Determination of total phenolic content and antioxidant capacity of onion (Allium cepa) and shallot (Allium oschaninii) using infrared spectroscopy

► We propose a novel rapid method using infrared spectroscopy to quantify total antioxidant capacity in plants in the substitution of traditional wet chemistry methodology. ► Several spectroscopic-based chemometric models were established and validated. Those models could be used in future for prediction of onion antioxidant profile. ► DPPH, TEAC and FRAP values of different types of onions and shallots were measured and those data are partially supplemented to previous relevant studies.