5 Ozone and MAP

8/22/2019 5 Ozone and MAP

1/23V.B. Alvarez/Ozone Tech/10-2007

Ozone Technology for

Foods

Valente B. AlvarezFood Industries Center

Department of Food Science and

technology

Ozone Technology for Foods

Contents

Ozone

O3 generationmethods

Applications

Advantages anddisadvantages



Ozone

Ozone is an unstable form of oxygenconsisting of 3 oxygen atoms (O3).

It reacts with other gases changing theirchemical structure.

As ozone oxidizes/disinfects, it destroys odor-causing and toxic gases, and then reverts to

normal oxygen.

Where can ozone be found?(Mustafa, 1990)

In the Stratosphere

In photochemical smog

Ozone can be produced in

UV sterilization lampsHigh voltage electric arcsGamma radiation plants



Ozone generation

Diatomic oxygenmolecule splits

Resulting free radicaloxygen reacts freelywith another diatomicoxygen to formtriatomic ozonemolecule

Properties of ozone

Nearly colorless gas at room temperature

Has a pungent, charateristic odor (similar to fresh air afterthunderstorm)

Readily detectable at 0.01-0.05ppm

Has a longer half-life in the gaseous state than in aqueoussolution

Ozone solubility in water is 13 times that of oxygen at 0-

30C (Rice, 1986)

Ozone cannot be stored since ozone spontaneouslydegrades back to oxygen atoms



Corona discharge method to initiate free

radical

High tension and low tension (ground) electrodeseparated by a ceramic dielectric medium and narrowdischarge gap

When the electrons have sufficient kinetic energy (@6-7eV), oxygen molecule dissociates

Molecules of ozone are formed with new oxygen atom

Ozone production rate:

1-3% if air is the feed gas

6% if pure oxygen is the feed gas Commercial method

Methods to initiate free radical oxygen

formation

O2 Discharge gap O3

Heat

HeatElectrode (high tension)

Electrode (low tension)

CeramicDielectric

Corona discharge (CD) method

Ceramic dielectric medium



Advantages of CD ozone generation

Corona discharge ozone generators can use oxygenpreparation thereby doubling the ozone output per given volumevs. dry air

Small construction allowing generator to be installed in virtuallyany area

Creates a more pure form of ozone without creating otherharmful or irritating gases

Corona cell life can exceed ten years

Can create high quantities of ozone (up to 100-lbs/day)

Can be more cost-effective than UV-ozone generation

UV/Ozone: How does it work?

Organic contaminant molecules are excited ordissociated by the absorption of UV (188 or 254 nm).

The excited contaminants react with the atomicoxygen to form volatile products, such as CO2, H2O,etc.

The whole process takes place in one to severalminutes at room temperature.



Comparison of UV Vs CD

Maximum ozone production rate is two grams/hr per UV bulb -depending on size

Highest concentration of ozone that can be produced by 185-nmUV lamp is 0.2 percent by weight, approximately 10% of theaverage concentration available by corona discharge

Considerably more electrical energy is required to produce agiven quantity of ozone by UV radiation than by coronadischarge

Lower gas phase concentrations of ozone generated by UVradiation translate into the handling of much higher gas volumes

than with CD-generated ozone UV lamps require periodic replacement

Ozone Vs Oxygen

1.232.07Electrochemicalpotential, V

1.4292.144Density (g/l)

0.0490.64Solubility in water(@ 0C)

OdorlessSmell after lightningstorms

Smell

ColorlessLight blueColor

3248Molecular weight

O2O3Molecular formula

OxygenOzoneProperty



Status of ozone in the food industry

1982 - O3 declared GRAS for treatment of bottledwater (Federal Register, Vol. 47, No. 113, November 5, 1982)

1997 - Expert panel report : Evaluation of the historyand safety of ozone in processing foods for humanconsumption. Vol. 2 : Abstracts. Electric Power Research Institute,Palo Alto, CA. R & D Enterprise, Inc. / GRAS self declaration (Federal

Register, v. 62 #74, April 19, 1997)

2000 - FDA and USDA approval granted.

Potential applications in the food industry

Microbial destruction

Food surface hygiene

Sanitation in food plant equipment

Reuse of waste water

Lowering BOD and COD of food plant waste Germicide in cold storage plants

Shelf life extension of fruits and vegetables



Antimicrobial mechanism of ozone(Victorin, 1992)

Destroys microorganisms by progressive oxidation ofvital cellular components

First, ozone oxidizes sulfhydryl groups and aminoacids of enzymes, peptides and proteins to shorterpeptides.

Second, ozone oxidizes polyunsaturated fatty acids toacid peroxides

Ozone degradation of the cell envelope unsaturatedlipids results in cell disruption and subsequent leakageof cellular contents

As a comparison based on 99.99% of bacterialconcentration being killed and time taken:Ozone is

25 times of that of HOCl (Hypochlorous Acid)

2,500 times of that of OCl (Hypochlorite)

5,000 times of that of NH2Cl (Chloramine).

Further more, ozone is at least 10 timesstronger than chlorine as a disinfectant.

Ozone does not leave any trace of residualproduct upon its oxidative reaction.

Ozone effectiveness



Oxidation mechanism of ozone

Use of ozone for food hygiene

Acc. To the Code of Federal Regulations (USDA,1997), there must be at least 60% reduction in totalmicroorganisms and similar reduction in coliforms,E.Coli, and Salmonellaspp.

Direct application of ozone to poultry carcassesdestroyed more than 2 log-units of all carcassmicroorganisms with no significant lipid oxidation, off-flavor development or loss in carcass skin color

(Sheldon and Brown, 1986)

Shelf life of fruits and vegetables increased due tooxidation of ethylene (Rice, et.al.,1982)



Treatment of beverage waters

Ozone as a replacement for the pre-chlorinating step

Sanitizing the granular activated carbon(GAC) filters

Sanitization of bottles prior to filling with thesoft drink

Sanitization of fill lines and vessels

Oxidizing agents and their oxidizing potential(Manley and Niegowski, 1967)

3.06

2.07

1.67

1.50

1.49

1.36

Fluorine

Ozone

Permanganate

Chlorine oxide

Hypochlorous acid

Chlorine gas

Oxidizing potential (mV)Oxidizing agent



Food plant equipment sanitation methods

Thermal sanitation very expensive

Radiation methods not practical

Chlorine has many disadvantages:

Harmful and irritating in high conc.

Prone to forming carcinogenic compounds

Toxic to the environment

When to apply ozone?

At pre-processing stage, during processing,or on the finished product while at storage

Advantageous to apply ozone on the rawthan the processed product

e.g., Whole grains require less ozone to

disinfect than the powder product



Advantages

More powerful oxidizer available

Instantly destroys microbes

eliminates chemical storage

environmentally friendly

stops mold spores

does not affect product taste

no harmful by-products can be used in air and water

Drawbacks

No residual antimicrobial effect duringstorage of treated food.

Cannot be stored and therefore, should beproduced on site.



Safety on exposure to ozone

In the US, current exposure level-time weightedaverage (PEF-TWA) in the work environment is 0.1ppm (8-h day/40-h working week)

Short term exposure limit is 0.3 ppm for an exposureless than 15 min and four times per day

Recommended by American Conference ofGovernmental Industrial Hygienists (ACGIH, 1986)and adopted by the United States OccupationalSafety and Health Administration (OSHA)

Ozone technology for foods

Summary

Ozone

Generationmethods

Advantages anddisadvantages

Applications



References

Kim, J.-G., Yousef, A.E., and Khadre, M. H. 2003. Ozone and its currentand future application in the food industry, p. 167-218. In S. Taylor (ed.).Advances in food science and nutrition, Vol 45. Elsevier Sci. Ltd.,London, UK

Manley,T.C and Niegowski, S.J. 1967. Ozone. In Encyclopedia ofchemical technology (Vol.14, 2nd ed., pp410-432). Wiley: New York, NY.

Sheldon,B.W., and Brown,A.L. 1986. Efficacy of ozone as a disinfectantfor poultry carcasses and chill water. Journal of Food Science, 51(2),305-309

USDA. Code of Federal Regulations, Title 9, Part 381.66-poultryproducts; temperatures and chilling and freezing procedures. 1997.Office of the Federal Registrar National Archives and RecordsAdministration,Washington,DC.

Victorin,K. 1992. Review of the genotoxicity of ozone. Mutation

Research, 277, 221-238. Zepnep, B.G., Annel, K.G., and Seydim,A.C. 2004. Use of ozone in the

food industry. Lebensm.-Wiss.u.-Technol. 37, 453-460.

Break



Modified Atmosphere

Packaging

Valente B. AlvarezFood Industries Center

Department of Food Science and

technology

Modified Atmosphere Packaging(MAP)

Modified atmosphere packaging (MAP)

Enclosure of food in a package in which

the atmosphere inside the package is modifiedwith respect to CO2, O2, N2, water vapor andtrace gases

Generally achieved by removing air andreplacing it with a controlled mixture of gases



Background

Known for over 100 years that thepreservative effect of chilling can be greatlyenhanced when it is combined with control ormodification of the gas atmospheresurrounding the food.

Air composition: 78% nitrogen, 21%, oxygen,0.9% argon, 0.3% carbon dioxide, and tracesof nine other gases

Atmosphere is changed by increasing ordecreasing the concentration of O2, and/or byincreasing the concentration of CO2

Important Factors of MAP

1. Temperature

2. Choice of gas

3. Choice of packaging material

4. Choice of packaging machinery



Temperature

Holding food at low temperatures

Biostatic effects of CO2 are temperaturedependent

O2 present in the package

Growth of aerobic spoilage organisms

Absence of O2 will favor the growth ofanaerobic microorganisms

Aerobic and anaerobic pathogens can grow at

temperatures as low as 4C and producetoxins

Choice of gas

Depends largely on the nature of the foodand its principal mode(s) of deterioration

Carbon dioxide is highly soluble in water andoils. It is absorbed by the food untilequilibrium is attained

The internal atmosphere will be modified by

the food during storage Dissolution of CO2 in water lowers the pH and

consequently slows reaction rates.



Choice of packaging material

A low water vapor transmission rate and a high gasbarrier

MAP packages are based on thermoplastic polymers.Such materials allow some gas transmission, even atlow temperatures

Mechanical strength to withstand machine handlingand subsequent storage, distribution and retailing

Materials in use are Laminations or co extrusions of polyethylene with:

Polyester or nylon, with or without the addition of ahigh barrier layer of vinylidene chloride/vinyl chloride

copolymer or ethylene/vinyl alcohol copolymer,depending on the barrier required

Choice of packaging machinery

Related to the two methods of packagingemployed:

Thermoforming

use of a rigid or semi-rigid base material which is

thermoformed into a tray

Pillow packaging

Horizontal form-fill-seal machine employs a singlereel of flexible packaging material



Modified Atmosphere Packaging

(MAP)


Flushing of food packaging with antimicrobialgases just before sealing

40 - 1100 ppm

Plant A Plant B Plant C0

10

20

30

40

50

60

70

Shelflife

(days)

Commercial Dairy Plants

Control CO2 Injection

Shelf-life Extension of CottageCheese With CO2 Injection


20/23V.B. Alvarez/Ozone Tech/10-2007 2

MAP

The gas enters microbial cells, lowering thepH so that microbes can no longer grow.

Disadvantage: Gas dissipates quickly duringmodern processing


Extends shelf-life ofsolid dairy foods

Shredded cheese

Increased the shelf lifeby 2-3 times

Had no effect on theproduct's flavor.



Modified Atmosphere Processing

Cottage cheese

Fluid Milk

Yogurt

Sour cream

Ice cream

Requirement

packaging the product

in high-barriermaterials

Fresh meat

Atmospheres of about 30% CO2 and up to70% O2 Extend the color stability and delay microbial

spoilage of display-packaged meat

100% nitrogen

As effective as vacuum for storing fresh meat

joints 100% carbon dioxide around fresh meat



Fish

Fillets of fresh fish in MAPs storedcontinuously at temperatures below 4 oC areavailable in Europe

Effective gas compositions vary according tofish species

Low O2 concentrations are used with fatty fishwhich are susceptible to oxidative rancidity

For non/fatty fish would be 30% O2, 40% CO2and 30%N2,

For smoked fatty fish 40% CO2 and 60% N2.

Real-time Oxygen Monitoring forMAP

Real-time oxygenmonitoring for MAP inboth batch process andform, fill and seal MAPmachines.

No sample atmosphereextraction

Can take and logmeasurements everysecond


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References

Brody, A.L. (ed.) (1989). ControIledlModifiedAtmospherelVacuuln Packaging of Foods,

Food & Nutrition Press, Inc., Trumball, Connecticut, USA.

Farber, J .M. (1991). Microbiological aspects of modified-atmosphere packaging technology

-a review. J. Food Protect. 54: 58-70.

Gill, c.a. (1990), Controlled atmosphere packaging of chilledmeat. Food Control2, 74-78.

Inns, R. (1987). Modified atmosphere packaging. ln ModernProcessing, Packaging and

Distribution Systemsfor Food, F.A. Paine (ed.), Blackie and SonLimited, Glasgow, Great

Britain, chap. 3.

Documents

5 Ozone and MAP