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How Pet Food Developers Whet Furry Appetites

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Untreated, a piece of dry kibble is largely flavorless. Made of various meals and fats and blended with wheat and soy grains to offer balanced nutrition for an animal’s body, it would fail to stir the interest of most domesticated pets. Dogs might eat it without enthusiasm; cats would let it grow stale on the floor. Indifferent to grains, they need some extra incentive to empty their bowls.

That’s where Nancy Rawson, Ph.D. comes in. The Associate Director of the Monell Chemical Senses Center in Philadelphia, Rawson is an expert in tastes and flavors relating to research palatants—additives that give bland foods their taste appeal—for both humans and animals alike.

“[Food companies] want to bring the pet to the bowl,” Rawson tells mental_floss. “Dog food companies are good at formulation, but look elsewhere for their flavor systems.”

A large part of the work of places pet food companies consult with--one, AFB International, was where Rawson worked from 2010 to 2016--is focused on developing coatings that will make pets enthusiastic. For cats, the results of a hit recipe might mean whining and weaving in between their owner's feet until dinner is served. For dogs, it might entail getting so excited that they eat too quickly and bring the food right back up.

“I wouldn’t say puke is a good sign,” Rawson says. “But it can mean dogs really like the food.”


After subsisting on table scraps or the carcasses of dead livestock for thousands of years, domesticated dogs and cats started enjoying commercially produced canned food beginning in the 1920s. (Dog biscuits were invented in England in the mid-19th century, but only found favor in wealthier families.) The first canned food was Ken-L-Ration; those who opened a tin were likely to find wet food consisting largely of horse meat.

The demand for ready-to-serve dog food—cats were a minority interest for the companies at that time—grew so much that the Chappel brothers, owners of Ken-L-Ration, started breeding and slaughtering up to 50,000 horses a year for the purpose of putting their remains in cans. Horse meat became a less common ingredient by the 1940s, replaced with other kinds of meat, but with the outbreak of World War II, the rationing of both meat and tin meant that wet food in general grew scarce. Pet owners turned instead to the enormous stacks of dry kibble, which had first gone on sale in 1928 in 100-pound bags.

It was breakfast cereal that ushered in the modern age of marketable chow. In 1950, Ralston-Purina, which made both pet food and human-grade foods, developed an extrusion process in which they could shape their grains into air-puffed shapes that would hold up to submersion in milk. Purina’s dog food division took notice, spent three years tinkering with the extrusion machine, and then released Purina Dog Chow in 1957 to great acclaim. Easier to digest, with a fatty coating and texture made possible by extrusion, it marked the first time food companies treated a dog’s palate as worthy of consideration.


With $22 billion in sales in 2014, pet food companies are using some exacting science and research to make sure their kibble is worth binging on. For that, they outsource to companies like AFB and Kemin, home to flavor experts who develop the palatants designed to appeal to a pet's appetite.

Because canines and felines are non-verbal, Rawson is an expert on using bowl tests to assess the appeal of various dry food palatants—made from chemical blends, soy, corn, and animal organs blended into powder or liquid form [PDF]—using bowl tests. (Wet food, while it can contain palatants, is often flavorful enough on its own.) Animals at AFB are presented with two different meals and measured on criteria such as how quickly they come to the bowl, which bowl they indulge in first, how long they take to empty it, whether they stop and come back, and in some cases, how much time they spend with their nose buried in food relative to how long the food was available. This metric, for dogs, is called the Nose in Bowl, or NIB, test [PDF].

“You kind of have to treat them like babies,” Rawson says. “They can’t respond in words, so you pay attention to their behaviors.”

Cats, Rawson says, are reliable addicts for polyphosphates, an additive that she likens to the salt humans pour over their food. Cats also prefer the easy breakage of X-shaped kibble over other shapes, meaning that fun extrusions aren’t just for human amusement. “Cats don’t have molars, so different shapes break into different sizes more easily.” X-shaped pellets are easier for them to chew.

Dogs, on the other hand, aren't nearly as choosy. “We did a study and found that dogs will eat the largest size of kibble, regardless of breed,” Rawson says. A more important goal in designing dog food, both in terms of palatants and food density, is cleaning the dog's teeth, as well as slowing them down so they don't eat too much at once.

“Dogs are pleasers,” she says. “They’ll eat a bowl of rocks if their owner puts it down in front of them. The palatants act as more of a preservative for the food.”

And while dogs focus on smell, the aroma coming from an open bag isn't strictly for them. When owners open a chicken or fish-flavored meal, Rawson says, a lot of that smell and presentation is meant as much for the human as their pet. If AFB indulged only in what drove dogs crazy, like compounds given off by decomposing protein, their owner would never buy a second bag.

“When you open a bag of chicken kibble, you want it to smell like chicken. The job of the palatants companies is, in a way, to serve two masters.”


For pet food experts like Rawson, how food exits an animal is almost as important as how well it’s enjoyed on the way in. Dyed food, while festive for owners, turned out not to be such a good idea when your cat barfs up a rainbow on the carpet.

Palatants can also incorporate stool-hardening agents to make clean-up easier. Ever wonder what makes certain chow puppy-appropriate? Aside from calories, it’s partially an ability to reduce loose stools in younger dogs. Companies are "always trying to optimize stool volume,” she says. Reducing odor is also key, and certain formulations can do a better job of that than others.

Recently, the pet food conglomerates have been eyeing the growing demand for food that resembles human-grade servings. Purina now offers premium meals containing rotisserie chicken and filet mignon and employs a full-time pet food chef.

For Rawson, the movement into food that could conceivably co-exist on both a dog’s and owner’s plate isn't one worth embracing. “One of the fundamental problems is one of sustainability,” she says. “We’re diverting millions of tons of chicken meat into pet food that could be going to humans. Pets evolved eating guts. That’s what we should be using.”

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iStock // Ekaterina Minaeva
Man Buys Two Metric Tons of LEGO Bricks; Sorts Them Via Machine Learning
May 21, 2017
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iStock // Ekaterina Minaeva

Jacques Mattheij made a small, but awesome, mistake. He went on eBay one evening and bid on a bunch of bulk LEGO brick auctions, then went to sleep. Upon waking, he discovered that he was the high bidder on many, and was now the proud owner of two tons of LEGO bricks. (This is about 4400 pounds.) He wrote, "[L]esson 1: if you win almost all bids you are bidding too high."

Mattheij had noticed that bulk, unsorted bricks sell for something like €10/kilogram, whereas sets are roughly €40/kg and rare parts go for up to €100/kg. Much of the value of the bricks is in their sorting. If he could reduce the entropy of these bins of unsorted bricks, he could make a tidy profit. While many people do this work by hand, the problem is enormous—just the kind of challenge for a computer. Mattheij writes:

There are 38000+ shapes and there are 100+ possible shades of color (you can roughly tell how old someone is by asking them what lego colors they remember from their youth).

In the following months, Mattheij built a proof-of-concept sorting system using, of course, LEGO. He broke the problem down into a series of sub-problems (including "feeding LEGO reliably from a hopper is surprisingly hard," one of those facts of nature that will stymie even the best system design). After tinkering with the prototype at length, he expanded the system to a surprisingly complex system of conveyer belts (powered by a home treadmill), various pieces of cabinetry, and "copious quantities of crazy glue."

Here's a video showing the current system running at low speed:

The key part of the system was running the bricks past a camera paired with a computer running a neural net-based image classifier. That allows the computer (when sufficiently trained on brick images) to recognize bricks and thus categorize them by color, shape, or other parameters. Remember that as bricks pass by, they can be in any orientation, can be dirty, can even be stuck to other pieces. So having a flexible software system is key to recognizing—in a fraction of a second—what a given brick is, in order to sort it out. When a match is found, a jet of compressed air pops the piece off the conveyer belt and into a waiting bin.

After much experimentation, Mattheij rewrote the software (several times in fact) to accomplish a variety of basic tasks. At its core, the system takes images from a webcam and feeds them to a neural network to do the classification. Of course, the neural net needs to be "trained" by showing it lots of images, and telling it what those images represent. Mattheij's breakthrough was allowing the machine to effectively train itself, with guidance: Running pieces through allows the system to take its own photos, make a guess, and build on that guess. As long as Mattheij corrects the incorrect guesses, he ends up with a decent (and self-reinforcing) corpus of training data. As the machine continues running, it can rack up more training, allowing it to recognize a broad variety of pieces on the fly.

Here's another video, focusing on how the pieces move on conveyer belts (running at slow speed so puny humans can follow). You can also see the air jets in action:

In an email interview, Mattheij told Mental Floss that the system currently sorts LEGO bricks into more than 50 categories. It can also be run in a color-sorting mode to bin the parts across 12 color groups. (Thus at present you'd likely do a two-pass sort on the bricks: once for shape, then a separate pass for color.) He continues to refine the system, with a focus on making its recognition abilities faster. At some point down the line, he plans to make the software portion open source. You're on your own as far as building conveyer belts, bins, and so forth.

Check out Mattheij's writeup in two parts for more information. It starts with an overview of the story, followed up with a deep dive on the software. He's also tweeting about the project (among other things). And if you look around a bit, you'll find bulk LEGO brick auctions online—it's definitely a thing!

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Nick Briggs/Comic Relief
What Happened to Jamie and Aurelia From Love Actually?
May 26, 2017
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Nick Briggs/Comic Relief

Fans of the romantic-comedy Love Actually recently got a bonus reunion in the form of Red Nose Day Actually, a short charity special that gave audiences a peek at where their favorite characters ended up almost 15 years later.

One of the most improbable pairings from the original film was between Jamie (Colin Firth) and Aurelia (Lúcia Moniz), who fell in love despite almost no shared vocabulary. Jamie is English, and Aurelia is Portuguese, and they know just enough of each other’s native tongues for Jamie to propose and Aurelia to accept.

A decade and a half on, they have both improved their knowledge of each other’s languages—if not perfectly, in Jamie’s case. But apparently, their love is much stronger than his grasp on Portuguese grammar, because they’ve got three bilingual kids and another on the way. (And still enjoy having important romantic moments in the car.)

In 2015, Love Actually script editor Emma Freud revealed via Twitter what happened between Karen and Harry (Emma Thompson and Alan Rickman, who passed away last year). Most of the other couples get happy endings in the short—even if Hugh Grant's character hasn't gotten any better at dancing.

[h/t TV Guide]