Penetration of juice into rice through vacuum drying

Abstract

Vacuum drying was employed to penetrate rice with juice. Red beetroot juice, good source of color and functional compounds, was used. After mixing with beetroot juice and vacuum drying, cracks were formed in the rice kernel surface and the rice kernels were a red-violet color. The degree of visual kernel surface cracking, the fracturability of whole rice kernels, and the DPPH scavenging activity were increased with increasing amounts of added juice. The visual kernel surface cracking was found to be beneficial for deep penetration and juice accumulation within three varieties of rice kernels (Sanpatong 1, Kaow Dok Mali 105, and Chainat 1) and two storage time periods (one month and one year). The final moisture content of the rice kernels after vacuum drying was sufficiently low for good storage quality. No heat treatment is required. The findings imply that other functional liquids/solutions would be also vacuum-impregnated in rice grains. Functional properties of rice could be effectively improved with a vacuum drying technique. (C) 2014 Elsevier Ltd. All rights reserved.