Detection and quantification of palmolein and palm kernel oil added as adulterant in coconut oil based on triacylglycerol profile

Economically motivated adulteration of expensive coconut oil with low cost oil, like palm kernel oil and palmolein is difficult to detect and quantify by available methods primarily due to their overlapping physicochemical properties with coconut oil. In the present work, a HPLC method has been developed to detect and quantify the degree of adulteration of coconut oil with palmolein and palm kernel oil based on triglyceride structure. The normalized area percentage of trilaurin (C36) among the three major TAG molecular species dilaurin-monocaprin/myristin-caprylin-laurin (C34), trilaurin (C36) and dilaurin-monomyristin (C38) of coconut oil was chosen as detection index for quantifying degree of adulteration of coconut oil with palm kernel oil, while the area ratio of dipalmitoyl-monoolein: trilaurin was chosen as detection index for quantifying adulteration of coconut oil with palmolein. The RP-HPLC based method developed in the present work is effective with a 2–4% minimum detection limit of adulterant oils and 78–98% detection accuracy depending on the degree of adulteration and types of oil.