Raisin (Vitis Vinifera)

Dried grape (Vitis vinifera) is a food with a distinctive taste, aroma, and nutritional value, obtained by drying table grape varieties. Despite its small size, it holds an important place in nutrition due to its high content of antioxidants, vitamins, and minerals. It offers numerous benefits, ranging from digestive, heart, and bone health to skin beauty, immune system enhancement, and rapid energy replenishment. As a natural sweetener, it is consumed directly and also used in baked goods, salads, energy balls, and desserts.

Global Production

Approximately 1.25 million tons of dried grapes are produced annually worldwide. The largest producers are Türkiye, the United States, and Iran. Türkiye is known as the “Cradle of Grapes” and has a deep-rooted viticulture tradition dating back to the 8th century. About 37 percent of its annual grape production of 4 million tons—roughly 353,000 tons—is processed into dried grapes. The most widely cultivated and exported variety is the seedless Sultan grape, prevalent in the Aegean Region.

In the United States, production is concentrated primarily in California, where approximately 330,000 tons of dried grapes are produced annually. The most common variety is Thompson Seedless, with additional cultivation of Muscat and Selma Pete. Iran produces an average of 122,000 tons of dried grapes annually and accounts for 27 percent of global exports. These three countries are followed by Greece, Chile, South Africa, Uzbekistan, and Afghanistan.

Grape Varieties and Types of Dried Grapes

The main grape varieties commonly used in dried grape production:

• Thompson Seedless: Long and oval-shaped; after drying, the berries easily separate and are among the most common varieties.
• Black Corinth: Small, round, thin-skinned, and reddish-black in color; preferred in pastry making.
• Muscat of Alexandria: Large berries, low in seeds, with a musky aroma.

Four types of dried grapes dominate the global market:

• Dark-colored grapes dried in the sun
• Golden-yellow grapes dried using heat
• Corinthian raisins: Small, dark-colored, and seedless
• Large-berried snack-grade grapes

Dried Grape Varieties (Ankara.edu)

Production Process and Drying Methods

Dried grape production occurs in four stages: Harvesting, drying, processing, and packaging.

Harvesting

Grapes are harvested either by hand or mechanically when they reach a total soluble solids (TSS) content of 19–24 percent. Mechanical harvesting systems facilitate pruning and the undamaged collection of grape clusters.

Drying

• Sun drying: Grapes are spread on concrete surfaces or polyethylene sheets and dry within 2–4 weeks. On average, 4 kg of fresh grapes yield 1 kg of dried grapes.
• On-vine drying: Grapes are left on the vines; branches are pruned and clusters are dipped in a solution of 0.5 percent ethyl oleate and 0.6 percent potassium carbonate to accelerate drying and achieve a lighter color.
• Hot air drying: Grapes are dried in hot air tunnels at 65–70 °C. Before drying, they are dipped in a 0.2–0.5 percent sodium hydroxide solution and treated with SO₂. This method is more expensive but produces a lighter color and more uniform quality.

Processing and Packaging

Dried grapes are cleaned and sorted in processing facilities to remove stems, seeds, and foreign matter. They are classified by size and packaged in quantities ranging from 15–20 gram retail units to 10–500 kg industrial packages. To preserve quality, they are stored at 10–15 °C, with 50–60 percent humidity and in a low-oxygen environment.

Nutritional Value

One hundred grams of dried grapes contain approximately 300 calories, most of which come from natural sugars—fructose and glucose. They also provide:

• 3 grams of protein
• 0.5 grams of fat
• 3.7 grams of dietary fiber
• 750–850 mg of potassium
• Folic acid, pantothenic acid, and vitamin B6
• Calcium, magnesium, phosphorus, iron, copper, and zinc

Cultural and Commercial Significance

Dried grapes feature in numerous recipes throughout history and today, from sweets and breads to salads and pilafs. Türkiye, the United States, and Iran are the top suppliers of dried grapes to the global market. Türkiye exports seedless Sultan grapes to over 100 countries, with Europe being the primary destination. In the United States, production is centered in California and regulated by the Raisin Administrative Committee. Iran supplies 27 percent of global exports through its golden, green, and black grape varieties.