It has nothing to do with bitter taste compounds
You’re probably familiar with the recipe: slice the aubergine, sprinkle generously with salt, leave to stand for about 15 minutes, pat dry, and only then start frying, grilling or roasting the aubergine. Almost every recipe and cookery book gives the same reason: the salt draws out the bitter compounds. It sounds logical, it’s written everywhere, and… it’s not true. Modern aubergine varieties contain hardly any bitter compounds at all. The real story lies in something far more interesting: the structure of the aubergine itself.
A sponge in disguise
Cut open a raw aubergine and take a close look at the flesh. It looks compact, but if you look very closely, you’ll see that it’s actually a loose network of cells filled with air. In short, an aubergine is a sponge. And sponges have two annoying characteristics when you want to cook, bake or fry them:
1. They soak up oil like crazy. That airy cell structure draws fluids in as soon as space becomes available. Put a slice of raw aubergine in a pan of oil and you’ll see it happen: the oil disappears into the flesh almost instantly, and before you know it, you’ve used half a bottle of olive oil on a few slices of aubergine.
2. They insulate themselves against heat. All those air bubbles in the spongy structure act as a sort of isolation material. As a result, the heat from the pan or oven penetrates only slowly to the centre. The result: the outside almost burns whilst the inside is still raw and chewy.
Adding salt can solve both these problems at the same time.
So what exactly does the salt do?
Through the process of osmosis, salt draws moisture out of the aubergine’s cells. As that water is drawn out, the spongy cell structure collapses. Literally: the airy, porous structure collapses into something denser and more compact.
And that random collapse of the structure produces exactly what you want:
- There’s no longer a sponge to soak up the oil, so the aubergine absorbs much less oil, resulting in a tastier and healthier dish.
- There’s no insulating layer of air in between anymore, so the heat simply penetrates right to the centre and the aubergine cooks evenly – no more half-raw, discoloured and chewy aubergines
After salting, pat the slices dry with kitchen paper or a clean tea towel.
Are you worried about salt for health reasons?
You might be wondering whether that salt is actually healthy. Well, it’s good to know that you remove almost all the salt you sprinkle over the aubergine along with the moisture you’ve drawn out of it. The salt dissolves in the water it has drawn out of the aubergine, and by dabbing away the moisture with kitchen roll or a tea towel, you remove almost all of the salt again. The amount of salt left in the aubergine is minimal. Would you prefer not to use any salt at all? If so, we’ll give you two alternative methods without salt later on in the article.
How to proceed?
For one aubergine: wash or peel the aubergine (our chef prefers peeled aubergine) and cut it into slices or cubes, depending on how you wish to prepare it; take approx. 1 tsp of salt and sprinkle it over both sides of the slices or over the aubergine cubes; leave the aubergine to stand for about 15 minutes, then pat the slices or cubes dry with kitchen paper. The aubergine is now ready for cooking: drizzle the slices with olive oil, pepper and thyme, for example, to grill on the barbecue or contact grill; or fry the cubes in a pan for ratatouille together with courgette, pepper and tomato, etc.
Not keen on salt? Here are some alternatives
Salt isn’t the only way to cause that sponge-like structure to collapse — heat does the job too, albeit via a different mechanism (denaturing cell walls rather than osmosis). Two quick options:
- Steam briefly. Steaming for a few minutes is enough to break down the cell structure, after which you can simply fry the aubergine as you intended — without it soaking up large amounts of oil
- Pre-cook in the microwave. Place the aubergine (cut into pieces) in a covered container and cook on full power for 1 to 2 minutes (depending on the amount of aubergine). This also causes the spongy structure to collapse, giving you a great starting point for further frying or roasting.
The steaming and microwave methods are ideal if you’re in a hurry or if you want to cook completely salt-free.
And what if you want to make a purée from aubergine?
For dishes such as baba ganoush or aubergine caviar, you don’t really need to worry about this problem at all. To make these, we place whole aubergines under the grill, in a piping-hot oven or, best of all, on a charcoal barbecue (for that smoky flavour). Cooking them in their skins means the flesh inside is steamed until completely soft, whilst the skin on the outside charred. You then halve the aubergine and scrape the flesh out of the skin, discarding the charred skin.
There is one important thing to remember when grilling or roasting whole aubergines: prick the aubergine a few times with a fork beforehand. During roasting, steam builds up inside the aubergine, and without an outlet, that steam has nowhere to go — resulting in a small explosion in your oven or on your barbecue, which can cause a startle and possibly burns to your arm or hands. A few pricks with a fork prevent that drama.
In summary
Don’t salt aubergines to remove bitter compounds — in most cases, there are hardly any left. Salt them because otherwise their spongy texture will soak up your oil and prevent the heat from penetrating. Salt (or steam, or the microwave) causes that structure to break down, allowing the aubergine to cook evenly and requiring much less oil. And if you want a creamy purée? Roast the whole aubergine until it’s soft — and don’t forget to prick it with a fork beforehand.
Enjoy cooking!
