Instructions: A sniff of a cheese sandwich on the griddle pulls television commercial producer Lisa von Drehle back to a childhood conflict with her health-conscious mother. The memory of stew simmering in his mothers kitchen, triggered by odors wafting from a stockpot, inspires chef Allen Sternweiler to create "my favorite dish ever." Preparing a meat loaf, author Nancy Hutchens is struck by the vision of Aunt Esther, author of the meat loaf, defending her as a child.

For Tony Kramer, one of nine children, the smell of chicken cooked by his mother brings back moments of family harmony at the dinner table. Preparing a

"contemporary incarnation" of an old-fashioned slaw recipe, restaurateur Barbara Shinn finds herself recalling the women of her family who shaped and altered the recipe over the years. Stirring bread dough, advertising executive Cate Erickson is momentarily again a 5-year-old comforted by the smell of baking bread.

These all are memories of food, and all of them are triggered to some degree by smell.

"Many authorities believe that the sense of smell has a more powerful impact upon the emotions than any of the other senses," says Dr. Alan R. Hirsch, a pioneer in research on memories triggered by smell. This is the button novelist Marcel Proust inadvertently pushed when he sniffed a spoonful of tea in which lay some cake crumbs and evoked his remembrance of things past.

Hirsch, neurological director of the Smell & Taste Research and Treatment Foundation in Chicago, talks of "flash-bulb memories," so vivid are the re-creations.

Sniff and Revert
Jacques Pepin, the French chef and television personality, adds: "Its immediate, unexpected and very powerful. You come into a kitchen, sniff something and suddenly you are 5 years old again." And Diane Ackerman, in her book "A Natural History of the Senses," writes "smell needs no interpreter. The effect is immediate, and undiluted by language, thought or translation."

This is because smell works somewhat differently than the other senses. As Hirsch explains it in a recently published book, "What Flavor Is Your Personality?," odor molecules are drawn into the nostrils each time we inhale. Moving at lightning speed, they race through a number of gateways and along corridors located directly behind the bridge of the nose to reach the limbic lobe of the brain, also known as the emotional brain.

"No other sensory receptors or processors have their home in the limbic center of the brain," Hirsch writes. "The sense of smell stands alone as a direct link to the emotional responses and emotional life."

This means odor molecules can dash right into the space occupied by emotions such as love and hate and moods such as anxiety and pleasure. They trigger an involuntary, immediate response. The reaction comes first, even before we have identified the source of the odor. Thus a frown of displeasure may turn to a smile when we finally see a piece of cheese whose pungent odor has preceded it to the table. "Its supposed to smell that way," we say to ourselves.

This becomes even more significant, Hirsch explains, when we consider that

"smell may account for more than 90 percent of the sense we call taste."
The Palate Path
As we chew, odor molecules from the food follow a route that begins at the back of the throat behind the soft palate to the olfactory nerves, reinforcing what the nose has learned. Add signals from the taste buds, located on the tongue and soft palate, and tactile sensations such as texture and temperature

(sometimes called mouthfeel), and you have "flavor," the scientists say.

Taste "in the strict sense," David V. Smith and Robert F. Margolskee explain in the March issue of Scientific American, "is limited to perception of saltiness, sourness, sweetness and bitterness, and perhaps the glutamate-inspired sensation called umami." Smell and taste, known as the chemical senses, are far less developed in humans than in animals - perhaps, scientists theorize, because vision and hearing, which are processed through the rational side of the brain, the cortex, are more important in a society of humans. Furthermore, smell is emotional. It does not have to be rational.

Combine this loose-cannon element with the realization that another area to which odor molecules have direct access is the storehouse of memories.

From here
come the odor-inspired flash-bulb recollections Hirsch and others cite.

A study Hirsch conducted, asking nearly 1,000 people, "Do any particular odors remind you of your childhood?" brought an 85 percent positive response. "Food and cooking" were cited by 38.9 percent of the participants, with fresh baked goods the odor mentioned most often. Odors from nature, such as trees, rain and hay, rated 31.6 percent. No other odor - including smoke and soap - rated even 7 percent. (Curiously, pleasant odors are not as insistent as foul odors. We may lean forward, the better to inhale the odors from a flower, but will be repelled by a foul odor and seek to escape it.)

Idealized Past
Nostalgia, meanwhile, is playing with our psyches, Hirsch says. It is not just a yearning for the past, but "a longing for an idealized state, a sanitized impression of the past ... with all negative emotions filtered out." It is a "bittersweet" emotion because it represents a return to a past that "never truly existed." That explains why the food served at the re-creation of a long-ago dinner party can be curiously unsatisfying.

For some, a food odor may evoke no sweet, only bitter. For example, while a whiff of pumpkin pie spice mix or hot turkey stuffing triggers nostalgic recollections of Thanksgiving dinner in many of us, it may cause an opposite reaction in those with dysfunctional families.

Another rude shock: Only 61 percent of participants ages 60 or older said they had experienced olfactory-evoked recall. Among those under 60, the rate was 87 percent. Of course the elderly, many of whom suffer memory loss as well as the loss of the ability to smell, may have smell-inspired visions of things past - and then forget them.

Those under 60 had a burden of their own to carry. Their attacks of nostalgia often were brought on by artificial odors such as Play-Doh and plastic, while the oldsters cited natural odors such as sea air and pine.

Therefore, as the young inherit the role of taste arbitrators, will food memories be linked increasingly to artificial flavors?

That seems unlikely when, in many restaurants if not homes, real mashed potatoes and pristine vegetables are providing fresh food memories for a new generation.

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