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

Influence of Mucilage Viscosity On The Globule Structure And Stability Of Certain Starch Emulsions

A study was carried out to determine the influence of mucilage viscosity on the globule structure (i.e. size and number) of certain starch emulsions. The starches investigated were cassava, potato and maize. The emulsions were prepared by mixing the starch mucilage of a predetermined concentration 4%w/v with arachis oil in the ratio 50:50, using a silverson mixer fitted with a dispersator head. The emulsions were stored at room temperature (28±20C) for 7 days. Changes in globule size were monitored by photomicroscopy. Viscosities of the mucilage and those of resulting emulsions were determined using a capillary flow method. The viscosities of the emulsions expressed as time of flow (seconds), were 680 (cassava starch), 369 (potato starch) and 270 (Maize starch), and for the mucilage 510 (cassava), 336 (potato) and 248 (maize). The corresponding mean globule sizes of the fresh emulsions were (µm) 28±6, 42±6 and 45±5 respectively. The increase in globule size during storage (measure of globule coalescence rate) was 1.8±0.2µm day -1 (cassava), 3.5±0.2µm day -1 (potato) and 4.6±0.3µm day -1 (maize). Thus, a higher viscosity of the dispersion medium is associated with the production of finer and more stable emulsions

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

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

Factors affecting sorghum protein digestibility

In the semi-arid tropics worldwide, sorghum (Sorghum bicolor (L.) Moench) is cultivated by farmers on a subsistence level and consumed as food by humans. A nutritional limitation to its use is the poor digestibility of sorghum protein when wet cooked. The factors affecting wet cooked sorghum protein digestibility may be categorised into two main groups: exogenous factors (grain organisational structure, polyphenols, phytic acid, starch and non-starch polysaccharides) and endogenous factors (disulphide and non-disulphide crosslinking, kafirin hydrophobicity and changes in protein secondary structure). All these factors have been shown to influence sorghum protein digestibility. More than one factor may be at play at any time depending on the nature or the state in which the sorghum grain is; that is whether whole grain, endosperm, protein body preparation, high-tannin or condensed-tannin-free. It is proposed that protein crosslinking may be the greatest factor that influences sorghum protein digestibility. This may be between ?- and ß-kafirin proteins at the protein body periphery, which may impede digestion of the centrally located major storage protein, a-kafirin, or between ?- or ß-kafirin and a-kafiri

Value Added of Resistant Starch Maize-Based Matrices in Breadmaking: Nutritional and Functional Assessment

The ability of white (W) and yellow (Y) maize flour as basic ingredients to make nutritious and healthy breads meeting functional and sensory standards is investigated. Resistant starch (R) and common wheat flour (WF) were incorporated into formulations as single and associated extra ingredients, and dough machinability, bread nutritional and functional profiles, starch hydrolysis kinetics and keeping behaviour were assessed in blended maize matrices and compared with the maize and wheat flour counterparts. Simultaneous replacement of maize flour samples by R and WF at 40 % significantly modified textural profile, crumb grain features and firming kinetics, and free polyphenol pattern of breads thereof compared to the respective Y or W maize counterparts. Bigger specific volume (+28 % Y-R-WF, +36 % W-R-WF), softer crumb bread (−64 % Y-R-WF, W-R-WF), more aerated structure and homogeneous crumb grain, and lower and slower staling kinetics are observed in composite Y and W maize-based breads, respectively. Nutritional information on maize-based blended breads showed most appealing nutritional quality than WF breads, in terms of lower digestible starch (up to −21 % in Y-R-WF, W-R-WF, WR) and rapidly digestible starch (up to −37 % in W-R-WF), higher slowly digestible starch (up to three times in WR) and resistant starch contents (from five to six times in Y-R-WF, W-R-WF, W-R, Y-R) of medium-high sensorially rated bread matrices. All single and blended maize-based breads can be labelled as high-fibre breads (6 g dietary fibre (DF)/100 g food). According to health-related benefits and prebiotic dosage of resistant starch a daily intake of 100 g of single Y-R, W-R, W-R-WF and W-R-WF provides enough resistant starch to positively affect postprandial glucose and insulin levels, while 170 g covers the amount necessary to enhance health.The authors acknowledge the financial support of the Spanish Institutions Consejo Superior de Investigaciones Científicas (CSIC) and Ministerio de Economía y Competitividad (Project AGL2011-22669) for carrying out this research. The Interdepartamental Centre for Agri-Food Industrial Research (F. Balestra) and the Department of Food Science (D. Ancarani) at Alma Mater Studiorum of University of Bologna granted and funded stages performed at IATA-CSIC.Peer Reviewe

Changes of Weight and in-Kernel Content Values of Maize Hybrids (Occitan, Colomba, DK-471) as a Result of Damaging dy European Corn Borer. Kukorica hibridek (Occitan, Colomba, DK-471) súly- és beltartalmi érték változása a kukoricamoly (Ostrinia nubilalis Hbn.) károsítása következtében.

ÖSSZEFOGLALÁS Vizsgálatunkat 2001-ben két tábla három különböző hibriddel elvetett állományában vizsgáltuk véletlenszerű mintaterek kijelölésével. Első felmérésünket egy 120 ha-os COLOMBA és OCCITAN, míg a második vizsgálatunkat egy 50 ha-os DK-471-es hibrid vegetációjában végeztük. Értékelésünk az egészséges és a károsított növények által nevelt csövek közötti súly-, fehérje, zsír és keményítő tartalom különbségeket célozta meg. A hibridek a kukoricamoly károsítására egyértelmű csosúly-vesztéssel válaszoltak. A COLOMBA zsírtartalmának, míg az OCCITÁN keményítőtartalmának csökkenése szignifikánsan összefüggött a kukoricamoly károsításával. Az eredmények azt mutatták, hogy a fehérje, zsír és keményítő anyagcseréje, beépülése is igazolhatóan zavart szenvedett. Megállapítottuk, hogy lárvaszám növekedése és a hibrid szem- csutka aránya között szoros, szignifikáns kapcsolat van. A lárvakárosítás helye illetve a lárvaszám nagymértékben meghatározza a DK-471-es kukorica hibrid csöveinek súlyát és a szemekbe beépülő alapvető tápanyagok (nyersfehérje, nyerszsír, keményítő) mennyiségét. ABSTRACT The research was conducted in the year 2001 on two fields sown with three different maize hybrids and was based on randomly chosen sample plots. The first survey was carried out on the field sown with hybrids COLOMBA and OCCITAN (total area 120 ha), the second survey was performed on 50 ha of hybrid DK-471. The assessment was focused primarily on the difference between the cobs developed by healthy and damaged maize plants with regards to their weight and the content of protein, fat and starch in the maize kernel. The hybrids unambiguously reacted to infestation by the European Corn Borer by cob weight reduction. The decrease of kernel fat content in the case of COLOMBA and that of the starch content in the case of OCCITAN displayed significant dependence on the degree of infestation by the European Corn Borer. The results of the survey verifiably showed that in both cases either metabolism, or incorporation of protein, fat and starch had experienced disorder. A close link has been ascertained between the growth of larvae population and the kernel-cob rate of the examined hybrids. The distribution and number of larvae significantly affected the weight of maize cobs of hybrid DK-471 and the quantity of the basic nutrient components (raw protein, fat and starch) incorporated in the kernel

In vitro study of dietary factors affecting the biohydrogenation shift from trans-11 to trans-10 fatty acids in the rumen of dairy cows

On the basis of the isomer-specific effects of trans fatty acids (FA) on human health, and the detrimental effect of t10,c12-conjugated linoleic acid (CLA) on cows’ milk fat production, there is a need to identify factors that affect the shift from trans-11 to trans-10 pathway during ruminal biohydrogenation of FA. This experiment was conducted in vitro and aimed at separating the effects of the diet of the donor cows from those of the fermentative substrate, which is necessary to prevent this shift. A total of four dry Holstein dairy cows were used in a 434 Latin square design. They received 12 kg of dry matter per day of four diets based on maize silage during four successive periods: the control diet (22% starch, ,3% fat); the high-starch diet, supplemented with wheat plus barley (35% starch, ,3% crude fat); the sunflower oil diet, supplemented with 5% of sunflower oil (20% starch, 7.6% crude fat); and the high-starch plus oil diet (33% starch, 7.3% crude fat). Ruminal fluid of each donor cow was incubated for 5 h with four substrates having similar chemical composition to the diets, replacing sunflower oil by pure linoleic acid (LA). The efficiency of isomerisation of LA to CLA was the highest when rumen fluids from cows receiving dietary oil were incubated with added LA. The shift from trans-11 to trans-10 isomers was induced in vitro by high-starch diets and the addition of LA. Oil supplementation to the diet of the donor cows increased this shift. Conversely, the trans-10 isomer balance was always low when no LA was added to incubation cultures. These results showed that a large accumulation of trans-10 FA was only observed with an adapted microflora, as well as an addition of non-esterified LA to the incubation substrate

Sequence-specific protein aggregation generates defined protein knockdowns in plants

Protein aggregation is determined by short (5-15 amino acids) aggregation-prone regions (APRs) of the polypeptide sequence that self-associate in a specific manner to form beta-structured inclusions. Here, we demonstrate that the sequence specificity of APRs can be exploited to selectively knock down proteins with different localization and function in plants. Synthetic aggregation-prone peptides derived from the APRs of either the negative regulators of the brassinosteroid (BR) signaling, the glycogen synthase kinase 3/Arabidopsis SHAGGY-like kinases (GSK3/ASKs), or the starch-degrading enzyme alpha-glucan water dikinase were designed. Stable expression of the APRs in Arabidopsis (Arabidopsis thaliana) and maize (Zea mays) induced aggregation of the target proteins, giving rise to plants displaying constitutive BR responses and increased starch content, respectively. Overall, we show that the sequence specificity of APRs can be harnessed to generate aggregation-associated phenotypes in a targeted manner in different subcellular compartments. This study points toward the potential application of induced targeted aggregation as a useful tool to knock down protein functions in plants and, especially, to generate beneficial traits in crops