Why do crackers have holes in? And five other tasty questions about food

Do carrots improve vision?

The myth that carrots help with night vision was actually started by the Royal Air Force during World War II. To keep their new radar system a secret, they claimed that eating lots of carrots was helping their pilots spot enemy planes. Although this wasn’t true, carrots can help promote healthy eyesight. They contain a chemical compound called beta-carotene, which your body converts into vitamin A and then retinal. Retinal is found in your eyes and helps to convert light into a signal that can be transmitted to the brain, but this won’t actually help to improve your vision.

They won’t give you night vision, but they can help to promote healthy eyesight


Why is milk white?

Milk is about 87 per cent water, with the remaining 13 per cent consisting of fat, proteins, lactose, vitamins and minerals. The fats and proteins in milk are what give it its white colour. These molecules reflect all visible wavelengths of light, which, when combined, are perceived by our eyes as white. Without the fats, the smaller protein molecules in milk reflect more blue wavelengths of light, which is why skimmed milk can have a slight blue tinge.

With the fats removed, milk will often have a blue tinge


Why do crackers have holes in?

The holes in crackers aren’t there for decoration; they actually ensure the tasty treats bake properly. The cracker dough contains lots of trapped air bubbles, and when it is heated in the oven, these pockets of air expand. To stop these bubbles from expanding and bursting, a machine called a docker pricks holes in the dough to allow the air to escape. This keeps the crackers flat and crispy, with minimal air bubbles.

The holes in crackers are all about the taste!


Why do avocados go brown so quickly?

When an avocado is cut open and its flesh is exposed to oxygen, the enzyme polyphenol oxidase converts chemical compounds called phenols into quinones. These quinones produce polymers called polyphenols, which turn the flesh a brown colour. Of course, most fruits turn brown eventually, but the process occurs more quickly in avocados because they contain more polyphenol oxidase. To slow this down, wrap it in cling-film to limit oxygen exposure, or add acidic lemon juice which can slow down the enzymes.

Avocados go brown quicker than most fruits, but this can be slowed by the addition of lemon juice


Why does garlic make your breath smell?

When garlic is chopped or crushed, enzymes convert the chemical compound alliin into allicin, which is then broken down into a four further compounds. It’s these four compounds that are responsible for garlic breath. Allyl methyl sulphide is the main contributor, as it takes longer for your body to break it down, leaving it to pass into your bloodstream and be excreted in your sweat, breath and urine.

Your body can’t help but break down garlic into smelly compounds

Why doesn’t honey go off?

Honey is one of the very few foods that doesn’t spoil over time. This is down to several factors, the first being its very low water content which dehydrates bacteria, making it unable to grow. On top of this, honey is very acidic, because when bees regurgitate nectar to produce it, enzymes in their stomach break it down into gluconic acid and hydrogen peroxide. These chemicals also create a hostile environment for bacteria, killing it off before it can spoil the honey.

It’s true – in the right conditions honey can last forever!


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Plus, take a look at:

The biology of hunger

The science of hangry

Can we get addicted to cheese?