Effect of high pressure processing on rancidity of brown rice during storage

Hydrolytic and oxidative rancidity are the main cause of brown rice quality deterioration during storage. Brown rice was soaked in water and treated with high pressure (HP) at 100-400 MPa, for 0-10 min. The effect of HP treatment on moisture content, fat acidity, conjugated dienes (CD) and 2-thiobarbituric acid (TBA) value during 3 months storage at room temperature, was evaluated and compared with soaked (0.1 MPa) brown rice and untreated brown rice. After storage, moisture content of HP treated brown rice were significantly higher than the untreated but lower than the soaked, apart from the brown rice treated at 400 MPa-0 min, which was the lowest in moisture content. HP treatment at 400 MPa enhanced the fat acidity immediately after the treatment, while samples treated at 200 MPa-0 min showed lower level of hydrolytic rancidity during storage. Better stabilities based on CD content and TBA value were observed in brown rice when HPP at 200 MPa - 10 min was applied.