Effect of high hydrostatic pressure on the bioactive compounds, antioxidant activity and in vitro digestibility of cooked black rice during refrigerated storage

Extractable phenols, total flavonoid , total anthocyanin , antioxidant activity and in vitro digestibility of cooked black rice (BR) following high hydrostatic pressure (HHP) treatments (200–500 MPa/15 min) during 40 days of storage at 4 °C were evaluated in this study. Results showed that extractable phenols significantly (p < 0.05) increased between 12.07% and 4.89% for treated samples with 400 MPa and 500 MPa at day 1. Similar trends occurred in flavonoid, anthocyanin and antioxidant activity of cooked BR regardless of storage days, suggesting that HHP had a better retention of the above-mentioned compounds. However, all the samples showed a significant (p < 0.05) reduction in these antioxidant compounds during storage time. Compared with the control, higher in vitro hydrolysis , increased amount of rapidly digestible starch (RDS) and slowly digestible starch (SDS), as well as lower levels of resistant starch (RS) were observed in BR samples with HHP treatments. These findings indicate that HHP treatment could be a potentially applicable technique for producing cooked BR with enhanced nutrition and high quality.