We’ve all been there: You’ve just spent the past hour working the grill, flipping perfect patties, and searing juicy steaks. By the time you can finally dig in, your mouth is watering and your stomach is growling. But before you take that first bite, you go to put on the finishing touch: a smear of tomato ketchup. Then, one of three things happens: you forget to shake the bottle, and watery goo drips onto your burger. Or, you shake the ketchup so vigorously that half the bottle splatters onto your sandwich. Either way, you’re left in a pickle (which we hope is on that burger, too).
Luckily, Dr. Anthony Strickland, a senior lecturer at the University of Melbourne in Australia, took the frustrating phenomenon into his own hands—and into the science lab. Strickland, whose research primarily focuses on the flow and deformation of particulate suspensions, determined that ketchup (and other concentrated suspensions, such as mayonnaise and melted chocolate), does not obey Sir Isaac Newton’s Law of Viscosity. The Law states that a fluid flows at a speed proportional to the force it is applied. But in the case of ketchup, the viscosity (which can be thought of as the thickness of the ketchup) decreases the faster it flows.
“Suspension rheology explains all the phenomena seen in tomato sauce bottles and provides the answers to the perennial sauce question, which can be tackled in three main steps,” Dr. Strickland said in a statement.
The first step? Shake! With the lid on, shake vigorously enough so that the solid particles that may have settled at the bottom of the jar are re-incorporated into the rest of the sauce. Next, with the lid screwed on tight, turn the bottle upside down and thrust downwards at high speeds. This should help move the ketchup into the neck of the bottle, which is particularly important if your bottle's nearly empty. Lastly, turn the bottle upright and remove the lid. It’s time to pour.
“You need to find the ‘sweet spot’ of force needed to move it towards your burger,” Strickland said. “Start by pointing the open end of the bottle toward your food at an angle of around 45 degrees with one hand around the bottle neck, and the other delivering gentle but firm taps on the bottom of the bottle. Increase the force of the taps until you balance the force applied with the mechanical strength of the sauce in order to get it to flow.”
If you’ve been tapping the 57 on the Heinz bottle, you’re not necessarily wrong—in fact, that’s what Heinz suggests on their website. But Strickland’s three steps will likely ensure more reliable results. Oh, and in other ketchup news, we’ve settled the debate on whether you need to refrigerate the condiment.