Composition, structure, physicochemical properties, and modifications of cassava starch.

In 2012, the world production of starch was 75 million tons. Maize, cassava, wheat and potato are the main botanical origins for starch production with only minor quantities of rice and other starches being produced. These starches are either used by industry as such or following some conversion. When selecting and developing starches for specific purposes, it is important to consider the differences between starches of varying botanical origin. Here, an overview is given of the production, structure, composition, morphology, swelling, gelatinisation, pasting and retrogradation, paste firmness and clarity and freeze–thaw stability of maize, cassava, wheat, potato and rice starches. Differences in properties are largely defined by differences in amylose and amylopectin structures and contents, granular organisation, presence of lipids, proteins and minerals and starch granule size.

Production, structure, physicochemical and functional properties of maize, cassava, wheat, potato and rice starches

Physicochemical characterization of sweet potato starches popularly used in Chinese starch industry

The quality of cassava starch, an important trait in cassava breeding programs, determines its applications in various industries. For example, development of waxy (having a low level of amylose) cassava is in demand. Amylose is synthesized by granule-bound starch synthase I (GBSSI) in plants, and therefore, down-regulation of GBSSI expression in cassava might lead to reduced amylose content. We produced 63 transgenic cassava plant lines that express hair-pin dsRNAs homologous to the cassava GBSSI conserved region under the control of the vascular-specific promoter p54/1.0 from cassava (p54/1.0::GBSSI-RNAi) or cauliflower mosaic virus (CaMV) 35S (35S::GBSSI-RNAi). After the screening storage roots and starch granules from field-grown plants with iodine staining, the waxy phenotype was discovered: p54/1.0::GBSSI-RNAi line A8 and 35S::GBSSI-RNAi lines B9, B10, and B23. Sodium dodecyl sulfate-polyacrylamide gel electrophoresis showed that there was no detectable GBSSI protein in the starch granules of plants with the waxy phenotype. Further, the amylose content of transgenic starches was significantly reduced (<5%) compared with the level in starch granules from the wild-type (about 25%). The inner structure of the waxy starch granules differed from that of the untransformed ones, as revealed by transmission electron microscopy analysis as well as morphological changes in the iodine-starch complex. Endothermic enthalpy was reduced in waxy cassava starches, according to differential scanning calorimeter analysis. Except B9, all waxy starches displayed the A-type X-ray diffraction pattern. Amylogram patterns of the waxy cassava starches were analyzed using a rapid viscosity analyzer and found to have increased values for clarity, peak viscosity, gel breakdown, and swelling index. Setback, consistency, and solubility were notably reduced. Therefore, waxy cassava with novel starch in its storage roots was produced using the biotechnological approach, promoting its industrial utilization.

Development of waxy cassava with different Biological and physico‐chemical characteristics of starches for industrial applications

Review on the physicochemical properties, modifications, and applications of starches and its common modified forms used in noodle products

The genetic variation of starch of Indonesian cassava genotypes with various morphological characteristics of roots and eco-geographical origin was characterized and compared. The morphological characteristics of the roots of 71 collected cassava genotypes were classified into yellow and white for flesh colors, purple, pink, light brown, yellow, cream and white for cortex colors, dark brown and light brown for external colors, as well as conical and cylindrical for root shapes. Starch samples extracted from 17 genotypes showed that the amylose content varied from 17.1 to 21.3%. The mean particle size was around 7.3 to 9.7 mu m, and the gelatinization onset temperature was in the range of 63.5-66.1 degrees C. Seven genotypes were analyzed in more detail for their physicochemical properties. The granule size distribution was in the range of 3.2 mu m to 17.6 mu m for d10 and d90 (i.e. 90% of the granules were bigger than 3.2 pm and 90% were smaller than 17.6 mu m), respectively, and the median granule size was around 7.7-10.8 mu m. The gelatinization temperatures of the different cassava starches were in the range of 63.5-66.1 degrees C. The phosphate content varied from 23.5-25.3 nmol/mg starch. Particle size distribution and gelatinization temperature as well as the phosphate content of the starch of the selected seven genotypes also showed minor differences among the genotypes. The swelling power of all starches showed some differences between genotypes, but the profiles were similar. The opacity of starch of all the tested genotypes increased twofold within six days, but no large differences among the different genotypes could be detected except for the genotype Ketan. Strength of the gels, which are indicated with force, adhesiveness, cohesiveness, and elasticity, also did not show large differences.

Vivi Anggraini

Papers

Characterization of cassava starch attributes of different genotypes