Pure oil is a colorless and odorless liquid in the molten state. It becomes a white waxy solid when solidified. Most natural oils are light yellow to brown and have a certain smell. Various odors are generally caused by non-fermented ingredients. For example, the aroma of coconut oil comes from nonyl ketone, rapeseed oil and mustard oil can produce pungent and odor due to their glucosinolates, and oxidative rancidity can also Produces odor. The color of natural oils is due to the carotenoid substances they contain.
The following will take you to learn about the hydrogenation and hydrolysis of oils:
1. Hydrogenation of oils:
Hydrogenation is the hydrogenation of the unsaturated double bonds of oil and fat under the action of a catalyst. Hydrogenation is an effective method of modifying oils. It can increase the melting point of oils, change plasticity, enhance antioxidant capacity, and prevent aftertaste, and has high economic value.
The mechanism of oil hydrogenation is complex, but the Horiuti-Polanyi theory is quite accepted. The double bonds of oil and hydrogen dissolved in the oil are adsorbed by the catalyst surface active points, forming hydrogen-catalyst-double bond instability. The complex then decomposes and the hydrogen atoms combine with the carbon chain to form a semi-hydrogenated intermediate. Semihydrogenated intermediates form various isomers via four different pathways.
2. Oil hydrolysis:
Under the action of higher temperature, pressure and catalyst, oil can be hydrolyzed to generate glycerol and free fatty acids. The hydrolysis reaction of oil is carried out in steps, that is, it is first hydrolyzed into diglyceride, then into monoglyceride, and finally into glycerol and fatty acids. Oil hydrolysis reaction is the reverse reaction of fatty acid esterification reaction. Using inorganic acids, alkali, enzymes and metal oxides as catalysts can speed up the hydrolysis rate of oil. The increase in acid value is a sign that the oil has undergone hydrolysis reaction.
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