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The quality changes and the concentrations of tocopherols and c-oryzanol, during successive steps of rice bran oil refining (RBO), were studied. For this purpose, samples of crude, degummed, neutralized, bleached, dewaxed and deodorized RBO were taken from an industrial plant and analyzed. The moisture, pH, acidity, peroxide value and unsaponifiable matter, were determined. The fatty acid composition was evaluated by GC, and the concentrations of tocopherols and c-oryzanol were determined using HPLC with fluorescence and UV-Vis detection, respectively. To identify c-oryzanol components, fractions of the HPLC eluant were collected and analyzed using mass spectrometry. Oil refining reduced the peroxide value and acidity to 1 and 3% of the values obtained in crude RBO, respectively. The fatty acid composition were not significantly altered during refining. The concentrations of the tocopherols in RBO followed the order a [ (b ? c) [ d.The total concentration of tocopherols was 26 mg/100 g, and remained practically unaltered during refining. Up to nine components were distinguished in c-oryzanol. After collecting the elution fractions, up to six components were identified by electrospray mass spectrometry. Refining reduced the total concentration of c-oryzanol to 2% of its initial value.

The influence of different procedures of pulp drying and oil extraction methods on the concentrations of a-tocopherol, squalene and several phytosterols in avocado oil was evaluated. Pulp portions of Fortune variety avocados were dried either by lyophilization or under circulating air at 40 or 70°C. For lyophilization and for each air drying temperature, the oil was obtained either by cold pressing or with Soxhlet extraction using petroleum ether. The dehydrated pulp (73 % of the pulp weight) yielded 25-33 % oil by cold pressing, and 45-57 % oil by Soxhlet extraction. Infrared spectroscopy and gas chromatography with FID and mass spectrometry detection were used to analyze the oils. a-Tocopherol, squalene, cycloartenol acetate, b-sitosterol, campesterol and stigmasterol were present in all the oil samples. In comparison to lyophilization, hot air drying resulted in smaller concentrations of a-tocopherol, squalene and b-sitosterol, and larger relative concentrations of campesterol and cycloartenol acetate. On the other hand, extraction by cold pressing produced a smaller amount of oil, with greater concentrations of atocopherol and squalene, and lower contents of campesterol and cycloartenol acetate, than Soxhlet extraction. Thus, the oil yield was maximal with lyophilization and Soxhlet extraction, but lyophilization and cold pressing produced oils which had greater concentrations of antioxidants and other bioactive compounds.

Rice bran oil (RBO) contains significant amounts of the natural antioxidants γ-oryzanol and tocopherols, which are lost to a large degree during oil refining. This results in a number of industrial residues with high contents of these phytochemicals. With the aim of supporting the development of profitable industrial procedures for γ-oryzanol and tocopherol recovery, the contents of these phytochemicals in all the residues produced during RBO refining were evaluated. The samples included residues from the degumming, soap precipitation, bleaching earth filtering, dewaxing and deodorisation distillation steps. The highest phytochemical concentrations were found in the precipitated soap for γ-oryzanol (14.2 mg g(-1), representing 95.3% of total γ-oryzanol in crude RBO), and in the deodorisation distillate for tocopherols (576 mg 100 g(-1), representing 6.7% of total tocopherols in crude RBO). Therefore, among the residues of RBO processing, the deodorisation distillate was the best source of tocopherols. As the soap is further processed for the recovery of fatty acids, samples taken from every step of this secondary process, including hydrosoluble fraction, hydrolysed soap, distillation residue and purified fatty acid fraction, were also analyzed. The distillation residue left after fatty acid recovery from soap was found to be the best source of γ-oryzanol (43.1 mg g(-1), representing 11.5% of total γ-oryzanol in crude RBO).