Ever eaten cold spaghetti first thing in the morning and wondered why it tastes so much better than it did the night before? There's actually science behind it. And, even better, health benefits.
Dr Hazel MacTavish-West, Tasmania-based food scientist and nutritionist, says cooking an ingredient that's high in starch such as potato or pasta opens some of the structure of the starch, making it easier to digest and increasing the glycemic index (that's how quickly your blood sugars increase in response to eating it.) Putting lasagne in the fridge overnight closes those structures. "Eating [pasta] cold is actually really good if you want to have less of an impact on your blood sugar from the carbohydrates," says MacTavish-West.
The delicious factor comes down, essentially, to time for the ingredients to get to know each other in the fridge. If there's a fat or sauce component that's dressed the starch, it will be captured as the starch structures close up, so the experience of eating leftover pizza, pasta, or even a roast potato is intensified as they act as a flavour vacuum.
When those foods are cooked fresh, the fats and sauces are merely sitting on the surface - the overnight soak is where the true joy of a leftover comes into play. "If you're doing roast meats or fried chicken," says MacTavish-West, "you actually get a better experience if you slice them up and put them with a sauce overnight and then heat them up the next day because the flavours merge in."
According to recent research conducted by Deliveroo, 55 per cent of people surveyed feel the same way when it comes to dinner-for-breakfast, with 62 per cent voting leftover pizza as the crowd favourite. The research, which surveyed 1,000 countrywide, found 48 per cent of Australians purposefully over-order on their takeaway in order to have next-day leftovers.
When it comes to storing and re-heating those leftovers, there's a science to that too. "The most important thing about leftovers is to get them into the fridge as soon as possible so they cool quickly," says MacTavish-West. "The best way of re-heating quickly is in the microwave. There's a historical fear around leftovers. The thing is to not feel like you have to overheat it - that just sends everything into a tailspin of tightness."
When it comes to heating leftovers, chef Matt Wilkinson is less about the microwave and more about utilising the jaffle iron. He's currently setting up the menu at the new Four Pillars gin bar in Sydney which includes - surprise surprise - a jaffle menu. He reckons just about anything will go in a jaffle, from mapo tofu (his favourite) to curry, as long as you add a lot of extra cheese.
And failing that, whip out the good old spuds. "There's nothing like a bit of leftover beef, ginger and spring onion on a jacket potato."