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Halogenated Hydrocarbons: Persistence, Toxicity, and Problems
Published in Richard J. Sundberg, The Chemical Century, 2017
The ability to produce chlorine economically by electrolysis (see Topic 4.1) led to methods for chlorination of hydrocarbons. The chlorinated compounds found several large-scale applications. One of the most widely disseminated uses of halogenated solvents is in dry-cleaning. Industrial degreasing and cleaning of electronic components was also an important use. Other uses included “blowing” of polymeric foams and in pressurized aerosol cans. Among the most widely used solvents was dichloromethane (CH2Cl2, also known as methylene chloride) which for many years was the main solvent for decaffeination of coffee (see Section 9.4).
Online measurement of dissolved oxygen in shake flask to elucidate its role on caffeine degradation by Pseudomonas sp.
Published in Indian Chemical Engineer, 2022
Manoj Kumar Shanmugam, Sundarajan Sriman, Sathyanarayana N. Gummadi
Previously, we have isolated Pseudomonas sp. which grows by utilising caffeine as sole carbon source and this strain showed to degrade caffeine at the highest rate ever reported [16]. This strain degrades caffeine through a sequential demethylation pathway which leads to the formation of theobromine, 7-methylxanthine, and xanthine as intermediates. Theobromine (3,7-Dimethyl xanthine) is a multifaceted drug which has an antitussive, anti-adipogenic effect and anti-oxidant activities [17–19]. It has been reported that the conversion of caffeine to theobromine by induced cells of Pseudomonas sp can be enhanced by cobalt salt [20]. It has been identified that caffeine demethylation, which is more predominant in bacterial decaffeination, is catalyzed by a series of oxidoreductase enzymes. These enzymes oxidatively remove the methyl group from caffeine and their intermediate methylxanthines with the formation of formaldehyde and water as by-products [21]. It has also been reported that oxygen is very crucial for this process [22,23]. In this study, we determine the role of DO availability using the SFR vario on caffeine degrading potential as well as theobromine production by induced cells of Pseudomonas sp.
Microencapsulation of antioxidant phenolic compounds from green coffee
Published in Preparative Biochemistry and Biotechnology, 2019
Nivas M. Desai, Devendra J. Haware, K. Basavaraj, Pushpa S. Murthy
The total phenolic content of the green coffee extract was 12.78 ± 2.1 mg GAE g −1 and corroborates the reported values by others.[15] The decaffeination was successfully achieved using a GRAS ethyl lactate and caffeine accounted to 0.9 ± 0.2mg g−1. The extraction yield of green coffee extract was 23 ± 2%. The proximate analysis of GCE revealed to contain significant amounts of crude proteins (220 ± 12 mg g−1), 5 ± 1 mg g−1 of crude fiber, 70 ± 5 mg g−1 of ash, 380 ± 10 mg g−1 of carbohydrates, with a calorific value of 991.6 ± 14 Joules (Table 1). Minerals present in GCE (Table 1) are essential micronutrients for human health and regulate multiple metabolic and physiological functions of the human body including hormonal and enzymatic activities, electrolyte balance, and average growth.[16,17]
The Green Chemistry Initiative’s contributions to education at the University of Toronto and beyond
Published in Green Chemistry Letters and Reviews, 2019
Alexander E. Waked, Karl Z. Demmans, Rachel F. Hems, Laura M. Reyes, Ian Mallov, Erika Daley, Laura B. Hoch, Melanie L. Mastronardi, Brian J. De La Franier, Nadine Borduas-Dedekind, Andrew P. Dicks
As a second example, Chemistry: Physical Principles (CHM 135H) and Introductory Organic Chemistry I (CHM 136H) are two U of T first-year undergraduate classes with a combined enrollment of 1600 life science and health science students per year. Content slides have been developed by a GCI member via the CTFP that highlight the Twelve Principles of Green Chemistry (including fundamental toxicology concepts), with a corresponding list of topics for the instructor to discuss with the class. This material will be implemented in each course during the near future. With a focus on real-world examples, these slides provide students with a means to visualize green chemistry approaches, which aids in knowledge retention. A sample slide for course CHM 135H describing use of supercritical carbon dioxide (scCO2) as a solvent in the textile dyeing industry is shown in Figure 2. Both solvent recyclability and the application of carbon dioxide as a renewable feedstock are introduced, culminating with the decaffeination of coffee to provide contextualization. As these examples illustrate, the CTFP program has proved an effective mechanism to introduce green chemistry content into undergraduate curricula via collaboration with the GCI.