Addition of grape pomace in the hydration step of parboiling increases the antioxidant properties of rice

The conventional parboiling process decreases the total phenolic compounds (TPC) and the antioxidant activity (AA) of rice. In order to change this nutritional disadvantage, in this research we have proposed an unusual solution. Here, we added grape pomace (agro‐industrial waste) in the process during the parboiling as a source of bioactive compounds (BC). An increase in the concentrations of TPC, flavonoids anthocyanins and antioxidant activity was found. Moreover, there was slightly change in the final colour of the rice (which tended towards red) in addition to added proline (NMR spectra), which is an amino acid that is characteristic of grapes. Therefore, we concluded that it is possible to improve the functionality of parboiled rice with the addition of grape pomace, besides promoting the valorisation and use of an agro‐industrial waste rich in secondary metabolites. The conventional parboiling process decreases the bioactive compounds of rice. In order to change this nutritional disadvantage, we added grape pomace during the parboiling. An increase in the antioxidant activity was found.