Understanding the role of cell disruption methods in extracting lipids.

Biodiesel is emerging as an alternative fuel for diesel engines, which refers to long-chain alkyl fatty acid esters. The increase in petroleum prices and the environmental benefits have resulted in an increased production of biodiesel. Biodiesel occupies 10% of total biofuel production, and the production is about 6 billion L/year globally (Nogueira, 2011). The basic requirements for biodiesel production are feedstock (oil), an alcohol, and a catalyst (e.g., base, acid, or an enzyme). The reaction of biodiesel production occurs in the following steps: production of free fatty acids from triacylglycerols (TAGs) and transesterification of free fatty acids to methanol. This results in the formation of new chemical compounds called methyl esters. The important process variables during the production of biodiesel are reaction temperature, ratio of alcohol to vegetable oil, amount of catalyst, mixing intensity (RPM), raw oils used, and catalyst (Marchetti et al., 2007; Avhad and Marchetti, 2015). In the alkali-based process, generally sodium hydroxide (NaOH) or potassium hydroxide (KOH) is used as the catalyst.