Paper No.: 03
 Paper Title: FOOD MICROBIOLOGY
 Module – 12: Preservation of foods by chemical methods – the 
        ideal chemical preservatives
    CONTENTS
   1. Introduction
   2. An ideal antimicrobial preservative and added preservatives
   2.1 Organic acid and their salts
   2.2 Nitrites and Nitrates
   2.3 Sulfur Dioxide and Sulphites
   2.4 Ethylene and Propylene Oxides
   2.5 Sugars and Salts
   2.6 Alcohol
   2.7 Formaldehyde
   2.8 Woodsomke
   2.9 Spices and other condiments
   2.10 Other food additives
   2.11 Antibiotics
         INTRODUCTION
      Food preservation includes a variety of   methods that allow
      food to be kept for extended periods of time without losing its
      nutritional quality and avoiding the growth of unwanted
      microorganisms.
      In  general,  there  are   three  basic  objectives for  the
      preservation of foods:
         a) Prevention of contamination of food from damaging
          agents (microbes, insects etc.
         b) Hinder or prevention of growth of microbes in the food
          and
         c) Delay of enzymic spoilage such as self-decomposition of      http://deliciousunderpressure.com/wp-
                                                                     content/uploads/2012/09/photodune-2488969-three-
          the food by naturally occurring own enzymes.                   jars-of-preserved-mixed-vegetables-xs.jpg
      ANIDEALANTIMICROBIALPRESERVATIVE ANDADDEDPRESERVATIVES
    An ideal antimicrobial preservative should have following attributes:
     Demonstrate broad spectrum of microbial activity, so that wide range of microbes can be killed or
      destroyed.
     It should be non-toxic to handlers and consumers.
     The cost of production should be low (economical)
     It is expected that it should not affect organoleptic properties of food to be preserved and should
      not be inactivated by food.
     Preservative should not promote the growth of resistant strains and
     It should kill microbes effectively rather than inhibit multiplication.