Comparative effects of ultrasound and high hydrostatic pressure treatments on cooking properties and antioxidant activity of brown rice

In the current study, different treatments of ultrasound ( 160, 280, 400 W) and high hydrostatic pressure ( 100, 300, 500 MPa) were employed for the pretreatment of brown rice. The effects of both technologies on cooking properties and antioxidant activity were determined. The relationships among parameters were also analyzed. Results showed that hardness, gumminess and chewiness were significantly reduced ( p < 0.05) by over 12% in the samples with both treatments.Cooking time of ultrasound-treated samples was shorter than those treated by high hydrostatic pressure ( 4.17 ~ 4.34 min) . The antioxidant activity was higher after all treatments.Ultrasound treated samples showed higher ferric reducing antioxidant potential ( FRAP) and DPPH radical scavenging capacity, being 18.86% ~ 23.14% and 6.81% ~ 13.41% higher than high hydrostatic pressure treated samples, respectively. The correlation analysis indicated that cooking time was significantly correlated with chewiness and resilience ( p < 0.05) . And a significant correlation ( p < 0.05) was observed between FRAP and DPPH radical scavenging capacity, whereas no significant correlation ( p > 0.05) was observed between total phenol contents and antioxidant ability.Therefore, the results obtained from this investigation indicate that ultrasound treatment could be used as an economical and simple pretreatment method to improve the cooking properties and nutritional value of brown rice.