Food preservation involves preventing spoilage using various methods like preventing microbial growth through asepsis, low temperatures, drying, chemicals like sulfur dioxide and benzoic acid, or high temperatures through pasteurization or sterilization. Proper post-harvest management of fruits and vegetables is important to reduce significant losses between production and availability in India through operations like washing, sorting, grading, packaging and storage.

2. Food Preservation can be defined as the science which deals with the method
of prevention of decay or spoilage of food. Thus, allowing it to be stared in a
fit condition for future use.
Principle of preservations are:
1. Prevention or delay of Microbial decomposition
a) by keeping out microorganism (asepsis)
b) by removal of microorganism eg: by filtration
c) by hindering the growth and activity of microorganisme.g. by low
temperature, drying anaerobic conditions, chemicals or antibiotics and
d) by killing the microorganisme.g., heat or radiation

3. 2. Prevention or delay of the self decomposition of food
a) by destruction an inactivation of enzymes eg: by blanching
b) by prevention or delay of chemical reaction e.g., prevention of
oxidation by of an antioxidant
3. Prevention of damage by insects, animals, mechanical causes, etc.
1. Asepsis (Absence of infection)
 Asepsis means preventing the entry of microorganism
 Washing or wiping of the fruit and vegetables before processing
should be strictly fallowed as dust particles adhering to the raw
material contain microorganism and by doing so the number of
organisms can be reduced.

4. 2. Prevention by high temperature
 Coagulation of proteins and inactivation of their metabolic enzyme by
the application of heat leads to the destruction of microorganism in
foods.
 The treatment varies with
a) The organism that has to be killed
b) The nature of the food to be preserved
c) other means of preservation thatmay be used in addition to high
temperature
 High temperatures used for preservation
(i) Pasteurization temperature (below 100%)
(ii) Sterilization temperature (100% or above)

5. ii) Pasteurization
 The process of heating at boiling temp. or slightly below it for a sufficient
length of time to kill the microorganism which cause spoilage is called
pasteurization
 Does not kill all microorganisms presentin the juice
 Can be pasteurized two ways
(I) LTHT - by heating it at a low temperature for high period (62-66oC
for 20-30 min.)
(II) HTST - by heating at a high temperature for a short time only (79°C
for 5-10 min.)

6. (II) Sterilization
 Means the destruction of all viable microorganism by temperature above
100 C.and it can be obtained by using stem pressure sterilizers such as
pressure cookers and autoclave
 Diverse effect on vitamins and nutritional quality of protein.
 Sterilized at 116°C for 30 to 90 minutes
 Difference between Pasteurization and sterilization
1. Partial destruction of
microorganism
Complete destruction of
Microorganism
2. Temperature below 100oC Temperature 100oC and above
3. Normally used for fruits Used for vegetable

7. Aseptic Canning
 It is a technique in which food is sterilized outside the can and then
aseptically placed in previously sterilized cans which are
subsequently sealed in an aseptic environment.
 Also Known as Martin Aseptic Canning
 149oC for 1 or 2 seconds (HTST), ultra high temperature.
Hot Pack can Hot Fill
 Refers to the filling of previously pasteurized sterilized food while
still hot, into clean but not necessarily sterile container under clean
but not necessarily aseptic conditions.
 Hot Jam into Jars in home

8. 3. Prevention by Low Temperature
 Microbial growth and enzyme reactions are retarded in foods stored at
Low temperature.
(i) Cellar storage (about 15oC)
 Underground rooms
 Used for root crops, potatoes,onions and apples for limited duration
(ii) Refrigeration or chilling (0 to 5oC)
Commercial cold storage with proper ventilation and automatic control
of temperature used for semi-perishable foods such as potatoes and
apples.
(iii) Freezing (–18oC to 40oC)
 Activity micro-organism are reduced to a minimum

9. 4. Preservation by chemicals
According to the British Food and Drug Act of 1928, a preservative is
any substance which he capable of inhibiting retarding or arresting the
process of fermentation, acidification or other decomposition of food
 Not include salt, sugar, spices essential oil.
 2 Important chemical preservatives
(i) Sulphur dioxide (Sulphites)
(ii) Benzoicacid (include benzoates )

10. (i) Sulphur dioxide (Sulphites)
 Good preserving action against bacteria and moulds and inhibit enzymes
etc.
 Also retards the development of nonenzymatic browning or discoloration.
 Generally used in farm of sulphite, bisulphite and metabisuphite.
 Potassium + Citric  Potassium + Sulphure
Metabisulphite acid Citrate dioxide + water
 In fruit juice is 700 ppm, in squash,crush and cordial 350 ppm and in RTS
and nectar 100 ppm.
 Advantage -
(i) Better preserving action. against bacterial fermentation .
(ii) Helps to retain the colors of the beverage far longer time.
(iii) Preserving surface layer of juices
(iv) Highly soluble in juices and squashes.

11. Disadvantage
(i) Cannot be used in naturally colored juices like phalsa, jamun, pomegranate
strawberry, colored grapes plum etc. on account of its bleaching action.
(ii) Cannot be used juices packed in tin containsbecause it not only corrodes the
tin causing pinholes but also term hydrogen sulphide which has a disagreeable
smell.
(ii) Benzonic acid
 Partially soluble in water hence its salt sodium benzoate is used.
 Na benzoate is nearly 170 times as soluble as benzoic acid.
 Pure sodium benzoate is tasteless and Odorless.
 More effective against years the that against moulds.
 According to FPO in RTS and nectare 100 ppm and in squash, crush and
cordial 600ppm
 Mostly used in colored products of tomato phalsa, jamun pomegranate ,
plums , water melon , strawberry ec.

12. 5) Preservation by Drying
 Microorganism need moisture to grow so when the concentration
water in the food is brought down below a certain level , they are
unable to grow
 Moisture can be removed by the application of heat as in sun
drying on by mechanical drying (controlled temperature, humidity
and airflow
 Green peas, cauliflower , mango and mahua etc.
 Juices are presented in the form of powder. Mango Juices powder
but not popular in India

13. 6. Preservation by filtration
 Juices are clarified by using ordinary and then passed through special
filters which are capable of retaining yeasts and bacteria
 Various typed green proof filters are used.
 In USA and Germany for preserving apple and grape juices , soft drinks
and wines
7. Preservation by carbonation
 The process of dissolving sufficient CO2 in water or beverages so that the
product when served gives off the gas as fine bubbles and has a
characteristic taste.
 1 to 8 g per litre of water.
 Advantage of carbonation is the removed of air this creating an anaerobic
condition, which reduces the oxidation of ascorbic acid and prevents
browning.
 High carbonation - destroy the flower of the juice.

14. 8. Preservation by Sugar
 Syrups containing 66 percent or more of sugar do not ferment sugar
absorbs most of the available water with
 Hence multiplication of microorganisms is inhibited
 Preservation by osmosis
 Fruit syrup, jam jelly, marmalade, preserve, candy, crystallized and glazed
fruits
9. Preservation by Fermentation
 Decomposition of carbohydrates by microorganism or enzymes is called
fermentation
 Preserved by alcohol or organic acid formed by microbial action
 14 percent alcohol and 2 percent acetic acid act as preservative

15. 10. Preservation by salt
 15 – 25 % to preserve most products
 inhibits enzymatic browning and discoloration and act as an antioxidant
 High osmotic pressure resulting in the plasmolysis of microbial cell
11. Preservation by Acids
 Acetic acid (vinegar), citric (lime juice) and lactic acid
 Vinegar in pickles, chutneys, sauce and ketchup
 2 percent acetic acid.
12. Preservation by oil and spices
 A layer of oil on the surface of any food products anaerobic conditions
which prevent the growth of mould and yeast

16. 13. Preservation by Antibiotics
 Nisin – Streptococcus lactis
 Commonly used in canning of mushroom, tomatoes and milk
products
 Suppresses the growth of spoilage organism, gas producing and spore
forming bacteria and toxin producing.
 Subtilin– Bacillus subtilis
 canned pea and tomatoes
 10 to 20 ppm subtilin
 Pimaricin – an antifungal antibiotic used for treating fruit and fruit
juices

17. 14. Preservation by Irradiation
 Sterilization of food by ionizing radiations
 Not gaining importance due to unacceptable flavor of some
irradiated food and the fear that radioactivity might be induced
 Production of ion pairs and free radical inactivate microorganism
in the food
 Also known as cold sterilization free of microorganism without
high temperature treatment.

18. Post-Harvest Management
 India is the second largest producer of the world both fruit and vegetables in
the world
 A considerable amount of fruits and vegetables produced in India is lost due
to improper post-harvest operations as there is a considerable gap between
the gross production and net availability.
 Post harvest losses: Mean a measurable quantitative and qualitative loss in
given product after harvesting and during transportation, storage and
handling.
 Post harvest Management: Includes number of unit operations- washing
(removing field heat), sorting and grading, pretreatment or other minimal
processing techniques, packaging, storage and transportation, secondary
process of and value addition and packaging transportation and marketing.