Ultrasound was applied for the extraction of pectin from chaenomeles . The content of pectin was evaluated by carbazole colorimetric method. Based on the results of the single factor experiment and the orthogonal tests, the optimum extraction parameters are as follows: the solid-to-liquid ratio is 1:4 g/mL, the ultrasonic power is 320 W, the ultrasonic-assisted extraction temperature is 60 °C, the ultrasonic-assisted extraction time is 50 min, and pH value is 2.0. Compared with acid hydrolyze methods, the extraction time of the present technique decreases from 70 min to 50 min, and the extraction yield increases from 1.39% to 2.61%. The results show that ultrasonic-assisted extraction is time-saving and highly efficient, so it provides a new way to extract pectin from chaenomeles .
In this study, flavonoids were extracted from pomelo peels and naringin was isolated from the flavonoid extract. The effects of extraction parameters, namely, ethanol concentration, solid-to-liquid ratio, and extraction time, on the yield of flavonoids extracted from pomelo peels were analyzed according to the Box-Behnken design of response surface methodology. The experimental conditions for flavonoid extraction were optimized, and naringin was separated from the extracted flavonoids using Sephadex LH-20 column chromatography. Experimental results showed that the influence of factors on the extraction rate of flavonoids from pomelo peels was in the order of ethanol concentration > solid-to-liquid ratio > extraction time, and the optimal extraction parameters were 85% ethanol concentration, 1:20 solid-to-liquid ratio, and 4-h extraction time for extracting flavonoids from pomelo peels. Under these conditions, the yield of flavonoids was 6.07 ± 0.06 mg/g. After three times of extraction, the flavonoid extraction rate reached 96.55%, and the residual naringin in the pomelo peels was 0.017 mg/g, at which point the bitterness in the pomelo peels disappeared. Two components, namely, PF1 and PF2, were separated from the crude flavonoid of pomelo peels through Sephadex LH20 column chromatography. PF2 was identified as naringin by high-performance liquid chromatography tandem mass spectrometry, with a purity of 95.7 ± 0.23%. Both flavonoids and PF2 exhibited good in vitro radicals scavenging activities on DPPH, ABTS, superoxide anion and hydroxyl.
Mechanochemistry is a process that could convert mechanical energy into the substance's internal energy to induce changes. In the current study, mechanochemistry was employed for the first time to extract the essential oil from Citrus aurantium L . var. amara Engl . Materials and reagents were ground at high speed in a planetary ball mill and exposed to solvent extraction. To achieve the best extraction from Citrus aurantium L . var. amara Engl . , the following parameters were selected: 5% fumed silica A200 as solid reagent, ball milling at 300 r/min for 10 min and extraction with n-hexane (1 g/5 mL) during 30 min. These settings gave an essential oil yield of 6.60 ± 0.20%. This is 26 times higher than by hydrodistillation (0.25 ± 0.03%) and more than 3 times higher compared to reflux extraction (2.08 ± 0.16%). The extracts obtained by the three approaches were analysed applying GC-MS. A total of 65 components was identified, including 60 by mechanochemical-assisted extraction, 27 by hydrodistillation and 49 by reflux extraction. Furthermore, scanning electron microscopy was used to observe the changes in material surface structure by the effect of mechanochemical-assisted extraction.
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