An Improved Ultrasonic-Assisted Extraction Method by Optimizing the Ultrasonic Frequency for Enhancing the Extraction Efficiency of Lycopene from Tomatoes

Abstract

In order to assess the optimization of the ultrasonic frequency in a range of 18–146 kHz for extracting lycopene from tomatoes and evaluate its influence on the extraction efficiency, an improved ultrasonic-assisted extraction (IUAE) method was proposed by using a novel ultrasonic extraction and detection system, in which the ultrasonic frequency information could be converted to intuitive waveforms that are easily identified by eyes. Additionally, to improve the extraction yield of lycopene, in this work, the optimization of various process parameters by ultrasonic treatment, including extraction time, solvent/material ratio, extraction temperature, and ultrasonic power for improving the yield of lycopene were investigated. These results indicated that all of the considered parameters had effected on the yield of lycopene significantly, and the optimum extraction conditions were as follows: extraction time duration 20 min; ratio of solvent to material 2:1; extraction temperature 25 °C; ultrasonic power 200 W; ultrasonic frequency 46–48 kHz. In comparison with other extraction methods, such as conventional solvent extraction (CSE), supercritical fluid extraction (SFE), supercritical carbon dioxide co-extraction (SC-CO2), and existing UAE, the IUAE method achieved a far more extraction yield, a reduction of extraction time, and a smaller amount of solvent at lower temperature, which showed a great promising prospect in the extraction and separation of natural products.