Abstract:

Oat (Avena sativa L.) has abundant polyphenols and strong antioxidant activity. Based on single factor experiments, extraction conditions of polyphenols in oat were optimized through quadratic regression orthogonal design. A quadratic regression orthogonal model was established to express the relationship between total polyphenol yield (Y) and four factors including temperature (X1), time (X2), ethanol concentration (X3), and oat flour and solvent ratio (X4), as shown in the equation, Y = 5.2119 + 0.6358X1 + 0.1947X2 － 0.4213X3 + 0.452X4 － 0.1016X12 － 0.2786X22 － 0.1963X32 － 0.1526X42. The factor order on extraction yield from strong to weak was extraction temperature, oat flour and solvent ratio, ethanol concentration and extraction time. According to this model, extraction at 60 ℃ for 65.2 min using 50.6% ethanol and 1:20 (g/ml) of oat flour and solvent revealed the highest yield of polyphenols, which was 6.6717 mg/g. The experiment result was consistent with the theoretical result of 6.3989 mg/g.

Key words: oat polyphenol, extraction, optimization, quadratic regression orthogonal design