Bilberry

Bilberry is the fruit that teaches you what a blueberry should taste like. It is smaller, darker, far more intensely flavoured, and it stains everything it touches a purple that does not come out of cotton. The whole craft of picking it is about the two hours you spend bent double at ankle height, and about not putting them in the same basket as anything else.

Picking at ankle height, efficiently

Bilberry grows on low bushes 15–40 cm high, and the berries sit singly on the twig rather than in clusters, which is why a litre takes about ninety minutes. The efficient method is a comb or a plastic scoop with the tines set at 6 mm, drawn upward through the bush so the berries come off and the leaves stay. In a good year a scoop gets you a litre in twenty minutes against ninety by hand.

Do not use a scoop on a bush you have not looked at first, because it takes unripe fruit with the ripe. Check a handful: the ripe berry is a dull blue-black with a faint waxy bloom, and it should come off the twig with a light touch. A shiny black one with no bloom is unripe and will be sour. A red one is three weeks off.

Bilberry does not ripen off the bush. What you pick is what you get, and an unripe bilberry stays sour and gritty even in a cooked dish. That is the argument for hand-picking at least the first pass and using the scoop only where the crop is heavy and even.

The staining problem, and what to do about it

Bilberry juice is a genuine dye and it does not wash out of cotton, so plan for it: wear dark clothing, use containers that are not white, and keep the fruit away from anything you care about. On the plus side, the anthocyanins that do the staining are the same compounds that make the fruit worth eating.

For freezing, freeze them dry on a tray first and then bag them, or you will get a solid purple block. A tray-frozen bilberry keeps twelve months with almost no loss, and it is the single best way to hold the crop — better than jam, better than bottling, because it preserves the fresh acidity.

For jam, use 700 g of sugar per kilo of fruit and add the juice of one lemon. Bilberry is low in pectin and will not set without help, so either add 8 g of pectin per kilo or cook it much harder for a soft set. The classic accompaniment is apple — 30 % apple by weight gives both the set and a pleasant roundness.

The leaf, and the honest position on it

Bilberry leaf is sold as a tea and has a long folk use for blood sugar. The evidence is thin and the safety position is not: bilberry leaf in medicinal doses has been associated with hypoglycaemia in people taking insulin or oral diabetes medication, and long-term high-dose use of Vaccinium leaf has been linked to liver and other organ effects in animals.

As an occasional tea, 1 g of dried leaf per 200 mL, it is a mild and pleasant astringent drink with a faint fruity note, and it is fine. As a daily supplement taken for months, it is not a food use and the guidance is different. Anyone on diabetes medication should not take it at all.

The fruit has none of these concerns and can be eaten freely. If in doubt, eat the berries and leave the leaves — which is also the better-tasting recommendation.