Ultrasound-assisted extraction of phenolic compounds from ear mushrooms (Auricularia auricula-judae): Assessing composition and antioxidant activity during fruiting body development

Auricularia auricula-judae (ear mushroom) exhibits significant biological and pharmacological properties, particularly as an antioxidant due to its phenolic compounds. This study introduces a novel ultrasound-assisted extraction technique to quantify phenolic compounds and assess antioxidant activity in ear mushrooms. Key extraction factors, including solvent-to-sample ratio (10:1, 20:1, 30:1 mL/g), pulse duty cycle (0.2, 0.5, 0.8 s−1), and temperature (10, 35, 60 °C), were optimized using a Box–Behnken design and response surface methodology (RSM). Methanol was identified as the most effective solvent, yielding the highest total phenolic content (TPC) and antioxidant activity. The optimal conditions for TPC and 2,2-diphenyl-1-picryl hydrazyl (DPPH) inhibition were determined to be 1 g of sample with 18 mL of methanol at 59 °C and a pulse duty cycle of 0.7 s−1. This 1135 method achieved a recovery rate of 94.85% for TPC and 92.71% for antioxidant inhibition and was validated with high precision (CV < 5%). Application of this method during fruiting body development (7–19 d) revealed that the optimal harvest time for maximum TPC and antioxidant activity was 8 d fruiting age.