Potential of the small-granule starch mutation for the Bioethanol Industry.

The industrial starch market is undergoing major expansion, but certain specific industrial uses cannot be satisfied by native starches and, therefore, chemical or physical modification is necessary. Mutations in the cassava starch biosynthesis pathways were discovered at CIAT (Cali, Colombia) few years ago. A starch mutation induced by gamma rays radiation resulted in a deeply modified branching pattern of amylopectin as well as other starch characteristics and properties. These modifications include changes in starch granule ultrastructure (e.g. decreased starch crystallinity), a weak organized structure, and increased susceptibility to mild acid and enzymatic raw starch hydrolysis (fastest and most efficient hydrolysis of all studied native starches). This mutation could offer interesting advantages for the production of bioethanol. Surprisingly this mutation also results in increased proportion of amylopectin. Hydrolysis was more dependent on granule morphology than on starch chemical composition. Recent crosses produced segregating progenies whose starch had the small-granule characteristics, but amylopectin content ranged from 19 to 42%. Rapid viscoamylograms of the latter starch showed very distinctive patterns. (Résumé d'auteur

Evaluation of industrial potential of novel cassava starches with low and high amylose contents in comparison with other commercial starch sources

The industrial starch market is undergoing major expansion, but certain specific industrial uses cannot be satisfied by native starches and, therefore, chemical or physical modification is necessary. These modifications are often harmful to the environment and generate additional costs. Mutations in the cassava starch biosynthesis pathways were recently discovered at CIAT, Cali, Colombia. CIRAD, in partnership with CIAT, carried out a study on the physicochemical and functional properties of these starches, which could result in interesting industrial applications and create new market for cassava starch. Among the new cassava starch types, two new mutant cassava starches with extreme amylose contents (0% and 31%) have been recently reported. These mutants are drastically different from normal cassava starch whose amylose content typically ranges between 15-25%. The new mutants were compared with normal cassava starches and commercial versions of amylose-free or normal potato, rice and maize starch. 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. On the contrary, the higher-amylose mutations induced by gamma rays radiation in cassava deeply modified the branching pattern of amylopectin as well as other starch characteristics and properties. These modifications resulted in changes in starch granule ultrastructure (e.g. decreased starch crystallinity), a weak organized structure, and increased susceptibility to mild acid and enzymatical raw starch hydrolysis (fastest and most efficient hydrolysis of all studied native starches). This mutation could offer interesting advantages for the production of bioethanol. Gels from normal root and tuber starches (potato, cassava) after refrigeration and freeze/thaw had lower syneresis than cereal starches (maize, rice). Gels from waxy starches (except for potato) did not present any syneresis after 5 weeks of storage at 4°C. Waxy cassava starch was the only one not showing any syneresis after 5 weeks of storage at -20°C. The distinctive properties of the new cassava starches suggest new opportunities and commercial applications for tropical sources of starch. Supporting information: Journal of Agricultural and Food Chemistry (2007), 55(18): 7469-7476. http://dx.doi.org/10.1021/jf800603p; Journal of Agricultural and Food Chemistry (2008), 56(16): 7215-7222. http://dx.doi.org/10.1021/jf800603p; Journal of Agricultural and Food Chemistry (2010), 58(8): 5093-5099. http://dx.doi.org/10.1021/jf1001606; Food hydrocolloids (2012), 27(1): 161-174. http://dx.doi.org/10.1016/j.foodhyd.2011.07.008. (Texte integral

Multi-scale structure, pasting and digestibility of adlay (Coixlachryma-jobi L.) seed starch

peer-reviewedThe hierarchical structure, pasting and digestibility of adlay seed starch (ASS) were investigated compared with maize starch (MS) and potato starch (PS). ASS exhibited round or polyglonal morphology with apparent pores/channels on the surface. It had a lower amylose content, a looser and more heterogeneous C-type crystalline structure, a higher crystallinity, and a thinner crystalline lamellae. Accordingly, ASS showed a higher slowly digestible starch content combined with less resistant starch fractions, and a decreased pasting temperature, a weakened tendency to retrogradation and an increased pasting stability compared with those of MS and PS. The ASS structure-functionality relationship indicated that the amylose content, double helical orders, crystalline lamellar structure, and surface pinholes should be responsible for ASS specific functionalities including pasting behaviors and in vitro digestibility. ASS showed potential applications in health-promoting foods which required low rearrangement during storage and sustainable energy-providing starch fractions

An assessment of environmental impacts of cassava starch extraction technologies

The environmental impacts of the transformation of cassava roots into starch were assessed for three contrasting technologies at small and large scale (1-2 and 100-200t starch per day), using the Life Cycle Assessment (LCA) methodology. The objective was to assess impacts for each unit operation, so as to identify impacts hotspots as well as sustainable practices, with a view to uncover opportunities for improving the environmental performance of cassava starch production. The system boundaries were defined as the unit operations used to transform fresh cassava roots delivered at factory gate into loose, dry cassava starch. Inventory data indicated wide variations in energy and water consumption. The large scale technology required 702kWh/t starch, mainly (75%) from fuel oil used for the drying operation, but was most efficient in terms of water use (10m3/t starch) due to water recycling between unit operations. The two small scale technologies were similar in terms of electricity use (59kWh/t starch), and relied on solar energy for drying. In contrast, their water consumption varied from 20 to 60m3/t starch due to differences in the design of the rasping and starch recovery (extraction) operations. The LCA characterizations, using the ReCiPe method, indicated that the main impact contributions were at the drying operation for the large scale technology, and at the extraction operation for the small scale technologies, mainly because of energy use, as well as water use in the case of the most water-intensive technology. Hence strategies to reduce the impacts of cassava starch production could focus on: Increasing the energy efficiency of the drying operation or replacing fossil energy with a renewable source (biogas), which can be produced from the factory wastewater; Improving the design of some unit operations with regards to water and energy efficiency; and Promoting the transfer and adoption of water recycling practices. (Texte intégral

Characterization of a partially purified carom (Trachyspermum ammi) extract and its influence on starch functionality and digestibility : a thesis presented in partial fulfilment of the requirements for the degree of Master of Food Technology (MFoodTech) at Massey University (Manawatu Campus), New Zealand

The interactions between starches and the components in spices and herbs have been poorly studied so far. This study investigated the preliminary effects of thirty-six different spices and herbs on pasting properties of rice starch. It largely concentrated on the characterization of a partially purified carom extract (from the dried fruit of the Trachyspermum ammi plant) and its influence on the structural, thermal, pasting properties and digestibility of native rice starch. Rheology, differential scanning calorimetry, size exclusion chromatography coupled with a multi-angle laser light scattering, zeta potential, hot-stage optical microscopy, scanning electron microscopy (SEM), and in-vitro starch digestion analysis were carried out to characterise the carom extract and starch-carom system. The results showed that carom, cumin, fennel, mulberry leaf, perilla leaf, neem and coriander seed extracts showed peak and final viscosity-suppressing effect, while mesona, rosemary, green tea, thyme, and clove extracts showed peak viscosity-enhancing effect on rice starch during starch pasting. The water-soluble fraction of carom had the highest degree of viscosity-suppressing effect as compared to other spices and herbs. With increasing concentration of carom, the peak and final viscosities of rice starch decreased; the onset, peak, and end temperatures of rice starch increased; and granular swelling of potato starch was restricted and delayed. The viscosity-suppressing effect was not caused by pH or small molecular carom compounds such as mineral salts and phytochemicals. A protein polymer in carom extract with an Mw of ~2.08 + 0.10 x 105 Da and isoelectric point of ~3.5 was found responsible for the suppression effect. The protein fraction completely denatured at ~83oC. Micrographs of SEM showed that carom protein appeared as raisin-like clusters. The ability of carom protein to suppress the peak viscosity of starch was also observed in potato, tapioca, glutinous rice, waxy maize, waxy rice, rice, sweet potato, maize, wheat, and pea starches, suggesting that the effect was independent of the source and ratio of amylose to amylopectin. It was proposed that the protein molecules could be interacting with the starch granular surface and/or starch molecules. In-vitro starch digestion study showed that dialysed carom extract with rice starch caused an unusual increment in glucose release. The lower viscosity of the starch-carom gels and/or a carom enzyme stimulatory effect were proposed to be responsible for increasing the rapid breakdown of starch

A comparison between cassava starch production at small-scale in Vietnam and in Colombia

In Colombia and in Vietnam, small-scale cassava starch processing is conducted at similar scales but with contrasted extraction technologies. Based on the methodology of diagnosis previously applied in Vietnam, two set of trials with two different cassava cultivars (var. mper183 and var. algodona) were carried out in a typical processing plant from Northern Cauca in Colombia. Moisture, starch, crude fibres and ash content analysis were carried out on samples collected from the manufacturing process to establish the mass balance of starch. Production capacity, water consumption, electrical requirements and capital-labor costs per tonne of starch (12% moisture) were also reported. The manufacturing process enabled 65% recovery of the starch present in fresh roots, with no significant change observed in the composition of starch for the two varieties. The bottleneck of the manufacturing process occurred at extraction stage were low capacity were observed (0.3 t of peeled roots per hour). Water consumption per ton of starch was 67 m3, in which washing, rasping, and extraction stages accounted for 9, 3, and 42 m3, respectively. Electrical power per tone of starch was 59 kWh, in which, washing, rasping, and extraction stages accounted for 8, 14 and 38 kWh. The comparison proposed in this study allowed to recommend technological options for small-scale cassava processing industries. (Résumé d'auteur

Experimental and modeling studies on the synthesis and properties of higher fatty esters of corn starch

This paper describes a systematic study on the synthesis of higher fatty esters of corn starch (starch laurate and starch stéarate) by using the corresponding vinyl esters. The reactions were carried out in DMSO using basic catalysts (Na2HPO4, K2CO3, and Naacetate). The effect of the process variables (vinyl ester to starch ratio, catalyst intake, reaction temperature and type of the catalyst) on the degree of substitution (DS) of the starch laurate and starch stearate esters was determined by performing a total of 54 experiments. The results were adequately modeled using a non-linear multivariable regression model (R2≥0. 96). The basicity of the catalyst and the reaction temperature have the highest impact on the product DS. The thermal and mechanical properties of some representative product samples were determined. High-DS products (DS = 2.26-2.39) are totally amorphous whereas the low-DS ones (DS = 1.45-1.75) are still partially crystalline. The thermal stability of the esterlfied products is higher than that of native starch. Mechanical tests show that the products have a tensile strength (stress at break) between 2.7-3.5 MPa, elongation at break of 3-26%, and modulus of elasticity of 46-113 MPa.

Starch and oil in the donor cow diet and starch in substrate differently affect the in vitro ruminal biohydrogenation of linoleic and linolenic acids

Trans isomers of fatty acids exhibit different health properties. Among them, trans-10,cis-12 conjugated linoleic acid has negative effects on milk fat production and can affect human health. A shift from the trans-11 to the trans-10 pathway of biohydrogenation (BH) can occur in the rumen of dairy cows receiving high-concentrate diets, especially when the diet is supplemented with highly unsaturated fat sources. The differences of BH patterns between linoleic acid (LeA) and linolenic acid (LnA) in such ruminal conditions remain unknown; thus, the aim of this work was to investigate in vitro the effects of starch and sunflower oil in the diet of the donor cows and starch level in the incubates on the BH patterns and efficiencies of LeA and LnA. The design was a 4 × 4 Latin square design with 4 cows, 4 periods, and 4 diets with combinations of 21 or 34% starch and 0 or 5% sunflower oil. The rumen content of each cow during each period was incubated with 4 substrates, combining 2 starch levels and either LeA or LnA addition. Capillary electrophoresis single-strand conformation polymorphism of incubates showed that dietary starch decreased the diversity of the bacterial community and the high-starch plus oil diet modified its structure. High-starch diets poorly affected isomerization and first reduction of LeA and LnA, but decreased the efficiencies of trans-11,cis-15-C18:2 and trans C18:1 reduction. Dietary sunflower oil increased the efficiency of LeA isomerization but decreased the efficiency of trans C18:1 reduction. An interaction between dietary starch and dietary oil resulted in the highest trans-10 isomers production in incubates when the donor cow received the high-starch plus oil diet. The partition between trans-10 and trans-11 isomers was also affected by an interaction between starch level and the fatty acid added to the incubates, showing that the trans-10 shift only occurred with LeA, whereas LnA was mainly hydrogenated via the more usual trans-11 pathway, whatever the starch level in the substrate, although the bacterial communities were not different between LeA and LnA incubates. In LeA incubates, trans-10 isomer production was significantly related to the structure of the bacterial community

In vitro starch binding experiments: Study of the proteins related to grain hardness of wheat

Two friabilin components, puroindoline a and GSP-1 were expressed in Escherichia coli. Starch binding properties of the recombinant polypeptides and of friabilin extracted from wheat flour were compared in vitro. The produced proteins as well as native wheat friabilin bound to starch granules prepared from different (soft, hard and durum) wheat cultivars. Starch granules also bound specifically several wheat endosperm proteins other than friabilin

Novel cassava starches with low and high amylose contents: Structural and macro-molecular characterization in comparison with other commercial sources

Cassava (Manihot esculenta Crantz) is one of the most important sources of commercial production of starch along with potato, maize and wheat particularly for tropical and subtropical regions of the world. It is the third most important source of calories in tropics, after rice and maize. Natural mutation, and induced ones in cassava starch have recently been reported leading to new starches with low and high-amylose contents (0 and 30-31 %). These mutants are drastically different from normal cassava starch whose amylose content typically ranges between 15-25 %. The aims of this study were to have an overview of the structural variability among the recently discovered cassava mutants comparatively to normal and amylose-free potato and maize starches. The macromolecular features, the crystallinity, the granule sizes, and the thermal properties of these 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. 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 amylopectins show similar molar masses and radii of gyration (from 408×106 g mol-1 to 520×106 g mol-1; and from 277 to 285 nm, respectively). Waxy potato amylopectin exhibit lower molar mass and size. Inversely, 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: molar masses and radii of gyration decreased, while branching degree increased. These modifications resulted in changes in starch granule ultrastructure (lowered 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 these tropical sources of starch. (Résumé d'auteur