NOVEL TECHNOLOGİES FOR FOOD PROCESS

Applications of Pulsed Electric Fields Technology for the Food Industry (PEF)

Iğdır University

Food Engineering

Özen Sökmen

İNTRODUCTİON Pulsed electric field processing (PEF) is an

efficient non-thermal food processing technique using short, high voltage pulses.

PEF or Pulsed Electric Field technology is a alternative process to pasteurisation and sterilisation methods.

WHAT İS PULSED ELECTRİC FİELDS ?

These pulses induce portion of plant, animal and microbial cells, leading to cell disintegration and microbial inactivation.

Pulsed electric field processing (PEF) is an efficient non-thermal food processing technique using short, high voltage pulses.

PEF: HOW İT WORKS ?

High intensity (PEF) processing involves the application of pulses of high voltage (typically 20-80 kV/cm) to foods placed between 2 electrodes.

PEF affects Cell membrane and Loss of barrier function;

Cell cytoplasm is surrounded by a thin semi-permeable layer, the cell membrane. The membrane acts as a semi-permeable barrier for the intra- and extracellular transport of ions and macromolecules.

This cell membrane is a phospholipid bilayer with a thickness of 5 nanometer (nm). By exposing the cell to a pulsed electrical field the cell membrane becomes punctured. The membrane is punctured with small pores of 50-100 nanometer each . This effect is called electroporation, which is the loss of the cell’s barrier function allowing access to the cell’s valuable contents.

Electroporation takes places after 1 microsecond (µs). The process is quick, flexible, energy-efficient and because heat is minimized, products have a longer shelf life whilst maintaining better nutritional value than with traditional food processing techniques.

The high voltage pulses applied induce pores in cell membranes, causing a loss of barrier function, leakage of intracellular content and loss of vitality. The treatment is applied continuously in a chamber ‒ a setup of multiple electrodes

While being pumped (liquids and semi viscous liquids) or transported (solids) through the treatment chamber, the product is exposed to the high voltage pulses. The required treatment time is less than a second.

TARGET OF PEF Pulsed Electric Field (PEF) processing or electroporation works

by puncturing the cell membrane, whatever the size of cell. The process is targeted, gentle and clean. As a result, we measure dramatic increases in yield and the preservation of pigments, antioxidants and vitamins. PEF makes healthy products last longer.

Loss of cell membrane barrier function causes microbial death. Despite its targeted effect on cell membranes PEF does not affect vitamins, flavors or proteins. This allows microbial decontamination of heat sensitive liquids whilst retaining their sensory qualities and functional value.

Membrane disruption occurs when the induced membrane potential exceeds a critical value of 1 V in many cellular systems, which corresponds to an external electric field of about 10 kV/cm in the case of E. coli. In case of killing E. coli and reducing the microbial load of a liquid you need a minimum threshold value of about 10 kV/cm. Electroporation is irreversible above a certain threshold.

And more Self Life.

E.Coli with TEM

WHAT TYPES OF FOODS CAN BE TREATED ? Solid, semi-liquid and liquid foods can be treated.  Treatment of plant or animal tissue aiming on cell disintegration

has practically no size limitations. It can be applied to whole fruits, vegetables and potato tubers,

fruit or vegetable pieces and fruit or vegetable mashes, prior to separation processes. However, the maximum size of the plant or animal tissue must be smaller than the gap of the treatment chamber.

Example ; Bread

Milk

Orange Juice

Liquid eggs.

And we can see some examples

http://www.pulsemaster.us/pef-products

MİCROBİAL INACTİVATİON Microbial Inactivation increases with an increase in the electric field

intensity

-Above the critical transmembrane potential Gram-positive are more resistant to PEF than Gram-negative Yeasts are more sensitive to electric fields than bacteria due to

their large size At low electric fields they seem to be more resistant than gram

negative cells

Listeria innocua with TEM

Whereas all kinds of vegetative spoilage and pathogenic microorganisms can be inactivated, a limited effect on enzymes, spores and viruses are found.

Other constituents such as vitamins, minerals, pigments and flavors are also retained. In contrast to heat treatment the functionality and nutritional value of proteins is hardly affected

A comparison between the inactivation of 2 yeast spp. of different size showed that the field intensity need to achieve the same inactivation level was inversly proportional to cell size

PEF EFFECTS ON ENZYMES 51,7% and 83% of pepsin was inactivated at 37,0 kV/cm and 71,8kV/cm

for a treatment time of 126 µs, respectively

Activity of polyphonol oxidase (PPO) decreased 38,2% when treated at 34,9 kV/cm 34,2 kV/cm, respectively

Enzyme inactivation was determined for lactoperoxidase in milk in comparison to thermal inactivation.

Both PEF and the induced heat contributed to the observed inactivation effect, depending on the properties of enzymes and test conditions

Graphices demonstrate to activation decrease (Iysozyme) during the PEF processing.

Activation decrease (Iysozyme) during the PEF processing.

ADVANTAGES Less treatment time Low treatment temprature Increase shelf life and maintain food safety with low

processing costs. Fresh guality, higher nutritional value (unchange color and

flavor) PEF inactivates vegatative micro organisms including yeast,

spoilage micro organisms and pathogens.

Reduction in microorganisms: 4-6 log (especially milk)

It can be uses to pasteurize fluids such as juices, milk and soups without using additives

It can support or replace conventional processing techniques such as enzymatic maceration and mechanical disintegration.

Low electric field strength and/ or pulse number causes reversible cell rupture stimulating a stress reaction in plants or cell cultures and allowing enzymes or proteins with potential health benefits to be harvested.

Used for pretreatment applications for improvement of metabolite extraction

DİSADVANTAGES High capital cost.

PEF treatment is effective for the inactivation of vegetative bacteria only.

Micro-organisms are destroyed by PEF but spores, with their tough protective coats, and dehydrated cells are able to survive.

Refrigeration is required to extend shelf-life.

Enzymes more resistant than vegetative bacteria to treatment

PEF treatment has considerable added value for specific product ranges.

PEF is a continuous processing method, which is not suitable for solid food products that are not pump able.

PEF processing is restricted to food products with no air bubbles and with low electrical conductivity.

https://www.youtube.com/watch?v=fFa3NFUHzWE https://www.youtube.com/watch?v=YBhrj6W9N2M

REFERANCES http://www.intechopen.com/books/structure-and-function-of-food-

engineering/pulsed-electric-fields-for-food-processing-technology#SEC15

http://italianfoodmaterialsandmachinery.com/pulsed-electric-fields-an-alternative-method-to-heat-treatment-technologies/

http://www.pulsemaster.us/pef-pulsemaster/faq http://www.elea-technology.eu/elea-pef http://www.foodsafetymagazine.com/magazine-archive1/februarymarch

-2015/novel-food-safety-technologies-emerge-in-food-production/ https://www.safaribooksonline.com/library/view/case-studies-in/978184

5695514/ http://link.springer.com/article/10.1007%2Fs12393-009-9011-7 http://link.springer.com/article/10.1007%2Fs11947-011-0731-3 http://link.springer.com/chapter/10.1007/978-94-007-1100-6_1 https://www.youtube.com/watch?v=fFa3NFUHzWE https://www.youtube.com/watch?v=YBhrj6W9N2M

Thank you for listening and attantion