Blue „berries“ from the wayside: Sloes — are they eatable?

And my favorite recipe for sloe jam.

Photo by the author

Today I went for a walk and discovered sloes by the wayside. Blue-black fruits the size of marbles. At first glance, they look like blueberries, but they don’t grow near the ground, but on board, spiny bushes.

Then a first taste of the fruit: sour, astringent, relatively large stone. Yuck! Are they eatable?

What kind of plant is sloe?

Sloes or blackthorn (prunus spinosa) often grow wild and can be found on many waysides, slopes, or hedges. Birds love the berries and find plenty of food on the bushes in autumn. But also humans can use and eat the fruits of the sloes.

The spread-area of the sloes reaches from Europe to Asia Minor and North-Africa. The plant belongs to the rose family (rosaceae) and is classified within the stone fruit plants of the genus Prunus. The species name spinosa indicates the appearance of the shoots, as it means thorny or spiny. You can find sloes on sunny forest edges, in vineyards, and field shrubs from the lowlands to the Alps’ heights.

The right time to harvest sloes

Sloes are ripe when the skin is an intense blue-black color up to the stem base. You can pick the first ripe sloes already in autumn. One advantage of harvesting sloes early is that the chance of not all fruits being robbed by birds is the highest. However, the berries still contain many tannins and bitter substances in the autumn, which do not let the fruits taste exactly delicious. This changes after the first frost. Because once the fruits are frozen through, their cell walls become more permeable, and the starch converts into sugar. At the same time, the tannin content decreases. As a result, the fruits taste milder, sweet. Sloes are therefore best harvested between the end of November and mid-December when the first frost occurs.

If you do not want to share your sloes with birds, you can also harvest the fruits in autumn and then put them in the freezer. This way, the fruits have experienced an artificial first frost and also taste sweet.

Harvesting the sloes today, i.e., in mid-September, is perhaps a little premature. But we had a hot summer here. The degree of ripeness of the shrubs varies greatly. Some grow in somewhat shady places and where the fruits are not yet ripe (as in the photo), and others where the fruits almost fell off when I touched them.

I picked just over 400 grams and put them in the freezer. Harvesting them after the first frost is almost impossible here. In some years, the first frost does not appear until January. Until then, the birds will have eaten all fruits. Besides, there was very little rain in the last weeks. Therefore, I have seen many wholly dried sloes on the bushes.

Can you eat sloes raw?

There is a persistent rumor that sloes are poisonous raw and cannot be eaten fresh. However, this is only partly true, because sloes can be eaten raw — but only in moderation. The seeds of the blackthorn contain amygdalin. This substance is converted into prussic acid by our body after consumption, which is toxic. However, the content in the tiny seeds of the sloes berries is only small, so that one would have to eat huge amounts of sloes to be poisoned.

Besides, the stone is big enough that you can spit it out without any problems. On my way today, I also ate three sloes, but they were quite sour because they haven’t had a frost yet. After the first frost, I will see if there are still sloes. They will undoubtedly be tastier then.

What you can do with these fruits

Sloes are incredibly versatile, and there have been numerous recipes with sloes for centuries. The classic is the sloe liqueur, but jam or juice made from sloes also taste delicious and healthy.

I will make a jam from the collected sloes.

My favorite recipe:

Ingredients for about 1–2 glasses:

  • About 300 g of sloes
  • Approx. 300 g gelling sugar
  • Water
  • ½ Vanilla bean

Besides the ingredients, you also need:

  • 1–2 jam jars with lid
  • a sieve
  • a potato masher

Work steps:

  1. Sterilize the jam jars by placing the jars and lids in a pot and boil for 10 minutes.
  2. Put the sloes together with enough water and the ½ vanilla pod into a pod. The fruits need not be completely covered by water. Then increase the heat and cook the sloes until they burst open. This usually takes a few minutes.
  3. Next, take the potato masher and squeeze the sloes well while still in the pot. Then pass them through a sieve and separate the mush from the seeds and remove the vanilla pod.
  4. Weigh the obtained sloe jam and fill it into a pod with the same amount of jam sugar. Bring the mixture to the boil and let it simmer for about five minutes until it gels. The gelling test goes like this: Put a teaspoon of the jam on a plate and check if the mass becomes noticeably firmer after one or two minutes. When the jam thickens, it is ready.
  5. Now fill the hot jam into the cleaned jam jars and close them immediately. Turn them upside down for ten minutes and then store the jam in a cool, dark place.

Unopened, the jam will keep for about a year.

What is your experience with sloes? Are there sloes where you live? What do you do with them?

I write on Self Improvement 🌱, Productivity 🎯, and Agile Product Development 🏄. My goal is to provide Inspiration.💡https://www.britta-ollrogge-consulting.de

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