Compared to the other varieties of fruits which may be picked from their branches and readily eaten, the olive fruit does not easily surrender. For it is bitter. In time, methods have been developed which shall eliminate the acerbity of the olive. First, acerbity of the olive was eliminated by storing it in water. Then, it was sweetened by dipping into ash, vinegar or lime water. It was made resistant to time by pickling in brine as it was or upon cuttinging or cracking. The brine was added with lemon, fennel, mastic, thyme, peppermint and other herbs, thus making the flavour of olive more pleasant. Such methods as storing the olives in must, wine or even honeyed water instead of brine were also tried.
We may briefly examine the methods applied in sweetening black olives as follows:
II - Gemlik method:
This method has been being applied in our country for many centuries. It is applied by preparing the brine in advance and by pouring water on the olive; thus both edible olives of good quality are obtained and production process is shortened.
In this method, olives my be placed in brine in concrete, polyethylene, polyester and fiberglass tanks. However, whatever material brine tanks are made of, they should be 2 m high and the height of the olives which shall be put in should not exceed 1,80 meters.
Brine which has been prepared at 10 baumes (10% brine) is poured over the olives and olives are left to cure.
Brine should completely cover the olive fruits. There shuld not be any air gap between the top cover and the surface of the liquid.
Once the olives have been placed in brine, salt transition into th fruit commences and baume reduces to 5-6. Salt in the brine should be frequently checked by means of a baume areometer and reduced salt should be supplemented, thus keeping the salt degree of the brine at 10 baumes.
Fermentation commences in the olives placed in brine 2-3 days afterwards. Some good brine left from the preceding year or some sour yoghurt may be aded to the brine at 1-2% so that fermentation may progress well.
Glucose available in the olive fruits is converted into lactic acid by the lactic acid bacteria. The lactic acid so formed maintains the olives without deterioration. For good maintenance, the brine should have 0,9% lactic acid.
- Salt degree may be increased to 12-13 baumes in order to prevent the olives from deteriorating in the months whem the weather gets warmer.
- During fermentation, yeast and mold forming on the top surface of the brine should be cleaned, brine circulated and salt and acidity checked.
The best fermentation temperature is about 20°C, in other words, room temperature. Therefore, one should try to keep the brine tempeature fort he initial 2-3 weeks if possible.
As the time for curing the olives corresponds to winter months in our country, fermentattion slowly progresses due to low temperature and only finishes in summer months. Thus, olives prepared by this method reach the edible maturity in 6 to 9 months.
II – Salt-alternation method:
Olives are alternately placed in fermentation tanks in the form of a layer of salt and a layer of olives.
Salt is calculated at 10% of the weight of the olives. Then, covers of the fermentation tanksa re placed over the olives. A weight of 10-15% of the weight of the olives is placed on top of such cover.
Olives are kept in dry salt and under pressure in the fermentation tank for a week.
sal waer accumulated on the bottom of the fermentation tank is discarded or circulated by the addition of potable water to it. Olives are left to ferment in the brine.
If the water accumulated on the bottom the fermentation tank is discarded, then the olives are fermented in a new brine of 13-15 baumes.
In this method, the fact that the brine is of 13-18 baumes and that the olives ae kept under a heavy pressure causes the olives to have a yanaklý and wrinkled structure.
Although olives’ reaching the edible maturity depends on the variety and ripeness, it varies between 6 and 12 moths.
III – Olive Salt-Cured in Baskets:
In this method, the olive fruits are harvested once they have been well blackened and ripened on the tree.
Firm olives are cleaned, washed and stowed in baskets or wooden crates in the form of a layer of granulated salt and a layer of olives on 15 kg salt to 100 kg olives basis. The opening of the container is covered with a proper cloth.
Containers are turned upside down or tilted left and right so that all the fruits may contact the salt. The fruits release their juice due to the salt. In this way, the olives lose their acerbity in 3-4 weeks, thus being edible.
IV – Curing black olives by aeration:
Amount of oxygen in the media is increased by aeration of the brine and the acidity caused by the microorganisms developing in the aerated media decreases the acerbity in the olives. In this way, olives sweeten in such a short time as 3-4 months.
Colour of the olives sweetened by this method is black and their texture harder.
V – Olive production instant method (Konfi type):
In this method, olives are placed in 1-ton tanks to remove their acerbity. 1,5-2% lye is poured over them. Once caustic has penetrated into 3/4 of the flesh of the olives, the undesired acerbity of the olives disappears and the lye is discharged. Water is filled in the container; washing proces is repeated four times and olives are aerated.
In the meantime, the colour of the olives blackens. After this process, olives are treated with ferrogluconate or ferrolactate, thus ensuring to fix the black colour so acquired.
Olives are kept in brine at 10-12 baumes for some 1,5 months, thus allowing them to ferment.
Olives prepared in this manner are placed in packaging brine prepared with low salt or passed through pasteurisation or sterilisation process.
If it is not possible to apply a thermal process, they are launched into the market in packaging brine with a pH value of 4,2-4,5 prepared at 10 baumes by the addition of preserving substances.
VI – Olives in Tin Cans:
In this method, 20 kg lacquered tin cans are used. 10 kg olives which have completed their ripening are filled in tin cans with a kilo of medium-granulated salt, ensuring that salt spreads through the olives. Then a kilo of olive oil is added and the lid of the tin can is solder-closed. Tin cansa re stored in a cool place and turned upside down every 2-3 days. Acerbity of the olives disappears due to osmosis caused by the salt and to fermentation in the sealed container in a short time.
VII - Calamata Olives:
In this method, fruits are placed in water-filled tanks or brine containing 2-3% salt in order to eliminate the acerbity of the olives. Water or brine is replaced every day or every second day until the acerbity of the olives is gone. Depending on the frequency of water replacement, aerbity is gone in a week to 4 weeks. De-acerbated olives are left in vinegar for a day or two or the necessary sourness and flavour are given by the addition of vinegar together with 8-10% brine in order to prevent loss of vinegar.
Calamata olives which are usually launched into the market in 8% brine in laquered tin cans are added with sliced lemon, olive oil and bayleaves as well. In another preparation method of Calamata olives, cutting process is applied to the fruits.
VIII – Cut Olives:
Varieties of olives with hard flesh are used. Olive fruits are longitudinally cut at three places down to the halfway into the fleshy parts by means of a knife. Cutting process may also be performed by machines. The cut olives are filled in water-filled containers and the water is replaced every da yor every second day. This process continues until acerbity disappears (15-30 days). De-acerberated olives are placed into 8-10% brine and stored for 8-10 days. At the expiration of this period, olives are packed into tin cans together with such aromitising substances as 5-8% brine, 1% citric acid, some olive oil, lemon slices, garlic and mustard. Cans are filled up with brine and sealed. Olives are stored in such packages for 8-10 days and then marketed.
5. Selection, classification, packaging:
Olives having reached an edible maturity are subjected to selection and classification processes. In the meantime, if there are any olives which have not yet blackened, they contact with air and blacken through oxidation.
In our country, edible olives are launched into the market in wooden crates, polyethylene bags or lacquered tin cans.
In order to prevent the packed olives from deteriorating at the sales and consumption stages, polyethylene ad other plastic packages should be sealed under nitrogen or carbondioxide gas and tin cans pasteurised at 75-95°C.
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