system was introduced to simply prepare a well-mixed solution of both components. In this experiment, methanol was used as a conjugated solvent between PLA/DCM solution and cassava starch/DMSO solution to create well-mixed solution. Conjugated solvent selection was based on values of polarity index, intermediate between values of DCM and DMSO. Smoothed electrospun fiber of PLA/cassava starch was obtained.     

Development of a new procedure for lipid extraction from Hevea brasiliensis natural rubber

Non‐isoprene components and especially lipids have been reported to be involved in some key properties of natural rubber. Unfortunately, these results are hardly comparable due to different extraction methods. This work aimed to optimize lipid extraction from natural rubber either in the liquid state (latex) or in the dry state (unsmoked sheets). Extraction of unsmoked sheets from the RRIM 600 clone was carried out with different combinations of organic solvents (chloroform/methanol and hexane/isopropanol mixes). Chloroform/methanol (2 : 1 vol/vol) was found to be the most suitable for lipid extraction from unsmoked sheet rubber. The lipid extraction yield was improved by increasing the exchange surfaces by grinding rubber under liquid nitrogen and extracting the ground rubber for 6 h at room temperature, leading to 1.82% lipid extraction yield (versus dry rubber). Concerning latex extraction, the problem of lipid entrapment in the coagulum from immediate coagulation of latex in the solvent was solved by preliminary two times dilution of latex, giving a 3.24% extract (versus dry rubber) containing a minimum quantity of contaminating polyisoprene. Concerning the nature of lipids, dilution increased mainly neutral lipid extraction, which may suggest that neutral lipids were those entrapped by coagulation.     

Use of starch granules melting to control the properties of bio‐flour filled polypropylene and poly(butylene succinate) composites: Mechanical properties

The feasibility and industrial potential of using bio‐flours from tropical crop residues, in particular starch containing bio‐flours, for the manufacture of bio‐composites was investigated. Polypropylene (PP) and poly(butylene succinate) (PBS) were compounded with bio‐flours from pineapple skin (P) and from non‐destarched (CS) and destarched (C) cassava root by twin‐screw extrusion. In CS composites, two levels of starch granules melting were achieved by adjusting the extrusion temperature, enabling control of morphological and mechanical properties. The use of bio‐flours reduced tensile strength by 26–48% and impact strength by 14–40% when the proportion of bio‐flour was increased to 40% w/w, while flexural strength initially increased upon addition of bio‐flours, before decreasing at higher loads. The use of compatibilizers, in particular maleic anhydride‐polypropylene (MAPP) in PP composites with 30% bio‐flour resulted in tensile strength similar to non‐compatibilized composites with 10% bio‐flour (34–35 MPa). MAPP also increased flexural strength to higher levels than pure PP, resulting in a stronger, but less flexible material.     

Effect of high‐pressure microfluidization on the structure of cassava starch granule

Microfluidization has been applied to modify starch granules. The study was conducted to investigate the effect of microfluidization on the structure and thermal properties of cassava starch–water suspension (20% w/w). The means of optical microscopy, SEM, FTIR spectroscopy, XRD, and DSC were applied to analyze the changes in microstructure, crystallinity, and thermal property. Microscopy observations revealed that native starch granules were oval, round, and truncated in shape. After the microfluidization treatment, a bigger starch granule was partially gelatinized, and a gel‐like structure was formed on a granular surface. No significant difference in XRD patterns of the samples were observed and all samples exhibited A‐type allomorph. Crystallinity decreased with the pressure. Sample treated at 150 MPa contains 17.1% crystalline glucan polymer, lower than that of native granules which have crystallinity of about 25.8%. A lower crystallinity means poor order of crystalline glucan polymer structure in starch granules. The disruption of crystalline order within the granule was also observed by FTIR measurement. Thermal analysis using DSC indicated that the microfluidization treatment brought about a significant decrease of melting enthalpy. The gelatinization enthalpy was 12.0 and 3.0 J/g for the native sample and samples treated under the 150 MPa, respectively. The results indicate that high‐pressure microfluidization process induced the gelatinization of cassava starch, which is evaluated by a percentage of the degree of gelatinization, due to a pronounced decrease with increasing microfluidizing pressure.