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The Biosphere
Published in Stanley E. Manahan, Environmental Chemistry, 2022
Polysaccharides consist of many simple sugar units hooked together. One of the most important polysaccharides is starch, which is produced by plants for food storage. Animals produce a related material called glycogen. The chemical formula of starch is (C6H10O5)n, where n may represent a number as high as several hundreds. What this means is that the very large starch molecule consists of many units of C6H10O5 joined together. For example, if n is 100, there are 6 times 100 carbon atoms, 10 times 100 hydrogen atoms, and 5 times 100 oxygen atoms in the molecule. Its chemical formula is C600H1000O500. The atoms in a starch molecule are actually present as linked rings represented by the structure shown in Figure 21.5. Starch occurs in many foods, such as bread and cereals. It is readily digested by animals, including humans.
Biopolymer Electrolytes for Energy Storage Applications
Published in Prasanth Raghavan, Fatima M. J. Jabeen, Polymer Electrolytes for Energy Storage Devices, 2021
Starch is a polymeric carbohydrate consisting of numerous glucose units joined by glycosidic bonds. It is a polysaccharide and produced by most green plants for energy storage. It is the most common carbohydrate in human diets and is contained in large amounts in staple foods, such as potatoes, wheat, maize (corn), rice, and cassava.
Introduction
Published in Jean-Luc Wertz, Bénédicte Goffin, Starch in the Bioeconomy, 2020
Jean-Luc Wertz, Bénédicte Goffin
Starch must be broken down into glucose before the cells can use it, either as a source of energy or as building blocks for other molecules. This preliminary stage in the breakdown of starch is called digestion. The large polymeric molecules are broken down during digestion into glucose through the action of enzymes. After digestion, glucose enters the cytosol of the cell, where its gradual oxidation begins: glycolysis, the initial stage of glucose metabolism, does not involve molecular oxygen and produces a small amount of ATP and the three-carbon compound pyruvate. In aerobic cells, pyruvate formed in glycolysis is transported into the mitochondria, where it is oxidized by oxygen to carbon dioxide. Through chemiosmotic coupling, the oxidation of pyruvate in the mitochondria generates the bulk of the ATP produced during the conversion of glucose to carbon dioxide. The oxidation of pyruvate involves the citric acid cycle, in which acetyl CoA derived from pyruvate is modified to produce energy precursors in preparation for the next step, and the oxidative phosphorylation, in which ADP is transformed into ATP.
A review on surface modification methods of poly(arylsulfone) membranes for biomedical applications
Published in Journal of Biomaterials Science, Polymer Edition, 2021
Vahid Hoseinpour, Laya Noori, Saba Mahmoodpour, Zahra Shariatinia
In order to enhance the biocompatibility and blood compatibility of poly(arylsulfone)s membranes, many researchers have studied their modification [30,60–64]. Outstanding results have been obtained by employing surface modification methods [1]. Many natural and artificial polymers have been used to modify these biomedical membranes. Natural polymers include gelatin, collagen, silk protein, chitosan, FBG, casein, cellulose, cellulose acetate, carboxymethyl cellulose, and chitin. Biomaterials prepared from natural polymers exhibit superior clinical properties [24,65–71]. In addition to denaturation of natural polymers, there are also other problems in preparation of some natural polymers. Artificial polymers mostly reveal several advantages over natural polymers as they illustrate a broader range of properties such as higher mechanical properties (strength and viscoelasticity), and degradation rates. Natural polymers such as collagen, hyaluronic acid, alginate, FBG, silk protein, starch can be employed in providing nanofibrous biomaterials due to their higher biocompatibility and functional groups. It is notable that blending the natural and artificial polymers with each other can improve the cytocompatibility of the resultant materials [69,72].
Ozone Processing of Cassava Starch
Published in Ozone: Science & Engineering, 2021
Dâmaris Carvalho Lima, Nanci Castanha, Bianca Chieregato Maniglia, Manoel Divino Matta Junior, Carla Ivonne Arias La Fuente, Pedro Esteves Duarte Augusto
Chemical, enzymatic and physical processes are used for starch modification. Chemical modification through acetylation, oxidation, cross-linking, hydroxypropylation and etherification are the most commonly applied (Vanier et al. 2017). However, by using chemical agents, different residues are produced, which can be unsafe for consumers, employees, and/or environment, or, at least, demand treatment and limit “clean labels”. Ozone (O3) is an attractive chemical technology for starch modification because it decomposes into oxygen, leaving no toxic residues in food or environment, and is considered a “green” and “environmentally friendly” technology with “clean label” (2019; Pandiselvam et al. 2017). Starch ozonation is further than a simple oxidation process, once this technology is able to promote important changes in both molecular size and chemical properties, leading to new properties and applications (Castanha, da Matta Junior, and Augusto 2017; Castanha et al. 2019).
Effect of Physicochemical Properties of Native Starches on Cleaning in Falling Film and Plane Channel Flow Experiments
Published in Heat Transfer Engineering, 2022
Sebastian Kricke, Kristin Böttcher, Susann Zahn, Jens-Peter Majschak, Harald Rohm
Starch is a polymeric carbohydrate consisting of α-D-glucose monomers forming two types of molecules, amylose and amylopectin. Amylose is a linear, helical molecule of molecular mass, whose glucose units are connected through α(1→4) glycosidic bonds. In addition to the α(1→4) glycosidic bonds, the amylopectin molecule also contains α(1→6) glycosidic bonds, which form branched clusters. Amylopectin has a molecular mass of Those structural differences result in dissimilar swelling behavior of starches with varying amylose contents, and an increased gel strength and retrogradation of high amylose starches [3]. Amylose also increases the adhesivity of starch [20].