Pickling uses the salt combined with the acid, such as acetic acid (vinegar), oil and spices. Based on the ingredients, the pickles differ. Different methods of pickling are:
Pickles with salt
Pickles with vinegar
Pickles with oil
Pickles with salt, vinegar, oil and spices
Pickles with salt Vegetables are usually preserved by salting. Salt content of 15 per cent or above prevents microbial spoilage as well as inhibits enzymatic browning and discolouration. Salting improves the taste and renders firmness in tissues of vegetables and controls fermentation. This method is suitable for vegetables as they contain very little sugar, as a result lactic acid is not formed in sufficient amounts to act as preservative. However, some fruits viz. mango, lemon, etc. are also preserved with salt.
Pickles with vinegar Vinegar pickles are the most important pickles consumed in other countries. Vinegar in concentrations up to 4 per cent acetic acid and higher concentrations has bacteriostatic and bactericidal action, respectively. The final concentration of 2-3 per cent acetic acid is required to ensure preservation. For this, 6-9 per cent acetic acid vinegar is used, to overcome dilution by water oozing out of tissues. Such higher concentration helps to expel the gases present in the intercellular spaces of vegetable tissue. In vinegar pickles, salt (2-3 per cent) and sometimes sugar (2-5 per cent) are also added. If the vinegar concentration is lower than 2 per cent, vinegar pickles need to be subjected to pasteurization in order to assure their preservation. Mango, garlic, chilies, etc. are preserved in vinegar.
Pickles with oil Highly spiced oil pickles are quite popular in India. Oils like mustard oil, rapeseed oil, sesame oil are generally used for pickling. The fruits or vegetables should be completely immersed in the edible oil. Cauliflower, lime, mango and turnip pickles are the most important oil pickles. The pickle remains in good condition for one to two years if handled properly.
Pickles with salt, vinegar, oil and spices This method combines the advantages of fermentative action of salt and the preservation action of both vinegar and oil . The flavouring and antibacterial property of spices is also made use of in this kind of pickle. The powdered spices are usually fried in oil and mixed to the prepared fruit/ vegetable before the addition of vinegar.