According to the latest American Chemical Society (ACS) Weekly PressPac, French researchers have developed an artificial mouth that chews apples like you and me. Here is a link to this PressPac, from which you'll be able to read a very short note titled 'Munch-o-matic: Scientists develop the artificial mouth.' The tasting device is able to reproduce the effects of chewing by analyzing a number of factors which are involved in the release of aromatic and flavor compounds in the mouth, such as the release of saliva or the rate of food breakdown. If this machine can chew food like us, it might pave the way for future machines which can learn to taste food and improve quality. But read more...
You can see above a schematic representation of the artificial mouth. "The artificial mouth is composed of a sample container (600 mL), a notched plunger, and variable-speed motors to control precisely the speed of compression and rotation movements. The container is maintained at 37 °C by means of a laboratory thermostat (Bioblock Scientific) via an outer layer. The container is sealed with a cap maintained by a circlip." (Credit: Gaëlle Arvisenet and colleagues, via ACS). Hre is a link to a larger version of this diagram.
This research work has been led by Gaëlle Arvisenet at the French ENITIAA school which trains engineers for the food industry sector. Unfortunately, Arvisenet has not her own research page on the University site.
The ENITIAA research work is available online from the ACS's Journal of Agriculture and Food Chemistry under the name "Effect of Apple Particle State on the Release of Volatile Compounds in a New Artificial Mouth Device." It should appear in the printed version in the May 14, 2008 issue of the scientific paper.
Here is a link to the abstract. "Varying the crushing parameters in a model mouth apparatus gave different crushed apple samples, which were compared to apples crushed in the human mouth by six people. An image analysis method was developed to measure the similarity between apple particles after crushing in the artificial mouth and in the human mouth. Thus, experimental conditions were determined that produced fruit in a state closest to that obtained after mastication in a human mouth. The influence of these different conditions on the quantity of released volatile compounds was then studied."
The full paper is also currently available in an HTML version and as a PDF document (9 pages, 1.82 MB).
Here is an excerpt from the introduction. "To be perceived while eating a food, aroma compounds must be released from the food matrix before being transported to the receptors. In solid foods, a succession of events takes place, which influence volatile release. When the food is crushed and mixed with saliva, its structure is modified and the diffusion of its volatiles from the resulting bolus to the headspace is affected. With mastication, the food surface area exposed to the air increases, and the food matrix is separated from the water it contained initially. These processes involve not only the composition and structure of foods but also the conditions in the mouth, that is, temperature, presence of saliva, rate at which food is broken down during chewing, and possible adsorption by the mouth mucosa. Moreover, the disruption of tissues can induce the enzymatic generation of volatiles. Two experimental approaches have been developed to study volatile release in the mouth."
So what approach was used by the scientists? "In the present work, an artificial mouth was designed in which we studied apples as a model of real foodstuffs with a complex structure and chewy texture. Using a previous artificial mouth (26), we showed that the amounts of extracted volatile compounds were not the same when apples were crushed, cut into slices, or reduced to a puree state. It follows that to study the aroma compounds responsible for global aroma perception, it is necessary to reproduce the changes that the foodstuffs undergo in the human mouth. Our objectives were, first, to find artificial mastication settings that best reproduce human mastication and, second, to determine if artificial mastication conditions have an effect on the release of volatile compounds."
Arvisenet said that "Our aim was not to reproduce human mouth conditions exactly, but to reproduce the result of mastication. Some control parameters of the artificial mouth were determined by comparison with in vivo mastication. Parameters that could not imitate exactly in vivo conditions were assigned different values, with an experimental plan. Fruit crushed in the artificial mouth were compared with fruit chewed in vivo by image texture analysis. Volatile compounds extracted in each experimental condition were analyzed. We did not compare volatile compounds released after in vitro and in vivo mastication in the present study."
So what will happen next? "Now that a method to characterize apple state has been successfully applied, the next steps will concern the optimization of aroma release. To know which artificial mouth settings best mimic the human mouth, it will be necessary to compare the volatile profile obtained with volatiles released in vivo. The compounds responsible for the aroma of fresh apple may then be distinguished from those produced during the extraction. It can be stated that, coupled with more sensitive analysis conditions or with online analysis such as APCI-MS or PTR-MS, the present device would allow a real improvement in extraction from hard foods."
Sources: American Chemical Society weekly news release, April 30, 2008; and various websites
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