Know your walnuts

History

Walnuts and pecans belong to the same family of trees, Juglans, (latin for Jupiter’s acorn), but walnuts are by far the more popular choice of tree nut worldwide, (almonds are the most popular). In many European languages the word for “walnut” is also the word for “nut”. The walnut is a drupe, a hard shell enclosing an edible kernel all covered with a thin fleshy fruit. It is when the ‘fruit” part has decayed, dried and fallen off that the familiar hard shelled walnut is revealed. In English cookery, immature, softshelled walnuts are also used pickled with vinegar, sugar and spices and served as accompaniments for cheese or cold meat. My Oxford Companion to Food also says sour tasting green walnuts are used for jams and chutneys and half-ripe walnuts are preserved in syrup in the Middle East.

A shelled walnut has an uncanny resemblance to the human brain — again the Oxford Companion informs me that the Afghani word for walnut is “charmarghz” which means four brains, a reference to the four lobes which make up the flesh of the walnut. Spookily, they have a high percentage of omega-3 polyunsaturated linolenic acid which is said to be good for brain function.

Storage

We have just received our yearly gift of two huge bags of walnuts from my generous cousin in Hawke’s Bay and having plenty of fresh walnuts is a luxury I am very grateful for. They taste fresh and creamy and will be going into all sorts of sweet and savoury dishes.

Many people tell me they don’t like the taste of walnuts. It often turns out that the taste they are describing is that of rancid walnuts. To summarise Harold McGee in McGee on Food and Cooking (Hodder and Stoughton 2004) on the subject, the delicious oil content of nuts is also part of their fragility. The oil in nuts easily absorbs other unwanted flavours if exposed to them and is adversely affected by being exposed to oxygen and light. Nuts are even more susceptible to rancidity if bruised or moistened. So shelled nuts should be refrigerated in airtight containers and can be frozen if they are to be kept for a long time. As ours are still in their shells, we do not need to refrigerate them.

Rancid or stale walnuts have an irritating astringent effect on the mouth, a bitter flavour and smell like cardboard or paint. Obviously they taste best when fresh, which is the good news about walnuts in New Zealand these days. We are no longer reliant on stale imported ones. There are several excellent producers of walnuts in New Zealand, (look out for Cracker of a Nut and Uncle Joe’s brands), so now we can easily enjoy the delicious taste of fresh, sweet, pale, creamy textured walnuts.

Cooking with walnuts

In Liguria in Northern Italy they make a winter pesto from walnuts, parsley, extra virgin olive oil, garlic and a little cream, which is great stirred through hot pasta with a sprinkling of parmesan.

Baklava, syrup soaked layers of crisp filo pastry filled with walnuts, is an all-time favourite of mine when it comes to sweet walnut dishes.

Walnut oil

Some New Zealand producers also produce walnut oil, a condiment long used in the walnut-producing regions of France as part of an exquisite salad dressing. Try it. A vinaigrette made with walnut oil, a little lemon juice, salt and pepper over crisp crunchy green leaves is sublime. Good also over steamed cauliflower or new potatoes. Walnut oil is particularly susceptible to rancidity, so keep it in the fridge.