描述
The olive is the fruit of the olive tree (Olea europaea, meaning "Oil from/of Europe"). It is an important food crop in countries around the Mediterranean Sea, and places with a Mediterranean climate. The olive is of major agricultural importance in the Mediterranean region as the source of olive oil; it is one of the three core ingredients in Mediterranean cuisine. About 90% of all harvested olives are turned into oil, while about 10% are used as table olives.
Table olives are classified into three groups according to the degree of ripeness achieved before harvesting:(1) Green olives are picked when they have obtained full size, but before the ripening cycle has begun; they are usually shades of green to yellow. (2) Semiripe or turning-colour olives are picked at the beginning of the ripening cycle, when the colour has begun to change from green to multicolour shades of red to brown. Only the skin is coloured, as the flesh of the fruit lacks pigmentation at this stage, unlike that of ripe olives. (3) Black olives or ripe olives are picked at full maturity when fully ripe. They are found in assorted shades of purple to brown to black.
Olives are a rich source of vitamin E (25% of the Daily Value, DV), and contain a large amount of sodium (104% DV); other nutrients are insignificant. Green olives are 75% water, 15% fat, 4% carbohydrates and 1% protein. The polyphenol composition of olive fruits varies during fruit ripening and during processing by fermentation when olives are immersed whole in brine or crushed to produce oil. In raw fruit, total polyphenol contents, as measured by the Folin method, are 117 mg/100 g in black olives and 161 mg/100 g in green olives, compared to 55 and 21 mg/100 g for extra virgin and virgin olive oil, respectively. Olive fruit contains several types of polyphenols, mainly tyrosols, phenolic acids, flavonols and flavones, and for black olives, anthocyanins. The main bitter flavor of olives before curing results from oleuropein and its aglycone which total in content, respectively, 72 and 82 mg/100 g in black olives, and 56 and 59 mg/100 g in green olives. Polyphenol content also varies with olive cultivar (Spanish Manzanillo highest) and the manner of presentation, with plain olives having higher contents than those that are pitted or stuffed [Wikipedia].