M i n i m a l F o o d P r o c e s s i n gV I R A J N A L I A P A R A

What is it? Increasing shelf life of food treated with: washing, sorting, trimming, cutting, slicing or dropping without changing in nutritional values and fresh like quality.

Why should people chose minimal processing over conventional processing?#Which factors do people/you consider when you chose any food?

Factor Conventional food

Minimally processed food

Appearance Changes Almost remains same

Taste Not that of fresh food Very little change or no change

Nutritional Value Many nutritions are destroyed

Almost no changes due to “cold” process

Shelf life Longer than minimal Shorter but good for fresh product

Low Temp. Storage

MAP/CAS

High Hydrostatic

pressure

Oscillating Magnetic

Field

OhmicHeating

High Intensity Pulsed Electric

field

Pulsed Light

Ozone Technology

AsepticProcessing

𝐎𝟑Techniques For Minimal Processing

L O W T E M P E R A T U R ES T O R A G E

WHY LOW TEMPARATURE STORAGE ?

Low metabolic breakdown of cell tissuesMany biological reactions, enzyme activity decreasedRetards respiration of fresh foodsThus shelf life increases without much change in food

Quality…..

SOME DRAWBACKS

Tropical and subtropical fruits subjected to chillinginjury @ < 10-12“C

Plus : discolouration, pitting, necrosis, and growthinhabitation

M A S / CAS

WHAT IS MAP / CAS ?

MAP (or gas flushing) is the introduction of an atmosphere, otherthan air, into a food package without further modification orcontrol.

In CAS, the concentrations of oxygen, carbon dioxide andsometimes ethylene (ethene) are monitored and regulated.

𝐶𝑂2 𝑂2

ORRetardssenescence

For minimally processed products optimum 𝑂2 range of 2-8% and𝐶𝑂2 range of 5-15% is recommended.

Polyvinylchloride(PVC),Polypropylene(PP) and Polyethylene(EE)are widely used for MAP of minimally processed foods.

Multi=layered films often with Ethylene Vinyl Acetate(EVA) can bemanufactured with different gas transmission rates for MAP.

Thus shelf life increases without much change in food Quality…..

Cabbage without MAP Stored in MAP

H I G H HY D R O S T A T I C P R E S S U R E

T E C H N O L O G Y

The Technology As it’s name suggests, the product is packed in

flexible package and placed in pressure chamber inwhich pressure will be applied through water inrange of 4000-9000 Atm. for specific time

How does it preserve food?

When high pressures are applied to packages offood that are submerged in a water, the pressure isdistributed instantly and uniformly throughout

the food (i.e. it is ‘isostatic’). The high pressurecauses destruction of micro-organisms.

At this much high pressure (4000-9000) enzymes and bacteriaare inactivated by protein denaturation and cell wall rupturerespectively, but the flavour and taste remain unaffected.

Besides preservation it also improves rheological and functionalproperties of food.

It extends shelf life of refrigerated products from 2 to 6 months@ 4“C.

Pressure treatment of non pasteurized citrus juice are found tohave “17 months” of shelf life plus no loss in taste and nutritions.

Pressure can be lowered by using bacteriocins or high temp. withpulsed pressure application

O S C I L L A T I N G M A G N E T I C F I E L D

The TechnologyMagnetic field usually generated by supplying

current to electric coilA magnetic field of 5-50 tesla(T) with short pulses of

10-25 ohms-cm and frequency 5-50 Hz are requiredto inactivate microorganisms

How does it preserve food?

There are three theories about inactivation ofmicroorganisms by magnetic field1. By loosening of bonds b/w ion & protein.2. By calcium vibration in calcium bound protein3. breakdown of covalent bonds in the DNA

1. By loosening of bonds b/w ion & protein. The first theory stated that a OMF could loosen the bonds between ions and proteins. Many proteins vital to the

cell metabolism contain ions. In the presence of a steady background magnetic field such as that of the earth, thebiological effects of OMF are more pronounced around particular frequencies, thus it stops metabolic activities ofcells.

2. By calcium vibration in calcium bound protein A second theory considers the effect of SMF and OMF on calcium ions bound in calcium-binding

proteins, such. The calcium ions continually vibrate about an equilibrium position in the binding site.A steady magnetic field causes the plane of vibration to rotate, or proceed in the direction ofmagnetic field. Adding a "wobbling" magnetic field at the cyclotron frequency disturbs the precisionto such an extent that it loosens the bond between the calcium ion and the protein

3. breakdown of covalent bonds in the DNA the inactivation of microorganisms may be based on the theory that the OMF may couple energy

into the magnetically active parts of large critical molecules such as DNA. Within 5-50 T range, theamount of energy per oscillation coupled to 1 dipole in the DNA is 10-2 to 10-3 eV. Severaloscillations and collective assembly of enough local activation may result in the breakdown ofcovalent bonds in the DNA molecule and inhibition of the growth of microorganisms

O H M I C H E A T I N G( J O U L E H E A T I N G

ORE L E C T R O H E A T I N G )

The TechnologyPrinciple mechanisms of microbial inactivation in

ohmic heating are thermal in nature.Electric currents are passed through foods and thus

due to resistance heat generates internally in foodand minor electroporation takes place

How does it preserve food?

The heat created inactivates the microorganismsplus minor electroporation helps in speeding upprocess by pore formation in cell walls

This process to food reveal that there are noparticular pathogenic strains with a uniqueresistance to technology.

Advantages of ohmic heating. Relatively rapid and uniform heating. Less use of total thermal energy compared to conventional process Conventional heat transfer technology problems overcome by

ohmic heating No large temp. gradient in product (liquid plus particles both

heated same time) No scale formation or burnt particles in end product. Product can be made to heat transfer more quickly by addition

of ionic contents(salts etc..).

H I G H I N T E N S I T Y P U L S E D E L E C T R I C F I E L D

ORE L E C T R O P O R A T I O N

The TechnologyElectric field is applied to fluid food in the form of

short pulse and pulse duration ranging a fewmicroseconds to milliseconds rather than usingelectricity directly.

Food susceptible to dielectric breakdown are notsuitable for this technology

How does it preserve food?

The electric field produces potential in cell membrane,when field strength exceeds 1v, pores form in cellmembrane because of repulsive effect.

Thus if the field strength is very great, the poresbecome irreversible and cell membranes are destroyed

For microorganisms the critical electric field strength is about 15 𝐾𝑉𝑐𝑚 and the impulse lasts from 1-10 m second.

This tech. is only useful for liquid foods because of their high dielectricbreakdown points.

It inactivates enzymes and spores but avoids changes like proteindenaturation and vitamin denaturation.

Generally high field strengths are more effective than low fieldstrengths at short exposure of time.

P U L S E D L I G H T

The TechnologyThe intense burst of light in rapid pulses of tens per

second is directed over the surface of the food orpackaging material to be treated.

The process is best suited to foods that have a smoothsurface, and contain few fissures that could shieldmicro-organisms from the light.

How does it preserve food?

Pulsed light inactivates micro-organisms by acombination of photothermal and photochemicaleffects. The UV component of light has aphotochemical effect, but photothermal: a largeamount of energy is transferred rapidly to the surfaceof the food, raising the temperature of a thin surfacelayer sufficiently to destroy vegetative cells.

𝑂3O Z O N E T E C H N O L O G Y

The TechnologyFresh foods are immersed in ozonised water or ozone

gas is passed through foods.Ozone is highly unstable in nature so it should be

produced on site.It is formed by high energy splitting of oxygen molecule

How does it preserve food?

Ozonization is non thermal method of killingmicroorganisms using ozone, through the oxidationof their cell membrane.

Most of the pathogenic food borne microbes aresusceptible to oxidizing effect

It is most powerful disinfectant than the most commonly usedchlorine for deactivation of large no. of microorganisms

It does not remain in water for a very long time thus much safer thanother disinfectants

Any by-product from ozone treatments are less likely to havedangerous health effect than chlorine.

A S E P T I C P A C K A G I N G

The TechnologyAs we know that in this technology: The product, the

packaging material and the processing environmentare sterile when the process is carried out.

How does it preserve food?

It does inactivate microorganisms by HTST process andheat treated food is filled in sterile package in sterileprocessing environment.

Thus when product is packed there is no intrusion orformation of microbes inside the product, and shelf lifeincreases by the minimal process

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