Lunchtime is fast approaching and there's a couple of stomach rumbles echoing through the Her office. That's partly due to the below Reactions video, hosted by the American Chemical Society, which promises the best sandwich ever. Now while a cheese toastie seems like a simple snack you can rustle up, there's a couple of things science says you should consider. https://www.youtube.com/watch?v=rttkpPFNkmY The Consumerist has delved into the science behind this and there are some types of cheese that ensure the runny melted goodness that we love. According to the experts, it's all down to PH levels: if the PH is too high, then you're going to get a clump of hardened greasy cheese but one with a low PH won't hold together at all. You want your sandwich to separate perfectly. First world problem, we know. With this in mind, the best types of cheese to melt are Gouda, Gruyere and Manchego but if you're a cheddar fan, mild not sharp is the way to go. Other considerations include avoiding cheddar slices (one word, rubber), grating your cheese first AND thinking your bread choice through. We're all about crusty farmhouse doorstep slices....and now, we're STARVING.