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Graphene from Honey
Published in Amir Al-Ahmed, Inamuddin, Graphene from Natural Sources, 2023
One of the most appealing nanomaterials is graphene, a two-dimensional (2D) carbon atoms layer stuck through sp2 bonding [1]. Various methods for processing graphene have been developed over the years, including ultrasonic exfoliation [2, 3], chemical vapor deposition (CVD) [4], epitaxial growth [5], and chemical reduction of graphene [6]. Scientists used a variety of aqueous phytoextracts to reduce graphene oxide as reducing agents. Different naturally derived procedures are widely available to reduce graphene from graphite because of its less toxic [7], eco-friendly [8], and nonhazardous nature [9]. The plant extracts contain a high concentration of phenolic compounds such as vanillic acid, caffeic acid, gallic acid, protocatechuic acid, salicylic acid, chlorogenic acid, and others, as well as a high concentration of OH group, which provide them with slight reducing activities [10, 11]. Graphene is commercially produced from graphite in the form of multilayer nanoplates. The best quality graphene is monolayer, but it is not easy to produce.
An Overview of Cocoa and the Coffee Industry
Published in Hii Ching Lik, Borém Flávio Meira, Drying and Roasting of Cocoa and Coffee, 2019
Ching Lik Hii, Flávio Meira Borém
Coffee contains caffeine (methylxanthine) which can help in increasing alertness, energy and ability to concentrate. Coffee accounted for almost all the caffeine consumed by adults (80.6%) followed by tea (12.3%) and soft drinks (5.9%) (Messina, 2015). However, consumption of 1–3 cups of coffee per day is recommended and not exceeding 5 cups daily (Nehlig, 2004). Epidemiological studies have reported that caffeine could have a preventative effect on the likelihood of developing Alzheimer’s disease (Arendash et al., 2009) and an inverse correlation between coffee consumption and the incidence of cancers (bladder, breast, buccal and pharyngeal, colorectal, endometrial, esophageal, hepatocellular, leukemic, pancreatic and prostate cancers) has been observed (Yu et al., 2011). Similar to cocoa, coffee contains antioxidants which are beneficial to human health. The predominant phenolic compounds in coffee are such as hydroxycinnamic acid, and the major component of this class is caffeic acid which mainly occ urs as esters known as chlorogenic acid (George et al., 2008). It was reported that between 15–325 mg of chlorogenic acid is available based on 10 g of coffee per cup (Nardini et al., 2003).
Assessment of Agricultural Wastes as Biosorbents for Heavy Metal Ions Removal from Wastewater
Published in Girma Biresaw, K.L. Mittal, Surfactants in Tribology, 2017
Nabel A. Negm, Hassan H.H. Hefni, Ali A. Abd-Elaal, Girma Biresaw, K.L. Mittal
Coffee is rich in phenolic acids such as caffeic, ferulic, and quinic acids. Phenolic acids are polyphenols and possess antioxidant properties. A 2009 study by Simões et al. [67] suggests that the caffeic acid in coffee may possess anticarcinogenic properties as well.
Black locust flowers: antioxidant extraction kinetics, reducing capacity, mineral composition, and antioxidant activity
Published in Chemical Engineering Communications, 2022
Ivana A. Boskov, Ivana M. Savic Gajic, Ivan M. Savic, Boban R. Spalovic, Nada D. Strbac
The different extracts of black locust flowers were prepared by advanced extraction technique (UAE) and using the solvents with increasing polarity estimated based on the dielectric constants. The different polarities were achieved by the addition of water in pure methanol and ethanol. The two mathematical models were used to define the kinetical parameters that can describe the extraction of antioxidants from black locust flowers. Based on the described extraction kinetics of antioxidants, it is possible to scale up the process from the laboratory level to the industrial level. The saturation in antioxidants yield was achieved after 60 min of UAE. Based on the FCR, it can be concluded that the higher polar solvents (the mixtures of water and alcohol) were more effective for the extraction of antioxidants. The increase in the solvent polarity leads to enhance the antioxidant activity of the extract. Based on the carried out analysis, it was confirmed that the antioxidant activity of the extract most originates from caffeic acid. Using the HPLC method, most polyphenols were identified in the aqueous extract so that it can be safely consumed. One more confirmation that the prepared extracts are safe for use was confirmed after ICP-OES analysis. The presence of heavy metals (Pb, Cd, Sr) was very low so that the prepared extracts have the ability of further potential application in pharmaceutical or cosmetic purposes.
Microencapsulation of caffeic acid and its release using a w/o/w double emulsion method: Assessment of formulation parameters
Published in Drying Technology, 2019
The application of natural and biologically active compounds as functional ingredients in cosmetics has been gaining significant interest over synthetic functional ingredients in the past few years [1, 2]. Nowadays, the consumers of cosmetics are increasingly concerned about the skin damage by oxygenation. The skin is the first and the most important external barrier that protects the human body from illness, acting against radical-chain oxidation from different sources such as smokes, pesticides, radiations among others [2]. Therefore, antioxidants have been used in anti-oxygenation therapy, delaying radical-chain reactions, helping skin reparation and skin cells rejuvenation [3, 4] as well they may prevent the natural oxidation of cosmetic formulations. Additionally, skin-cancer may be prevented. The key feature of antioxidant molecules is their physicochemical properties as they can oxidize themselves instead of other vital molecules or delay this process of oxidation [5, 6]. Among antioxidants, caffeic acid (CAF) (3,4-dihydroxycinnamic acid) is a simple phenolic acid with proven antioxidant, antibacterial and fungicide properties [7–10]. It has been isolated from several plants as coffee tree (Rubiaceae family, genus Coffea) [11], Melissa officinalis, Ilex paraguariensis, Achyrocline satureioides and Baccharis genistelloides [12, 13]. It is also reported other important bioactive properties of CAF as an anti-inflammatory, anti-cancer and even anti-acquired immunodeficiency syndrome bioactive ingredient [12, 14, 15]. It is also described as possessing increased antioxidant capacity compared to other antioxidants. This is due to the delocalization of the unpaired electrons in the conjugated side chain [12, 16] and to the stabilization given by the hydrogen bond formation when the ortho-dihydroxyl group is used after the O–H breaking [12, 17]. Aladedunye et al. [18] described that the increased antioxidant activity of CAF is associated to the o-quinone formation and the regeneration of CAF by semiquinone primarily radical produced through the reaction of antioxidant and the free radical present in the medium.
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
Conversely, most soluble phenolic compounds are present in the vacuoles of plant cells and the insoluble-bound phenolic compounds are located in the cell wall matrix. As shown in Figure 5, microstructure of lotus pollen revealed that DBD plasma drying exerted an electroporation effect, which indicated that the integrated cell wall structure of lotus pollen had been destroyed to release additional phenolic compounds. The skeleton of cell membrane is the key part of cell membrane perforation. When the membrane perforation occurs under the action of low voltage (about 16 kV or less), the membrane pore will be smaller than the size of the skeleton of the membrane, so only the interaction force between phospholipid molecules and phospholipid molecules limits the expansion of the membrane pore. When the electric field is canceled, the interaction force will self-repair the membrane pore. If the electric field intensity is very high (about 24 kV or more), the aperture of the cell membrane perforation reaches the size of the skeleton or larger than that of the skeleton, only part of the cell membrane pore can be repaired, and some of them cannot be repaired, thus causing irreversible cell membrane perforation. As shown in Figure 9, ferulic acid formed dihydroxyphenylpropionic acid via the dehydrogenation and demethylation reactions. Thereafter, the latter underwent dehydroxylation to produce hydroxyphenylpropionic acid. Ferulic acid formed caffeic acid by demethylation. Similarly, vanillic acid formed protocatechuic acid via the demethylation reaction.[40] Notably, no demethylation reaction occurred in the DBD plasma drying process because protocatechuic and caffeic acids were not detected in the fresh and dried samples. The results indicated that ferulic acid was oxidized by ozone generated in the process of DBD discharge, which undergoes the oxidative dehydrogenation reaction to produce vanillic acid. Generally, the increase in the electric field voltage was accompanied by increased oxidation, which promoted the conversion of additional ferulic acids into vanillic acid. In general, under the conditions of this study, although the ozone and other chemically active ions produced by DBD convert ferulic acid into vanillic acid and have a positive effect on the content of sinapic coumaric acid, it has a certain negative effect on the total content of phenolic acid. Therefore, the work and failure of ozone produced by DBD need to be further studied.