Gulp: Adventures on the Alimentary Canal (5 page)

Enough stalling. Time to try the palatant. I raise the cup to my nose. It has no smell. I roll some over my tongue. All five kinds of taste receptors stand idle. It tastes like water spiked with strange. Not bad, just other. Not food.

“It may be that that otherness is something specific to the cat,” says Rawson. Perhaps some element of the taste of meat that humans cannot perceive. The feline passion for pyrophosphates might explain the animal’s reputation as a picky eater. “We make [pet food] choices based on what we like,” says Reed, “and then when they don’t like it, we call them finicky.”

There is no way to know or imagine what the taste of pyrophosphate is like for cats. It’s like a cat trying to imagine the taste of sugar. Cats, unlike dogs and other omnivores, can’t taste sweetness. There’s no need, since the cat’s diet in the wild contains almost nothing in the way of carbohydrates (which include simple sugars). Either cats never had the gene for detecting sweet, or they lost it somewhere down the evolutionary road.

Rodents, on the other hand, are slaves to sweetness. They have been known to die of malnutrition rather than step away from a sugar-water drip. In an obesity study from the 1970s, rats fed an all-you-can-eat “supermarket” diet that included marshmallows, milk chocolate, and chocolate-chip cookies gained 269 percent more weight than rats fed standard laboratory fare. There are strains of mice that will, over the course of a day, consume their own bodyweight in diet soda, and you do not want the job of changing their bedding.

Does that mean rodents feel pleasure in tasting sweet things the same way we do? Or is it simply a sequence of programmed responses, receptors sending signals and signals driving muscles? Video footage Danielle Reed sent me suggests that rodents do consciously perceive and savor the taste of something sweet. One clip shows a white mouse that has just been drinking sugar solution. She is shown in ultra-slow motion, filmed from below through a clear plastic floor, licking the fur around the sides of her mouth. (The caption uses the scientific term for lip-licking: “lateral tongue protrusion.”) Another clip shows a mouse that has just tasted denatonium benzoate, a bitter compound that parents used to paint on their children’s fingertips to discourage nail-biting. The mouse is doing everything it can to rid itself of traces of the chemical. It shakes its head and rubs its face with its hairy white forelegs. It pulls a “gape”: mouth opened wide, tongue stuck out to eject the offending food. (Humans do this too. The scientific term here is “the disgust face.”)

“If it’s exceedingly nasty,” Reed told me, “they will actually drag their tongue on the bedding to try to get it off.” Clearly taste matters to them.

Conversely, do animals with no taste buds derive no pleasure from eating? Is it just a daily chore? Has anyone observed—in, say, a python eating a rat—those same parts of the brain that light up when humans are experiencing taste delight? Reed doesn’t know. “But no doubt somewhere in the world there’s a scientist trying to get a live python into an fMRI machine.”

Rawson points out that although snakes can’t taste, they have a primitive sense of smell. They’ll extend their tongue to gather volatile molecules and then pull it back in and plug it into the vomeronasal organ at the roof of the mouth to get a reading. Snakes are keenly attuned to the aroma of favored prey—so much so that if you slip a rat’s face and hide, Hannibal Lecter–style, over the snout of a non-favored prey item, a python will try to swallow it. (University of Alabama snake digestion expert Stephen Secor did this some years back to reenact a scene for National Geographic television. “Worked like a charm,” he told me. “I can get a python to eat a beer bottle if I put a rat head on it.”)

For part of their development, human fetuses have a vomeronasal organ, though no one knows whether it’s functional. You can no more ask a fetus about these things than a python. Rawson surmises that the organ is a holdover from “when we were crawling out of the primordial soup,
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and we needed to sense the chemicals in the environment and know which ones to go toward or away from.”

Rawson has an idea of what it is like to eat without perceiving tastes, because she has talked to cancer patients whose taste receptors have been destroyed by radiation treatments. The situation is well beyond unpleasant. “Your body is saying, ‘It’s not food, it’s cardboard,’ and it won’t let you swallow. No matter how much you tell your brain that you need to eat to survive, you’ll gag. These people can actually die of starvation.” Rawson knows a researcher who has been experimenting with using potent flavors—which, as we know from the last chapter, are mainly smells—to make up for absent tastes. Taste and smell are intertwined in ways we don’t consciously appreciate. Food technologists sometimes exploit the synergy between the two. By adding strawberry or vanilla—aromas we associate with sweetness—it’s possible to fool people into thinking a food is sweeter than it really is. Though sneaky, this is not necessarily bad, because it means the product can contain less added sugar.

Which takes us back to palatants, and why pet-food manufacturers love them. As one AFB employee put it, “The client can go, ‘Here’s my product. I want to cut corners here and here and here, and I want you to cover up all the sins.’” This is especially doable with dog food, as dogs rely more on smell than taste in making choices about what to eat and how vigorously. (Pat Moeller estimates that for dogs, the ratio for how much aroma matters to how much taste matters is 70/30. For cats, the ratio is more like 50/50.) The takeaway lesson is that if the palatant smells appealing, the dog will dive in with instant and obvious zeal, and the owner will assume the food is a hit. In reality it may have only smelled like a hit.

Interpreting animals’ eating behaviors is tricky. By way of example, one of the highest compliments a dog can pay its food is to vomit. When a “gulper,” to use Pat Moeller’s terminology, is excited by the aroma of a food, it will wolf down too much too fast. The stomach overfills, and the meal is reflexively sent back up to avoid any chance of a rupture. “No consumer likes that, but it’s the best indication that the dog just loved it.” Fortunately for the staff at the AFB Palatability Assessment Resource Center, there are other ways to gauge a pet food’s popularity.

“E
VERYONE WANTS TO
be Meow Mix.” Amy McCarthy, head of PARC, stands outside the plate-glass window of Tabby Room 2, where an unnamed client is facing off against Meow Mix, Friskies, and uncoated kibble in a preference test. If a client wants to be able to say that cats prefer its product over Meow Mix, they must prove it at a facility like PARC.

Two animal techs dressed in tan surgical scrubs stand facing each other. They hold shallow metal pans of kibble in various shades of brown,
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one in each hand. Around their ankles, twenty cats mince and turn. The techs sink in tandem to one knee, lowering the pans.

The difference between dog and cat is immediately obvious. While a dog almost (and occasionally literally) inhales its food the moment it’s set down, cats are more cautious. A cat wants to taste a little first. McCarthy directs my gaze to the kibble that has no palatant coating. “See how they feel it in their mouth and then drop it?”

I see an undifferentiated ground-cover of bobbing cat heads, but nod anyway.

“Now look there.” She directs my gaze to the Meow Mix, where the bottom of the pan is visible through an opening in the kibble. I ask McCarthy if there’s an industry term
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for the open spot.

“
Um
. . . ‘The space where kibble used to be’?” McCarthy speaks louder than you expect a person to, perhaps a side effect of time spent talking over barking. She is in her thirties, with blonde hair that is center-parted and wants to fall in her face. Every few minutes, she’ll raise both forefingers to the sides of her face to nudge it back. Rawson’s hair, by contrast, is cropped close to her head. It’s a “pixie cut,” but those probably aren’t the words she used when she discussed it with her haircutter. Rawson has come with me to PARC because she hasn’t yet visited and wants to learn how the preference testing is being done and how the techniques might be improved.

Meanwhile, down the hallway, dog kibble A, dressed in a coat of newly formulated AFB palatant, is up against the competitor. The excitement is audible. One dog squeals like sneaker soles on a basketball court. Another makes a huffing sound reminiscent of a two-man timber saw. The techs are wearing heavy-duty ear protection, the kind worn on airport tarmacs.

A tech named Theresa Kleinsorge opens the door of a large kennel crate and sets down two bowls in front of a terrier mix with dark-ringed eyes. Theresa is short and brassy, with spiky magenta-dyed hair.
Kleinsorge
is German for “little trouble,” and it seems like a good name—
trouble
in the affectionate sense of well-intentioned mischief. She owns seven dogs. Amy McCarthy shares her home with six. Dog love is palpable here at PARC. It is the first pet-food test facility to “group-house” its animals. Other than during certain preference tests, when animals are crated to avoid distractions, PARC is a cageless facility. Groups of dogs, matched by energy level, spend their days roughhousing in outdoor yards.

The terrier mix is named Alabama. His tail thumps a beat on the side of the crate. “Alabama is a gobbler real bad,” Theresa says. In making their reports, the AFB techs must take into account the animals’ individual mealtime quirks. There are gulpers, circlers, tippers, snooters. If you weren’t acquainted with Alabama’s neighbor Elvis, for example, you’d think he was blasé about both foods just now set before him. Theresa gives a running commentary of Elvis’s behavior while a colleague jots notes. “Sniffing A. Sniffing B. Licking B, licking his paws. Going back to A. Looking at A. Sniffing B. Eating B.”

Most dogs are more decisive. Like Porkchop. “You’ll see. He’ll sniff both, pick one, eat it. Ready?” She puts two bowls by Porkchop’s front paws. “Sniffing A, sniffing B, eating A. See? That’s what he does.”

PARC techs also try to keep a bead on doggy interactions in the yards. “We need to know,” says McCarthy. “‘Are you down because you don’t like the food or because Pipes stole your bone earlier?’” Theresa volunteers that a dog named Rover has lately had a stomach upset, and Porkchop likes to eat the vomit. “So that’s cutting into Porkchop’s appetite.” And probably yours.

In addition to calculating how much of each food the dogs ate, PARC techs tally the first-choice percentage: the percentage of dogs who stuck their snout in the new food first. This is important to a pet-food company because with dogs, as Moeller said earlier, “if you can draw them to the bowl, they’ll eat, most of the time.” Once the eating begins, though, the dog may move to the other food and wind up consuming more of it. Since most people don’t present their dog with two choices, they don’t know the extent to which their pet’s initial, slavering, scent-driven enthusiasm may have dimmed as the meal went on.

The challenge is to find an aroma that drives dogs wild without making their owners, to use an Amy McCarthy verb, yack. “Cadaverine is a really exciting thing for dogs,” says Rawson. “Or putrescine.” But not for humans. These are odoriferous compounds given off by decomposing protein. I was surprised to learn that dogs lose interest when meat decays past a certain point. It is a myth that dogs will eat anything. “People think, Dogs love things that are old, nasty, drug around in the dirt,” Moeller told me earlier. But only to a point, he says. And for a reason. “Something that’s just starting to decay still has full nutritional value. Whereas something where the bacteria have really broken it down, it’s lost a lot of its nutritional value and they would only eat it if they had no choice.” Either way, a pet owner doesn’t want to smell it.

Some dog-food designers go too far in the other direction, tailoring the smell to be pleasing to humans
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without taking the dog’s experience of it into account. The problem is that the average dog’s nose is about a thousand times more sensitive than the average human’s. A flavor that to you or me is reminiscent of grilling steak may be overpowering and unappealing to a dog.

Earlier in the day, I watched a test of a mint-flavored treat marketed as a tooth-cleaning aid. Chemically speaking, mint, like jalapeño, is less a flavor than an irritant. It’s an uncommon choice for a dog treat.
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The manufacturers are clearly courting the owners, counting on the association of mint with good oral hygiene. The competition courts the same dental hygiene association but visually: the biscuit is shaped like a toothbrush. Only Rover preferred the minty treats. Which maybe explains the vomiting.

A dog named Winston is nosing through his bowl for the occasional white chunk among the brown. Many of the dogs picked these out first. They’re like the M&M’s in trail mix. McCarthy is impressed. “That’s a really, really palatable piece in there.” One of the techs mentions that she tried some earlier, and that the white morsels are chicken. Or rather, “chickeny.”

I must have registered surprise at the disclosure, because Theresa jumps in. “If you open up a bag and it smells really good—”

The tech shrugs. “And you’re hungry . . .”

I
N 1973 THE
nutritional watchdog group Center for Science in the Public Interest (CSPI) published a booklet titled
Food Scorecard
, which made the claim that one-third of the canned dog food purchased in housing projects was consumed by people. Not because they’d developed a taste for it, but because they couldn’t afford a more expensive meat product. (When a reporter asked where the figure had come from, CSPI founder Michael Jacobson couldn’t recall, and to this day the organization has no idea.)

To my mind, the shocker was in the scores themselves. Thirty-six common American protein products were ranked by overall nutritional value. Points were awarded for vitamins, calcium, and trace minerals, and subtracted for added corn syrup and saturated fats. Jacobson—believing that poor people were eating significant amounts of pet food, and/or exercising his talent for publicity—included Alpo in the rankings. It scored 30 points, besting salami and pork sausage, fried chicken, shrimp, ham, sirloin steak, McDonald’s hamburgers, peanut butter, pure-beef hotdogs, Spam, bacon, and bologna.