The Effect of Microwave Heating of Pandanus Leaves with Vacuum Dried Non-Aromatic Milled Rice on Consumer Acceptability of Cooked Rice

Abstract

The aroma of cooked rice is contributed mainly by the compound 2-acetyl-1-pyrroline (2-AP) and it is also found in aromatic Pandanus leaves (Pandanus amaryllifolius). Therefore, this experiment was conducted to investigate a physical mechanism of transferring 2-AP from Pandanus leaves to non-aromatic polished rice. Milled Samba rice (medium/ bold) grains were vacuum dried for 24 hours to remove moisture and develop a porous structure on the grain. Then the rice samples were mixed with Pandanus leaves and microwaved for predetermined times in sealed bags to 65°C to explode oil glands and release 2-AP. After three weeks of chemical exchange time in bags, the consumer acceptability was tested based on preference. The results revealed that the consumer acceptability of rice could be significantly increased with appropriate microwave heating time. Data has shown that the mean acceptability rank value of 3.47 with 45 minutes microwaving (about 65°C) against the rank mean of 1.4 for the control in a five-point hedonic test. However, the increase of microwaving time above the optimum level produced an unpleasant aroma in rice and decreased the acceptability. Therefore, this physical treatment could be used to increase the palatability and acceptability of non-aromatic rice.