Grapes

Availability and types of grapes

Grapes are fruits that people have eaten and used for thousands of years. Their original homeland probably lies around the Caucasus and Central Asia – where Europe and Asia are close together. From there people took grapes as they traveled and moved to other countries. Over the centuries grapes have been cultivated in many warm regions of the world.

Today grapes grow in many places. Important growing regions include:

Grapes come in many different varieties and forms. They can be roughly divided into three groups:

Further differences are color and whether the grapes have seeds:

Regarding availability: fresh grapes in the northern hemisphere are typically available from late summer to autumn. But because many countries export grapes, you often find them in supermarkets year-round. It works like a long chain: grapes are harvested, cooled and shipped by ship or plane so they stay fresh. If you look for organic grapes, they are sometimes available only in certain stores or at certain times.

A simple tip: if grapes look plump and shiny and are firmly attached to the bunch, they are fresh. Better to leave those with soft spots or a musty smell. That way you will find the tastiest option for your preference – whether for snacking, baking or for grape juice or wine.

Grapes (genus Vitis) are the spherical berries of the grapevine and form the basis for table fruit, grape juice, wine and dried products such as raisins. Botanically, grapes consist of three main compartments: the outer skin (epidermis and cuticle), the juicy pulp (parenchyma) and the seeds (pips), which may be present or reduced depending on the variety. The skin contains most of the polyphenolic compounds, especially in red varieties.

Chemical composition and nutritional values: Fresh grapes are about 70–82% water. Energy density is around 60–80 kcal per 100 g, depending on sugar content. Main carbohydrates are the monosaccharides glucose and fructose, typically together 15–18 g/100 g. Other constituents include organic acids (mainly tartaric acid and malic acid), which influence acidity and taste. Fiber content is about 0.5–1.5 g/100 g; protein and fat are negligible. Mineral-wise, potassium, calcium and magnesium are relevant; vitamin C is present in moderate amounts (approx. 3–10 mg/100 g).

Phytochemistry: Grapes are rich in secondary plant compounds. In red grapes there are anthocyanins, flavonols and tannins with antioxidant properties. The landmark polyphenol resveratrol is often associated with health-promoting effects but is present in small amounts and concentrated mainly in the skin and seeds. Seeds also contain oil rich in unsaturated fatty acids and proanthocyanidins.

Processing methods: Industrial processing of grapes includes several standard procedures:

Microbiological and chemical processes: After harvest, enzymatic processes such as the action of polyphenol oxidase occur, causing browning when tissue is damaged. In cellar technology sulfur dioxide (SO2) is used to inhibit oxidation and control microbial spoilage. During alcoholic fermentation the activity of Saccharomyces yeasts is central; subsequent malolactic fermentation by lactic acid bacteria converts malic acid into the milder lactic acid.

Health aspects: Research shows that intake of grapes and grape polyphenols can have positive effects on cardiovascular risk factors, for example by improving endothelial function and reducing oxidative stress. Clinical data are heterogeneous, so claims about preventive effects remain limited. Critical points are the high sugar content, which can affect blood glucose when consumed excessively, and possible pesticide residues. People with sulfite sensitivity should avoid sulfite-containing products.

Overall, grapes are a versatile food with a complex chemical composition. Their technological properties and bioactive constituents make them relevant both for food production and for nutrition science research.