What's that smell?

I was well aware that food smells can make us hungry, but thought that the reverse -- smells taking our appetite away -- was limited to the ones that were nauseous or disgusting. Apparently that's not so. There are good tasting foods that simultaneously promote a feeling of fullness by stimulating nerves in back of the nasal area. Could this be used to control appetite in the war against obesity? Maybe I'm putting it too simplistically. I'll let the authors of a review in the Journal of Agricultural and Food Chemistry (R.M.A.J. Ruijschop, et al., ""Retronasal Aroma Release and Satiation: A Review", 57(21): pp 9888-9894) explain it in more scientific terms:

“The application of aroma in food product development for inducing satiation is promising and appealing,” according to its authors, led by Rianne Ruijschop from NIZO Food Research.

“Complementary to ingredients that focus on the postingestive and postabsorptive stage of the satiety cascade, retronasal aroma release, operating during food ingestion, has a consumer benefit that is immediately noticeable,” they added. (via Stephen Daniells, The Dairy Reporter):

Translation: you'll eat less. OK. There's a bit more to it, of course. The interesting science here has to do with what the appetite suppressing chemicals are, how they are released when eating (e.g., do you have to chew them to release them?), what areas of the brain are stimulated and how is that related to appetite suppression, etc. There are all sorts of methodological problems to be solved, too. For example, how do you administer a food's aroma independently from its ingredients and the texture and taste of foods?

This research hasn't gone very far but I believe it's a reasonable approach. It's been my experience there are some foods where just a little bit seems to "fill me up." I never thought about why. I assumed that foods high in fat (the ones we often call "rich" when there is a lot of cream in them, for example) were liked that because of the high fat content. It never occurred to me there might be alternative pathways at work I wasn't aware of.

The authors have been doing research on how organic acids from fermentation alter the extent of "retro-nasal aroma release," as does a food's physical structure. The article says that solid foods generate these aromas for a longer time than liquid products. There's obviously a broad and promising research area here and a lot of interesting problems in food engineering, a topic I know almost nothing about. If I knew more about it, I might put it like this:

“Among the proof-of-principle studies that were performed, the prolongation of the duration of retronasal aroma release, the addition of specific ingredient-related aroma cues, the engineering of more complex aroma compositions, and the adaptation of bite size or duration of oral processing may prove to be valuable aroma concepts for the development of foods containing triggers that induce or increase the feeling of satiation.

“The next challenge is to implement these concepts into real food products,” they concluded.

And the challenge after that? Making them taste good?