Kuakoon Piyachomkwan

Processing of cassava waste for improved biomass utilization

Cassava (Manihot esculenta Crantz) pulp is the solid waste produced as a consequence of starch production. This pulp contains a high starch content (50–60% dry basis), causing an environmental problem with disposal. In order to recover this starch, physical or biological treatment of the material must be employed. Pulp was treated either by sonication or incubation with a multi-enzyme mixture of cellulase and pectinase. Both methods were found to improve efficiency of starch extraction by disrupting the complex structure of polysaccharides associated with and entrapping starch granules. In the enzymatic treatment, the content of cellulase and pectinase for high efficiency of starch extraction determined as the yield of liberated starch was investigated using Response Surface Methodology. Use of either cellulase or pectinase alone failed to effectively improve starch extraction. Cellulase concentration seemed to have a greater effect on efficiency of starch yield than pectinase concentration. Treatment of pulp with 15 Novo cellulase units (NCU) of cellulase and 122.5 polygalacturonase (PG) units of pectinase per g dry pulp for 60 min resulted in 40% starch recovery. Quality characteristics of the liberated starch, including paste viscosity (measured by Rapid Visco Analysis) and thermal properties (measured by Differential Scanning Calorimetry) were comparable to a primary starch obtained by root extraction. Susceptibility of the liberated starch to α-amylase was inferior to that of a primary starch. Cellulase and pectinase, however, increased α-amylase susceptibility of the starch remaining in the pulp.

Cassava starch granule structure–function properties: influence of time and conditions at harvest on four cultivars of cassava starch

Abstract Impact of environmental conditions on cassava starch variability was examined by studying four commercially important cultivars, Rayong 1, Rayong 60, Rayong 90, and Kasetsart 50 (KU 50). Age of the root and environmental conditions at harvest influenced granule structure and hydration properties. All cultivars were grown under identical field conditions, and harvested at different times. Starches extracted from cassava roots harvested at different times were characterised by unique starch granule structure and function. Apparent amylose size of starches from all cultivars did not change significantly during the trial period. However, apparent amylose content of starches changed, decreasing in the older roots. Granule size distribution was affected by age of the root, gradually changing from normal to bimodal distribution when harvested very late during the trial. The integrity and crystalline structure of starch granules also depended on the environmental conditions, evidenced as a change in peak profile obtained by thermal analysis. This can result in the difference in water uptake of starches, and their consequent swelling power and gelatinization. Pasting temperature of all starches increased during the dry period, and was lowered during the wet period. Peak and final viscosity of starch decreased from early to mid-harvest time when environmental conditions became drier, and increased close to or greater than the original value when conditions became wet again. Breakdown and setback also followed a similar trend to viscosity. This study suggests an impact of time and conditions of harvest on the structural and functional properties of all cassava cultivars, and based on this study, it is recommended that starch should be extracted from either early or very late harvested roots.

A comparative study of edible canna (Canna edulis) starch from different cultivars. Part I. Chemical composition and physicochemical properties

Abstract The chemical composition and physicochemical properties of starches isolated from three cultivars (Japanese-green, Thai-green and Thai-purple) of edible canna rhizomes were studied. Scanning electron microscopy investigations showed that the starch granules from all cultivars of canna were oval-shaped granules with smooth surfaces and were around 10–100 μm in sizes. Proximate composition studies showed that the protein content in the canna samples varied between 0.069 and 0.078%, lipid between 0.014 and 0.019% and ash between 0.25 and 0.33%. All canna starches contained considerably high phosphorus (371–399 ppm), followed by calcium (113–154 ppm) and potassium (35–61 ppm). The absolute amylose content ranged from 19 to 25%. All three starches displayed a B-type X-ray diffraction pattern. The viscograms of canna starches determined by Rapid Visco Analyzer showed that Thai-green and Japanese-green starches paste were quite stable during cooking and had high setback. The enthalpy for gelatinization and dissociation of retrograded canna starches, investigated using differential scanning calorimeter, were 17.6–18.4 and 12.3–15.0 J/g of starch, respectively. The results obtained from freeze-thaw stability and light transmittance measurements indicated that all canna starches had a high tendency for retrogradation.

Impact of water stress on yield and quality of cassava starch

Abstract Cassava ( Manihot esculenta Crantz) is an important source of industrial raw materials. Products obtained from cassava include chip/pellets for animal feed and starch. Important for major industrial uses are the amount and quality of starch obtained from this crop. Production efficiency, including yield and quality of starch, from cassava is markedly influenced by environmental conditions, especially water stress during early plant development and immediately before root harvest. In early plant development plants deprived of water for the first 6 months were characterized by a lower yield of starch compared to plants without water stress (starch yields of six varieties including Rayong 1, Rayong 5, Rayong 60, Rayong 90, Kasetsart 50 and CMR 33-57-81 were 0.1–0.2 and 5.0–8.7 t/ha for water-stressed and without water-stressed plants). Furthermore, starch from plants deprived of water for the first 6 months of growth, was functionally different to that laid-down under optimum growing conditions. Plants responded to subsequent rainfall and after 2 months contained significant amounts of starch, though this amount was less than was expected. Despite the fact that water-stressed plants responded to the availability of water by producing starch, most functional properties remained different. The portfolio of changes was sufficient as regards the starch of lower quality. Most effected were the hydration properties. Starch granules despite being smaller (mean size and distribution) than expected were morphologically normal. A second drought period further influenced some of the starch properties, but the sustained influence of the early drought seemed to dominate the response of the plants starch metabolism. All varieties were similarly affected.

Cassava Starch Technology: The Thai Experience

Cassava starch is an important export commodity of Thailand, about 2 × 106 t are expected annually. Initially, cassava was mainly processed to meal and flour. Due to the high market demand for cassava products, the Thai cassava starch industry was established and has developed from small to large-scale with improved processing technology. At present, a production capacity of one factory is, on average, 200 t starch per day. Transition from small to large-scale production was accompanied by varietal development of root having high starch yield and technological improvement of starch production with shorter processing time and better starch quality. Most process technologies are still imported and adopted from those of other starches. The Thai cassava starch industry still encounters impediments, including high production cost, high resource consumption, starch loss, and adverse environmental impact especially sulfur, cyanide, solid and liquid waste. This industry continues to develop, in order to remain internationally competitive.

Edible canna (Canna edulis) as a complementary starch source to cassava for the starch industry

Abstract Edible canna (Canna edulis Ker) as an alternative starch source was evaluated on the basis of genetic characteristics, agronomic traits and starch properties. Four canna varieties indigenous to Thailand were examined including Thai-green, Japanese-green, Thai-purple and Chinese-purple and compared with cassava (Manihot esculenta Crantz). Using the Random Amplified Polymorphic DNA (RAPD) technique employing ten 10-base primers, four primers implied that at least three types of canna including Thai-green, Japanese-green and Thai/Chinese-purple existed and corresponded to plant characteristics as identified by flower, stem, leaf and rhizome colors. Despite genetic diversification, starch properties were not variable. All four varieties produced 30.4–38.4 tonne/ha of rhizomes with starch content about 13% (wet basis). Starch yields of canna (4.1–4.9 tonnes/ha) were comparatively lower than cassava (6.5 tonnes/ha). The starches were characterized by giant granules (10–80 μm), and compared with cassava starch pastes had a higher peak viscosity (930–1060 BU for canna starches and 815 BU for cassava starch), occurring at a higher temperature. Pastes of canna starch were more stable and when cooled, viscosity increased to 1800 BU. Gelatinized pastes of canna starches also rapidly formed good gels on cooling. It is evident that edible canna provides starches with very attractive properties and totally different from cassava and is the greatest promise for the new base starch to be employed complementarily with cassava starch.

The fine structure of cassava starch amylopectin Part 1: Organization of clusters

The enzyme alpha-amylase from Bacillussubtilis was applied to partly hydrolyze purified cassava amylopectin into groups of clusters, which were called domains. The domains were further size-fractionated by methanol precipitation and then subjected to a second stage of alpha-amylolysis until the rate of hydrolysis was slow in order to release the single clusters. All domain and cluster fractions were hydrolyzed with beta-amylase into beta-limit dextrins. The size distribution and chain composition of the beta-limit dextrins were analyzed by gel-permeation chromatography and high-performance anion-exchange chromatography with pulsed amperometric detection, respectively. The sizes of the clusters in the form of beta-limit dextrins were uniform with an average degree of polymerization of 67-78. The distribution profiles of B-chains were similar in all cluster fractions, which suggested that the internal structure of the cassava amylopectin clusters was homogenous. Long B-chains were involved in the interconnection of clusters in the domain fractions. These were cleaved and a new group of chains of intermediate length was produced by the alpha-amylase together with short chains. In the isolated clusters, however, some chains corresponding to long B-chains still remained, which is not predicted by the traditional cluster model of the amylopectin structure. Instead, the alternative two-directional backbone model could explain the mode of interconnection between the clusters.

The influence of time and conditions of harvest on the functional behaviour of cassava starch: a proton NMR relaxation study

The extent of irrigation of crops in the field not only affects crop yield but also the functionality of the harvested product. This irrigation effect severely affects the processing response of starch harvested from Cassava and leads to industrial quality control problems. In this paper we show how the NMR transverse proton relaxation spectrum is a sensitive probe of the effect of irrigation on cassava starch functionality. The results suggest that increased irrigation results in a looser packing of the amylose and amylopectin chains in the cassava starch granule that facilitates their plasticization and gelatinization.

Tapioca/Cassava Starch: Production and Use

Publisher Summary Tapioca starch is obtained from the roots of the cassava plant, which is found in equatorial regions between the Tropic of Cancer and the Tropic of Capricorn. The name cassava is generally applied to the roots of the plant, whereas tapioca is the name given to starch and other processed products. The large central pith of the cassava roots is the starch-reserve flesh and can range in starch content from as low as 15% to as high as 33%. The machinery of tapioca processing is highly varied. There are well-equipped factories that utilize local, custom-built devices for processing roots, product streams, by-products and effluent. Tapioca starch is differentiated from other starches by its low level of residual materials, lower amylose content than for other amylose-containing starches, and high molecular weights of amylose and amylopectin. Starch modifications can be classified as physical modifications, chemical modifications, and genetic modifications. The greatest diversity of uses of tapioca starch is in the food industry. As an ingredient in foods, native and modified tapioca starch has been widely utilized. Other food applications generally make use of tapioca starch as a thickener and stabilizer, with special emphasis on its lack of flavor contribution to food systems, allowing full and immediate detection of the flavor of the food itself. Tapioca starch consumption in industrial applications has been more related to economics than to any unique functionality. Paper manufacturing industry and textile industry are significant users of starch.Publisher Summary Tapioca starch is obtained from the roots of the cassava plant, which is found in equatorial regions between the Tropic of Cancer and the Tropic of Capricorn. The name cassava is generally applied to the roots of the plant, whereas tapioca is the name given to starch and other processed products. The large central pith of the cassava roots is the starch-reserve flesh and can range in starch content from as low as 15% to as high as 33%. The machinery of tapioca processing is highly varied. There are well-equipped factories that utilize local, custom-built devices for processing roots, product streams, by-products and effluent. Tapioca starch is differentiated from other starches by its low level of residual materials, lower amylose content than for other amylose-containing starches, and high molecular weights of amylose and amylopectin. Starch modifications can be classified as physical modifications, chemical modifications, and genetic modifications. The greatest diversity of uses of tapioca starch is in the food industry. As an ingredient in foods, native and modified tapioca starch has been widely utilized. Other food applications generally make use of tapioca starch as a thickener and stabilizer, with special emphasis on its lack of flavor contribution to food systems, allowing full and immediate detection of the flavor of the food itself. Tapioca starch consumption in industrial applications has been more related to economics than to any unique functionality. Paper manufacturing industry and textile industry are significant users of starch.

The fine structure of cassava starch amylopectin. Part 2: building block structure of clusters.

The aim of this work was to analyse the organization of unit chains inside clusters of cassava amylopectin. beta-Limit dextrins of the clusters and partly fragmented clusters (sub-clusters) were isolated previously [Laohaphatanaleart et al., Int. J. Biol. Macromol. (2010) doi:10.1016/j.ijbiomac.2010.01.0049] and were now hydrolysed extensively with the alpha-amylase (liquefying type) of Bacillus subtilis into small, branched building blocks. The blocks were size-fractionated and characterized structurally. The smallest blocks predominated in the clusters. They were single branched and possessed a degree of polymerization (DP) of 5-9. Blocks with DP 10-15 were double branched and constituted the second largest group. The clusters of cassava amylopectin, which were of rather uniform size, possessed typically 7-9 building blocks, and all clusters contained similar size-distributions of the blocks. The inter-block chain length was 7-8 residues. The possible mode of attack by the enzyme between the building blocks is discussed. A model of the building block organization in the clusters is presented, in which the structural roles of different sub-groups of clustered chains are suggested. A three-dimensional model suggests a possible organization of the building blocks inside the amorphous lamellae in the granular starch.