Kouryoku Kiwi
Estimated Inventory, lb : 0
Description/Taste
Kouryoku kiwis are a medium to large varietal and have a distinct elongated, cylindrical shape with blunt, tapered ends. The fruits average 200 to 300 grams in weight, while most other commercial kiwis reach around 100 grams. Kouryoku kiwis have a uniform appearance due to their strict cultivation requirements, and the fruit’s surface is taut, thin, and brown, enveloped in a layer of long hairs. Underneath the skin, the dark green, pigmented flesh is dense, aqueous, and semi-firm with a succulent, tender consistency. The flesh encases many tiny black seeds, contributing a crisp nuance, and the pale yellow to ivory, oblong core extends throughout center of the entire fruit. Kouryoku kiwis are known for their rich and sticky flesh. The flesh emits a mellow fragrance, and the fruit is considered ripe when the ends are springy and soft. It is recommended to gently squeeze the ends of the fruit rather than the center to determine ripeness, as kiwis mature from the bottom to the top. Ripe Kouryoku kiwis have a high sugar content mixed with low acidity. The flesh ranges between 12 to 14 degrees Brix, a sugar measurement, but can reach as high as 18 degrees. This sugar content creates a refreshing, sweet, and subtly fruity flavor. In Japan, Kouryoku kiwis are viewed as having one of the richest flavors of the green varieties grown in the country.
Seasons/Availability
Kouryoku kiwis are available in Japan from late fall through mid-winter. The variety is harvested between October and December and stored for ripening. The fruits are later sold in commercial markets, typically between November and January.
Current Facts
Kouryoku kiwis, botanically classified as Actinidia deliciosa, are a Japanese variety belonging to the Actinidiaceae family. The green-fleshed cultivar is a specialty fruit only grown in small, seasonal quantities. Kouryoku kiwis are favored for their large size, elongated shape, coloring, and sweet taste. Annual production volumes of the variety are small, and the harvest window is short, leading to limited availability. Despite their rarity, Kouryoku kiwis are an early-season cultivar that arrives in markets before the Hayward variety, a commercially dominant kiwi variety in Japan. Kouryoku kiwis also arrive during a gap in the market between imported and domestic fruit sales, filling a commercial need for fresh fruits. The variety is not fully ripened on the tree and is picked before it drops to prevent damage to the fruit’s surface. Only a few fruits are also cultivated on each branch to allow them to expand to larger sizes with better flavoring. Kouryoku kiwis are tested with an optical sensor before harvest to ensure the sugar content has met expectations. Fruits with an above-average sugar content are sold under the name Sanuki San fruits, and kiwis with the highest sugar content are labeled as Sweet 16. Kouryoku kiwis are often given as gifts in decorated boxes to family and friends. The green kiwis have a rich, sweet taste and are usually reserved as a fresh-eating fruit to savor their premium qualities.
Nutritional Value
Kouryoku kiwis have not been extensively studied for their nutritional properties. Some research says the fruits are a source of vitamins C and E, which are nutrients believed to help strengthen the immune system, reduce inflammation, and guard the cells against the damage caused by free radicals. Kouryoku kiwis also contain fiber to stimulate and regulate the digestive tract. Kiwis, in general, provide potassium, vitamin K, and folate to balance fluid levels within the body, aid in faster wound healing, and assist in producing red blood cells.
Applications
Kouryoku kiwis have a sweet and fruity taste suited for fresh preparations. The rare variety is primarily eaten fresh to savor its low-acid taste and is peeled before consumption. The fruit’s elongated shape allows it to be sliced into thin, uniform pieces and added to salads or incorporated as a topping over yogurt and chia seed pudding. In Japan, it is customary to chill kiwis before eating fresh. Kiwis are also chilled, sliced, and served with crackers as a snack or light appetizer. In addition to consuming the fruits in pieces, Kouryoku kiwis can be blended into juices and smoothies as a fresh alternative. They are also sliced and used as colorful decorations for tarts and cakes. Beyond fresh uses, Kouryoku kiwis are sometimes simmered into jams and spread over pastries as a specialty topping. It is less common in Japan to cook the variety due to its rarity, but some consumers may use the kiwis for their proteolytic enzyme content in the flesh. These enzymes can help tenderize meat, similar to using pineapple in dishes, ultimately helping to make the meat softer and easier to chew. Kouryoku kiwis pair well with other fruits such as strawberries, mangoes, and grapes, vanilla, chocolate, and honey. The fruits should be ripened at room temperature away from direct sunlight and can take up to twenty days to ripen, depending on the producer and age at harvest. They can also be placed in an open bag with a fruit that produces ethylene to help speed up ripening. Once ripe, Kouryoku kiwis should be immediately consumed or stored in the fridge for a few days.
Ethnic/Cultural Info
Kouryoku kiwis were named for their dark green, emerald flesh, and rich nature. It is said the name is a combination of Japanese and Chinese characters comprised of “Ka” or “Kou,” meaning “aromatic,” and “ryoku,” meaning “green.” Kouryoku, or “aromatic green,” was given this name in homage to its site of origin, the Kagawa Prefecture, a land rich with nature. Its green descriptor highlights the fruit’s dark-colored flesh and also the natural greenery seen throughout the prefecture. Kouryoku kiwis are unique to the Kagawa Prefecture as they are one of the only kiwis covered by hand in bags during cultivation. This contributes to the fruit’s pristine appearance and uniform shape.
Geography/History
Kouryoku kiwis are native to Japan and were developed in the late 20th century in the Kagawa Prefecture. Commercial kiwi cultivation began in the Kagawa Prefecture in the 1960s and the first widespread variety grown in the prefecture was Hayward, a cultivar from New Zealand. Hayward kiwis were valued for their size, flavor, and productive nature. In the 1970s, breeding programs within the Kagawa Prefecture began developing improved kiwi varieties using Hayward kiwis as a parent plant. Kouryoku kiwis are one of the notable varieties bred from Hayward kiwis in the Kagawa Prefecture through the Fuchu branch of the Kagawa Prefectural Agricultural Experiment Station. The cultivar was chosen for its distinct, elongated shape, large size, and improved sweet taste. Kouryoku kiwis were submitted for registration in 1983 and were officially registered with the Japanese government as a new variety in 1987. Since their release, Kouryoku kiwis have become well-known throughout the prefecture through the efforts of former agricultural scientist Mr. Masao Fukui. Mr. Fukui previously worked at agricultural experiment stations in Kagawa and began cultivating and promoting Kouryoku kiwis upon retirement. Today, Kouryoku kiwis are primarily grown in the Kagawa Prefecture, and central production occurs in the cities of Mitoyo, Takamatsu, Zen Tsuji, and Tonosho. The fruits are seasonally sold through select high-end department stores, fruit parlors, specialty shops, and greengrocers in Japan. Kouryoku kiwis are also grown in very small quantities in home gardens for personal use, as the variety’s protective rights under the Seed and Seedlings Act expired in 2005, allowing the cultivar to be cultivated by the public.
