Optimization of supercritical carbon dioxide extraction of rye bran using response surface methodology and evaluation of extract properties

• CCD-RSM was applied to optimize rye bran SFE with CO2.
• Highest yield (2.49%) was obtained using 55 MPa, 70 °C and 120 min.
• Temperature was most important followed by pressure and dynamic extraction time.
• SC-CO2 extract of rye bran oil is rich in unsaturated fatty acids.
• SC-CO2 extract of rye bran is strong antioxidant.

Rye bran, which is often discarded after flour milling, contains valuable compounds that may be used in the production of functional ingredients. In this study supercritical CO2 extraction process of rye bran was optimized to obtain the highest extract yields by applying central composite design with three independent variables, pressure (25, 40, 55 MPa), temperature (30, 50, 70 °C) and dynamic extraction time (60, 90, 120 min). The importance of evaluated parameters could be arranged in the following order: temperature > pressure > dynamic extraction time. Calculated response surface model was found to be significant and enabled to select preferable extraction parameters: the highest extract yield (∼2.5%) was obtained at 55 MPa, 70 °C, and 120 min. The interactions between different parameters were also evaluated. The dominant fatty acids in extracted oil were linoleic (61.09%), palmitic (13.74%), oleic (13.65%) and linolenic (6.37%); oxygen radical absorbance (ORAC) and DPPH scavenging capacities of rye bran extract were 683.8 ± 45 and 62.28 ± 1.2 μM trolox equivalents/g, respectively, while total phenolic content was 14.62 ± 0.61 mg gallic acid equivalents/g.

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