Plums

Availability and types of plums – that is: where they come from, when you can buy them and which varieties there are – is actually quite simple to understand. Zwetschgen are a type of plum, but you can often tell the difference: they are usually more elongated, have firm flesh and are particularly good for baking. They are often called a 'baking plum' because they do not get mushy so quickly when cooked.

Origin: Zwetschgen originally come from countries east of Europe – many plum species first grew in Central Asia. Long ago people brought the trees to Europe, where they thrived. Today zwetschgen are found in many gardens and farms across Central Europe. One can therefore say: their family comes from far away, but they feel very much at home in our gardens.

Growing regions: In Germany zwetschgen grow especially well in regions with warm, sunny summers and cool winters. These include parts of Baden-Württemberg, Rhineland-Palatinate and Bavaria. Many are also grown in Austria and Switzerland as well as in countries such as France, Italy, Spain and Balkan states. These places have the right climate and often many orchards where the trees stand.

Available varieties: There are many different zwetschgen varieties. Some ripen early in the year, others later. Here are a few well-known types and how you can distinguish them:

Forms in trade: You won't find zwetschgen only fresh. Many forms are available year-round:

Tips for buying and storing: Look for firm skin and the white 'bloom' (that is a natural protective film). If they smell sweet they are usually ripe. In the refrigerator zwetschgen stay fresh for a few days; for freezing you should remove the stone (pit), then they are easier to use.

Zwetschgen are therefore very versatile: different varieties for different times of the year, and many processing methods so you can enjoy the fruit's aroma all year round.

Zwetschgen are a cultivated form of the European plum (botanically often assigned to Prunus domestica) and are characterized by an elongated to elliptical fruit shape, a firm, juicy fruit mass and comparatively firm flesh. They ripen late from summer to autumn and in Central Europe are traditionally processed fresh, dried, into jams, compotes or distillates. Typical cultivar groups differ in skin colour, acidity and storage potential.

Composition and macronutrients
Fresh zwetschgen consist mainly of water (approximately 80–87%). The main energy source is carbohydrates, particularly simple sugars such as glucose and fructose as well as the sugar alcohol sorbitol, the content of which is decisive for the laxative effect of dried fruits. Typical values (per 100 g fresh weight) are in the range of:

Secondary plant compounds
Zwetschgen contain a diverse mix of phenolic compounds. The skin is particularly rich in anthocyanins (mainly cyanidin derivatives), which are responsible for dark to purple colour hues. Other relevant substances are flavonols (e.g. quercetin), chlorogenic acid as well as hydrolysable and condensed tannins. These polyphenols contribute to oxidative stability, flavour and possible health-promoting properties.

Vitamins and minerals
Fresh zwetschgen provide vitamin C in moderate amounts (typically 5–10 mg/100 g), small amounts of provitamin A (carotenoids) and vitamin K. Important minerals include potassium (commonly ~150–250 mg/100 g), traces of magnesium, calcium and phosphorus. When dried these nutrients concentrate proportionally to the water loss.

Processing technology
Common procedures include cooling for storage, heating (pasteurisation) to stabilise compotes and jams and thermal treatment in baked goods. Heating leads to losses of heat-labile vitamins (especially vitamin C) and to chemical changes such as Maillard reactions and polyphenol oxidation, which affect colour and aroma. Drying (at 50–70 °C or by freeze-drying) concentrates sugars and fibers; dried plums (zwetschgen-based dried fruits) are often used as a natural laxative. For high-quality colour and flavour retention modern methods such as vacuum drying or gentle pasteurisation are used. Distillation to fruit brandies (e.g. plum brandy) extracts volatile aroma compounds and ethanol.

Health aspects
The combination of fiber, sorbitol and polyphenols explains the positive effect on bowel function; sorbitol draws water into the intestine, soluble fibers are fermented by gut bacteria to short-chain fatty acids that can support intestinal health. Antioxidant polyphenols may have anti-inflammatory effects. Zwetschgen have a moderate glycaemic load, so they should be considered in moderation when monitoring blood sugar. Allergic individuals should note that stone fruit can trigger oral allergy symptoms and the pits contain small amounts of amygdalin, which at very high intake can lead to cyanide release; however eating pits is uncommon and not recommended.

Storage and ripening behaviour
Zwetschgen are climacteric fruits; they produce ethylene and can further ripen after harvest. Cooling reduces metabolism and extends storage life; optimal storage is at low temperatures and moderate relative humidity to avoid shrivelling and mold. Industrial processing takes respiration, effective hygiene measures and packaging atmosphere into account to extend shelf life.

Overall zwetschgen are nutritionally valuable fruits with a favourable nutrient profile, specific secondary plant compounds and versatile processing options that are relevant both culinarily and for health.