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Overview of food preservation technology
Overview Of Food Preservation
Presented By, CHINMAI R DASTIKOP
UNIVERSITY OF AGRICULTURAL SCIENCE DHARWAD
What is Food Preservation?
Why is Food Preservation important?
Principles of Food Preservation
Safety of preservation methods
Food preservation involves number of different methods to preserve/store the food without
spoilage/contamination by microbes.
It tends to increase the shelf life of the product.
This technology of food preservation helps to deliver the food product to consumers at the best
possible value for consumption.
Different kinds of foods require different methods of preservations based on the type, composition,
method of preparation, moisture content etc.
The main objective of food preservation to avoid spoilage of food by hindering micro-organism growth
such as bacteria, fungus, molds etc.
Why Food Preservation is Important?
Increase the shelf
life of the product
throughout the year
Variety in diet
To save food for future
(During drought, floods
tends to reduce cooking
time and energy required
To stable the price of product
throughout the year (Seasonal
foods can be preserved and made
available throughout the year)
Reduces loss/wastage of perishable
E.g.: Fruits stored at ambient
temperature can be edible for 2-3
days but storing in low temperature
can make them edible for 10-
Overall food supply is
Principles of Food Preservation
• Avoiding invasion of
microorganisms E.g. Asepsis
• Removing microbes E.g.
• Inhibiting the growth & activity
of microorganisms E.g.
Freezing, Drying, Chemicals etc.
• Killing the microorganism E.g.
of the growth of
• Destruction/inactivation of
inherent enzymes naturally
existing in food. E.g. Blanching
• Prevention/delay of chemical
reactions. E.g. Prevention of
oxidation by addition of
• By using suitable chemicals to
kill insects or animals from
destroying the foods.
• By storing foods in dry, air tight
containers to prevent the
insects or animals from
Food preservation techniques combines science-based knowledge with technologies,
to prevent spoilage and extend shelf-life and ensure consumers free of pathogenic
Deterioration of food leads to loss of quality including color, texture, taste as well as
Cause of deterioration may be due to physical, chemical or biological, microbial factors.
Preservation methods should be applied as early as possible in production pipeline and
therefore include proper postharvest handling before processing of both plant and
Major Food Preservation Techniques
Food preservation methods
Inhibition Inactivation Avoid Recontamination
Low-temperature storage Sterilization Packaging
Reduction of water activity Pasteurization Hygienic Processing & Storage
Decrease of oxygen Irradiation Aseptic Processing
Increase of carbon dioxide Electrifying HACCP
Acidification Pressure GMP
Fermentation Blanching ISO 9000
Adding preservatives Cooking TQM
Adding antioxidants Frying Risk analysis & management
Control pH Extrusion
Concentration Magnetic Field
Changes in phase
Methods of Preservation
It refers to the absence of disease-causing micro-organism.
The main aim of asepsis is to prevent contamination which can be done through using sterile devices,
materials and instruments & by creating an environment low in microbial volume.
Natural protection – outer layer of animal and plant tissue protects the inner layer free from micro-
organism. This protective layer will delay/prevent the microbial decomposition. E.g. Shells of nuts, skin
of fruits and vegetables etc.
Packaging of foods – prevents entry of microbes such as in wrapping, hermetically sealing.
In food industries mainly is concerned with prevention of contamination of foods concerning the
“bioburden” of microorganism on/or in food.
Filtration is one of the method to remove microorganism from liquids like water, juices, beer etc.
Sterilized filter is used to separate the microbes by passing the liquid through the filter by application of pressure.
Microorganism get struck and cannot pass through the filter and liquid free of microbes are passed through the
(C) Anaerobic Condition
Refers to condition with no or minimum air/oxygen that helps to hinder the growth of bacteria.
Food is completely filled in container and air in unfilled space is replaced by carbon dioxide or nitrogen.
(D) Heat treatment
Most common method of preservation to kill the microorganisms.
There are types of heat treatment which depends on the kind of microbes and food composition.
1.Pasteurization (temperature below 100℃) – tends to kill part of microbes below 100ºC
Temperature ranges from 65ºC-75ºC.
There are two ways of pasteurization:
❖ HTST (High temperature-short time)
Food product is heated at high temperature for a short time. For example,
milk is heated to 72℃ and held for 15 seconds.
❖ LTLT (Low temperature-long time)
Food product is heated at a lower temperature for longer period of time.
For example, milk is heated to 62.8℃ and held for 30 minutes.
2.Boiling or heating at about 100℃
Most fruits and vegetables can be preserved for a longer time by applying heat at
about 100℃. Inherent enzymes which initiate self-decomposition can be destroyed
after boiling at 100℃. This process is called blanching.
3.Sterilization(temperature 100ºC or above)
It is a process that all micro-organisms are being killed at high temperature or
radiation. The time and temperature necessary for sterilisation vary with the type
Type of Food Temperature Duration
Fruits & Tomato 100℃ 30min
Vegetables 116℃ 30-70min
Milk (UHT) 135℃ Not less than 1 sec
Major difference between pasteurization &
Function Partial destruction of
Complete destruction of
Temperature Below 100ºC Above 100ºC
Advantage Minimum damage to flavor,
texture and nutritional
Long shelf life
No other preservatives
Disadvantage Short shelf life
method must be used like
Food is overcooked. Major
changes in texture, flavor &
It’s a method that sterilizes food by heat in airtight containers to achieve a commercially sterilized product, which
allows food to be stored at room temperature while maintaining food safety & organoleptic quality for months/years.
(E) Use of low temperature and cold preservation
Low temperature helps to slow down the microbial activities.
Refrigerated temperature reduces microbial growth rate and chilling temperature inactivates the enzymatic activities.
Usual cold storage temperature ranges from 4.5-7ºC and frozen food temperature is below -18ºC
(F) Drying or dehydration
Drying is one of the old technique used for preservation.
It simply means the removal of water from the food which inturn reduces
water activity and hence helps in preventing the growth of microbes.
Drying is done naturally under sun-drying method for specific time
Dehydration is done by artificial application of heat.
A faster process A slower process
Under controlled hygienic condition Under open-air condition with little hygienic
Not dependent on weather Not possible in cloudy/rainy days
Investment on machinery & processing cost is
No machinery & processing cost needed.
Difference between drying & dehydration
(G) Use of preservatives
Preservatives serve as antimicrobials which prevent or slow down the growth of
molds, yeasts and bacteria.
An ideal preservative
should meet the following criteria:
(i) can inhibit the growth of a wide range of micro-organisms
(ii) should be non-toxic to humans
(iii) should not be expensive
(iv) should not affect the flavor, taste or aroma of the food product
(v) should not be inactivated by the food itself
(vi) should not promote the development of resistant micro-organisms
(vii) should kill rather than inhibit the micro-organisms
(H) Use of salt and sugar
Sugar binds moisture and thus can preserve food by preventing the growth of microorganisms if a high
concentration (65% or above) is used. Products such as jams and jellies are preserved by using sugar.
Salt in high concentration (15-20%) can prevent the water from being available for bacterial growth. It
slow down the growth rate of bacteria and thus the food ispreserved. Salt can be used in brine (salt
water) or applied to food directly.
(I) Use of acids (vinegar or citric acid)
Acids lower the pH and thus inhibit the growth of many micro-organisms. It is more effective against
and bacteria than molds. About 20% vinegar (acetic acid) prevents the spoilage of most products like
pickles, sauces and chutney.
Citric acid, is used in the preservation of certain fruits and vegetables. Products of jams, jellies and
squashes may contain citric acid. It can prevent the growth of molds.
Radiant energies can kill microorganisms without marked increase of temperature as well as marked
changes in the nature of food. Gamma rays, x-rays and electromagnetic, ultra-violet radiations are
commonly used for food preservation. Irradiation can be used in a wide range of area in food
(i) Poultry products and seafood
(iii) Prevention of sprouting in potatoes and onions
(iv) Delaying ripening in fruits
(v) Preservation of seafood
(vi) Prevention of insect infestation in dry foods and food products
Are Preservatives Safe?
All preservatives must go through rigorous safety assessment and approval procedures. They are
for food use only when they are proved to present no hazard to the health at the level of use proposed.
All preservatives must go through rigorous safety assessment and approval procedures.
They are permitted for food use only when they are proved to present no hazard to the
health at the level of use proposed.
Nitrite is mainly used in sausages, ham, bacon and pickled meat to inhibit the growth
of Clostridium botulinum.
Accidental intake of large amount of nitrite can cause a kind
of blood disorder called methaemoglobinaemia.
Ingested nitrite, in the presence of protein substances in the stomach, may form N-nitroso compounds,
which have been shown to be probable human carcinogen and may increase the risk of stomach cancer.
Nitrite also occurs naturally in food like cereals and vegetables.
If consumers have balanced diets, exposure to a specific chemical will be lowered and
so is the risk.
Food Preservation Technology Strand PDF
Science Direct - https://www.sciencedirect.com/topics/food-science/food-preservation
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