Optimization of ultra-high pressure-assisted extraction of total phenols from Eucommia ulmoides leaves by response surface methodology

The ultra-high pressure-assisted extraction (UHPE) of total phenols from Eucommia ulmoides leaves (TPEU) was optimized and its antioxidant activity on Eucommia ulmoides seed oil was studied. The effects of UHPE pressure, UHPE time, and ethanol concentration on the extraction yield of TPEU were examined by response surface methodology. In addition, TPEU was added to Eucommia ulmoides seed oil, and the effects of TPEU on the antioxidant activity (acid value, peroxide value) of Eucommia ulmoides seed oil during storage were studied. The optimal UHPE conditions were as follows: UHPE pressure, 406 MPa; UHPE time, 8.3 min; and ethanol concentration, 60.2%. Under these UHPE conditions, the yield of TPEU was 7.58%. TPEU had a good antioxidant effect when the TPEU content was 0.06%. The antioxidant effect of TPEU was lower than that of BHA. Both TPEU and BHA have a synergistic effect.