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April 29, 2009

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A machine with a taste—for espresso

Feb. 7, 2008
Courtesy American Chemical Society
and World Science staff

Can a ma­chine taste cof­fee? The ques­tion has plagued sci­en­tists stu­dy­ing the caf­fein­ated bev­er­age. Re­search­ers say they can now an­swer with a re­sound­ing “yes.” A study on their cof­fee-tasting ma­chine is sched­uled for the March 1 is­sue of An­a­lyt­i­cal Chem­is­try, a re­search jour­nal.

A new ma­chine judg­es cof­fee qual­i­ty near­ly as ac­cu­rate­ly as con­nois­seurs, a study re­ports. (Im­age © C.W. Sil­lero)
For the food in­dus­try, “elec­tronic tasters” like these could prove use­ful as qual­ity con­trol de­vices to mon­i­tor food pro­duc­tion and pro­cess­ing, sci­en­tists say. 

Chris­tian Lind­inger and col­leagues at Nes­tlé Re­search in Switz­er­land not­ed that cof­fee sci­en­tists have long been search­ing for in­stru­men­tal ap­proaches to com­ple­ment and even­tu­ally re­place hu­man sen­so­ry pro­fil­ing. 

How­ev­er, the mul­ti­sen­so­ry ex­pe­ri­ence from drink­ing a cup of cof­fee makes it a par­tic­u­lar chal­lenge for fla­vor sci­en­tists try­ing to rep­li­cate these sensa­t­ions on a ma­chine, they added: more than 1,000 sub­s­tances may con­trib­ute to the com­plex aro­ma of cof­fee. 

The new ma­chine as­sessed the taste and aro­matic qual­i­ties of es­pres­so cof­fee nearly as ac­cu­rately as a pan­el of trained hu­man es­pres­so tasters, the study re­ported. 

It an­a­lyzed gas­es re­leased by a heat­ed es­pres­so sam­ple, then trans­formed the most per­ti­nent chem­i­cal in­forma­t­ion in­to taste qual­i­ties like roasted, flow­ery, woody, tof­fee and ac­id­ity. 

“This work rep­re­sents sig­nif­i­cant prog­ress in terms of cor­rela­t­ion of sen­so­ry with in­stru­men­tal re­sults ex­em­pli­fied on cof­fee,” the au­thors wrote.

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Can a machine taste coffee? The question has plagued scientists studying the caffeinated beverage for decades. Researchers say they can now answer with a resounding “yes.” A study on their coffee-tasting machine is scheduled for the March 1 issue of Analytical Chemistry, a research journal. For the food industry, “electronic tasters” like these could prove useful as quality control devices to monitor food production and processing, scientists say. Christian Lindinger and colleagues at Nestlé Research in Switzerland noted that coffee scientists have long been searching for instrumental approaches to complement and eventually replace human sensory profiling. However, the multisensory experience from drinking a cup of coffee makes it a particular challenge for flavor scientists trying to replicate these sensations on a machine, they added: more than 1,000 substances may contribute to the complex aroma of coffee. The new machine assessed the taste and aromatic qualities of espresso coffee nearly as accurately as a panel of trained human espresso tasters, the study reported. It analyzed gases released by a heated espresso sample, then transformed the most pertinent chemical information into taste qualities like roasted, flowery, woody, toffee and acidity. “This work represents significant progress in terms of correlation of sensory with instrumental results exemplified on coffee,” the authors wrote.