China
Africa
Explore chapters and articles related to this topic
Tracers
Published in Werner Käss, Tracing Technique in Geohydrology, 2018
The outer layer of the spore (Exine) is extremely resistant to chemical and microbiological influences. In 1931, Zetzsche and Kälin described this substance and named it sporopollenin, most likely it is an oxidated polymer of carotenolds and their ester. Deposited in sediments, it can survive many million years (KlRCHHElMER 1933). Sporopollenin is most likely the most resistant substance of the entire living world (Faegri & Iverson 1964).
Bionanocomposite Materials and Their Applications
Published in Shrikaant Kulkarni, Ann Rose Abraham, A. K. Haghi, Renewable Materials and Green Technology Products, 2021
One more very common strategy to improve the activity and stability of enzymatic moieties is to entrap it in alginate–silica beads.163 Industrially important reaction of starch hydrolysis was focused upon and elaborated these materials with the help of simple mixing of silica and alginate before the formation of beads.85 Nanocomposite architecture has a substantial effect on the enzyme stability as it has caused the enzyme use in 20 starch hydrolysis operations in succession, to reduce the starch hydrolysis reaction cost.85 One more architecture using alginate beads has also been proposed164 and alginate core–silica shell structure was derived by preparing alginate beads cross-linked with calcium, followed by successive coating of poly-l-lysine and silica. The alginate–silica beads were then treated with citrate ions which acted as a calcium chelating agent, thereby the inner alginate core was left liquefied. The catalytic activity of β-galactosidase for the degradation of 4-nitrophenyl-β-d-galactopyranoside was marginally lower than that of the free enzyme, the beads could be washed and reused exhibiting catalytic activity in semblance.165 An alternative morphology with entrapment of Chromobacterium viscosum lipases in gelatin–silica hardened gels was obtained. The device so resulted catalyzed transesterification of fatty acids into cyclohexane quite efficiently, with 85% product recovery.166 Similarly, Candida rugosa lipases were encapsulated in a biopolymer/silica gel for applications of hydrolysis. The biopolymer chosen was sporopollenin, found in spore membranes, a very potential candidate for encapsulation as it tends to form small cavities. The device exhibited encouraging results, typically in the form of enantioselectivity. The typical use of silica provided for sound mechanical properties as against biopolymer in isolation, prevented leaching of the encapsulate, and presenting a better storage and thermal stability in these examples.
Effects of dielectric barrier discharge (DBD) plasma on the drying kinetics, color, phenolic compounds, energy consumption and microstructure of lotus pollen
Published in Drying Technology, 2022
Jia-Bao Ni, Jia-Shu Zhang, Bhesh Bhandari, Hong-Wei Xiao, Chang-Jiang Ding, Wen-Jun Peng, Xiao-Ming Fang
Drying is an essential processing method to extend the shelf life of bee pollen by inhibiting the growth of microorganisms and biochemical reactions. Further, natural open sun drying is a traditional natural method of drying pollen. The structure of a fresh bee pollen wall is very complex, and its outer layer particles are rich in sporopollenin, which is a stiff, chemically resistant, water-impermeable biomaterial.[7] This is an obstacle to the diffusion of moisture during drying. To accelerate drying and improve the quality of bee pollen, many drying techniques have been developed and applied commercially. Thermal processing including hot air drying, infrared drying, and microwave drying leads to several undesirable quality changes, including browning, oxidation, surface hardening, and product degradation, in the product.[8,9] Vacuum freeze-drying is a drying technique that can avoid the degradation of heat-sensitive components and maintain the biological activity of materials.[10,11] However, the drying equipment is expensive, challenging to operate, and consumes high energy. Therefore, to improve the drying process to minimize color and nutrient losses, it is imperative to explore new techniques for drying bee pollen.
Candida rugosa lipase encapsulated with magnetic sporopollenin: design and enantioselective hydrolysis of racemic arylpropanoic acid esters
Published in Preparative Biochemistry and Biotechnology, 2018
Elif Ozyilmaz, Kubra Etci, Mehmet Sezgin
Sporopollenin, a natural biopolymer, has two layers, intine, and exine. The latter has better structural stability and resistance in a chemical environment, even when in continued contact to minerals and alkalis.[13,14] The sol-gel technique was selected as the method for Candida rugosa lipase immobilization in this study because it has been shown to be a suitable method for most enzyme immobilizations and other biological molecules.[15–17] The most widely utilized silica precursors are tetramethoxysilane (TMOS) or tetraethoxysilane (TEOS).[18] The final structure of the material is identified by the differences in chain length, functionality, and hydrophobic character of the precursors; however, it can be tailored via the addition of other molecules, including surfactants, crown ethers, ionic liquids, beta-cyclodextrins, or calixarene derivatives.[19–23]