Waxy Cassava Starch Research Articles

On the architecture of starch granules revealed by iodine vapor binding and lintnerization. Part 1: Microscopic examinations.

Structural nature of glucan chains in the amorphous part of granular starch was examined by iodine vapor treatment and lintnerization. Four iodine-stained amylose-containing normal starches and their waxy counterparts were examined under a microscope before, during, and after lintnerization. The presence of amylose retarded the lintnerization rate. The degree of retardation correlated with the structural type of the amylopectin component, suggesting that potato amylopectin (type 4 structure) interacts with amylose in the granules, whereas in barley granules (type 1 structure) the interaction is very weak. The inclusion complexes with iodine were not degraded by the acid treatment. Therefore, the iodine-glucan chain complex formation could be used to study the structural nature of the flexible, amorphous parts of the starch granules. Indeed, at the end of lintnerization, when 20%-30% of the granules remained, substantial amounts of blue-stained complexes were washed out from the granules especially from amylose-containing barley and maize starch, but also from both normal and waxy cassava and potato starch. The complexation with iodine did not affect the rate of lintnerization. This suggested that single helical structures were present during lintnerization also in the absence of iodine and this conformation was the reason for the acid resistance.

Glass transition temperature, rheological, and gelatinization properties of high amylose corn starch and waxy cassava starch blends

In the present study, the physicochemical properties of high amylose corn starch (HACS) with waxy cassava starch (WCS) blends were investigated at different ratios. Glass transition temperature, pasting properties, rheological properties, and textural properties of the starch blends were studied by various techniques. The interactions of the starch blends were studied by plotting and comparing the correlation between the proportions of starch and physicochemical properties. The obtained results indicated that the glass transition temperature, pasting properties, rheological properties showed non-additive effects. In addition, the textural properties of starch blends were significantly improved, which was in a positive relationship with HACS contents. The mixture of HACS and WCS could lead to unexpected physicochemical properties of starch blends, which is beneficial for creating novel texture food products. Practical applications Blending of different starches is a clean-label alternative to modify the properties starches, and the interaction between different starches could lead to unexpected physicochemical properties of starch blends. High amylose corn starch is an important resistant starch with lots of beneficial health effects such as lowering blood lipid levels, increasing laxation, and preventing gall stone formation. Waxy cassava starch is less susceptible to retrogradation and has greater cold-storage stability. The blending of high amylose corn starch and waxy cassava starch has great potential for developing starch-based products with particular functionalities.

Fabrication of starch blend films with different matrices and their mechanical properties

The objective of the study was to determine the effects of molecular sizes of amylose (AM) and starch granules on the mechanical properties of thermoplastic starch (TPS) blend films. Leached amylose solution from cassava (CS_ AM) and mung bean (MB_AM), and two forms of amylopectin (AP) (granular; g and non-granular; ng) of waxy cassava (WxCS) starch were used. Four types of film matrices were fabricated and all TPS blend films contained same amount of AM and glycerol. Results displayed that molecular weight profiles of starch films and presence of granule remnants significantly controlled the film matrix formation, types of crystal formation, and percent of relative crystallinity (%RC) (p < 0.05). Tensile property of TPS films was controlled by %RC and presence of granule remnants. Percent elongation at break (%Eb) of TPS films increased when the films had a large range of molecular weight distribution (from 5.5 × 107 g/mol to 0.4 × 105 g/mol) and contained a high weight fraction (~58%) of starch molecules with Mw~0.4 × 105 g/mol.

Genome-wide association studies for waxy starch in cassava

Cassava (Manihot esculenta Crantz) is an important crop for starch production, and recently much effort has been directed towards improving its starch properties. Waxy cassava starch has some advantages over starch from other sources due to its neutral flavor and pasting properties. The genetic inheritance of the waxy starch phenotype is considered to be monogenic and recessive; however, it is possible that other genomic regions contribute to the waxy phenotype. The aim of this study was to evaluate the power of genome-wide association studies (GWAS) to detect variants related to waxy starch and to identify alternative genes or genomic regions. For this purpose, a set of 382 samples (waxy and non-waxy) was analyzed using a panel of 20,956 single nucleotide polymorphisms (SNPs). All genotypes were evaluated in relation to the presence of waxy starch, determined using the 2% iodine test. The GWAS was performed using the retrospective CAse–control Retrospective Association Testing (CARAT) model. Kinship and population structure were also investigated and added to the model. Ten SNPs were found to be significant and located on chromosome 2 and co-located in genomic regions. The significant SNPs are in a region near the Granule-bound starch synthase I (GBSSI) and Beta-amylase genes. Additive and epistatic effects were also found among the significant SNPs, and these need to be better investigated in segregant populations of waxy sources. The regions and genes identified in this work may drive further studies and reveal biological processes related to the waxy phenotype.

Outstanding Characteristics of Thai Non-GM Bred Waxy Cassava Starches Compared with Normal Cassava Starch, Waxy Cereal Starches and Stabilized Cassava Starches.

Waxy cassava roots of nine varieties successfully developed in Thailand by a non-genetic modification (non-GM), conventional breeding method were used for extracting starches and their starch physico-chemical properties were evaluated and compared with normal cassava starches, commercial waxy starches (i.e., waxy maize starch and waxy rice starch) and commercial stabilized starches (i.e., acetylated starch and hydroxypropylated starch). All waxy cassava varieties provided starches without amylose while normal cassava starches contained 18%–20% amylose contents. As determined by a Rapid Visco Analyzer (RVA) at 5% (dry basis), waxy cassava starches had the highest peak viscosity and the lowest setback viscosity. Cooked paste of waxy cassava starches had the greatest clarity and stability among all starches during storage at 4 ℃ for 7 days as evidenced by its high light transmittance (%T) at 650 nm. No syneresis was detected in waxy cassava starch gels after subjecting to four freeze-thaw cycles (4 weeks) indicating high potential use of waxy cassava starches, free from chemicals, to replace stabilized starches as thickening and texturing agents in food products.

Effect of amylose content and chemical modification of cassava starch on the microencapsulation of Lactobacillus pentosus

This study aimed to assess the potential of two types of cassava starch with different amylose content (normal and waxy) for the encapsulation of Lactobacillus pentosus. These two cassava starches were modified via acid hydrolysis, phosphatized, and succinated, and evaluated as material for the encapsulation after administering the following four treatments for each type of starch: octenylsuccinate (OSA), sodium tripolyphosphate salt (TPS), 75% OSA/25% TPS, and 25% OSA/75% TPS. Optimal conditions were established for hydrolysis (2.15 M HCl for both starches; 4.56 h for waxy cassava starch [WCS] and 2.44 h for normal cassava starch [NCS]), and the solubility index of the modified starches was significantly increased (p ≤ 0.05) relative to their native and hydrolyzed forms in terms of the morphology of the starch granules; this was affected owing to chemical modification. Together with chemical modifications, amylose content and solubility index were the primary factors influencing the encapsulation. The highest percentage of Encapsulation Efficiency (EE) was achieved using 75% OSA/25% TPS-NCS (93.72%) and TPS-WCS (99.22%). In these mixtures, a synergistic effect was observed between the modified starches, thereby enhancing the (EE); however, the phosphatized starches yielded optimal microencapsulation.

Impact of Environment and Genotype‐by‐Environment Interaction on Functional Properties of Amylose‐Free and Wildtype Cassava Starches

Ten and thirty cassava genotypes producing wildtype and amylose‐free (waxy) starch respectively, are grown at low (LA) and intermediate (IA) altitudes (&lt;213 and &gt;900 m above sea level (m.a.s.l.) respectively). The functional properties of the starch from these materials are analyzed. The relative importance of environment, clones (within starch type) and genotype‐by‐environment interaction (GxE) is assessed through an analysis of variance. GxE effects are non‐significant, whereas environment and clones (within starch type) are highly significant in most of the cases (particularly for waxy starches). Results confirm that waxy cassava starches consistently show higher peak viscosity (PV) compared with wildtypes. Peak viscosity is statistically higher in plants grown in IA compared with those from the same genotypes grown in LA, both for waxy and wildtype genotypes. In a second experiment, a single waxy genotype is grown in five locations ranging from 934 to 1485 m.a.s.l. PV is highest in the location with higher altitude. The second highest PV is measured in starches from the second highest location at 1071 m. Both experiments clearly indicate that PV is positively correlated with altitude above sea level where cassava is grown. Altitude above sea level influenced starch granule size: the higher the altitude the larger the average granule size. Waxy starch granules tend to be larger than those from wildtype genotypes.

Effect of acid hydrolysis and OSA esterification of waxy cassava starch on emulsifying properties in Pickering-type emulsions

The emulsifying properties of waxy cassava starch modified by acid hydrolysis and esterification with octenyl succinic groups in Pickering-type emulsions were evaluated using zeta potential, emulsification index, light microscopy and rheology behavior. The optimal conditions of acid hydrolysis to achieve the highest emulsification index were determined to be a hydrochloric acid concentration of 4 mol/L for 5.20 h. After that, the starch was esterified to obtain a double modification. The emulsification index values were acid treated/succinated starch > optimal acid treated starch > native starch. The acid treated/succinated starch emulsion presented higher storage modulus (G′) values, without G’ and loss modulus (G”) crossing point in the evaluated frequency range. Acid hydrolysis modified the emulsifying properties of waxy cassava starch improving its interaction at the oil/water interface. According to observations by light microscopy and rheology behavior, the double modification formed a more uniform and stable network over time through granule-granule and granule-interface interactions.

Thermomechanical characterization of an amylose-free starch extracted from cassava (Manihot esculenta, Crantz)

The aim of this study was to determine and compare the melting (Tm), glass transition (Tg) and mechanical relaxation (Tα) temperatures of a new waxy cassava starch. Thermal transitions measurements were obtained by Differential Scanning Calorimetry (DSC) and Dynamical Mechanical Thermal Analysis (DMTA). The experimental data showed a high correlation between water volume fraction and melting temperature (Tm) indicating that the Flory–Huggins theory can be used to describe the thermal behavior of this starch. The Tm of waxy cassava starch-water mixes were lower than a waxy corn starch-water reference system, but differences were not statistically significant. The mechanical relaxation temperatures taken at tan δ peaks were found 29–38°C larger than Tg. The Tα and Tg measured for waxy cassava starch exhibited similar properties to the ones of waxy corn starch, implying that waxy cassava starch can be used in food and materials industry.

Discovery of new spontaneous sources of amylose-free cassava starch and analysis of their structure and techno-functional properties

Waxy cassava starch (WS) from a spontaneous mutation offer enough advantages to encourage the development of commercial varieties. However, breeding work is limited because only one source of WS was available. This article reports the discovery of five new sources of WS which were compared with commercial (CC) and high amylose (HA) cassava starches (19.9 and 30.2% amylose, respectively). Waxy starch gels were considerably clearer and had higher solubility and swelling power than those from CC. Pasting temperature and peak viscosity in WS were higher (68.5 °C and 1149 cP) than in CC (64.2 °C and 993 cP). No retrogradation or syneresis could be detected in refrigerated gels or after freeze/thaw cycles in any WS gel. Average λmax for WS, CC and HA were 540.2, 591.3 nm, and 607.0 nm, respectively. Amylopectins from WS displayed M¯w between 271 × 106 and 551 × 106 g mol−1, R¯G ranged between 229 and 298 nm and νG values ranged between 0.38 and 0.40 (between the sphere and the random coil). The apparent density distributions in all WS suggested close densities and branching structure. The corrected average number of glucosyl units in a linear chain averaged 21.2 in WS and 23.1 in CC. Amylopectins from WS showed a slightly more branched structure (average 4.8%) than in CC (average 4.3%), but lower than in HA (7.0%). WS exhibited larger average granule size (15.9 μm) compared with CC (14.3 μm). New sources of WS will contribute the breeding efforts to develop successful commercial varieties.

Molecular and supra-molecular structure of waxy starches developed from cassava (Manihot esculenta Crantz)

The aim of this work was to characterize the amylopectin of low amylose content cassava starches obtained from transgenesis comparatively with a natural waxy cassava starch (WXN) discovered recently in CIAT (International Center for Tropical Agriculture). Macromolecular features, starch granule morphology, crystallinity and thermal properties of these starches were determined. M¯w of amylopectin from the transgenic varieties are lower than WXN. Branched and debranched chain distributions analyses revealed slight differences in the branching degree and structure of these amylopectins, principally on DP 6–9 and DP>37. For the first time, a deep structural characterization of a series of transgenic lines of waxy cassava was carried out and the link between structural features and the mutated gene expression approached. The transgenesis allows to silenced partially or totally the GBSSI, without changing deeply the starch granule ultrastructure and allows to produce clones with similar amylopectin as parental cassava clone.

Molecular Characterization of a Spontaneous Waxy Starch Mutation in Cassava

ABSTRACTCassava (Manihot esculenta Crantz) starch is traded in international markets more than starch from any other source. The starch industry requires cassava cultivars with novel starch characteristics for commercial exploitation. A natural source of waxy (amylose‐free) cassava starch, clone AM 206‐5, was identified at the International Center for Tropical Agriculture (CIAT). The granule‐bound starch synthase I (GBSSI) gene is related to the waxy starch trait. The objectives of this study were to introgress the waxy starch mutation into Thailand's cassava breeding populations, to analyze the inheritance of waxy starch in cassava, and to develop molecular markers for this trait. AM 206‐5 (wxwx) was crossed with several elite cultivars (WxWx) to transfer the wx allele. Unrelated “F1” (Wxwx) genotypes were crossed among themselves to produce a “F2” segregating population with negligible levels of inbreeding depression. The waxy starch phenotype was recovered in 25.7% of the 11,192 genotypes tested. This result provides further evidence that cassava is a functional diploid and that only one copy of GBSSI is present in cassava. A full‐length genomic DNA sequence of GBSSI was isolated and characterized from C8, a waxy starch “F2” clone derived from AM 206‐5. We exploited these sequence differences to develop two diagnostic single‐nucleotide‐amplified polymorphism (SNAP) markers to differentiate homozygous waxy (wxwx) from the heterozygous (Wxwx) and homozygous (WxWx) nonwaxy genotypes.

Structural characterization of novel cassava starches with low and high-amylose contents in comparison with other commercial sources

Two new mutant cassava starches with extreme amylose contents (0 and 30–31%) have been recently reported. These mutants are drastically different from normal cassava starch whose amylose content typically ranges between 15 and 25%. The new mutants were compared with five normal cassava starches (ranging from 16.8 to 21.5% amylose) and commercial versions of amylose-free or normal potato and maize starch. Macromolecular features, crystallinity, granule sizes, and thermal properties of these starches were compared. The structure of cassava amylopectin was not modified by the waxy mutation and waxy cassava starch exhibited properties similar to the ones of waxy maize starch. Waxy cassava and maize show similar M ¯ w and R ¯ G of amylopectin (between 408 × 10 6 g mol −1 and 520 × 10 6 g mol −1; 277–285 nm, respectively), whereas waxy potato amylopectin has lower M ¯ w and R ¯ G . On the contrary, the higher-amylose mutations induced by gamma rays radiation in cassava, modified deeply the branching pattern of amylopectin as well as the starch characteristics and properties: M ¯ w and R ¯ G decreased, while branching degree increased. These modifications resulted in changes in starch granule ultrastructure (e.g. decreased starch crystallinity), a weak organized structure, and increased susceptibility to mild acid hydrolysis. The distinctive properties of the new cassava starches demonstrated in this article suggest new opportunities and commercial applications for tropical sources of starch.

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

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.

Comparison of Pasting and Gel Stabilities of Waxy and Normal Starches from Potato, Maize, and Rice with Those of a Novel Waxy Cassava Starch under Thermal, Chemical, and Mechanical Stress

Functional properties of normal and waxy starches from maize, rice, potato, and cassava as well as the modified waxy maize starch COLFLO 67 were compared. The main objective of this study is to position the recently discovered spontaneous mutation for amylose-free cassava starch in relation to the other starches with well-known characteristics. Paste clarity, wavelength of maximum absorption (lambda(max)), pasting properties, swelling power, solubility, and dispersed volume fraction measurements and gel stability (acid and alkaline resistance, shear, refrigeration, and freeze/thaw stability) were evaluated in the different types and sources of starch included in this study. lambda(max) in the waxy cassava starch was reduced considerably in comparison with that of normal cassava starch (535 vs 592 nm). RVA peak viscosity of waxy cassava starch was larger than in normal cassava starch (1119 vs 937 cP) and assumed a position intermediate between the waxy potato and maize starches. Acid, alkaline, and shear stability of waxy cassava starch were similar to normal cassava except for alkaline pH, at which it showed a low effect. Gels from normal root and tuber starches after refrigeration and freeze/thaw had lower syneresis than cereal starches. Gels from waxy starches (except for potato) did not present any syneresis after 5 weeks of storage at 4 degrees C. Waxy cassava starch was the only one not showing any syneresis after 5 weeks of storage at -20 degrees C. Natural waxy cassava starch is, therefore, a promising ingredient to formulate refrigerated or frozen food.

Shear flow properties of carbon fibre-filled polyethylene melts

Waxy cassava starch (WS) from a spontaneous mutation offer enough advantages to encourage the development of commercial varieties. However, breeding work is limited because only one source of WS was available. This article reports the discovery of five new sources of WS which were compared with commercial (CC) and high amylose (HA) cassava starches (19.9 and 30.2% amylose, respectively). Waxy starch gels were considerably clearer and had higher solubility and swelling power than those from CC. Pasting temperature and peak viscosity in WS were higher (68.5 °C and 1149 cP) than in CC (64.2 °C and 993 cP). No retrogradation or syneresis could be detected in refrigerated gels or after freeze/thaw cycles in any WS gel. Average λmax for WS, CC and HA were 540.2, 591.3 nm, and 607.0 nm, respectively. Amylopectins from WS displayed M¯w between 271 × 106 and 551 × 106 g mol−1, R¯G ranged between 229 and 298 nm and νG values ranged between 0.38 and 0.40 (between the sphere and the random coil). The apparent density distributions in all WS suggested close densities and branching structure. The corrected average number of glucosyl units in a linear chain averaged 21.2 in WS and 23.1 in CC. Amylopectins from WS showed a slightly more branched structure (average 4.8%) than in CC (average 4.3%), but lower than in HA (7.0%). WS exhibited larger average granule size (15.9 μm) compared with CC (14.3 μm). New sources of WS will contribute the breeding efforts to develop successful commercial varieties.