New Food Processing Technologies
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Transcript of 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
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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High Pressure Processing
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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High Pressure Processing
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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High Pressure Processing
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