New Food Processing Technologies

8/8/2019 New Food Processing Technologies

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New Processing Technologies


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Ohmic processing

The aseptic technique holding the

greatest promise for fresh, restaurant-quality food is known as "ohmic"processing, which uses electrical-

resistance heating to sterilize food.Ohmic processing has the potential toimpinge on the frozen foods market

because its end-product has the taste,texture, color and vitamins of fresh,homemade food.


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Ohmic processing

Ohmic heating involves passing an electric

current through the food to create heat dueto electrical resistance within the food. With

ohmic heating, food particles heat at the

same rate as the carrier medium or sauce.Ohmic heating can enhance food quality by

limiting heat damage to the sauce and food

particles.


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Ohmic processing

In the ohmic process two electrodes

literally pass electric current through thefood, where it flows on a continuousbasis in a static column.


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Ohmic processing

As electricity flows through the food, it heats

the product in a vertical-column configuration.If two wires are put into a hot dog, it willbecome brown near the surface where the

wires entered. The food would be ionized andits flavor altered. To prevent this, the BritishElectric Research Board (BERB) hasdeveloped a patented system that transmitsthe electricity evenly into the food


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Two electrodes(near right) areneeded to heatfood duringohmicprocessing. The

necessarycomponents (farright) for anohmic

processing linecan beextremelyexpensive.


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Advantages of Ohmic Processing

1. One is that the system instantaneously and

evenly heats both liquids and solids. In thetraditional "retort" canning process, food isheated from the outside to the inside in a

process that takes about an hour.2.With the ohmic system, you can heat it up to

290 degrees and immediately cool it down,

because you have instant sterilization. Youcan also go to higher temperatures in ashorter time, like three seconds."


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Advantages of Ohmic Processing

With ohmic processing, you sterilize, but you

do it at very high temperatures, very quickly,and therefore, get a very high qualityproduct."


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High Pressure Processing


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High pressure processing (HPP) is

gaining in popularity with the NorthAmerican food industry because of itscapacity to inactivate pathogenic

microorganisms with minimal heattreatment, resulting in the almostcomplete retention of nutritional and

sensory characteristics of fresh foodwithout sacrificing shelf-life.


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Advantages of HPP Other advantages of HPP over traditional thermal

processing include

reduced process times;

minimal heat damage problems;

retention of freshness, flavor, texture, and color;

no vitamin C loss;

no undesirable changes in food during pressure-shiftfreezing due to reduced crystal size and multiple ice-

phase forms; and minimal undesirable functionality alterations


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HPP

High-pressure processing uses very high

pressure, often thousands of atmospheres, to

pasteurize foods without heat. This

technology is ideal for heat-sensitive foods,

but some enzymes are difficult to inactivate

with high-pressure processing.


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Any phenomenon in equilibrium (chemical

reaction, phase transition, change inmolecular configuration), accompanied by adecrease in volume, can be enhanced by

pressure (Le Chateliers Principle: LEADLEYand WILLIAMS, 1997).

Thus, HPP affects any phenomenon in food

systems where a volume-change is involvedand favors phenomena which result in avolume decrease.


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How HPP Works The HPP affects non-covalent bonds (hydrogen,

ionic, and hydrophobic bonds) substantially as some

non-covalent bonds are very sensitive to pressure,which means that low molecular weight foodcomponents (responsible for nutritional and sensorycharacteristics) are not affected,

whereas high molecular weight components (whosetertiary structure is important for functionality-determination) are sensitive.

Some specific covalent bonds are also modified bypressure.


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The other principles which govern HPP

are;

the Isostatic Principle

the Microscopic Ordering Principle


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Isostatic Principle

implies that the transmittance ofpressure is uniform andinstantaneous (independent of sizeand geometry of food), however,transmittance is not instantaneous

when gas are present,


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Microscopic Ordering Principle

implies that at constanttemperature, an increase inpressure, increases the degree ofordering of the molecules of asubstance (HEREMANS, 1992).


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Another interesting rule concernsthe small energy needed tocompress a solid or liquid to 500MPa as compared to heating to100C, because compressibility is

small.


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Advantages of HPP HPP offers several advantages:

reduced process times; minimal heat penetration/heat damage

problems;

freshness, flavor, texture, and color arewell retained;


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Advantages of HPP

there is no vitamin C loss; multiple changes in ice-phase forms

resulting in pressure-shift freezing; and

functionality-alterations are minimizedcompared with traditional thermal

processing


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Pulsed Electric Field


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Pulsed electric field Pulsed electric field processing uses a very

strong pulsed electric current to disruptmicrobial cells and pasteurize foods with

little or no heating.


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Bright light processing Bright light processing uses an intense

white light to kill bacteria on the surface offoods; this light does not penetrate deeply

into foods and can only be used for surface

pasteurization


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Novel food preservation systems

Food processors have also explored novel food

preservation systems. An ideal food preservative

would come from a natural source and preserve

food without being labeled a synthetic chemical

preservative.

Such preservatives include bacteriocins, dimethyl

dicarbonate (Velcorin), competitive microbial

inhibition, controlled and modified atmospheres,

and irradiation...


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Bacteriocins

Bacteriocins are not new; however, likenisin, they are now being used to extend

shelf life and enhance the safety of a variety

of food products. The use of bacteriocins islikely to be expanded in the future.


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Dimethyl dicarbonate

Dimethyl dicarbonate, a relatively newpreservative used in beverages such as

wine, tea, and juices, is particularly

effective in preventing spoilage caused byyeasts.


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Competitive microbial inhibition

Competitive microbial inhibition relies on the factthat many harmless bacteria, notably lactic acid

bacteria, can inhibit the growth of both spoilage

bacteria and pathogens. Inhibitory strains of lactic acid bacteria can be

selected for use in dairy cultures or be added to

refrigerated foods to extend shelf life and enhancesafety.


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Modified and controlled atmospherepackaging

Modified and controlled atmosphere packaging arealready widely used by the food industry. They have the

potential for even wider use, particularly with fresh

fruits and vegetables sold at retail. These methods rely

on inhibiting microbial growth by excluding oxygen or

by inhibitory concentrations of carbon dioxide.

Carefully selected gas mixtures can also delay theripening of certain fruits and vegetables and extend the

shelf life of fresh meats


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Food Irradiation

Finally, irradiation, also not a new technology, is

poised for widespread use to enhance the safetyand shelf life of many foods. With proper

controls, irradiation could be a valuable means

of reducing Salmonella contamination of poultry

andEscherichia coli O157:H7 contamination of

ground beef

New Food Processing Technologies

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