Rice Bran Stabilization Improves Shelf Life in Oil Production

Rice bran is an important by-product of rice processing, containing lipids, proteins, dietary fiber, and lipophilic companions such as oryzanol and tocotrienols, which endow it with significant potential for development and utilization.

Rice bran oil is an edible oil extracted from rice bran, also known as rice oil. It is rich in functional components such as oryzanol and phytosterols, and contains a balanced profile of fatty acids, making it highly beneficial for managing hyperlipidemia and regulating autonomic nerve functions.

Solvent extraction is a commonly used method for rice bran oil production due to its high yield, large processing capacity, production efficiency, and oil extraction rate. This method is particularly suitable for low-oil-content materials like rice bran, as a single extraction process can fully recover the oil while producing high-quality extracted meal. However, the high susceptibility of fresh rice bran to rancidity and the often decentralized processing conditions lead to low utilization rates. If not processed promptly, the quality of rice bran oil and its extraction efficiency can be significantly compromised. Therefore, stabilizing rice bran to slow down rancidity and improve raw material quality is a prerequisite for producing high-quality rice bran oil and enabling its deep processing. This step is critical for ensuring the production of premium rice bran oil and expanding its utilization.

Rice bran contains highly active lipases that rapidly catalyze the hydrolysis of lipids in fresh rice bran into free fatty acids during storage, causing a sharp increase in acid value within hours and accelerating rancidity. In industrial production, extrusion expansion is a widely adopted stabilization technique that inactivates lipases, transforms powdery rice bran into porous, highly permeable granules, and facilitates subsequent oil extraction, thereby improving production efficiency and oil yield. This treatment extends the shelf life of rice bran and lays the foundation for its advanced processing.

Extrusion expansion significantly reduces the phospholipid content, moisture, and volatile substances in crude rice bran oil. Moreover, as storage time extends, the difference in phospholipid content between extruded stabilized and non-stabilized crude rice bran oil becomes more pronounced. Additionally, extrusion stabilization notably increases the oryzanol content in crude rice bran oil. These findings indicate that extrusion stabilization of rice bran may reduce degumming costs for rice bran oil production from raw materials with varying storage durations and better preserve physiological active components such as oryzanol.