Abstract Ultrasound-assisted extraction (UAE) was used to extract procyanidins (PC) from the perilla seed hull. Four independent variables, namely, liquid-to-solid ratio, ethanol concentration, UAE time, and UAE temperature were investigated. Response surface methodology was performed on the basis of results of single-factor tests. The optimal conditions for PC extraction were as follows: a liquid-to-solid ratio of 15:1, an ethanol concentration of 62%, a UAE time of 29 min, and a UAE temperature of 53 °C. Under these conditions, the experimental yield of PC was 2.185 mg/g (n = 3), which is correlated with the predicted value of 2.2 mg/g. The extracted and purified PC showed excellent antioxidant activity against 2,2-diphenyl-1-picrylhydrazyl, hydroxyl, and 2,2’-azino-bis (3-ethylbenzothiazoline-6-sulfonic acid) radicals in vitro.

Abstract Response surface methodology (RSM) was used to optimize the ultrasound-assisted extraction parameters of perilla protein isolate (PPI), which has functional properties. A central composite experimental design was applied to investigate the effects of three factors (ultrasonic power, extraction time, and liquid-to-solid ratio) on six responses: protein yield, water solubility index (WSI), water absorption capacity (WAC), oil holding capacity (OHC), emulsifying activity (EA), and foaming ability (FA). Based on the RSM results, the optimum conditions were an ultrasonic power of 206 W, and extraction time of 32.4 min, and a liquid-to-solid ratio of 10.34:1. Under these conditions, PPI had high protein yield (26.1%) and functional properties (55.2% WSI, 3.6% WAC, 1.76 g/g OHC, 60.25 m2/g EA, 63.2% FA). Differential scanning calorimetry revealed that PPI was slightly denatured at 75.16 °C, and the amount of heat required to induce this denaturation was 0.03 J/g. SDS-PAGE presented protein bands that ranged from 14.4 to 66.2 kDa. Based on its functional properties, PPI can be used in the food industry.

Abstract Response surface methodology (RSM) was used to optimize ultrasound-assisted extraction (UAE) of functional components from perilla leaves. The factors investigated were ethanol concentration, extraction temperature, and extraction time. The results revealed that ethanol concentration had significant effects on all extraction parameters. Based on the RSM results, the optimal conditions were an ethanol concentration of 56%, a UAE temperature of 54 °C, and a UAE time of 55 min. Under these conditions, the experimental TPC (total phenolic content), RA (rosmarinic acid), FRAP (ferric reducing antioxidant power) and DPPH (1,1-diphenyl-2-picrylhydrazyl) values were 48.85 mg GAE/g DW (mg gallic acid equivalent /g of dry weight), 31.02 mg/g DW, 85.55 μmol Fe2+/g DW and 73.35%, respectively. The experimental values were in agreement with those predicted by RSM models, confirming suitability of the model employed and the success of RSM for optimization of the extraction conditions.