What international standards for olives ripening?

Green : Olives that are harvested when the fruit has reached its full size and before it starts turning to a dark colour. The fruit usually turns green to a straw- green colour before darkening (green ripe)

Turning Colour: Olives that have turned from green to rose, wine rose or brown colour ,prior to turning to the black or dark purple colour of full-ripeness

Naturally Black: Olives that are harvested when fully –ripe, or just before full ripeness. The colour may vary from black, violet, greenish black or deep chestnut depending on the variety, region and time of harvesting.

Black: Fruit harvested when not fully ripe and then blackened by oxidation and debittered by lye treatment. The olives are canned and sterilised

What is the Nutritional value for olives?

One average-sized olive without stuffing contains only 4Kcal. Stuffed olives contain 7 to 20 Kcal. So you won't be consuming large amounts of calories from olives unless you're eating a lot of them (to put things in perspective, one serving of ice cream contains 350Kcal). Furthermore, dietology uses the concepts of "useful" and "empty" calories.

Empty calories are converted to fat, while useful calories are absorbed by the body, help one's metabolism, and leave the body without much trouble. Olives have little competition in terms of the amount of "useful" calories inside: they contain more than 100 beneficial substances, many of which are absent in the daily diet.

What is the average expiration date for olives?

3 years if stored in a glass container, or 2 years if stored in a tin one.

After their container is opened, olives can remain in the marinating liquid for several weeks without getting spoiled, but only if they are stored in non-metallic ware.

What additives are used in preserving olives? Could these additives be harmful to my health?

Allowed additives are prescribed in the directives of the EU, developed by an international committee of experts on food additives. These additives are not harmful to anyone's health. For instance, pectines and alginates purify the body of toxins; sweeteners, which replace sugar, are vital to those suffering from diabetes, obesity, as well as for those who like to stay and in shape and count calories.

Black olives are processed with ferrous gluconate - a food additive with code E 579. Its function is to maintain the color of the olives. The maximum level of this additive, measured by mg of iron per 1kg of olives, is 150mg. Black olives have another additive with similar qualities - E 585 Ferrous lactate. Both additives are allowed for use in food products.

What Methods are used in processing table olives?

There are three traditional methods for processing table olives:

Spanish Style : Green olives that are treated with Caustic soda to accelerate the process of debittering, and placed in brine to undergo the fermentation process.

Green Style : Ripe (black) olives are placed in a brine solution to undergo the fermentation process. The olives are sometimes slit before processing to increase the speed of debittering. This is unnecessary if the olives are not needed quickly. The slit may become an entry point for spoilage bacteria that soften the flesh.

Oxidised Style : Turning colour olives are treated with Caustic soda and then oxidized by injecting pressurised air into the water. This Caustic soda and oxidation process is repeated up to 5 times. The pitch black colour is then stabilised by treatment with a weak solution of ferrous gluconate.
NB. This industrial method is not suitable for home processing

Salt Dried Black : Over- ripe, often soft, shriveled olives are placed in a container in layers alternating with rock salt. The olives dehydrate, retain some bitterness and have a fruity flavour.