Table Olives Preparation
Raw olives are very bitter in taste as it contains very high quantity of oleuropein (glycoside). To make them edible olives are fermented or cured with lye, brine or packed in salt to remove oleuropein The curing process lasts from few days with lye to a few months with brine. The longer the olive is fermented, the less bitter and more flavourful it becomes.
In addition to oleuropein, freshly picked olives are not palatable because of phenolic compounds.
Image Courtesy: www.greenolive.com.au
There are many types of preparation process of curing Olives and make them edible. The most popular types are:
Spanish type (fermented):
Most commonly applied to green olive preparation. Olives are soaked in lye (2-4% sodium chloride solution) for 9–10 hours to hydrolyse the oleuropein. They are then washed in water to remove the caustic solution and transferred to fermenting vessels full of brine at typical concentrations of 8-12% Sodium Chloride. The fermentation process produces lactic acid which lowers the acidity of the brine and therefore stabilizes the product. Once fermented, the olives are placed in fresh brine and packed in bottles.
Sicilian or Greek type (fermented):
They are used on all type of Olive green, semi-ripe and ripe olives. This is similar to the Spanish type fermentation process, however the lye treatment process is skipped and the olives are placed directly in fermentation vessels full of brine (8-12% Sodium Chloride). As there is very little acid produced by the yeast fermentation, lactic, acetic or citric acid is often added to the fermentation stage to stabilize the process.
California or “artificial ripening” type (without fermentation):
They are applied on green and semi-ripe olives. Olives are placed in lye and soaked. Upon their removal they are washed in water injected with compressed air. This process is repeated several times until both oxygen and lye have soaked through to the pit. The repeated, saturated exposure to air oxidises the skin and flesh of the fruit, turning it black in an artificial process that mimics natural ripening. Once fully oxidised or “become black”, they are brined and packed.
Salt-cured type. (without fermentation):
This process is used only on ripe olives and usually produced in Turkey, Morocco and other eastern Mediterranean countries. Once picked, the olives are washed thoroughly and packed in alternating layers with salt. The high concentrations of salt remove the moisture out of olives, dehydrating and shrivelling them. They appear like a raisin. Once cured, they are sold without adding any preservatives.
Image Courtesy: www.stitchandboots.com
In India, we mostly find brands selling Spanish type processed Olives. Some of the commonly available brands in India are Fragata, Del Monte, Farrell, and Leonardo etc.
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