Stabilizing Rice Bran & Extracting Oil with Insta-Pro Mechanical Processing
Rice bran, a byproduct of milling white rice for human consumption, is an ingredient with a good source of protein, minerals, fiber, and fatty acids that represents an alternative product for feed and food applications. Rice bran accounts for about 12% of the entire rice grain kernel, which is naturally rich in lipases. These naturally present lipolytic and oxidative enzymes are activated during the milling process, causing rapid hydrolysis and rancidification of the kernel oil. Hence, to maintain feeding value in rice bran, stabilization needs to occur immediately after removal from the kernel to avoid enzyme activity, leading to hydrolysis and consequently production of free fatty acids (FFA) and glycerol.
Stabilization, an enzyme deactivation process, is widely used to extend the shelf life of rice bran. High-shear dry extrusion achieves enzyme deactivation, resulting in stabilized rice bran as a final product with an excellent nutritional value for animal feeding. The stabilized rice bran is also a source for the mechanical extraction of Rice Bran Oil (RBO). RBO provides health benefits given the high content of polyunsaturated fats (PUFA) and monounsaturated fats (MUFA),vitamin E, and minerals. Indeed, the American Heart Association indicates that RBO lowers blood pressure and improves cholesterol.
Insta-Pro developed a continuous, controllable, high-shear dry extrusion process by stabilizing freshly milled rice bran within 8 hours of milling to generate a high-quality ingredient for animal feeding. Furthermore, the process of stabilization followed by mechanical oil pressing allows for 46.5% oil extraction efficiency of crude RBO. Efficient mechanical RBO pressing was accomplished by using stabilized rice bran from a fresh raw (non-parboiled) bran with less than 15% starch content. As a result, the analysis of crude RBO indicated <2% free fatty acids and <5% peroxide value.
The results are significant and contribute to the use of high-shear dry extrusion and mechanical oil pressing (i.e., ExPress® process) to generate an innovative, chemical-free, crude RBO aligned with the tendency of consumers demanding safe and sustainable oil products.
Key points:
- High shear-dry extrusion followed by mechanical extraction of stabilized rice bran allows 46.5% oil extraction efficiency.
- A freshly milled, within 8 hours post-milling, rice bran source with 10-15% starch content is needed to maximize the efficiency of RBO extraction using mechanical pressing.
- High-shear dry extruded and mechanically extracted RBO contains < 2% FFA, which meets guidelines/specifications for economic refining purposes.
- High-shear dry extruded and mechanically extracted RBO is an alternative plant-based oil to meet market interest and consumer demands for chemical-free and sustainable products.
Rice bran and rice bran oil offer significant nutritional value. To fully take advantage of this potential, processors can first stabilize the rice bran and then extract the oil using mechanical pressing enhanced by Insta-Pro’s extrusion technology.
