No: 11 November 2007

Food Technologies to Reduce the Use of Food Additives
Safe food is simply described as the food appropiate for consumption by human, with controlled physical, chemical and biological hazards and good nutritional value. In food industry the use of food additives is one of the methods to achieve this. However, there are still some concerns about the use of additives. At this point it is essential to use different types of food preservation technologies to achieve safe food goal around the limits of food additives authorised.     
Some innovative food technologies are given as follows.

THERMAL METHODS

1. Microwave heating and radio frequency (RF) heating

Microwave and radio frequency heating refers to the use of electromagnetic waves of certain frequencies to generate heat in a material. Typically, microwave food processing uses the two frequencies of 2450 and 915 MHz. Of these two, the 2450 MHz frequency is used for home ovens, and both are used in industrial heating.
Microwave and radio frequency heating for pasteurization and sterilization are preferred to the conventional heating for the primary reason that they are rapid and therefore require less time to come up to the desired process temperature. This is particularly true for solid and semi-solid foods that depend on the slow thermal diffusion process in conventional heating. They can approach the benefits of high temperature-short time processing whereby bacterial destruction is achieved, but thermal degradation of the desired components is reduced.
Microbial inactivation kinetics for microwaves are essentially the same as the inactivation kinetics of conventional thermal processing. The microwave non-thermal effects have been reported to add to the destruction of microorganisms. Thus, ignoring the possible non-thermal effect can only provide an extra safety factor. To date, there do not appear to be any microwave-resistant foodborne pathogens.

2. Ohmic heating

Ohmic heating is an advanced thermal processing method wherein the food material, which serves as an electrical resistor, is heated by passing electricity through it. Electrical energy is dissipated into heat, which results in rapid and uniform heating. Ohmic heating is also called electrical resistance heating, Joule heating, or electro-heating, and may be used for a variety of applications in the food industry.
Ohmic heating can be used for heating liquid foods containing large particulates, such as soups, stews, and fruit slices in syrups and sauces, and heat sensitive liquids.
Like thermal processing, ohmic heating inactivates microorganisms by heat. Additional non-thermal electroporation type effects have been reported at low-frequency (50-60 Hz), when electrical charges can build up and form pores across microbial cells, however, it is not necessary to claim such effects since heating is the main mechanism.

NON-THERMAL METHODS
1. Irradiation
Irradiation is a non-thermal preservation method including physical treatment of food with high-energy, ionising radiation. The process uses three types of ionizing radiation sources including cobalt-60 gamma sources, electron beam generators and x-ray generators.
The treatment may be applied for different purposes, such as the prevention of germination and sprouting of potatoes, onions and garlic; disinfestation by killing or sterilising insects which infest grains, dried fruit, vegetables or nuts; retardation of ripening and ageing of fruit and vegetables; prolongation of the shelf life and prevention of food-borne diseases by reducing the number of viable micro-organisms in meat, poultry and seafood; reduction of micro-organisms in spices and herbs.
In Europe, EU Directive 1999/2/EC provides for the laws concerning foods and food ingredients treated with ionising radiation. The Directive specifies provisions including the source of ionising radiation, controls on the level of radiation permitted and food labelling requirements. In practice, the use of this technique is rather limited although it is authorised in many countries. To date, only one food category - dried herbs, spices and vegetable seasonings - has been included on the list of foods that may be irradiated. But five countries of the European Union (Belgium, France, Italy, the Netherlands and United Kingdom) allow irradiation for a much greater number of food, from onions to potatoes and chicken meat.

2. High Pressure Processing (HPP)

High Pressure Processing (HPP) is a method of food processing where food is subjected to elevated pressures (up to 87,000 pounds per square inch or approximately 6,000 atmospheres), with or without the addition of heat, to achieve microbial inactivation or to alter the food attributes in order to achieve consumer-desired qualities. Pressure inactivates most vegetative bacteria at pressures above 60,000 pounds per square inch. HPP retains food quality, maintains natural freshness, and extends microbiological shelf life. The process is also known as high hydrostatic pressure processing (HHP) and ultra high-pressure processing (UHP).
In a typical HPP process, the product is packaged in a flexible container (usually a pouch or plastic bottle) and is loaded into a high pressure chamber filled with a pressure-transmitting (hydraulic) fluid. The hydraulic fluid (normally water) in the chamber is pressurized with a pump, and this pressure is transmitted through the package into the food itself. Pressure is applied for a specific time, usually 3 to 5 minutes. The processed product is then removed and stored/distributed in the conventional manner. Because the pressure is transmitted uniformly (in all directions simultaneously), food retains its shape, even at extreme pressures. And because no heat is needed, the sensory characteristics of the food are retained without compromising microbial safety.
In general, HPP can provide shelf lives similar to thermal pasteurization. Pressure pasteurization kills vegetative bacteria and, unless the product is acidic, it requires refrigerated storage. For foods where thermal pasteurization is not an option (due to flavor, texture or color changes) HPP can extend the shelf life by two to three fold over a non-pasteurized counterpart, and improve food safety. As commercial products are developed, shelf life can be established based on microbiological and sensory testing.


3. Pulsed Light
Pulsed light is a non-thermal sterilization method that uses brief intense pulses or flashes of white light to kill microorganisms. 200 nm-1 mm wavelengths are used in this method. The surface planned to sterilize is exposed to one pulsed light, at least, carrying energy density of 0,01-50 J/cm2 approximately on the surface. At this point the wavelength changes between 170-2600 nm.


4. Ultraviolet light
Ultraviolet processing involves the use of radiation from the ultraviolet region of the electromagnetic spectrum for purposes of disinfection between the ranges of 200-280 nm. To achieve microbial inactivation, the UV radiant exposure must be at least 400 J/m2 in all parts of the product. The germicidal properties of ultraviolet irradiation are due to the DNA absorption of the UV light, causing crosslinking between neighboring pyrimidine nucleoside bases (thymine and cytosine) in the same DNA strand. Due to the mutated base, formation of the hydrogen bonds to the purine bases on the opposite strand is impaired. DNA transcription and replication is thereby blocked, compromising cellular functions and eventually leading to cell death. The amount of crosslinking is proportional to the amount of UV exposure. The level of mutations that can be reversed depends on the UV repair system present in the target microorganism.  Critical factors include the transmissivity of the product, the geometric configuration of the reactor, the power, wavelength and physical arrangement of the UV source, the product flow profile, and the radiation path length. UV may be used in combination with other alternative processing technologies, including various powerful oxidizing agents such as ozone and hydrogen peroxide, among others.

5. Pulsed electric field (PEF) or High Electric Field Pulses (HELP)
Pulsed electric field (PEF) processing is a non-thermal method of food preservation that uses short bursts of electricity for microbial inactivation and causes minimal or no detrimental effect on food quality attributes. PEF can be used for processing liquid and semi-liquid food products.
PEF processing involves treating foods placed between electrodes by high voltage pulses in the order of 20-80 kV (usually for a couple of microseconds). The applied high voltage results in an electric field that causes microbial inactivation. The electric field may be applied in the form of exponentially decaying, square wave, bipolar, or oscillatory pulses and at ambient, sub-ambient, or slightly above-ambient temperature. After the treatment, the food is packaged aseptically and stored under refrigeration.
In general, the shelf-life of PEF-treated and thermally pasteurized foods is comparable. PEF pasteurization kills microorganisms and inactivates some enzymes and, unless the product is acidic, it requires refrigerated storage. For heat-sensitive liquid foods where thermal pasteurization is not an option (due to flavor, texture, or color changes), PEF treatment would be advantageous.


6. Static and oscillating magnetic fields (SMF and OMF) 
Static (SMF) and oscillating (OMF) magnetic fields have been explored for their potential as microbial inactivation methods. For SMF, the magnetic field intensity is constant with time, while an OMF is applied in the form of constant amplitude or decaying amplitude sinusoidal waves.
Preservation of foods with OMF involves sealing food in a plastic bag and subjecting it to 1 to 100 pulses in an OMF with a frequency between 5 to 500 kHz at temperatures in the range of 0 to 50 oC for a total exposure time ranging from 25 to 100 ms. Frequencies higher than 500 kHz are less effective for microbial inactivation and tend to heat the food. Magnetic field treatments are carried out at atmospheric pressure and at moderate temperatures.


7. Ultrasound
The textbook definition of ultrasound is energy generated by sound waves of 20,000 or more vibrations per second. Presently, most developments of ultrasonics (sonication) for food applications are nonmicrobial in nature. High frequencies in the range of 0.1 to 20 MHz, pulsed operation and low power levels (100 mW) are used for nondestructive testing. Ultrasonic excitation is being examined for nondestructive evaluation of the internal quality and latent defects of whole fruits and vegetables.

PACKAGING TECHNOLOGIES
1. Modified atmosphere packaging (MAP)
Modified Atmosphere Packaging (MAP) simply means an alteration to the internal atmosphere of packaged goods so that it is different to the composition of the air. MAP creates different sets of values to extend the shelf stableness of food by inhibiting microbial spoilage and enzyme and chemical activity. To achieve this different mathematical combinations are used to alter the amount of gases used in most MAP applications. The major gases include O2, CO2, N2 and C2H4 with H2O (moisture) to be considered.
MAP has the potential to increase the shelf life of a number of food groups. Fat-filled milk powders, cheeses and fat spreadsa re examples from dairy products.  In general these products spoil due to the development of oxidative rancidity in the case of powders and or the growth of micro-organisms, particularly yeasts and moulds, in the case of cheese. Aerobic spoilage bacteria, such as Pseudomonas species normally constitute the major flora on red meats. Since these bacteria are inhibited by CO2 it is possible to achieve both red colour stability and microbial inhibition by using gas mixtures containing CO2 and O2.  These mixtures can extend the chilled shelf-life of red meats from 2-4 days to 5-8 days. 
MAP has the potential to extend the safe shelf life of many fruits and vegetables.  Unlike other chilled perishable foods, fresh produce continues to respire after harvesting. During MAP application respiration is reduced by lowering the O2 concentration and increasing the CO2 concentration extending the shelf life.

2. Active Packaging
Active packaging actively changes the  condition of the packaged food to extend  shelf life or to improve food safety or sensory properties, while maintaining the quality of the packaged food.
Some of active packaging concepts are as follows:

  • Scavenger systems
    • Oxygen absorbers
    • UV-light absorbers
    • Carbondioxide absorbers
    • Ethylene absorbers
    • Humidity absorbers
    • Absorbers of off flavors
  • Emitting systems
    • Carbondioxide emitters
    • Ethylene emitters
    • Antimicrobial preservative releasers
    • Antioxidant releasers
    • Sulphur dioxide emitters
    • Flavouring emitters
                           

3. Smart packaging
Smart or intelligent packaging is designed to sense the environment and to convey appropriate information to the user about the contents of the package. Use by date, time-temperature relation which has critical importance in cold chain management and pathogen indicators are some examples of smart packaging applications.
Some of smart packaging concepts are as follows:

  • Time- temperature indicators
  • Oxygen indicators
  • Leak indicators
  • Carbondioxide indicators
  • Freshness indicators         

References
http://www.cfsan.fda.gov/~comm/ift-micr.html
http://ohioline.osu.edu/fse-fact/0004.html
http://www.f4st-ec.org/site/bulten.aspx
http://ohioline.osu.edu/fse-fact/0001.html
http://www.cfsan.fda.gov/~comm/ift-uv.html
http://ohioline.osu.edu/fse-fact/0002.html
http://www.cfsan.fda.gov/~comm/ift-omf.html
http://www.modifiedatmospherepackaging.com/how.html
http://eng.auburn.edu/~wfgale/usda_course/section0_5.htm#cap
http://www.mindbranch.com/listing/product/R2-1097.html
http://akseli.tekes.fi/opencms/opencms/OhjelmaPortaali/ohjelmat/Pakkaus/fi/
Dokumenttiarkisto/Viestinta_ja_aktivointi/Seminaarit/seminaari_6.10.2004/SIP_Rolig.pdf
http://esn-network.com/fileadmin/inhalte/documents/Conference-ESN-Heini_WS.pdf
http://www.cambridgeconsultants.com/Downloads/Library_presentations/
InnovationDay03/ADMpresentation.pdf
http://www.cfsan.fda.gov/~comm/ift-pref.html#sab


Barbosa-Cánovas, G., Pothakamury, U.R.,  Palou, E., Swanson, G.B. (1998). Nonthermal Preservation of Foods. 1st edition. Marcel Dekker, Inc. New York.
Richardson, P. (2001). Thermal Technologies in Food Processing. 1st edition. Woodhead Publishing ve CRC Press
Sun, D. (2006). Thermal Food Processing.  1st edition. Taylor&Francis Group, CRC Press

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