Synthesis and properties of composites of starch and chemically modified natural rubber

A means is developed for forming polysaccharide-based composites with useful material properties through use of unmodified and chemically modified natural rubber latex (NRL). Starch was used as a model for polysaccharides. The NRL was modified by grafting with dimethylaminoethyl methacrylate (DMAEMA) to form a latex with cationic water-soluble polymeric “hairs” of polyDMAEMA, which should form hydrogen bonds with starch. Starch solutions, containing 20% glycerol as a film-forming aid, and the modified NRL were mixed and films allowed to form. The unmodified latex acted only as filler in the starch films, but with modified NRL, the mechanical properties of the films were significantly altered. The elastic modulus was greatly decreased and strain at break greatly increased. The glass transition temperature increased from –48°C to –32°C, suggesting significant compatibilization. Freeze-fracture TEM micrographs indicate strong interactions between the surface of the modified NRL and starch. The polyDMAEMA chains are more hydrophilic than the starch, and the addition of grafted latex results in a 20° drop of the water contact angle of the formed film, and a 25% increase of the water absorption compared to the native starch; with unmodified NRL, the opposite effect was observed

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

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

Pengaruh Perlakuan Sodium Tripolyphosphate (Stpp) Pada Pati Sagu Termodifikasi Terhadap Ketebalan, Transparansi Dan Laju Perpindahan Uap Air Edible Film

The use of native starch in production the edible film have weakness characteristic is vulnerable. Therefore, modified of the starch was necessary improved the functional properties of native starch. The purpose of this research was to determined the best of modified starch with concentrations of sodium tripolyphosphate (STPP) in making modified starch as raw material for edible film. This research used Completely Randomized Design (CRD) with four treatments and four replication followed by DNMRT test at 5%. The treatments in this research was S1 (STPP 0%), S2 (STPP 0.5%), S3 (STPP 1,0%) and S4 (STPP 1.5%). The resultsshowed that the use of modified starch in a different concentration of sodium tripolyphosphate (STPP) with has significant affected on the transparency, water vapor transmission rate, tensile strength and elongationhowever not significant affected on the thickness. The best treatment edible film of modified starch in a different concentration of sodium tripolyphosphate (STPP) in this research was S4 (STPP 1.5%) with thickness 0.0822 mm, transparency of the value 3.3110, water vapor transmission rate 22.7418 g /m2/h, tensile strength 1.7706 MPa, and elongation 19.3269%

Native and modified starches as matrix for edible films and covers

Among the natural n-polymers for to elaborate edible films is the starch. Though, it by itself can not to develop the satisfactory functional properties to produce an adequate film. Native starches have several drawbacks associated to their hydrophilic properties that limit its function as barrier The plasticizers, improves the characteristics and properties of the films, in addition it has been used native starch reinforced with non- starchy components, as palliative. However, a best solution could be the use of modified starch, which help them to reach those barrier properties that making them applicable to the function desired. Films from cross linked starch tend to be permeable to water vapor and have higher hydrophilic properties, which increased its thickness, permeability, solubility, and stability in acidic and alkaline medium. Acetylated starch- based films shown stability to the decomposition by temperature, but are sensible to degradation. Starch dual modified have produced films with strong tensile strength, elongation at break and solubility, while the transparency value decrease. The sequence of duality of modification procedure also has impact on the structure of the films. The chapter complicates and discusses the aspect regards to the use of modified starch as matrix for to produce films and coating

Modification of Pea Starch and Dextrin Polymers with Isocyanate Functional Groups

Pea starch and dextrin polymers were modified through the unequal reactivity of isocyanate groups in isophorone diisocyanate (IPDI) monomer. The presence of both urethane and isocyanate functionalities in starch and dextrin after modification were confirmed by Fourier transform infrared spectroscopy (FTIR) and C-13 nuclear magnetic resonance (C-13 NMR). The degree of substitution (DS) was calculated using elemental analysis data and showed higher DS values in modified dextrin than modified starch. The onsets of thermal degradation and temperatures at maximum mass losses were improved after modification of both starch and dextrin polymers compared to unmodified ones. Glass transition temperatures (T-g) of modified starch and dextrin were lower than unmodified control ones, and this was more pronounced in modified dextrin at a high molar ratio. Dynamic water vapor sorption of starch and dextrin polymers indicated a slight reduction in moisture sorption of modified starch, but considerably lower moisture sorption in modified dextrin as compared to that of unmodified ones.Reza Hosseinpourpia and Stergios Adamopoulos thank VINNOVA, Swedish Governmental Agency for Innovation Systems (VINNMER Marie Curie Incoming project, grant No. 2015-04825). Arantzazu Santamaria-Echart and Arantxa Eceiza wish to acknowledge the financial support from the Basque Government in the frame of Grupos Consolidados (IT-776-13) and SGIker from the University of the Basque Country for their Technical support

Variasi Penambahan Pati Sagu Termodifikasi Hmt (Heat Moisture Treatment) Terhadap Sifat Sensori Mi Sagu Instan

The objectiveof this research were to produce instant noodles made from nature sago starch and sago starch modified by heat moisture treatment and to get the best sensory properties that meets the Indonesian instant noodle standard (SNI 01- 3551- 2000). The design used in this study were completely randomized design with 5 treatments and 4 replications. The treatment were the ratio between nature sago starch and sago starch modified by heat moisture treatment. The data obtained were statistically analyzed using analysis of variance (ANOVA) and followed by a test using Duncan\u27s New Multiple Range Test (DNMRT) at the level of 5%. The results showed, that variation ofnature starch sago and sago starch modified by heat moisture treatment significanly affected organoleptic test except taste, that meets the Indonesian instant noodle standard (SNI 01- 3551- 2000). The best sensory propertis are in treatment according to descriptive test of ratio nature sago starch and sago starch modified by heat moisture treatment 1:1 is less colored brown to slightly brown, not flavored sago, slightly chewy texture, whille the hedonic test assessed according to the likes of panelist

Understanding the digestibility and nutritional functions of rice starch subjected to heat-moisture treatment

In this study, rice starch with well-controlled digestion resistibility achieved by heat-moisture treatment (HMT) was chosen as a supplementary diet for high-fat-diet-fed mice. Then, the nutritional functions of HMT-modified rice starch were evaluated by the physiological and biochemical indices, proliferation and distribution of intestinal microflora, and functional diversity by putative metagenomes analysis. Compared with the native-rice-starch mice (DM) group, the blood glucose, serum lipid, oxidative stress, and liver function metabolic levels/indices of the HMT-rice-starch mice (HMT-DM) group were worse due to the declined level of slowly digestible starch (SDS) in HMT-modified rice starch. Meanwhile, the species diversity index was observed to be higher in the DM group and Bifidobacteria was identified as a type of bacteria related to the relatively higher content of RS in HMT-modified rice starch. Overall, our results provide important information for the rational design of rice starch-based health-promoting foods with nutritional functions