Studies on the synthesis and properties of hydroxypropyl derivatives of cassava (Manihot esculenta Crantz) starch

Cassava starch was subjected to hydroxypropylation in three different media, which included water, water in the presence of a phase transfer catalyst, and 2‐propanol, all at 30 ± 2 °C for 24 h. Propylene oxide was used in four different concentrations (50, 100, 150 and 200 g kg^?1 of starch dry weight). The products were characterized by determining their molar substitution (MS), structural and functional properties. The analyses were done in triplicate and the data were analyzed using the statistical package 8.01. The MS of the products ranged from 0.26 to 1.41. The MS of the hydroxypropyl derivatives were found to be higher when the reaction was carried out in the aqueous medium in the presence of tetrabutylammonium bromide, a phase transfer catalyst, when compared to the reaction in 2‐propanol, which was found to be not very effective at 30 ± 2 °C. The etherification altered the granular properties of starch, as could be seen from scanning electron micrographs. Hydroxypropylation resulted in starch pastes which were stable and with higher swelling volume, solubility, light transmittance and water binding capacity as compared to native starch. The hydroxypropyl starches showed significantly lower pasting temperatures and setback viscosities. The enzyme digestibility of the derivatives was seen to decrease with increase in MS and there was a significant reduction in the syneresis of the starch pastes of hydroxypropyl derivatives. Texture profile analysis showed that hydroxypropylated starch gels exhibited higher hardness, springiness (elasticity) and gumminess and lower cohesiveness than the native starch. Copyright © 2007 Society of Chemical Industry     

Studies on the properties of citrate derivatives of cassava (Manihot esculenta Crantz) starch synthesized by microwave technique

Cassava starch citrates with degree of substitution (DS) ranging from 0.005 to 0.063 were synthesized by the microwave‐assisted reaction of cassava starch with citric acid. A response surface small composite design was used to study the effect of different reaction conditions, viz. time, temperature and reagent concentration. All these variables significantly affected the substitution level in the modified starches. The DS increased with increase in the time of reaction and temperature. However, reagent concentration had a negative effect on the DS. The modified starches showed higher viscosity with lower breakdown, lower setback and higher final viscosities in comparison to native starch. Differential scanning calorimetry showed that the modified starches exhibited a decrease in gelatinization temperatures, T_o, T_p, T_e, in comparison to native starch. However, the heat of gelatinization was not significantly affected. The citrate derivatives exhibited reduced swelling volume and enhanced water binding capacities. They were found to be less susceptible to enzyme hydrolysis than native starch. Copyright © 2007 Society of Chemical Industry     

Natural antimicrobial ingredients incorporated in biodegradable films based on cassava starch

Biodegradable films based on cassava starch and with addition of natural antimicrobial ingredients were prepared using the casting technique. The tensile properties tensile strength (TS) [MPa] and percent elongation (E) at break [%] and the water vapor transmission (WVT) of the biodegradable films were evaluated and compared with the control (without antimicrobial ingredients). The evaluation of the Colony Forming Units per gram [CFU/g] of pan bread slices packed with the best biodegradable films, in terms of packaging performance, was also determined. The addition onto the matrix of only clove and cinnamon powders could reduce the films WVT when compared to the control, however TS and E were lower than the control and the effect of cinnamon was milder regarding this property. Since water activity of the pan bread slices packed with the biodegradable films increased considerably during the storage period, the antimicrobial effect could not be clearly determined.     

Textural changes during cooking of cassava (Manihot esculenta Crantz) roots

Consumer acceptability of cassava food products depends mostly on the final texture of the cooked tissue. The age of the roots at harvest seems to be an important factor in determining the final texture. Two cassava cultivars harvested at 8, 17 and 30 months after planting were used for texture loss determination by a puncture test after cooking at constant boiling water temperature. Kinetic data were analysed using fractional conversion. The raw tissue showed decreasing or constant peak yield force values as the root aged. There was a gradual first‐order softening during cooking, with decreasing rate constant as the root aged. Copyright © 2004 Society of Chemical Industry     

Moisture stress during growth affects the breadmaking and gelatinisation properties of cassava (Manihot esculenta Crantz) flour

Breadmaking quality (judged by the regularity of the crumb) of cassava (in cassava flour/defatted soy flour/glyceryl monostearate recipes (80/20/3, w/w), Cereal Chem 68 323–327 1991) is related to crop age and the season of planting and harvesting. When taking the data sets of the dry season (J Sci Food Agric 66, 193–202 1994) and rainy season (ibid 68 167–174 1995) together, the following additional interpretation results: breadmaking quality of cassava is positively related to flour from roots with unrestricted growth, and therefore influenced by rainfall distribution, time of planting and harvesting. Variability in baking performance of cassava flour samples is related to the length and severity of the dry season, the growth behaviour of the genotype and the crop age. The highest flour breadmaking quality is obtained after 6 months of unrestricted growth of cassava irrespective of the planting season. © 1998 SCI.     

Cyanogenesis in somatic embryos and plantlets of cassava (Manihot esculenta Crantz)

A protocol was established for high frequency cyclic somatic embryogenesis and plant regeneration for the cassava variety PRC 60a. Linamarin content and linamarase activity were determined in various tissues of secondary somatic embryos and regenerated plants. Neither linamarin nor linamarase activity were detected in embryogenic callus and somatic embryos. The stems and leaves of regenerated plants, however, contained variable amounts of linamarin and linamarase activity whereas, in the root tissues, only linamarin was detected. This study suggests that the pathway for linamarin biosynthesis may be absent or not switched on in the embryogenic callus and somatic embryos. This system would be useful for investigating cyanogenesis in cassava. © 1999 Society of Chemical Industry     

Impact of genotype,crop age and planting season on the breadmaking and gelatinisation properties of cassava (Manihot esculenta Crantz) Flour

The breadmaking potential of cassava flour (in cassava flour/defatted soya flour/glyceryl monostearate recipes (80/20/3, w/w/w)) is not merely dependent on the age of the crop at harvest, but also on the season of planting and time of harvesting. Effects of cassava genotype are less important for determining bread quality. In flours obtained from crops harvested at different times after planting, differences in gelatinisation onset temperatures measured by Brabender visco-amylography and by differential scanning calorimetry accounted for the observed differences in breadmaking potential of cassava flour of single genotypes and planting seasons to some extent. Cassava starch produced breads with a drier crumb, with a finer structure and with a more bulged crust than cassava flour. Differentiations in baking performance between starch samples, although smaller, still existed. This showed that the breadmaking potential of cassava flour samples is determined both by the starch and by the non-starch fractions. Differentiation of cassava samples in the breadmaking process did not occur at the mixing or fermentation stage of the batter but during baking.     

The mutagenicity of cassava (Manihot esculenta Crantz) preparations

Different cassava products were found to contain mutagenic activities in the Ames test. This paper describes how the flavonol quercetin is released during the cooking of fresh cassava leaves, following a process very similar to culinary habits. The hydrolysis of the glucoside(s) and the release of free quercetin has been followed by the monitoring of mutagenic activities with a simultaneous isolation and purification by thin-layer chromatography. The fluorodensitometric method applied revealed that fresh leaves contained about 1300 mg quercetin per kg wet weight, of which 800 mg were released during a normal cooking process.     

Screening of Starch Quality Traits in Cassava (Manihot esculenta Crantz)

Cassava (Manihot esculenta Crantz) is one of the most important sources of starch in the tropics. There is limited and contradictory information regarding cassava starch characteristics. The International Center for Tropical Agriculture (CIAT) holds in trust FAO's cassava germplasm collection. Starches from 3272 landraces (including 12 wild relatives) and 772 improved clones were extracted and analyzed over a period of several years. In most cases only one starch sample per genotype was analyzed. Average cyanogenic potential was 327 ppm but considerably higher in the landraces (340 ppm) than in improved clones (267 ppm). Average total and reducing sugars were slightly higher in improved clones (4.06 and 1.56%, respectively) than in landraces (3.68 and 1.25%, respectively). Amylose content was similar in both types of germplasm with an average of 20.7%. Average pasting temperature was 65.3°C. Maximum viscosity was 777.5 mPa s, breakdown was 298.1 mPa s, consistency was 155.8 mPa s and setback was ‐144.5 mPa s. The large sample of starches analyzed provides very robust information regarding the actual characteristics of cassava starch.     

Effects of cultivar and growth season on the gelatinisation properties of cassava (manihot esculenta) starch

Starch was extracted from the roots of four different cassava cultivars (Munihot esculenta Crantz) grown in Colombia and harvested on four different occasions with a view to determining whether there was any relationship between the physicochemical properties of the starch and the texture of the cooked roots. The organoleptic quality of the cooked roots was evaluated by a trained taste panel and found to vary in terms of both their glassy texture and their hardness. Studies of the gelatinisation behaviour of the starches by DSC and amylography (with a Brabender amylograph), of the pasting properties by viscography and of the viscoelastic characteristics by a Bohlin rheometer demonstrated some differences between the physicochemical properties of the starches but insufficient to account for the pronounced textual differences.     

The effects of time to first shoot removal on leaf vegetable quality in cassava (Manihot esculenta Crantz)

A field trial was established on a sandy soil at IITA. Ibadan. Nigeria to investigate the effects of time to first shoot removal on cyanide content and chemical composition of leaves of two cassava clones: TMS 91934 and TMS 30572. Four different times to first shoot removal were imposed on each clone: 8. 14, 20 and 52 weeks after planting (WAP). Shoot removal was repeated at 8-week intervals until harvesting at 52 WAP. Shoot removal (SR) involved removing the shoot tips just below the most fully expanded leaf. Early shoot removal during the crop growth period (SR at 8 weeks and SR at 14 weeks 14) produced significantly (P < 0.01) more fresh shoot yield than late shoot removal (SR20 and SR52 weeks). Concentrations of crude protein, iron, phosphorus and zinc were higher in the early harvested leaves but declined in concentration with increasing age of the crop (430–280 g kg^?1, 680–85 mg kg^?1, 88–42 g kg^?1, 128–30 mg kg^?1, respectively). Leaf HCN concentration was about three times that in tuberous roots (137 mg kg^?1 fresh weight compared with 43 mg kg^?1 fresh weight). The variation in leaf HCN concentration was not significant for all the treatments over the period.     

The lipids of young cassava (Manihot esculenta,Crantz) leaves

Lipids were extracted quantitatively from young cassava (Manihot esculenta Crantz) leaves with a chloroform-methanol mixture. Total lipids were purified by the Folch procedure and separated into non-polar lipid, glycolipid and phospholipid fractions by column chromatography. Lipids of each fraction were further subjected to thin layer chromatography and gas-liquid chromatography. Young cassava leaves were found to have low content of lipids (3.02%) of which 22.4, 25.1 and 48.2 were non-polar lipids, glycolipids and phospholipids, respectively. Pigments (11.5%), wax and hydrocarbons (1.2%), steryl esters (2.9%), methyl esters of fatty acids (2.0%), trigly-cerides (1.5%), fatty acids (2.1%), diglycerides (1.1%) and sterols (0.1%) constituted the leaf non-polar lipids. The leaf glycolipids were made up of esterified steryl glycosides (2.1%), monogalactosyl diglycerides (12.5%), steryl glycosides (1.1%), cerebrosides (4.2%) and digalactosyl diglycerides (5.2%). The leaf phospholipids were found to include cardiolipin (3.6%), phosphatidylglycerol (21.5%), phosphatidylethanolamine (16.4%), phosphatidylserine (0.7%), phosphatidylinositol (4.0%) and other unidentified phospholipids (2.5%). Phosphatidylcholine was present only in trace quantity. Analysis of the fatty acid composition of each of the leaf lipids revealed that, with the exception of steryl esters, all leaf lipids have high content of polyunsaturated fatty acids.     

Production of Ethanol from Tapioca (Manihot esculenta Crantz)

Ethanol production from fresh tubers, flour and starch of tapioca was studied by simultaneous saccharification and fermentation procedure. A 20% enzyme-liquefied slurry showed about 2–3% reducing sugars, which increased to 10% on enzymic saccharification for 4h. Alcoholic fermentation of this hydrolysate with Saccharomyces cerevisiae, Var. ellipsoideus, yielded 8–9% alcohol showing about 95% fermentation efficiency. Large scale fermentation of tapioca flour by this process also showed fermentation efficiency of 90% thereby indicating the economic viability of the process.     

Synthesis and Characterization of low DS Succinate Derivatives of Cassava (Manihot esculenta Crantz) Starch

Succinylation of cassava starch was carried out in aqueous medium to prepare derivatives with low degree of substitution (DS) and the physicochemical properties of the products were determined. A response surface design was used for the experiment with three levels of each of the three variables viz., concentration of succinic anhydride, reaction time and pH of the reaction medium. The reaction was followed in terms of the DS of the products and reaction efficiency (RE). The degree of substitution of the derivatives varied from 0.001 to 0.022 and reaction efficiency from 2.2 to 46.8%. The DS and RE showed an adequate fit to a second order polynomial model of the variables used. Succinylation brought about increase in the swelling volume, peak viscosity and paste clarity of the starch. However, the pasting temperature and solubility did not show any significant change. The in‐vitro α‐amylase digestibility of the succinylated derivatives decreased in comparison to that of native starch and this decrease correlated with a corresponding increase in DS.     

Estimation of starch and total fermentables content in storage roots of cassava (Manihot esculenta Crantz.)

The relationships between the percentage of dry matter (DM), specific gravity, percentage of starch and percentage of total fermentables in cassava storage roots have been examined in detail. The results confirm the findings of earlier workers that specific gravity can provide a reliable estimate of storage root DM in the absence of drying facilities. A curvilinear relationship of the form 1/y = a + bx was found to exist between storage root DM and percentage of starch or fermentables within one cultivar over a range of ages and seasonal conditions. This relationship shows that the proportion of total DM present as starch or fermentables increases for samples of higher DM percentages. A similar relationship was shown to exist between specific gravity and percentage of starch or fermentables. A linear relationship was also developed between the percentage of DM and of fermentables based on 28 cultivars harvested at the same age and under the same seasonal conditions. More information is required on cultivar differences in these relationships over the entire range of DM and fermentable percentages, before widespread use is recommended. Once correctly established, relationships based on DM or specific gravity provide a simple and reliable method of estimating percentage of starch or total fermentables in the storage roots of cassava. Comparisons are made between these results and those reported earlier in the literature, using less precise methods of starch measurement.     

Isolation and physicochemical characterisation of starch from cocoyam (Colocasia esculenta) grown in Malawi

BACKGROUND: The aim of this study was to determine the physicochemical properties of starches isolated from Malawian cocoyams and compare them with those of cassava and corn starches. RESULTS: The purity of the isolated starches varied from 851 to 947 g kg^?1 and pH from 4.93 to 6.95. Moisture, ash, protein, fat and amylose contents ranged from 104 to 132, 0.3 to 1.5, 3.5 to 8.4, 0.9 to 1.6, and 111 to 237 g kg^?1, respectively. Cocoyam starches gave higher potassium and phosphorus but lower calcium levels than the other starches. The shape of starch granules varied from spherical to polygonal with cocoyam starches displaying smaller‐sized granules than cassava and corn starches. Cocoyam starches gave a higher wavelength of maximum iodine absorption and blue value but lower reducing capacity values than cassava and corn starches. The extent of acid hydrolysis of the starches also differed. Cocoyam starches exhibited amylopectin molecules of higher molecular weights but amylose molecules of lower molecular weights than cassava and corn starches. Cocoyam starches exhibited lower water absorption capacity and swelling power, paste clarity and viscosity but higher solubility, gelatinisation temperatures and retrogradation tendencies than cassava and corn starches. CONCLUSIONS: The physicochemical properties of native Malawian cocoyam starches vary among the different accessions and differ from those of cassava and corn starches. Copyright © 2010 Society of Chemical Industry     

Characterisations of cassava starch and poly(butylene adipate-co-terephthalate) blown film with silicon dioxide nanocomposites

Films with high permeability are necessary for the packaging of agricultural products that respire to avoid anoxic conditions. This research developed and characterised bioplastic nanocomposite films with enhanced permeation and increased strength. Thermoplastic starch (TPS) was compounded with silicon dioxide (SiO₂) and blended with poly (butylene adipate-co-terephthalate) (PBAT) to produce bioplastic PBAT/TPS blend films via blown-film extrusion. Different SiO₂ contents (0.5%–1%) were dispersed in the matrices, causing interaction via hydrogen bonding with the TPS phase. SiO₂ at 1% significantly improved melting of the polymer blends, giving increasing amorphous ratios of the polymeric films. Microstructures and surface topography indicated voids between incompatible components and porous structures that improved permeation. Increasing SiO₂ content linearly enhanced oxygen and water vapour permeability by up to 39% and 16%, respectively. Tensile strength and elongation at break increased and decreased up to 40% and 32%, respectively, indicating increased rigidity due to adding solid nanoparticles to 1%. Migration phenomena of the film components, that is molecules with diol structures and silicon compounds depended on types of simulant and microstructures that induced swelling and release of the compounds. Film permeabilities increased, thereby facilitating air and humidity flow through the packaging.     

Comparative study on the properties of flour and starch films of plantain bananas (Musa paradisiaca)

Biodegradable films were prepared by using the flour and starch isolated from plantain bananas of the variety “Terra” (Musa paradisiaca). Since the non-starchy fraction present in the banana flour represents 29.4% (on dry basis) of its composition, we considered it would be interesting to compare the properties of the film elaborated from this natural blend with that of the film produced from the banana starch only. Both films were characterized on the basis of their mechanical, barrier, optical, structural, and thermal properties. The banana flour film was less mechanically resistant but more flexible than the banana starch film. Despite the differences in the microstructure of the flour and starch films, the former was slightly soluble in water, and its water vapor permeability was similar to that of the starch film. Regarding the optical properties, the flour film was yellowish, which can be attributed to its protein content and the presence of phenolic compounds. The starch film, on the other hand, was lighter and less opaque. The FTIR spectra revealed the presence of the amide I group related to proteins only in the case of the flour film. Both plantain banana films displayed a C-type X-ray pattern and one glass transition temperature each, which was higher for the starch film (46.4 °C) as compared to the flour film (30.2 °C). The presence of other components (protein, lipids, and fiber) in the flour film had important effects on its properties. In general, the banana flour and starch are very promising materials for the formulation of coatings and films.