•Damaged starch, protein and fiber were effectively removed during starch isolation.•Isolated pulse starches displayed characteristics similar to commercial pea starch.•Pulse starches showed features ...different from commercial maize and tapioca starches.•Amylose content and branch-chain length of amylopectin impact starch functionality.•Cooked pulse, maize and tapioca starches exhibited comparable digestibility.
This study aimed to isolate starches of a high purity from starch-rich pea, lentil and faba bean flours and to characterize and compare the isolated starches with important commercial starches. Isolated pulse starches had a purity of 94.8–97.9% and contained only 0.9–1.1% damaged starch. The isolated pulse starches showed amylose contents and amylopectin branch-chain-length distributions similar to those of commercial pea starch. Therefore, the granular morphologies, crystalline structure, thermal properties, pasting properties, gelling ability and in vitro digestibility of the isolated pulse starches were comparable to those of commercial pea starch but different from those of commercial maize and tapioca starches. The desirable functionality of the pulse starches (e.g., strong gelling ability) renders them suitable for some specific industrial applications, and further modifications can be utilized to enhance their functionality for broader use. This research provided the fundamental knowledge required for future efforts to promote value-added utilization of pulse starches.
Studies in Arabidopsis and rice suggest that manipulation of starch synthase I (SSI) expression in wheat may lead to the production of wheat grains with novel starch structure and properties. This ...work describes the suppression of SSI expression in wheat grains using RNAi technology, which leads to a low level of enzymatic activity for SSI in the developing endosperm, and a low abundance of SSI protein inside the starch granules of mature grains. The amylopectin fraction of starch from the SSI suppressed lines showed an increased frequency of very short chains (degree of polymerization, dp 6 and 7), a lower proportion of short chains (dp 8–12), and more intermediate chains (dp 13–20) than in the grain from their negative segregant lines. In the most severely affected line, amylose content was significantly increased, the morphology of starch granules was changed, and the proportion of B starch granules was significantly reduced. The change of the fine structure of the starch in the SSI-RNAi suppression lines alters the gelatinization temperature, swelling power, and viscosity of the starch. This work demonstrates that the roles of SSI in the determination of starch structure and properties are similar among different cereals and Arabidopsis.
Starch properties can be modified by mutating genes responsible for the synthesis of amylose and amylopectin in the endosperm. However, little is known about the effects of such targeted ...modifications on the overall starch biosynthesis pathway and broader metabolism. Here we investigated the effects of mutating the OsSBEIIb gene encoding starch branching enzyme IIb, which is required for amylopectin synthesis in the endosperm. As anticipated, homozygous mutant plants, in which OsSBEIIb was completely inactivated by abolishing the catalytic center and C-terminal regulatory domain, produced opaque seeds with depleted starch reserves. Amylose content in the mutant increased from 19.6 to 27.4% and resistant starch (RS) content increased from 0.2 to 17.2%. Many genes encoding isoforms of AGPase, soluble starch synthase, and other starch branching enzymeswere up-regulated, either in their native tissues or in an ectopic manner, whereas genes encoding granule-bound starch synthase, debranching enzymes, pullulanase, and starch phosphorylases were largely down-regulated. There was a general increase in the accumulation of sugars, fatty acids, amino acids, and phytosterols in the mutant endosperm, suggesting that intermediates in the starch biosynthesis pathway increased flux through spillover pathways causing a profound impact on the accumulation of multiple primary and secondary metabolites. Our results provide insights into the broader implications of perturbing starch metabolism in rice endosperm and its impact on the whole plant, which will make it easier to predict the effect of metabolic engineering in cereals for nutritional improvement or the production of valuable metabolites.
A high-amylose transgenic rice line (TRS) modified by antisense RNA inhibition of starch branching enzymes revealed a resistant starch-rich quality. Compound starch granules in whole grains of the ...regular rice cultivar Teqing (TQ) were readily split during fracturing, whereas the starch granules in TRS were structurally intact and showed large voluminous, non-angular rounded bodies and elongated, filamentous structures tolerant of fracturing. In isolated preparation, TQ starch granules broke up into separate polygonal granules, whereas TRS starch granules kept their intactness. TRS starch granules consisted of packed smaller subgranules, some of which located at the periphery of starch granules were fused to each other with adjacent ones forming a thick band or wall encircling the entire circumference of the granules. TQ starch granules had a high concentration of amylose in the concentric hilum, whereas TRS starch granules showed a relatively even distribution of amylose with intense amylose in both hilum and band.
PII1 Vandromme, Camille; Spriet, Corentin; Dauvillée, David ...
The New phytologist,
01/2019, Letnik:
221, Številka:
1
Journal Article
Recenzirano
Odprti dostop
The initiation of starch granule formation is still poorly understood. However, the soluble starch synthase 4 (SS4) appears to be a major component of this process since it is required to synthesize ...the correct number of starch granules in the chloroplasts of Arabidopsis thaliana plants.
A yeast two-hybrid screen allowed the identification of several putative SS4 interacting partners. We identified the product of At4g32190 locus as a chloroplast-targeted PROTEIN INVOLVED IN STARCH INITIATION (named PII1).
Arabidopsis mutants devoid of PII1 display an alteration of the starch initiation process and accumulate, on average, one starch granule per plastid instead of the five to seven granules found in plastids of wild-type plants. These granules are larger than in wild-type, and they remain flat and lenticular. pii1 mutants display wild-type growth rates and accumulate standard starch amounts. Moreover, starch characteristics, such as amylopectin chain length distribution, remain unchanged.
Our results reveal the involvement of PII1 in the starch priming process in Arabidopsis leaves through interaction with SS4.
SUMMARY
The initiation of starch granule formation and the mechanism controlling the number of granules per plastid have been some of the most elusive aspects of starch metabolism. This review covers ...the advances made in the study of these processes. The analyses presented herein depict a scenario in which starch synthase isoform 4 (SS4) provides the elongating activity necessary for the initiation of starch granule formation. However, this protein does not act alone; other polypeptides are required for the initiation of an appropriate number of starch granules per chloroplast. The functions of this group of polypeptides include providing suitable substrates (maltooligosaccharides) to SS4, the localization of the starch initiation machinery to the thylakoid membranes, and facilitating the correct folding of SS4. The number of starch granules per chloroplast is tightly regulated and depends on the developmental stage of the leaves and their metabolic status. Plastidial phosphorylase (PHS1) and other enzymes play an essential role in this process since they are necessary for the synthesis of the substrates used by the initiation machinery. The mechanism of starch granule formation initiation in Arabidopsis seems to be generalizable to other plants and also to the synthesis of long‐term storage starch. The latter, however, shows specific features due to the presence of more isoforms, the absence of constantly recurring starch synthesis and degradation, and the metabolic characteristics of the storage sink organs.
Significance Statement
The initiation of starch granule formation and the mechanism controlling the number of granules per plastid have been some of the most elusive aspects of starch metabolism. This review covers the advances made in the study of these processes.
Starches and proteins are two major types of biopolymer components, especially in many flour (starch)-based foods consumed worldwide, which provide energy and nutrition needed by the human body. In ...many such starch-based matrices (the main structural component of such foods), proteins and their interactions with starches greatly influence the matrix structure and properties. Studying the different roles played by proteins (endogenous and exogenous) in various starch-based food systems can provide a frame of reference for the design and production of improved starch-based food products with tailored properties and desirable nutritional functions.
Significant efforts have recently been made to tailor the morphology, structure, and properties of many starch-based food systems, and thus to design various starch-based food products with satisfactory attributes. This review surveys the latest literature on starch-based matrices containing proteins. Discussed are the influences of proteins and their interactions with starches on the morphologies and structures (e.g. short- and long-range orders) of starch-based matrices, as well as on their pasting, thermal, rheological, textural, sensory, and digestive properties. Also, current understandings of structure–property links are presented, along with their implications on the production of various starchy foods (e.g. pastas, breads, cakes, and biscuits), including gluten-free versions.
Proteins in many starchy food matrices can encapsulate the starch phase (or be adsorbed on its surfaces) on a micron scale, and thereby interact with starch chains via both non-covalent (e.g. hydrogen bonding, hydrophobic, and electrostatic) and covalent bonds (e.g. via Maillard reactions). These facts and protein features (e.g. hydration and gelation abilities) can play major roles in inhibiting starch retrogradation (the reassembly of cooked starch chains into ordered structures) and in regulating various other properties of such starch-based matrices, including viscosity, transition temperatures, moduli, hardness, sensory, digestibility, and shelf-life. Despite the fact that the current literature presents considerable information on the structure–property relationships of many different starch-based matrices and their applications in the processing of various starchy foods (e.g. pastas, noodles, and biscuits), it is still highly necessary to define more comprehensive correlations among starch–protein interactions, starch–protein matrix structures, and the resulting properties of such food products.
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•Starch–protein interactions are affected by biopolymer type, proportion, and processing.•Proteins often inhibit starch gelatinization and restrict starch retrogradation.•Proteins affect the textural, sensory, and digestive properties of many starch-based foods.•Understandings that are instrumental to the development of high-quality, healthy foods are reviewed.
► Starches modified by octenyl succinic acid are used extensively in industry. ► Applications include nutritional products and stabilizers. ► Their synthesis, characterization and structure are ...reviewed.
Starches modified with octenyl succinic anhydride (OSA) have been used in a range of industrial applications, particularly as a food additive, for more than half a century. Interest in these products has grown in recent years as a result of new methods and applications becoming available. Due to a combination of OSA's hydrophobic and steric contribution and starch's peculiar highly branched macromolecular structure, these starch derivatives display useful stabilizing, encapsulating, interfacial, thermal, nutritional and rheological properties. We review the synthesis procedures, structural characterization methods and physico-chemical properties, and the influences of the botanical origins and structural parameters of OSA starches on physico-chemical properties. A better understanding of these features has the potential to lead to products with targeted macromolecular structures and optimized properties for specific applications.
•Xanthate and carboxylate groups were attached to the walls of porous starch.•Concentration effect on the adsorption capacity of Pb2+ was investigated.•Adsorption behavior of Pb2+ on modified porous ...starches fit the kinetic models.•Maximum adsorption capacities were 109.1 and 57.6mg/g for these modified starches.
Porous starch xanthate (PSX) and porous starch citrate (PSC) were prepared in anticipation of the attached xanthate and carboxylate groups respectively forming chelation and electrostatic interactions with heavy metal ions in the subsequent adsorption process. The lead(II) ion was selected as the model metal and its adsorption by PSX and PSC was characterized. The adsorption capacity was highly dependent on the carbon disulfide/starch and citric acid/starch mole ratios used during preparation. The adsorption behaviors of lead(II) ion on PSXs and PSCs fit both the pseudo-second-order kinetic model and the Langmuir isotherm model. The maximum adsorption capacity from the Langmuir isotherm equation reached 109.1 and 57.6mg/g for PSX and PSC when preparation conditions were optimized, and the adsorption times were just 20 and 60min, respectively. PSX and PSC may be used as effective adsorbents for removal of heavy metals from contaminated liquid.
•Grain weight of the new mutant lines developed was comparable to that of parent line.•Amylose content of the new lines was 10% higher than that of parent lines.•Amylopectin structure of the new ...lines was similar to the be2b parent line.•RS content of the new mutant lines was the same as or slightly higher than.•be2b.
Resistant starch (RS) is beneficial to human health. In order to reduce the current prevalence of diabetes and obesity, several transgenic and mutant crops containing high RS content are being developed. RS content of steamed rice with starch-branching enzyme (BE)IIb-deficient mutant endosperms is considerably high. To understand the mechanisms of RS synthesis and to increase RS content, we developed novel mutant rice lines by introducing the gene encoding starch synthase (SS)IIa and/or granule-bound starch synthase (GBSS)I from an indica rice cultivar into a japonica rice-based BEIIb-deficient mutant line, be2b. Introduction of SSIIa from an indica rice cultivar produced higher levels of amylopectin chains with degree of polymerization (DP) 11–18 than those in be2b; the extent of the change was slight due to the shortage of donor chains for SSIIa (DP 6–12) owing to BEIIb deficiency. The introduction of GBSSI from an indica rice cultivar significantly increased amylose content (by approximately 10%) in the endosperm starch. RS content of the new mutant lines was the same as or slightly higher than that of the be2b parent line. The relationship linking starch structure, RS content, and starch biosynthetic enzymes in the new mutant lines has also been discussed.
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