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Applications of marine polysaccharides in food processing
Published in Antonio Trincone, Enzymatic Technologies for Marine Polysaccharides, 2019
Alginic acid has a molecular formula of (C6H6O6)n, where the value of n varies from 80 to 83; alginic acid has a maximum molecular weight of 200 kDa. It contains units of d-mannuronic acid (M) and l-glucoronic acid (G). The polymeric linear structure of alginic acid consists of β-(1-4)-linked d-mannuronic acid (M), and α-(1-4)-linked l-guluronic acid (G) residues. The blocks are composed of consecutive G residues (GGGGGG…), consecutive M residues (MMMMMM.,), and alternating M and G residues (GMGMGM…). The ratio of d-mannuronic to l-glucoronic acids in alginic acids varies with the type, age, and location of the seaweed and according to which portions of the seaweed are used (Draget et al. 2005; Venugopal 2011a).
Protein- and Polysaccharide-Based Nanoparticles
Published in C. Anandharamakrishnan, S. Parthasarathi, Food Nanotechnology, 2019
S. Priyanka, S. Kritika, J.A. Moses, C. Anandharamakrishnan
Alginates are natural polymeric substances obtained from brown seaweed, which is also known as marine kelp. Commercially, alginate production involves an alkaline extraction process. It is an anionic polymer and forms a gel in the presence of divalent cations such as Ca2+. The industrial application of alginates is extensive, mainly as stabilizers and thickeners. Structurally, alginates consist of α-L-guluronic acid and β-D-mannuronic acid lin early linked by 1–4 linkages. Epimerase interconversion of mannuronic acid to guluronic acid leads to the formation of urinates (Panikkar and Brasch, 1996). The physical properties of alginates are governed by the concentration of cross-linking cation, molecular weight of the polymer, composition, and arrangement of uronate residues (Draget et al., 1990).
Bioartificial organs
Published in Ronald L. Fournier, Basic Transport Phenomena in Biomedical Engineering, 2017
An example of the microencapsulation approach was described by Soon-Shiong (1994) and demonstrated in large animals and several human patients. They used an alginate-poly-l-lysine encapsulation system. Alginates are natural polymers composed of the polysaccharides mannuronic acid and guluronic acid. Soon-Shiong (1994) showed that the high mannuronic acid residues in the alginate are responsible for the fibrotic response. Mannuronic acid was shown to induce the lymphokines IL-1 and tumor necrosis factor, which are known to promote the proliferation of fibroblasts and lead to fibrotic capsule formation. By reducing the alginate’s mannuronic acid content and increasing the guluronic acid content (>64%), they were able to minimize the fibrotic response. The higher guluronic acid content also provided another benefit. It was found that alginates with higher guluronic acid contents were mechanically stronger.
Recent advances in microbeads-based drug delivery system for achieving controlled drug release
Published in Journal of Biomaterials Science, Polymer Edition, 2023
Zafar Khan, Mohammed A.S. Abourehab, Neha Parveen, Kanchan Kohli, Prashant Kesharwani
These are isolated from brown sea wood using a dilute alkaline solution which solubilizes the alginic acid present in alginates [44]. Alginic acid is made up of linear polymer of D-mannuronic acid and L-guluronic acid that are arranged as blocks in the polymeric chain. Alginic acid when reacts with sodium hydroxide gets converted into sodium alginate[45]. Naturally occurring alginate polymers possess several favorable properties like its accessibility, pH sensitive hydrogels forming capability and the lack of toxicity [46]. Sodium and calcium salts of alginic acid are considered as non-hazardous and biocompatible. Over 200 different grades are available commercially. A variety of impurities including heavy metals, proteins and endotoxins were present in alginates as they are naturally obtained [47]. For parenteral use these impurities should be removed. Ultrapure grades of alginates have low pyrogenicity and combination with other drugs as implants may be used [48].
Differences in exopolysaccharides of three microbial aggregates
Published in Environmental Technology, 2022
Fan Yang, Hanxiang Li, Shuai Wang, Fan Zhao, Fang Fang, Jinsong Guo, Man Long, Yu Shen
The FTIR peaks of exopolysaccharides of the three microbial aggregates are similar, indicating that the samples contain the same type of chemical functional groups, but the relative content of functional groups is significantly different. 3287 and 2883 cm–1 are the characteristic absorption peaks of polysaccharides. The vibration at 3287 cm–1 represents the stretching vibration of O–H. O–H is a hydrophilic group and the main functional group that is electronegative in polysaccharides [46]. In this study, the O–H content of exopolysaccharides in granular sludge was the highest. The absorption peak near 2883 cm–1 represents C–H vibrations in alkane organics and polysaccharide molecules [47]. C–H is a hydrophobic structure, and its peak is the highest in granular sludge. The absorption peak near 1646 cm−1 is the characteristic infrared absorption of polysaccharides [48]. The peak near 1240 cm–1 is attributed to O-acetyl groups [49], and the O-acetyl content of exopolysaccharides of granular sludge is the highest. The peak at 1446 cm–1 is attributed to uronic acid [50], and 961 cm–1 is the characteristic peak of guluronic acid [51]. These compounds are the key components of polysaccharide gel formation [51]. The contents of these exopolysaccharides in granular sludge are also significantly higher than those in activated sludge and biofilms. This high content facilitates the cross-linking of polysaccharides to form gels and promotes aggregation. (Figure 5).
Urban wastewater treatment by microalgae, bacteria and microalgae–bacteria system (Laboratory-scale study)
Published in Urban Water Journal, 2022
Masoud Noshadi, Rouhollah Nouripour
Alginate is a polysaccharide that extracted from brown algae and there are two compounds α-L-guluranicacid and β-D- mannuronicacid in their structures, which they are placed in the form of multi-polymer linear blocks. These blocks are different based on the size and presence of M, Mannuronic acid, or G, Guluronic acid. The ratio of M to G in alginates affects its viscosity. The greater values of this ratio indicate that the gel is softer and vice versa. This ratio and the overall structure of the alginate, however, depends on species of algae that alginate extracted from it. The sodium ions (Na+) exists in the structure of both compounds. In general, the monovalent cations simply replaced by two or more capacity cations. The tendency of cations for replacement is as follow: