Now is the time to make the most of walnuts in their shells. Most of those you see in the shops will have been imported, but in years to come we are likely to see far more home-grown nuts. Changing weather patterns, in particular warmer springs and summers, have seen farmers in this country experimenting with everything from olives and apricots to tea and walnuts. Though walnut trees have been grown in Britain for thousands of years, it is only recently that growers have begun to reap consistent crops of ripe nuts, and as a result more and more are planting walnut orchards.

The main eating variety of walnut is the “common” Persian, more often known as the English walnut. The nuts can be harvested twice a year. In June/July when their shells haven’t formed and they are known as “green”, they are picked for pickling (pickled walnuts are traditional at Christmas with cold meats and cheese). Then, in October, when they are mature, the main crop is harvested. The nuts are then known as “wet”, and if eaten immediately their shells can be cracked easily by hand and they have a delicate “milky” flavour. However, warmth and moisture turn walnuts rancid very quickly, so those you find in the shops now have been dried so that they will keep. As a result their shells have hardened, and the nuts within have a more intense, slightly tannic flavour.

Are walnuts good for you? All sorts of health claims have been made for walnuts, since they are a good source of omega-3 fatty acids, antioxidants and nutrients. In an important on-going study in Barcelona, findings so far suggest that eating walnuts as part of a healthy diet may help guard against heart disease, because they also contain arginine, an amino acid, and other components that may combat the damage wreaked by saturated fats, helping to reduce inflammation of the arteries that can lead to hardening.

Why do some recipes ask you to toast walnuts? If you shell them, then toast them briefly on a baking tray in the oven at around 170-180C/Gas 3/4 until lightly golden, you will accentuate their sweetness and nuttiness. Once toasted, you can chop them for use in everything from stuffings and salads to cakes, or grind them with garlic and olive oil, adding herbs of your choice to make a sauce for tossing through pasta in a similar way to pesto. (If you are doing this, you might want to rub off as much as you can of the edible skin, known as the pellicle, after toasting.) However, cooking may reduce some of the positive health properties of walnuts.

How do you store walnuts? In the short term, keep them (in or out of their shells) in an airtight container in the fridge. Shelled nuts can also be frozen.

Readers' queries

Where can I order Arbroath smokies?

The smokies now have Protected Geographical Indication status, ie, they can only be made to traditional methods, using hot-smoked, headless, gutted haddock within an 8km radius of Arbroath. Order them from www.arbroath-smokie.co.uk (01241 872331).

food.detective@thetimes.co.uk

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