Grape

A grape is a fruit that belongs to the botanical category of berries. These fruits grow in clusters on the deciduous woody vines of the genus Vitis.

Grapes are incredibly important to human civilization. People have used them for food for thousands of years. They are also essential for making wine, juice, jam, vinegar, and oil. Because they are non-climacteric, they do not continue to ripen once they are picked from the vine.

The growth of a grape follows a complex biological sequence. It begins with flower buds that eventually undergo fertilization.

Within 60 days of fertilization, the small berries begin to develop. Initially, they produce tartaric acid, followed by malic acid. These organic acids create a sour taste in the young fruit. As the berries grow, they respond to the hormone ethylene, which causes the flesh to increase. Eventually, the grapes reach a ripening stage called véraison. During véraison, the berries increase in size and change to darker colors.

This period typically begins in August in the Northern Hemisphere and lasts about 45 days.

Water and sugar management is vital to the grape's structure. The fruit's flesh is composed of 75% to 85% water. Before ripening, the plant's xylem tissue provides this water to the berries. After the ripening stage begins, the phloem tissue supplies water along with soluble sugars like glucose and fructose. Grapes accumulate these sugars through photosynthesis in the leaves. The sucrose molecules produced by the leaves are transported to the fruit. During ripening, these sucrose molecules undergo hydrolysis to become glucose and fructose.

There are two main categories of commercially grown grapes: table grapes and wine grapes.

Table grapes are bred specifically to be eaten raw. They are usually large, have thin skins, and are often seedless. Wine grapes are different because they are smaller and usually contain seeds. They also have much thicker skins. This is important because much of the aroma in wine comes from the skin. Wine grapes are also much sweeter. While table grape juice is usually 15% sugar by weight, wine grapes are harvested when they reach approximately 24% sugar.

Color in grapes is determined by specific chemical compounds. Purple grapes contain anthocyanins, which belong to a larger family of chemicals called polyphenols. These pigments create the various shades of purple seen in the fruit and in red wine. Interestingly, "white" grapes are actually green in color. They evolved from purple grapes through genetic mutations. In these grapes, mutations in two regulatory genes turn off the production of anthocyanins. This results in the lighter colors seen in varieties like green or yellow grapes.

The history of the grape is deeply tied to human discovery. Most experts believe the Middle East is the homeland of the grape. Cultivation began there approximately 6,000 to 8,000 years ago. Archeological evidence shows that wine-making was a major part of human culture in Georgia 8,000 years ago. The oldest known winery, the Areni-1 winery in Armenia, dates back to around 4000 BC.

In the 19th century, Ephraim Bull of Massachusetts helped create the Concord grape. He used seeds from wild Vitis labrusca vines to develop this important American crop.

Global grape production is a massive agricultural industry. In 2023, the world produced 72.5 million tonnes of grapes. China was the leading producer, accounting for 19% of the total.

Other major producers include Italy and France. Most of the world's grape production, about 71%, is used for making wine. About 27% is used as fresh fruit, and 2% is used for dried fruit. The Sultana variety, also called Thompson Seedless, is believed to be the most widely planted. It occupies at least 3,600 square kilometers of farmland. Peru and Chile were the leading exporters in 2023, each exporting over half a million tonnes.