ORIGINAL PAPER Phytochemical Composition of Oryza sativa (Rice) Bran Oil Bodies in Crude and Purified Isolates Nantaprapa Nantiyakul • Samuel Furse • Ian Fisk • Timothy J. Foster • Gregory Tucker • David A. Gray Received: 17 October 2011 / Revised: 17 April 2012 / Accepted: 20 April 2012 / Published online: 19 May 2012 Ó AOCS 2012 Abstract We describe a procedure for isolating and purifying oil bodies (OBs) from Oryza sativa bran, and present evidence that strongly suggests a physical associ- ation between the OB organelles and several antioxidant phytochemicals (c-oryzanol and several tocochromanols). This suggestion arises from work showing that despite comprehensive washing steps (9 M urea, water), the majority of the tocotrienols and tocopherols (77 and 73 %, respectively) and oryzanols (91 %) remain integral to the oil bodies, not being released unless the latter are sacri- ficed. This in turn provides a valuable comparison with similar analyses of tocochromanols in other plant species, as well as indicating that rice bran, normally a waste product from the rice industry, may provide a valuable source of antioxidants as well as protein and unsaturated fat. Keywords Rice bran Á Oil bodies Á Oxidation Á Tocotrienols Á Oryzanols Introduction Oryza sativa, Asian rice, in common with many other food crops harvested for their seed, contains a significant quantity of fatty acid-based energy storage molecules. Typically, the fatty acid residues contained within these triacylglycerides (TAG) are mono- or poly-unsaturated and are thus sensitive to oxidative degradation (become rancid). The rate of this oxidation is a function both of exposure to oxygen in the air and to the number of unsaturated (olefin) bonds present in the fatty acid residues. The facile oxida- tion of poly-unsaturated fatty acid residues that gives rise to rancid fats is therefore at odds with the observation that seeds containing such poly-unsaturated fatty acids are able to exist in a stable, unoxidised state for some time before germination. This begs the question of what mechanism is employed by plants to protect their TAG from oxidation. An obvious chemical candidate is the group of lipophilic compounds related to tocopherol (vitamin E), called toco- chromanols, and one steroid-based antioxidant, c-oryzanol. These are known phytochemicals that have been isolated from plant species [1, 2] and are amongst other phenolic compounds in the seeds of plants [3–5]. Rice bran, a by-product from rice milling, is 15–20% fatty acids, depending on the variety of Oryza and type of milling [6]. They are known to contain the antioxidants noted above although levels recorded are influenced by the origin of the material [7], bran processing [8] and the method of extraction and purification [9, 10]. As well as anti-oxidant properties, they also help to maintain the sta- bility of cellular membranes, and prevent intracellular lipid oxidation [11]. The fatty acids produced by plants are stored as TAG in organelles called oil bodies (OBs) [12, 13]. Such OBs serve as an energy source for germination and radicle growth. N. Nantiyakul Á I. Fisk Á T. J. Foster Á D. A. Gray (&) Division of Food Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Nottinghamshire LE12 5RD, UK e-mail: David.Gray@nottingham.ac.uk S. Furse School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Nottinghamshire LE12 5RD, UK G. Tucker Division of Nutritional Sciences, School of Biosciences, University of Nottingham, Sutton Bonington Campus, Sutton Bonington, Nottinghamshire LE12 5RD, UK 123 J Am Oil Chem Soc (2012) 89:1867–1872 DOI 10.1007/s11746-012-2078-y