Co-extract of green tea and black rice: incremental effect of antioxidant and anti-inflammatory properties and their freeze-dried double emulsion encapsulated powder

Abstract

The study explored the combination effect between of green tea extract (GTE) and black rice extract (BRE) and the encapsulation process of the co-extract. A 2:1 (w/w) ratio of GTE to BRE in citric aqueous solution at pH 6 showed the highest antioxidant activity (IC50 = 0.306 mg mL−1) with the strongest incremental effect (combination index = 0.547). It exhibited potent anti-inflammatory effects, with sirtuin 1 enzyme-stimulating activity (28.593 of fluorescent intensity) and NF-κB protein suppression in RAW 264.7 macrophages (57.76% at 100 μg mL−1). Freeze-dried double emulsion encapsulated powder (CEP) with the highest encapsulation efficiency (73.38%) and total polyphenol content (218.28 mg GAE g−1) was prepared using a lecithin to O phase ratio of 2:25 (w/w) and a chitosan-carboxymethyl cellulose to W1/O emulsion phase ratio of 1:1 (w/w). Our findings suggest utilising CEP as a compound in functional food by contributing to improved health and well-being.