Scientists Invent a Way to Brew Espresso With Ultrasonic Waves—No Hot Water Required
Scientists Invent a Way to Brew Espresso With Ultrasonic Waves—No Hot Water Required
科学家发明超声波萃取浓缩咖啡新法：无需热水
What do you need to make a good espresso? Ground coffee, of course; a machine capable of generating pressure; and hot water, preferably heated to between 195 and 205 degrees Fahrenheit. And that’s it. But could one perhaps do without that last element? No, not the water itself, but the need to heat it. 制作一杯好的浓缩咖啡需要什么？当然是咖啡粉、一台能产生压力的机器，以及最好加热到 195 到 205 华氏度（约 90 到 96 摄氏度）的热水。仅此而已。但我们是否可以省去最后一个要素呢？不是省去水本身，而是省去加热水的需求。
The Colombian researcher Francisco Trujillo led a team at Australia’s University of New South Wales that claims to have invented what it calls “ultrasonic espresso.” As Trujillo explains, it is “a room-temperature brewing process that uses high-frequency sound waves to extract the flavor, oils, aroma, and caffeine from ground coffee.” 哥伦比亚研究员 Francisco Trujillo 带领澳大利亚新南威尔士大学的一个团队，声称发明了所谓的“超声波浓缩咖啡”。正如 Trujillo 所解释的那样，这是一种“室温萃取工艺，利用高频声波从咖啡粉中提取风味、油脂、香气和咖啡因”。
Although the process takes longer than the conventional method (three minutes versus 30 seconds), it consumes 75 percent less energy—a considerable benefit for coffee shops and restaurants, but especially for businesses that produce industrial quantities of coffee, such as those making ready-to-drink products. 尽管该工艺比传统方法耗时更长（三分钟对比 30 秒），但其能耗降低了 75%。这对咖啡店和餐厅来说是一项巨大的优势，对于生产工业级咖啡（如即饮咖啡产品）的企业而言，意义尤为重大。
Sonic Brew
声波萃取
The experimental system directs ultrasonic waves directly into the filter containing the ground beans in water. Instead of relying on heat, the technology harnesses a phenomenon known as acoustic cavitation. This involves the formation and collapse of tiny bubbles that generate microcurrents which, in this experiment, facilitate the extraction of soluble compounds from the coffee. 该实验系统将超声波直接导入装有咖啡粉和水的过滤器中。这项技术不依赖热量，而是利用了一种被称为“声空化”的现象。这涉及微小气泡的形成与破裂，从而产生微电流；在实验中，这些微电流促进了咖啡中可溶性化合物的萃取。
To generate those microcurrents, the scientists designed a device capable of transmitting ultrasonic vibrations throughout the entire filter basket, transforming it into a sort of acoustic reactor. This design allows the waves to hit multiple points simultaneously and accelerate the movement of liquids around the coffee particles. “Ultrasound helps us replace heat with mechanical energy,” explains Trujillo. 为了产生这些微电流，科学家们设计了一种能够将超声波振动传导至整个滤篮的装置，将其转化为一种“声学反应器”。这种设计使声波能够同时作用于多个点，并加速咖啡颗粒周围液体的运动。“超声波帮助我们用机械能取代了热能，”Trujillo 解释道。
The goal of this entire process, described in greater detail in this month’s issue of the Journal of Food Engineering, is to achieve a concentration comparable to that of an espresso. To do so, the researchers adjusted variables such as grind size, ultrasound power, and brewing time. Using a fine grind and 100 watts of power, they obtained beverages with levels of dissolved solids and extraction yields equivalent to those considered ideal by the Specialty Coffee Association. 这一完整工艺的细节发表在本月的《食品工程杂志》（Journal of Food Engineering）上，其目标是达到与浓缩咖啡相当的浓度。为此，研究人员调整了研磨度、超声波功率和萃取时间等变量。通过使用细研磨和 100 瓦的功率，他们获得的饮品在溶解固体含量和萃取率方面，均达到了精品咖啡协会（Specialty Coffee Association）所认定的理想标准。
When the experiments were repeated under the same conditions but without ultrasound, it was not possible to achieve these values. The ultrasonic system made it possible to produce coffee with an intensity similar to that of espresso in just a few minutes—the researchers found the optimal time to be between two and a half and three minutes—using water at room temperature. 当在相同条件下但不使用超声波重复实验时，无法达到这些数值。超声波系统使得在室温下，仅需几分钟（研究人员发现最佳时间为两分半到三分钟）就能制作出浓度与浓缩咖啡相当的咖啡。
The team also analyzed various chemical parameters. The concentrations of caffeine and chlorogenic acid were similar to those obtained by conventional methods. No significant differences were observed in pH or in the overall composition of the volatile compounds responsible for the aroma. 该团队还分析了各种化学参数。咖啡因和绿原酸的浓度与传统方法获得的结果相似。在 pH 值或决定香气的挥发性化合物的整体组成方面，也没有观察到显著差异。
Taste Test
口感测试
A group of 100 people participated in sensory tests in which they compared ultrasonic espresso with conventional espresso. Ultimately, the participants showed no notable preference for either method. The scores for aroma, flavor, bitterness, and overall acceptance were virtually equivalent. 100 名参与者参加了感官测试，对比了超声波浓缩咖啡与传统浓缩咖啡。最终，参与者对两种方法没有表现出明显的偏好。在香气、风味、苦味和整体接受度方面的评分几乎完全相同。
They also compared filtered coffee prepared using the conventional method and with ultrasound. “In the case of filtered coffee, the ultrasonically processed version was generally preferred, and participants rated its bitterness as more pleasant,” noted Trujillo. 他们还对比了使用传统方法和超声波制备的过滤咖啡。“在过滤咖啡的情况下，超声波处理的版本普遍更受欢迎，参与者认为其苦味更令人愉悦，”Trujillo 指出。
In addition to replicating the sensory characteristics of espresso, the new technique could offer environmental benefits. Measurements taken by the researchers indicate that, to produce beverages of the same intensity, the ultrasonic system used just 24 percent of the energy consumed by a typical espresso machine. 除了复制浓缩咖啡的感官特征外，这项新技术还具有环境效益。研究人员的测量结果显示，为了生产相同浓度的饮品，超声波系统仅消耗了典型浓缩咖啡机 24% 的能量。
The authors emphasize that coffee produced using ultrasound is not identical to traditional espresso. However, the results suggest that it is possible to produce beverages with comparable chemical and sensory characteristics without heating the water. 作者强调，使用超声波生产的咖啡与传统浓缩咖啡并不完全相同。然而，研究结果表明，在不加热水的情况下，完全有可能生产出具有相当化学和感官特征的饮品。
The research opens up the possibility of developing new coffee makers capable of preparing everything from espresso to filtered coffee and cold brew using the same technology. If these systems are ever brought to market, the characteristic sound of an espresso machine could be replaced by the inaudible vibrations of ultrasound. 这项研究开启了开发新型咖啡机的可能性，即利用同一技术制备从浓缩咖啡到过滤咖啡乃至冷萃咖啡的各种饮品。如果这些系统未来能够推向市场，浓缩咖啡机特有的轰鸣声可能会被超声波那不可闻的振动所取代。