From rice bag to table: Fate of phenolic chemical compositions and antioxidant activities in waxy and non-waxy black rice during home cooking

Abstract

The objectives of this study were to systematically analyze degradation rate of functional substances, such as total phenolic content (TPC), total flavonoid content (TFC), condensed tannin content (CTC), monomeric anthocyanin content (MAC), cyanidin-3-glucoside (Cy3glc), and peonidin-3-glucoside (Pn3glc), as well as antioxidant activities in cooked waxy and non-waxy black rice through different home cooking manners. Results showed that greater phenolics and antioxidant capacities were detected in non-waxy rice rather than waxy one. All processed black rice exhibited significantly (p<0.05) lower TPC, TFC, CTC, MAC, Cy3glc, Pn3glc, and antioxidants as compared to the raw rice. Different processing methods significantly degraded the content and activities of antioxidants of both waxy and non-waxy black rice. Under the same cooking time, black rice porridge retained more active substances than that of cooked rice by rice cooker. Therefore, to maintain bioavailability of active components, black rice porridge may gain more health promoting effects.

Keywords: (+)-Catechin (PubChem CID: 9064); Anthocyanin; Anthocyanin (PubChem CID: 145858); Anthocyanin 3′-O-beta-d-glucoside (PubChem CID: 56928084); Antioxidants; Black rice; Condensed tannin/proanthocyanidin (PubChem CID: 108065); Cyanidin-3-glucoside; Cyanidin-3-glucoside (PubChem CID: 197081); DPPH (PubChem CID: 2735032); Gallic acid (PubChem CID: 370); Peonidin-3-glucoside (PubChem CID: 443654); Phenolic compounds; Thermal processing; Trolox (PubChem CID: 40634).