33.4 Versatile Products as an Outcome of Valorized Waste Cooking Oil

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33.4.2

Green Chemical Lubricants

The presence of fatty acids and oleochemicals in WCO forms a rich source for

generation of versatile green chemicals. The WCO can be converted into a series

of industrially viable chemicals and lubricants exhibiting biodegradable and

environment-friendly properties. Several sophisticated extraction techniques have

been designed to utilize the different types of WCOs in order to generate value-added

chemicals [23].

Lubricant comprises of base oil which imparts it with desirable property of lubric-

ity, viscosity, and biodegradability. On the basis of base oil composition, lubricants

may be classified into classes like synthetic lubricants, mineral lubricants, and biol-

ubricants. Mineral lubricants exhibit properties like low viscosity and anticorrosion

properties, but they are non-biodegradable in nature [24]. Hence, there arises a need

to identify resources to synthesize biolubricants from natural sources with compa-

rable lubrication properties, but suitable biodegradation profile.

33.4.3

Biodiesel Production

Several biological sources like fats and vegetable oils have been explored as feed-

stock for biodiesel generation. Biodiesel shows distinct advantage over petroleum

diesels in terms of biodegradability. Biodiesels contribute to extensive reduction in

toxic emissions and emission of pollutant particulate matters. The use of biodiesel

provides the highest reduction in pollution issues without compromising on heat

of combustion values. Vegetable oils can be used as sources for biodiesel produc-

tion after effective modifications in composition using different processing strategies

[25]. Some vegetable oil properties like high viscosity, and variable composition of

fatty acids, make direct use of vegetable oil as biodiesel inappropriate. Some chemi-

cal transformative steps like transesterification aid to lower the viscosity of vegetable

oils making them more convenient to use as sources of biodiesel [26].

33.4.4

Microbial Lipids

Microbial oils are mainly comprised of TAGs and neutral lipids. Microbial oils are

enriched with essential fatty acids mainly polyunsaturated fatty acids belonging to

omega-3 and omega-6 class. Also, known as single cell oils (SCOs), microbial oils

can be used as a good source of food supplements. Microbial lipids are produced

and stocked as intracellular components in lipid body structures during the growth

phase of microbial species like Yarrowia lipolytica, Pseudomonas, and Bacillus [27].

The WCO has been extensively explored as a feedstock for the metabolism by micro-

bial strains for effective conversion of the lipidic contents of oil into organic acids and

enzymes with versatile industrial utilizations and applications. The mechanism of

lipid production in each type of microbial strain may vary depending on the inher-

ent metabolic processes in the microbial strains. In the model strains of yeast like

Y. lipolytica, the intracellular production of lipids is mediated by hydrolytic activity

of lipase enzymes on the oil infused in yeast media [28].