Welcome to Chinese Journal of Tropical Crops,

Chinese Journal of Tropical Crops ›› 2022, Vol. 43 ›› Issue (10): 2122-2131.DOI: 10.3969/j.issn.1000-2561.2022.10.019

• Post-harvest Treatment & Quality Safety • Previous Articles     Next Articles

Optimization of Ultrasonic-assisted Cold Extraction Process for Coffee Liquor Preparation and Its Physicochemical Characteristics

DU Jiao1,2, DONG Wenjiang2,5,*(), CHENG Jinhuan3,*(), HE Hongyan3, CHEN Gang4, CHEN Jianfei4, CHEN Xiaoai2,5, LONG Yuzhou2, HUANG Jiaxiong3   

  1. 1. College of Food Science and Technology, Huazhong Agricultural University, Wuhan, Hubei 430070, China
    2. Spice and Beverage Research Institute, Chinese Academy of Tropical Agricultural Sciences, Wanning, Hainan 571533, China
    3. Institute of Tropical and Subtropical Cash Crops, Yunnan Academy of Agricultural Sciences, Baoshan, Yunnan 678000, China
    4. Pu’er Fuming Agricultural Equipment Co. Ltd., Pu’er, Yunnan 665000, China
    5. Key Laboratory of Suitability Processing and Quality Control of Characteristic Tropical Crops, Wanning, Hainan 571533, China
  • Received:2022-03-07 Revised:2022-04-20 Online:2022-10-25 Published:2022-11-04
  • Contact: DONG Wenjiang,CHENG Jinhuan


Coffee is one of the three major beverages in the world, and it is mainly distributed in Hainan and Yunnan in China. In this paper, we investigated the optimal conditions for the preparation of coffee liquor by the ultrasonic-assisted cold extraction technology using Hainan Xinglong coffee beans as the raw materials, and determined the contents of caffeine, trigonelline, chlorogenic acid and the microstructure of coffee grounds. The extraction time, ultrasonic temperature and ultrasonic power were used as the single factors, and the extraction rate of total soluble solids from coffee liquor was used as the evaluation index. Based on the single-factor test, a 3-factor, 3-level response surface test was designed using the Box-Behnken principle to optimize the extraction conditions for ultrasound-assisted cold extraction to obtain the best extraction process, and the content of trigonelline, caffeine and chlorogenic acid in coffee liquor was determined by the ultra performance liquid chromatography and the microstructure of coffee grounds was determined by a scanning electron microscopy using the traditional cold extraction method as the control. The total soluble solids of coffee liquor increased with the appropriate increase of ultrasonic power, ultrasonic time, and ultrasonic temperature, and the main factors affecting the extraction rate of total soluble solids of coffee liquor were ultrasonic power > ultrasonic time > ultrasonic temperature, and the optimal process parameters for the preparation of coffee liquor by ultrasound-assisted cold extraction were: ultrasonic power 500 W, ultrasonic time 35 min, and ultrasonic temperature 20℃, and under the optimized conditions, the total soluble solids extraction rate was 22.92%±0.16%, which was basically consistent with the predicted value of the response surface optimization test regression model (22.85%±0.12%). Compared with the traditional cold infusion method, the content of trigonelline, caffeine, and chlorogenic acids in the coffee liquor prepared by ultrasound-assisted cold extraction was 175.19 mg/L, 317.71 mg/L and 257.77 mg/L, respectively, all were increased, and the microstructure on the surface of coffee grounds was more fragmented, indicating that ultrasound-assisted cold extraction broke the plant cell walls, thus releasing more soluble substances, and ultrasound-assisted cold extraction time was significantly shortened. This study optimized the extraction process of ultrasound-assisted cold extraction for the preparation of coffee liquor, and the results showed that ultrasound-assisted cold extraction is an effective extraction technique, which would provide a reference for the application of ultrasound-assisted technology in coffee processing industry.

Key words: coffee bean, ultrasound assisted cold extraction, response surface optimization, physical and chemical properties

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