The prooxidant effect of natural antioxidants combination when co-encapsulated to chia oil-based nutraceutical edible powders: More is not always better

Chia oil (CO) is the vegetable source with the highest omega - 3 polyunsaturated fatty acids (PUFAs) proportion known to date (61%-70%). Although this is favorable from a nutritional point of view, higher contents of omega - 3 PUFAs result in shorter shelf life and poorer oxidative stability. The objective of this work was to design edible oil powders of CO co-encapsulated with commercial antioxidant-rich sources-containing beta-carotene (BC), astaxanthin (ASX), and vitamin E (VE), either alone or combined (BC-VE and ASX-VE)-to prolong its oxidative stability. To carry out this, spray-dried microcapsules were produced through oil-in-water double-layered emulsions using whey proteins and pectin. Spray-dried capsules were stored at 4 and 30 degrees C, and weekly determinations of primary and secondary oxidation compounds were carried out, by measuring peroxide value (PV) and thiobarbituric reactive substances. CO microcapsules with just one commercial antioxidant-rich source played a key role to keep oxidative indicators below recommended limits (PV < 15 meq kg(-1) oil) when storing powders at 30 degrees C, being ASX the best option, whereas there was no significant effect in oxidation when stored at 4 degrees C. Nevertheless, when combining commercial antioxidant sources (BC-VE and ASX-VE), a marked prooxidant effect was observed, exceeding PV threshold at both temperatures after 2 months of storage.