modern trends in food preservation

1. Modern Trends in
Food Preservation
Presented by
SELVAPRAKASH N
B.Sc (Food Nutrition and Dietetics)

2. Introduction
• Food preservation has been defined "as the
science which deals with the process of
prevention of decay or spoilage of food allowing
it to be stored in a fit condition for future use".
• It has also been described as the state in which
any food may be retained over a period of time
without being contaminated by pathogenic
organisms or chemicals and losing optimum
qualities of colour, texture, flavor and nutritive
value.

3. Importance of food preservation
• Demand and supply not equal.
• surplus production of a food product,
whereas in some other place there is
inadequate supply.
• Perishable foods meets high spoilage.
• Important to improve and expand facilities for
storage and preservation of food
Demand
Supply

4. Advantages
• Increasing the self-life of foods.
• Perishable foods -preserved for a long time.
• Seasonal food -throughout the year.
• variety to the diet.
• Reducing preparation time &energy-Partial
processing

5. Advantages
• Stabilising prices of food.
• Decreasing wastage of food.
• Improving the nutrition of the population.
Preserved foods help people to bring a variety in
the diet, thereby decreasing nutritional
inadequacies.

6. Common Preservation Techniques
• Physical methods
• Chemical methods
• Biological methods

7. Emerging technologies
• High pressure processing
• Pulsed electric field processing
• Ohmic heating process
• Encapsulation technology

8. High Pressure Processing

9. High pressure processing
• Food is subjected to very high pressures (up
to 120,000 pounds per square inch) to kill
bacteria present in the food.
• Used to enhance desired food attributes in
some foods.
• High pressure to solid or liquid foods to
improve their safety and in some cases,
organoleptic properties and quality.

10. Diagram of operation of HPP unit

11. Principle
• Lechatlier principle –Any phenomenon
accompanied by a decrease in volume is
enhanced by pressure .Accordingly pressure
shifts to that of lowest volume.
• Isostatic principle –Food products are
accompanied by uniform pressure from every
direction and then returned to their original
shape when the pressure is released .

12. Functioning of HPP
• Prepacked in vacuum packs or flexible packaging materials
(plastic bottles)
• Selected packaging must be able to withstand the high
pressures used, without losing seal integrity.
• The foods are placed into a specially designed pressure
chamber which is sealed and completely filled with potable
water.
• A pump connected to the pressure chamber pressurizes the
water, i.e. hydrostatic pressure.
• Pressure acts instantaneously and is equally distributed, there
is no obvious crushing effect on the packaged food.
• Pressure is applied for a set time period typically from a few
seconds up to 20 minutes.

13. Functioning of HPP
• On completion of the time period, the chamber
depressurises and the food product can be
removed.
• Processing operations HPP is carried out
between 400 to 600 Mega Pascal (MPa), at
room temperature.
• Due to the effect of pressure, the temperature of
the product in the pressure chamber can rise by
3-6°C
• For every 100 MPa increase in pressure,
depending on the composition of the product.

14. Effect of HPP on microorganisms
• Inactivate certain enzymes.
• Reduce numbers of most vegetative bacteria.
• Spores of both bacteria and moulds are largely
inactivation by HPP.
• The effectiveness of HPP treatments will be
dependent on the pressure applied, the holding
time, temperature, the type of food matrix and
the target organism.

15. Applications of HPP
• Spoilage control – by reducing the foods microbial load.
• Pathogen control – by elimination or reduction to safe levels
pathogens of concern such as
Listeria monocytogenes etc.
• Organoleptic preservation- HPP can be used to tenderize and
improve the texture of meat products.
• Shucking of shellfish – HPP can be used for shucking
shellfish and other seafood.
• Product reformulation – the use of HPP for enhancing the
characteristics of reformulated products, e.g. low salt meats

16. HPP products

17. Pulsed Electric Field Processing

18. Pulsed Electric Field processing
• Pulsed electric field is one of the emerging techniques to
preserve the foods, especially the liquid ones such as
milk, yoghurt, juices, soups, rice pudding, and liquid
eggs, but not suitable for solid foods.
• It has the potential to produce the foods with excellent
sensory and nutritional quality besides extends shelf life
and ensures safety.
• Pulsed electric field uses short electric pulses to
preserve the foods.

19. Pulsed Electric Field processing
• Short pulses of electricity for microbial
inactivation & causes minimal detrimental effect
on food quality attributes.
• PEF technology aims to offer consumers high-
quality foods.
• For quality attributes considered superior to
traditional thermal processing methods because
it avoids or greatly reduces detrimental changes
in the sensory and physical properties of foods.

20. Pulsed Electric Field
• High intensity pulsed electric field (PEF)
processing involves the application
of pulses of high voltage (typically 20 - 80
kV/cm) to foods placed between 2 electrodes.
• High voltage Pulsed Electric Field (PEF)
treatment of food is a good alternative to heat
pasteurization which preserves the natural
quality of the foods and is energy efficient.

21. Process

22. Principle
• The processing time is calculated by multiplying the number of
pulses times with effective pulse duration.
• The process is based on pulsed electrical currents delivered to a
product placed between a set of electrodes
• The distance between electrodes is termed as the treatment
gap of the PEF chamber.
• The applied high voltage results in an electric field that causes
microbial inactivation..
• After the treatment, the food is packaged aseptically and stored
under refrigeration.
• Food is capable of transferring electricity because of the
presence of several ions.
• when an electrical field is applied, electrical current flows into
the liquid food and is transferred to each point in the liquid
because of the charged molecules present.

23. Microbial cell inactivation

24. Effect of Pulsed Electric Field
• The first is electroporation in which the cell is
exposed to high voltage electric field pulses that
temporarily destabilizes the lipid bilayer and proteins
of the cell membranes; and the second is electric
breakdown.
• In both cases, the phenomenon starts by electroporation
by which the cell wall is perforated and cytoplasmic
contents leak out causing cell death.

25. Application of Pulsed Electric Field
• The consumer demand has increased for minimally
processed foods that have a more natural color and
flavor.
• Enhance extraction of sugars(beet sugar) and cellular
contents from plant cells.
• Preservation of semi solid and liquid foods.
• Pulsed electric field is used to pasteurize variety of
liquid and semisolid foods such as milk, yoghurt, apple
juice, grape juice, orange juice, sugar cane juice, soups,
brine solutions, liquid eggs.

26. PEF processed products

27. Ohmic heating process

28. Ohmic heating process
Ohmic heating is also known as joule heating, direct
electric heating, electro heating and electro
conductive heating.
• It is a process in which alternating electric current is passed
through food material to heat them.
• Electric current is passed through food, resulting in a
temperature rise in the product due to the conversion of the
electric energy into heat.
• Electrical energy is dissipated into heat ,which results in rapid
and uniform heating with minimal thermal degradation.

29. Principle
• Based on the passage of alternating electrical current
through a body such as a liquid particulate food
system which serves as an electrical resistance in
which heat is generated.
• Foods contain water and ionic salts capable of
conducting electricity ,but also have a resistance
which generates heat when an electric current is
passed through.
• This resistance produces the heat energy.
• Inactivate the microorganisms by heat and additional
electroporatic effect.

30. Working
• Electrode: Plantinized titanium electrode is
used.
• Temperature : 40-140 oc is used for less
than 90 seconds followed by cooling for 15
minutes .
• Pressure : upto 4 bar is used.
• Voltage :5000v

31. Factors affecting Ohmic heating
• Electrical conductivity of food and food mixture which in
turn depends on food components (e.g) ionic
components (salt) ,acid and moisture mobility increases
electrical conductivity ,while fats and lipids and alcohol
decreases it.
• Fluid viscosity :Higher viscosity fluids shower faster
ohmic heating than lower viscosity liquids.
• Density and specific heat of the food product.
• Liquid +solid mixture ,the property difference of the two
components also affects the ohmic heating.

32. Applications
• Used for heating liquid foods containing large
particulate such as soups, stews and fruit slices in
syrups and sauces and heat sensitive liquids.
• Used for protein rich substances ,which tend to
denature and coagulated when thermally
processed.(e.g) liquid egg can be ohmically
heated in a fraction of a second without
coagulating it.
• Juices can be treated to inactivate enzymes
without affecting the flavor .

33. Processed products

34. Encapsulation technology

35. Encapsulation technology
• Incorporation of food ingredients, enzymes, cells or other
materials in small capsules.
• Protected from moisture, heat or other extreme
conditions- enhancing their stability and maintaining
viability..
• Various techniques are employed to form the capsules,
including spray drying, spray chilling or spray cooling,
extrusion coating, fluidized bed coating, inclusion
complexation.
• A wide variety of foods is encapsulated--flavouring agents,
acids bases, artificial sweeteners, colourants,
preservatives, leavening agents, antioxidants.

36. Encapsulation
• Encapsulation is the inclusion of one thing
within another thing so that the included
thing is not apparent.
• Two types are available.
Reservoir type
Matrix type

37. Reservoir type:
• It has the shell around the active ingredient.
• This type is also called capsule or single core or
mono core.
Matrix type:
• The active agent is much more dispersed over the
carrier material.It can be in the form of relatively
small droplets or homogenously distributed over
the encapsulate.

38. Reasons for encapsulation
• Provide barriers between sensitive bioactive materials
and to the environment.
• Stabilize food ingredients or increase their bioavailability.
• Provide improved stability in final products and during
processing.
• Less evaporation of volatile materials
• Prevent oxidation of food materials
• Immobilize cell or enzymes in food processing.
• Improve delivery of bioactive materials such as
antioxidants ,vitamins, phyotstreols and minerals

40. Materials used for encapsulation
technology
• Starch and their derivatives-amylose,
amylopectin,dextrin,maltodextrin,polydextrose,
sugar syrups.
• Plant extracts-pectin,gum arabic,souble soybean
polysaccharides.
• Marine extracts-carragenes and alginate.
• Proteins-milk,whey proteins and casein,gelatin &gluten.
• Lipids-fatty acids & fatty alcohols,waxes,glycerides and
phospholipids.

41. Advantages
• Increased nutritional and health benefits.
• Wide range of specific products for consumers
to choose from
• Sensory properties remain unaltered.
• Shelf life may be increased

42. Other technologies
• Pulsed light food preservation
• Preservation by Radiation
• Preservation using Modified Atmospheres
• Ultra sound technology