Physicochemical Properties of Edible Seed Hemicelluloses

Abstract

In this work, galactomannans and xyloglucans were isolated from the seed endosperm and cotyledon of Brazilian non-conventional sources, respectively. Extraction yields, monosaccharide ratios, macromolecular parameters and molar mass distributions were determined and compared to commercial guar gum and Locust Bean Gum (LBG). The extraction yield in relation to seed mass ranged from 7.0% to 40.63%, with xyloglucan yields being higher than galactomannan yields. Schizolobium parahyba and Caesalpinia pulcherrima galactomannans exhibited the lowest protein contents, 0.05% and 0.08%, respectively. Flow curves of 1% hemicellulose solutions (w:v) were measured by varying the shear rate from 0.1 to 100 s −1 . The resulting data were fitted to a Power Law model, and all the hemicelluloses presented shear-thinning behavior. Galactomannans and xyloglucans with different monosaccharide ratios showed similar consistency indices. Rheological properties were also compared, and the results suggest new hemicellulose sources, which can be studied for additional applications in areas such as materials science, medicine and biology.

Histochemical approach of the mobilization of reserve compounds in germinating coffee seeds

“…Hemicelluloses have both structural and storage roles in the analyzed seeds, and is a typical feature of the coffee bean, which has part of its reserve material stored in the walls of endosperm cells.. Hemicelluloses can account for ca. 40-60% of the dry weight of seeds and consist mainly in galactomannans and arabinogalacturonnan proteins (Clifford, 1985;Sousa et al, 2017).…”

Advanced material applications of starch and its derivatives

“…Native starch granule is composed of amylose, a linear glucose chain attached by α-1,4 glucosidase bond, and amylopectin, a branched glucose chain with branching at α-1,6 postition [6]. Many studies have shown that the amylose-amylopectin ratio affects the functionality and chemical properties of starch as a biopolymer [8,14].…”

“…Starch has A, B and C crystal structures, which is a function of its origin. In general, it has a small granule size and comes in various shapes based on the source [6]. The granule is composed of anhydroglucose units linked by α-1,4 glycosidic bonds to form amylose and amylopectin polymer entities.…”

“…It accounts for the amorphous structure in the starch granule. Amylopectin, on the other hand, has a higher molecular weight averaging about 1 x 10 8 g/mol and linked by short α-1,4 glycosidic bonds with [21,22] high branching at the α-1,6 positions that account for the crystallinity in starch [6,23]. The branching of amylopectin polymer creates double helix of approximately 5nm length in the starch granule that aligns in the crystalline region [24].…”

“…Among the natural materials, starch is one of the least expensive polysaccharides with a huge potential for solid plastic and other functional polymer applications. Starch, the focus of this work, is a polysaccharide synthesized by plants and found mainly in cereals, roots tubers, fruits and legumes in the range of 25-90% [6,7]. It is a semi-crystalline polymer comprised of about 1,000-2,000,000 anhydroglucose units (AGU) linked by α-1,4 glycosidic bonds [8].…”