Green extraction of phenolics and terpenoids from passion fruit peels using natural deep eutectic solvents

Abstract This work aimed to optimize the ultrasonic‐assisted extraction (UAE) and microwave‐assisted extraction (MAE) of phenolics and terpenoids from passion fruit peels using natural deep eutectic solvents (NADES). NADES formulated with choline chloride and polyols with organic acids were used to investigate the solubility of phenolics and flavonoids in the solvent. Among these formulations, those derived from lactic acid‐glycerine (LGLY) and citric acid‐glucose (CGLU) exhibited the highest efficiency in extracting phenolics and terpenoids, respectively, when combined with UAE. Then one‐factor experiments were conducted to examine the influence of the UAE conditions (liquid‐to‐solid ratios [LSR], water content in NADES, ultrasonic power, time, and temperature) and MAE conditions (LSR, water content in NADES, ultrasonic power, and time) on the extraction yield of phenolics and terpenoids. The Box‐Behnken design (BBD) model was employed to optimize the extraction conditions with conditional ranges determined based on the results of the one‐factor experiments. The optimal conditions for the CGLU‐based MAE of terpenoids were 387 W of microwave power, 30% water content, 2.4 min, and 20 mL/g of LSR. The optimized conditions for LGLY‐based MAE of phenolics were 299 W, 18.7%, 1.3 min, and 10 mL/g. Total terpenoid content acquired from NADES‐based UAE was higher than NADES‐based MAE, while total phenolic content obtained at the optimal conditions of NADES‐based UAE and MAE was statistically insignificant. The efficiency of the two extraction ways was compared to selecting the favorable extraction method for acquiring phenolics and flavonoids from passion fruit peels. The research proposed that NADES‐based UAE was a green and effective method for attaining phenolics and terpenoids from passion fruit peel. Practical application Passion fruit peels are a by‐product of beverage production, which causes environmental pollution and increases treatment costs in the factory. These peels contain various bioactive compounds which benefit human health. The traditional extraction method shows low efficiency and high energy consumption. Thus, the appropriate extraction method and green solvents are needed to improve the extraction efficiency of bioactive compounds and can be directly applied to food products. Ultrasonic‐assisted extraction (UAE) and microwave‐assisted extraction (MAE) combined with natural deep eutectic solvents can enhance the extraction efficiency of bioactive compounds. However, the detailed conditions of UAE and MAE are necessary to compare the performance of the two methods. In addition to showing the significant superiority of UAE with MAE, the research showed the optimized conditions of the UAE process, which can be applied on the industrial scale to extract bioactive compounds and directly add them to food products.