Optimization of the production process of germinated parboiled purple rice

Rice (Oryza sativa L.) is one of the main cereals produced in the world and is the major staple food for more than half of the world’s population. In recent years, much attention has been paid on the health benefits of consuming rice products, especially “Germinated parboiled rice, GPR”. The health benefits from the consumption of GPR that are scientifically proven include reducing the risk of diseases. Production of GPR consists of three major steps, germinating, steaming, and drying before husking. During germination, the development of the bioactive components such as total phenolic content, antioxidant activity, and especially gamma-aminobutyric acid have noticeably increased. Additionally, the parboiling technique leads to concomitant changes in the rice quality by inactivation of enzymes, which helps to retain some of the nutrients and improves the head rice yield after husking. Drying is an important step in the production process affecting the qualities of GPR. This final step is essential to remove moisture from the grain to inhibit the growth of microorganisms, delay physicochemical deteriorations, and therefore prolong the shelf life of GPR.

One of the most popular Thai pigmented rice cultivars is ‘Hom Nil’. The presence of anthocyanins is represented by a dark purple to almost black color of the grain. Moreover, it also contains high amounts of polyphenols, which are a good source of antioxidants. Therefore, using Hom Nil to produce GPR is preferred over white rice due to its higher bioactive compounds. To optimize the production process of germinated parboiled purple rice, this dissertation consists of three main parts that focus on sorption and drying behavior and the qualities of GPR during the production process and storage