Enzymatic Degradation of the Rice Bran: Problem or Opportunity?

This study shows rice bran as feedstock with high potential for biodiesel production by enzyme catalysis in situ, due their unique characteristics that allow to control its composition (triglycerides and free fatty acids). Among the characteristics evaluated of rice bran (particle size, moisture and metals concentration), the particle size significantly influenced the hydrolysis of triglycerides into free fatty acids. The oil content obtained from extraction of different granulometric ranges of rice bran (dry basis, 9h) was 43.6% (20-32 mesh), 28.2% (32-35 mesh), 25.8% (35-60 mesh) and 24.8% (60-100 mesh). The presence of trace elements Zn, Cu and Ca in larger concentration in the range of 20-32 mesh may explain the greater amount of oil in this fraction, because these metals act as inhibitors of the enzyme activity in the triglyceride degradation. Free fatty acids formation rate was around 0.73%day(-1) in the degradation conditions studied (10.5% moisture and 6 weeks).