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Emulsions undergo an oxidation process because of the presence of water. The undesired phenomenon of autoxidation needs to be prevented as the lipidic fraction in the emulsion undergoes degradation. The surface active compounds so formed in the process disturb the stability of the emulsion. Accordingly, the characteristics of the emulsions are altered. This autoxidation process can be prevented by means of antioxidant. In the present study, a well known hydrophilic antioxidant, ascorbic acid, was examined at various concentrations to stabilize water-in-oil emulsion. The outcome showed that the concentration of a compound played an important role in determining its antioxidant or pro-oxidant effect.

Owing to the tendency of essential fatty acids (EFAs) to undergo autoxidation, their storage becomes a key problem. Generally, they are stabilized by synthetic antioxidants like TBHQ that are toxic in nature. Recently many studies were reported where these EFAs are stabilized by natural antioxidants. In the present study, curcuminoids and kalonji seeds ethanol extract (KEE) were used to stabilize these EFAs in refined sunflower oil (RSFO), water-in-oil (w/o) emulsion and butter like products (BLPs). In RSFO, though curcuminoids alone exerted pro-oxidant effect, KEE and curcuminoids showed synergistic antioxidant activity that was comparable to TBHQ. KEE exhibited good antioxidant activity in emulsions and BLPs, providing fine physical properties like slipping point, dropping point and spreadability. EFAs increased the nutritional value of BLPs and antioxidants added for their stabilization provided their medicinal benefits.