Transcript FOOD PRESERVATION BY SALT, ACID, SUGAR AND …

FOOD PRESERVATION BY SALT, ACID,
SUGAR AND CHEMICAL PRESERVATION
SALT AND ACID
• Salt was used by man as one of the
earliest methods of food preservation.
• Smoking and drying is used extensively in
combination with salt, particularly for meat
and fish product.
• Salt and acid are use extensively in the
preservation of vegetable product of which
cucumbers, cabbage, and onions are
important examples.
ANTI-MICROBIAL PROPERTIES
OF SALT AND ACID
• Salt produces a number of effects when
added to fresh plant tissues
• Salt exerts a selective inhibitory action on
certain contaminating microorganisms.
• Salt also affects the water activity (aw) of
the substrate, thus controlling microbial
growth by a method independent of its
toxic effects.
• Acids, chiefly acetic and lactic, can be present in
preserved foods as a result of acid addition to
non-fermented foods, or as a result of microbial
fermentation of tissue carbohydrates.
• Acids have two anti-microbial effects : one is due
to their effect in pH, and the other is the specific
toxicity of the undissociated acid which carries
for different acids.
SUGAR
• Sugar are involved in the preservation and
manufacture of wide range of food products.
• Some of the more common include : jams,
jellies, fruit juice concentrates, sweetened
condensed milk.
• When sugars are added to foods in high
concentration (at least 40% soluble solids),
some of the water present becomes unavailable
for microbial growth and the aw of the food is
reduced.
CHEMICAL PRESERVATIES
To be in accord with good manufacturing
practices, the use of preservatives :
1. Should not result in deception.
2. Should not adversely affect the nutritive value
of the food.
3. Should not permit the growth of food-poisoning
organisms while suppressing growth of the
others that would make spoilage evident.
• Chemical preservatives vegetables
preservation are sulphur dioxide (SO2),
benzoates, and sorbates.
• The efficiency of chemical preservatives
depends primarily on the concentration of
the preservative, the composition of the
food, and the type of organisms to be
inhibited.
• The concentration of preservative
permitted by food regulations.
• It is essential that the microbiological
population of the food to be preserved is
kept to a minimum by hygienic handling
and processing.