Splat -- the tomato sauce finally comes out in a big, globby mess, despite the fact you've been shaking for minutes.
It's not your sauce technique, the truth is that it's actually really hard to get tomato sauce to come out of the bottle, and here's why:
Tomato sauce is a solid, not a liquid.
The University of Melbourne engineer Anthony Stickland said that effect when you shake and shake and nothing comes out and then it floods comes down to something called 'yield stress'.
"With tomato sauce, it's got all of the solid particles of the pulp of the tomato sticking it all together," Strickland said in the YouTube video.
"Those solid part create a network that has a strength to it, and you need to apply enough force to overcome that strength of that network.
"So it's all about applying the force to the sauce to push it out."
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How to make your sauce come out
1. Shake the sauce with the lid on to mix the solid and watery particles.
2. Flip the bottle upside down and give the bottle a strong whack to move the sauce to the bottle neck.
3. Open the lid and, depending on how much sauce is left, give it a shake. For a lot of sauce, gravity should do the trick on its own, but a near-empty bottle will need a fair shake.