Herb nutrients RAW v. COOKED

Whether you want to maximise the flavour or nutrient value of herbs, the way you use them could make all the difference.

What would roast lamb be without rosemary? Or pesto without basil? Whether used fresh or dried, there’s no doubt that herbs can take a dish from good to great with their lively, aromatic flavours. But the question is, do herbs lose their vitamins and minerals when cooked? The short answer is yes. The longer answer is yes and no.

Retention of vitamins depends on how the dish has been prepared. Some vitamins, in particular vitamins C and B5, are heat-sensitive and will dissipate when exposed to heat. Vitamin C is also soluble in water. One Danish study showed that boiling broccoli for just five minutes caused up to 65 per cent of its vitamin C to be lost.

The water-soluble B vitamins are also lost when boiled in water – or rather, they leach into the water. Some of it is lost altogether when boiled excessively, but much will remain, and that water can be saved to make sauces and soups to get the benefits of the vitamins.

This means that the less contact with water and shorter cooking time of fruit, herbs and vegetables, the more C and B vitamins are retained.

The same Danish study showed that almost 100 per cent of the water-soluble vitamins were retained when the broccoli was instead steamed for five minutes.

The fat-soluble vitamins (vitamins A,D, E and K), on the other hand, are unaffected by heat or water. These vitamins are absorbed into the oil of stir-fries or salad dressings, but that’s not a problem as you will be consuming these.

Vitamin E is, however, affected by light and air. It is in many dried herbs, which is one reason why they should be stored in low light in airtight containers.

Vitamin K, which is found in coriander, sage, thyme, chives, marjoram and parsley as well as dried and fresh basil, is affected by light too.

Vitamin C is also affected by exposure to air, which is why levels are often higher in frozen vegetables than fresh ones, which can degrade while in storage. Frozen vegetables are processed quickly after harvesting, so they retain a good deal of their nutrients.

Minerals are not affected by heat but they do leach out into the cooking water. When making an infusion, or a herbal tea, for medicinal purposes, you will get all the minerals from that herb in the water. You will also get most of the water-soluble vitamins, but not the fat-soluble ones.

Chop herbs with a mezzaluna, sharp knife or scissors. Use a food processor for large amounts.