2024-05-07 ニューサウスウェールズ大学(UNSW)
＜関連情報＞
- https://www.unsw.edu.au/newsroom/news/2024/05/Ultrasonic_cold_brew_coffee_ready_under_three_minutes
- https://www.sciencedirect.com/science/article/pii/S1350417724001330
コーヒーのコールドブリューの時間を数時間から数分に短縮するソノリアクターが開発される Coffee brewing sonoreactor for reducing the time of cold brew from several hours to minutes while maintaining sensory attributes
Shih-Hao Chiu, Nikunj Naliyadhara, Martin P. Bucknall, Donald S. Thomas, Heather E. Smyth, Jaqueline M. Nadolny, Kourosh Kalantar-Zadeh, Francisco J. Trujillo
Ultrasonics Sonochemistry Available online: 23 April 2024
DOI:https://doi.org/10.1016/j.ultsonch.2024.106885
Highlights
- The sonoreactor reduced the cold brew time from 24 h to less than 3 min.
- Vibrations through the wall of the sonoreactor generated multiple cavitation zones.
- Acoustic cavitation significantly increased the extraction yield.
- Decreasing the basket loading percentage (BLP) increased extraction yield.
- It produced coffee with sensory qualities similar to those of 24-hour cold brew.
Abstract
This research designed and developed an ultrasonic reactor for a fast and on demand production of cold brew coffee, remarkably reducing the brewing time from 24 h to less than 3 min. The technology was engineered by utilizing resonance to induce ultrasonic waves around the walls of the brewing basket of an espresso machine. The sound transmission system comprised a transducer, a horn and a brewing basket. This arrangement transformed the coffee basket into an effective sonoreactor that injected sound waves at multiple points through its walls, thereby generating multiple regions for acoustic cavitation within the reactor. Furthermore, acoustic streaming induced greater mixing and enhanced mass transfer during brewing. The design was accomplished by modeling the transmission of sound, and acoustic cavitation. Brew characterization and chemical composition analysis was performed, considering factors such as pH, acidity, color, and the composition of caffeine, fatty acids, and volatiles. The efficiency of the extraction increased by decreasing the basket loading percentage (BLP). For instance, sonicating at 100 W doubled the extraction yield and caffeine concentration, from 15.05 % to 33.44 % at BLP = 33 %, and from 0.91 mg/mL to 1.84 mg/mL at BLP = 67 %, respectively. The total fatty acids increased from 1.16 mg/mL to 9.20 mg/mL, representing an eightfold increase, at BLP = 33 %. Finally, a sensory analysis was conducted to evaluate appearance, aroma, texture, flavor, and aftertaste, which demonstrated that coffee brewed for 1 and 3 min in the sonoreactor exhibited almost undistinguishable properties compared to a standard 24 h brewing without ultrasound.
