The acorns from many species of oaks are edible raw, just as they are harvested. Sweet acorns have been reported for Quercus gambelii, Q. mongolica., Q. emoryi, Q. dumosa, Q. vaccinifolia, Q. stellata, Q. virginiana, Q. garryana, Q agrifolia Q. macrocarpa, Q. lobata, Q. pumila, Q. muehlenbergii, Q. alba, Q. michauxii, Q. brandeegei, Q. gramuntia, Q. E'sculus, Q. aegilops, and Q. ilex var ballota (Bainbridge and Asmus, 1986; Bainbridge, 1984; Coyle and Roberts, 1975; Loudon, 1844; Bohrer, 1972; Chestnut, 1974; Brandis, 1972; Hedrick, 1919; Michaux, 1810; Ofcarcik et al., 1971; Smith, 1950; Fray, 1986). Undoubtedly, other species and varieties are equally sweet and more flavorful.
A careful worldwide search for good cultivars is long overdue because there is hope of finding sweet acorns even in those species normally considered bitter. Some of these include the best tasting acorns, with cashew and chocolate overtones.
It is also practical to harvest and use the bitter varieties. The tannins which causes the bitterness can be leached from acorns or acorn meal with water. Using hot water hastens the process. Studies at Dong-guk University in Seoul, South Korea showed the tannin level was reduced from 9 percent to 0.18 percent by leaching, without loss of essential amino acids, (Kim and Shin, 1975). Virtually all of the acorns the native Californians used were bitter and were leached with water to remove the bitterness. They apparently based their acorn preference on oil content, storability, and flavor rather than sweetness. However, the Cahuilla people in Southern California remember sweeter acorns from their past (in the South-Central U.S.) and consider their loss as a fall from grace, like Adam and Eve's expulsion from the garden (Bainbridge, 1987a).
Native Americans also sweetened bitter acorns with iron-rich red earth, wood ashes (Editor's note, leaching with wood ashes hastens process by increases tannin solubility and might increase niacin availability), and other ingredients to neutralize the acids. Steaming or baking were sufficient for some acorns (Chestnut, 1974; Kavasch, 1979; and Gifford, 1936).
COOKING WITH ACORNS
Acorn meal can be substituted for corn meal in most recipes (Bainbridge, 1986b). Acorns can also be used in place of chickpeas, nuts, peanuts, and olives in a variety of dishes. Acorn meal and acorn pieces are excellent in soups and stews and were often used that way by native Californians. Acorns can also be treated with pickle brines or the lye treatment used for olives (Wolf, 1945; Bainbridge, 1986b). Acorns have also been used to make coffee-like drinks (Kavasch, 1979). The success of the venture depends on the particular acorn and technique used. Q. muehlenbergii was especially favored for this purpose in the Midwest, (Ofcarcik et al., 1971). Q. robur and Q. frainetto have been used in Europe where the resulting drink is referred to as "Eichel kaffee", or acorn coffee (Sholto Douglas, 1978; Readers Digest, 1984). A similar acorn coffee has been used in Mexico, (Usher, 1974). Raccahout, a spicy Turkish acorn drink more like hot chocolate, was included in the Larousse Gastronomique until recently.
Acorns can also be used to make acorn oil by boiling, crushing, or pressing. Acorn oil has been used as a cooking oil in Algeria and Morocco (Loudon, 1844; Hedrick, 1919; Smith, 1950). It was used by the Indians of the eastern U.S. for cooking and as a salve for burns and injuries (Michaux, 1810; Smith, 1950). Some varieties contain more than 30 percent oil, equal or greater than the best oil olives ( Wolf, 1945; Ofcarcik et al., 1971). The quality and flavor of the oil is comparable to olive oil (Wolf, 1945; Smith, 1950; Bainbridge, 1985a). Table 4 presents further information on acorn oil.
TABLE 4. ACORN OIL
Species Quercus Quercus 5 other Olive
agrifolia ilex speciesa
Specific 0.9170 0.9086 0.9100 0.914-.919
Refractive index 1.4709 1.4701 1.4627 1.466-1.468
Saponification 192.3 189.05 191.45 187-196
Olieic acid% -- 57.05 58.31 83.5-84.4
Palmatic acid% -- 12.40 11.43 6.9-9.4
Linoleic acid% -- 30.50 37.50 4.0-4.6
Flash point -- -- 360°C 343°C
aaverage of available data
Acorn data: Jameison (1943), Wolf (1945), Hopkins et al (1953), Khan (1977), Marwat et al (1978).
Olive and corn oil: Weast (1979) and Windholz (1976).