Food and nutrition.pdf

C1:Jutneys, Pickles, Salted Vegetables and Sauces 245IThe Preservation Index is a measure of the preserving power ofcombinations of acid and sugar (sugar is measured as 'total solids'). Thisis used to assess whether a chutney or pickle is safe from food spoilageand food poisoning micro-organisms. The value can be calculated asfollows:Total acidity x 100(100 - total solids) = not less than 3.6%Details of how to measure acidity and total solids are given in Section2.7.2. However, if a manufacturer has no access to basic laboratoryequipment or is not sure how to carry out the calculation, it is best to takea sample of product to a Bureau of Standards, University Food ScienceDepartment or food testing laboratory which can analyse it andrecommend adjustments to the recipe if necessary.PicklesVegetables such as cucumber, cabbage, olive and onion are fermentedby lactic acid bacteria which can grow in low concentrations of salt. Thebacteria ferment sugars in the food to form lactic acid, which then preventsthe growth of food poisoning bacteria and moulds or other spoilage microorganisms.The amount of added salt controls the type and rate of thefermentation. If for. _~Fimple 2-5% salt is used, a natural sequence ofdifferent types of bacteria produce the lactic acid.If higher concentrations of salt (up .to 16%) are used, a differentproduct called 'salt stock' pickle is prq9.yfed, which is preserved by thesalt and not by fermentation.Fruits and vegetables can be preserved in this way as a method ofintermediate storage to spread production over several months throughoutthe year.Sometimes, sugar is added to increase the rate of fermentation or tomake the product sweeter.Alternatively, vegetables may be packed in vinegar (acetic acid), saltand sometimes sugar to produce a variety of pickled products. Becausethese vegetables are not fermented they have a different flavour andtexture. They are usually pasteurised. Sweet pickles are made from singlefruits or mixtures of fruits and vegetables. They are preserved by thecombined action of lactic or acetic acid, sur;ar and in some cases addedspice~: .Salted VegetablesSalted vegetables are made by building up alternate layers of chopped