The preservation of food in common salt (or) in vinegar is known as pickling. It is one of
the most ancient methods of preserving fruits and vegetables. Pickles are good appetizers and add to the palatability of a meal. They stimulate the flow of gastric juice and thus helps in digestion.
Preservation by salt (NaCl2)
Sodium chloride is an indispensable component of food. At lower concentrations it contributes significantly to the flavour. At higher concentrations it exhibits an important
bacteriostatic action. Salt is easily available and not expensive.
Pickling is done in two stages (1) By curing (or) fermentation with dry salting (or) fermentation in brine (or) salting without fermentation (2) By finishing and packing.
Pickling is the result of fermentation by lactic acid forming bacterial which are generally
present in large numbers on the surface of fresh vegetables and fruits.
Theses bacteria can grow in acid medium and in the presence of 8-10% salt solution whereas the growth of a majority of undesirable organisms is inhibited. Lactic acid bacteria are most active at 30oC, so this temperature must be maintained as far as possible in the early stage of pickle making.
When vegetables are placed in brine, it penetrates into the tissues of the farmers and soluble material present in them diffuses into the brine by osmosis. The soluble material includes fermentable sugars and minerals. The sugars serve as food for lactic acid bacteria which convert them into lactic acid and other acids. The acid brine thus formed acts upon vegetables tissues to produce the characteristics taste and aroma of pickle.
There are two methods for pickling
1. Dry salting method
Alternate layers of vegetables and salt (20-30 gm of dry salt/kg vegetables) are kept in a
vessel which is covered with a cloth and a wooden board and allowed to stand for about 24 hrs.
During this period, due to osmosis, sufficient juice comes out from the vegetables to form brine.
The amount of brine required is usually equal to half the volume of vegetables. Brining is
the most important step in pickling.
The growth of a majority of spoilage organisms is inhibited by brine containing 15% salt. Lactic acid bacteria, which are salt tolerant can thrive in brine of 8- 10% strength though fermentation takes place fairly well even in 5% brine. In a brine containing 10% salt, fermentation proceeds somewhat slowly. Fermentation takes place to some extent upto 15% but stops at 20% strength. It is therefore, advisable to place the vegetables in 10% salt solution for vigorous lactic acid fermentation.
As soon as the brine is formed, the fermentation process starts and Co2 begins to evolve. The salt content is now increased gradually, so that by the time the pickle is ready, salt concentration reaches 15%. When fermentation is over, gas formation ceases. Under favourable conditions fermentation is completed in7-10 days. When sufficient lactic acid has been formed, lactic acid bacteria cease to grow and no further change takes place in the vegetables. However, precautions should be taken against spoilage by aerobic microorganisms, because in the presence of air, pickle sum is formed which brings about putrefaction and destroys the lactic acid. Properly brined vegetables keep well in vinegar for a long time.
II. Fermentation in brine
Steeping of the vegetable in a salt solution of pre-determined concentration for a certain length of time is called brining. This type of treatment is adopted in the case of cucumbers and similar vegetables which do not contain sufficient juice to form brine with dry salt. Brine can be prepared by dissolving in common salt in water and filtering it through the cloth to remove insoluble impurities. The remaining process is similar to that of dry salting method.
Raw materials used in pickling
1. Salt: Free from impurities, and salts such as lime (CaO), iron (blackening), magnesium
(results bitter taste) and carbonates (makes the pickle soft in texture).
2. Vinegar: Vinegar of good quality should contain atleast 4% acetic acid. Synthetic vinegar
(or) low quality vinegar are not suitable for pickle preparations. Usually malt (or) cider vinegar is
used. In order to ensure good keeping quality pickle, the final concentration of acetic acid in the
pickle should not be less than 2%. Acetic acid (commercial) is also used because it is highly
3. Sugar: Used in the preparation of sweet pickles should be of high quality.
4. Spices: Spices are added practically to all pickles, the quantity added depending upon the
kind of fruit (or) vegetable taken and the kind of flavour desired. The spices generally used are
bay leaves, cardamom, chillies, cinnamon, clove, coriander, dill herb, ginger, mace, mustard,black pepper, cumin, turmeric, garlic, mint, fenugreek, asafoetida etc.
5. Water: Only potable water should be used for the preparation of brine. Hard water contains
salts of Ca, Na, Mg etc., which interfere with the normal salt curing of the vegetable. If hard
water is to be used, a small quantity of vinegar should also be added to the brine the neutralize
its alkalinity. Iron should not be present in the water in any appreciable quantity as it causes the
blackening of the pickle.
6. Cooking utensils: Metallic vessels should be non-corrodiable. Vessels made of iron (or)
copper are not suitable. Glass -lined vessels, and stainless steel vessels are preferred. The
laddles, spoons and measuring vessels should also be masde on non-corrodible materials. At
present, pickles are prepared with salt, vinegar, oil (or) with a mixture of salt, oil, spices and
These methods are discussed below
I. Preservation with salt
Salt improves the taste and flavour and hardens the tissues of vegetables and controls
fermentation. Vegetables do not ferment when they are packed with a large quantity of salt.
Spoilage is prevented by adding sufficient common salt, bringing its final concentration in the
material from 15-20%. At this high salt concentration, mould and even lactic acid forming
bacteria do not grow.
This method of preservation is applicable only to vegetables which contain very little sugar because sufficient lactic acid cannot be formed by fermentation to act as preservative. Some fruits like lime, mango, etc. are also preserved with salt.
1. Lime pickle: Lime – 1 kg, salt – 200 g red chilli powder –15 g, cinnamon, cumin, cardamom
and black pepper (powdered) each –10 g cloves – 5 Nos.
Limes → Washing →Cutting into 4 pieces → Squeezing out juice from ¼ amount of fruit
→ Mixing spices and salt with juice → Mixing with lime pieces → Filling in jars → Covering with
lid → Keeping in sun for 4-6 days (shaking jar atleast twice a day) → Storage at ambient
II. Preservation with vinegar
In vinegar pickles, vinegar acts as a preservation. The final concentration of acid as
acetic acid in the finished pickle should not be less than 2%. To avoid dilution of vinegar below
this strength by the H2O liberated from the tissues, the vegetables (or) fruits are generally
placed in strong vinegar of about 10% acidity for several days before final packing. This
treatment helps to expel the gases present in the intercellular spaces of vegetable tissues.
Papaya, pears, onion, garlic, chillies, mango and cucumber pickles are prepared in this method.
Cucumber – 1.0 kg, salt – 200 g red chilli powder – 15 g, cardamom (large), cumin,
black pepper (powdered) each – 10 g, cloves – 6 Nos., vinegar – 750 ml.
Cucumbers → Washing → Peeling → Cutting into 5 cm round pieces → Mixing with salt →
Filling in jar → Standing for 6-8 hrs → Draining off H2O → Adding spices and vinegar →
Keeping in sun for a week → Storage.
III. Preservation with oil
The fruit (or) vegetable should be completely immersed in the edible oil. Cauliflower,
lime, mango, amla, karonda, bittergourd, brinjal, turnip pickles are prepared from this method.
Green chilli pickle:
Green chillies – 1 kg, salt – 150 gm, mustard (ground) – 100 gm lime juice
– 200 ml (or) amchur – 200 gm, fenugreek cardamom (large), turmeric, cumin (powdered) each
– 15 gm, mustard oil – 400 ml.
Green chillies → Washing →Drying → Making incision → Mixing all spices in a little lime
juice → Mixing with chillies → Filling into jar → Adding lime juice and oil → Keeping in sun for a
week – Storage.
IV. Preparation with mixture of salt, oil, spices and vinegar
Tomatoes – 1 kg, salt 75 g, garlic (chopped) – 10 g, ginger (chopped)- 50 g,
red chilli powder, cumin, cardamom (large), cinnamom, turmeric, fenugreek – each – 10 g,
cloves – 50 nos, asafoetida (powdered) – 2g, vinegar – 250 ml, oil – 300 ml.
Tomatoes (ripe, firm and pulpy) → Washing → Blanching for 5 min → Cooling immediately in
water → Peeling → Cutting into 4-6 pieces (or) mashing → Frying all ingredients in a little oil
except vinegar → Mixing with pieces → Heating for 2 min → Cooling → Addition of vinegar and
remaining oil → Filling in jar → Storage.