Effects of High-Intensity Ultrasound-Assisted Extraction Duration on the Quality of Monopterus albus Bone Broth

To investigate the effects of varying durations of high-intensity ultrasound-assisted extraction on the quality of Monopterus albus bone broth, the fish bone broth, prepared at atmospheric pressure, was subjected to low-frequency and high-intensity ultrasound (power 360 W, and frequency 20 kHz) treatment for 0, 1, 2, 3, 4, 5, and 6 min. Subsequently, color, microscopic distribution, zeta potential, particle size, water-soluble protein, soluble solids, and mineral contents (e.g., Mg, K, Ca, and Na) were measured. Results indicated that as ultrasonic treatment time increased, the absolute value of the ζ-potential first rose (up to 9.28 mV) and then declined (to 7.39 mV) (P < 0.05), and the average particle size plummeted to 97 μm before rebounding to 119 μm (P < 0.05), both peaking at 4 min of ultrasonic treatment. Water-soluble protein content increased initially and then decreased (P < 0.05), peaking at 1.06 mg/mL at 5 min, which was 45.20% higher than the level before treatment. Soluble solids content peaked at 0.31 g/100 mL at 6 min, and then remained unchanged significantly (P > 0.05). Compared with those before treatment, the contents of Mg, K, Ca, and Na increased by 10.20%, 37.18%, 5.82%, and 28.75%, respectively, after 4 min of treatment. Electronic tongue analysis indicated that the response values for bitter taste and aftertaste initially increased and then decreased, reaching peak values of 8.56 and 1.53 at 1 min of ultrasonic treatment, respectively. Additionally, the response values for bitter taste and bitter aftertaste were reduced at durations equal to or more than 3 min. Gas chromatography-ion mobility spectrometry (GC-IMS) analysis demonstrated that ultrasonic treatment significantly enhanced the concentrations of fruity, oily, meaty, and nutty flavor compounds (e.g., methyl heptanoate, butyl butyrate, β-cyclocitral, n-octanal, 2-methoxy-3-sec-butylpyrazine, and 2-ethyl-5-methylpyrazine), while effectively reducing the concentrations of pungent odor substances such as hexanal and butyric acid. The sensory score of the fish bone broth was the highest at 4 minutes of ultrasound treatment. In conclusion, high-intensity ultrasonic treatment can significantly improve the quality of M. albus bone broth, providing a theoretical foundation for its efficient and high-quality processing.