Effect of puffing on physical and antioxidant properties of brown rice

Effect of soaking and single/two cycle high pressure treatment on water absorption, color, morphology and cooked texture of brown rice

Water absorption, color, morphology and cooked texture of brown rice were evaluated after selected soaking (30-50 °C, 30 min) and high pressure treatment (HPT) (100-500 MPa; single or two cycle; total holding time 10 min). Water absorption ratio and lightness values of brown rice were increased by soaking and HPT. Hardness and gumminess values of cooked brown rice were reduced while springiness and cohesiveness were elevated by HPT. Scanning electron microscopy indicated that HPT improved the texture of brown rice by disrupting the structure of rice bran layer, which allowed easier water penetration into the rice grain during cooking. Moreover, the two cycle HPT resulted in lighter color and softer texture for cooked brown rice than single cycle HPT primarily caused by the more severe structural disruption of bran layer. Overall, two cycle HPT after soaking could potentially improve the quality of brown rice, taking about the same time as the single cycle HPT. Further, the quality improvements with the two cycle HPT were facilitated at lower pressure levels thereby providing better commercial processing opportunities.

Effect of presoaking high hydrostatic pressure on the cooking properties of brown rice

Effects of presoaking-high hydrostatic pressure (PHHP) on cooking time, hardness, gumminess, springiness, and microstructure of brown rice were evaluated. Compared with traditional soaking treatment, PHHP significantly shorten the cooking time of brown rice from 34 to 14 min. The hardness of brown rice treated by PHHP reduced remarkably, which is lower than that treated by soaking process and similar to that of white rice. The gumminess and springiness of brown rice dramatically decreased under pressure above 500 MPa. However, the water uptake capacity of brown rice treated by PHHP was not obviously affected, whose moisture contents were much lower than that of soaked samples. The analysis of thermal properties revealed that the enthalpy of brown rice was influenced by PHHP, and the denaturation of brown rice components generated. These results and microstructure analysis revealed that the structures of pericarp and aleurone layer of brown rice were damaged by PHHP, which allows water to be easily absorbed by the rice kernel during cooking process. PHHP treatment could be a potentially applicable pretreatment for improving cooking properties of brown rice.

Rice: Parboiling and Milling Properties

Parboiling is a hydrothermal processing technique during rice has to pass through many stages which alter the physicochemical properties and nutritional profile of grain. Different parboiling techniques have been developed for preparation and industrialization of rice. During parboiling process, starch granules are gelatinized and retrograded as a result various changes occur in rice kernel, which affects its quality parameters. Parboiling has marked influence on organoleptic properties, improved the strength and nutritional profile of grain. Parboiling treatment principally brings the characteristic change in rice grain such as milling, cooking, storage and eating qualities. Milling is an important unit operation for removing the husk and bran from the rough rice. Milling significantly affects the cooking and nutritional properties of rice. The important parameters focussed during milling are the head rice yield and kernel hardness. Milling technology is therefore geared to obtain maximum outturn of milled rice and to reduce breakage.