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Industrial Oleochemicals from Used Cooking Oils (UCOs)
Published in Subhas K. Sikdar, Frank Princiotta, Advances in Carbon Management Technologies, 2021
A deep understanding of the chemical changes that occur during the frying process is fundamental in comprehending the nature of used cooking oils and defining the required upgrading processes, operating conditions, potential valorization routes, and their final uses. During oil frying, most chemical reactions occur by interaction with the carboxylic moiety and the unsaturations of the fatty acid chains (De Alzaa et al., 2018). Water from food and the evolved steam can hydrolyze the ester bonds, producing partial glycerides (i.e., monoglycerides (MG) and diglycerides (DG), free fatty acids (FFAs) and glycerol (G)). Due to hydrolysis, the acidity of the oil increases over time, thus, the FFA content in the oil is an important quality factor and a good indicator of the degree of use of a frying oil.
Biomolecules and Complex Biological Entities
Published in Simona Badilescu, Muthukumaran Packirisamy, BioMEMS, 2016
Simona Badilescu, Muthukumaran Packirisamy
All fats and oils are composed of esters of fatty acids with glycerol called glycerides or acylglycerols. Glycerol (1,2,3-trihydroxy propane) is an alcohol that contains three hydroxyl groups (OH). Glycerol can combine with up to three fatty acids to form monoglycerides, diglycerides, and triglycerides. The reaction is called esterification. Animal fats are solid because of the large percentage of saturated fatty acids, while oils originate mostly in plants, consist of unsaturated fatty acids, and are liquid at room temperature. The formula of a mixed triglyceride formed from two molecules of unsaturated acids (oleic) and one saturated one (palmitic) is shown in Figure 3.22.
Organic Oils and Fats
Published in John Mark, Roger Strange, Jim Burns, The Food Industries, 2020
John Mark, Roger Strange, Jim Burns
Oils and fats are chemically very similar, the difference between them being that oils are liquids at normal temperatures (i.e. around 20 degC), whereas fats are normally solids or plastic semi-solids at similar temperatures. Edible fats and oils are known chemically as "glycerides", and are composed of the elements carbon, hydrogen and oxygen — hence the use of the term "organic". All glyceride molecules consist of glycerol to which are attached three fatty acid molecules. It is the nature of these latter molecules that determine the characteristics of the fat or oil.
The critical techno-economic aspects for production of B10 biodiesel from second generation feedstocks: a review
Published in International Journal of Sustainable Energy, 2022
Timothy Tibesigwa, Peter Wilberforce Olupot, John Baptist Kirabira
Several studies show that transesterification is the most common and widely accepted technology of biodiesel production and is presently one of the most attractive techniques. Transesterification (alcoholysis) is a chemical reaction that involves reaction of triglycerides and alcohol in the presence of a catalyst to form esters and glycerol. This process involves three consecutive reversible reactions; the conversion of triglycerides to diglycerides, followed by the conversion of diglycerides to monoglycerides. Glycerides are converted into glycerol, giving one ester in each step (Fattah et al. 2020). Depending on the FFA content of the feedstock, biodiesel production is done either through a single step (alkali catalysis) or a two-step reaction, in which esterification precedes transesterification, as shown the schematic drawing in Figure 1 (Fattah et al. 2020; Mofijur et al. 2014). Transesterification can be carried out by catalytic and non-catalytic methods as described in the following sections.