Minimal food processing
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Minimal food processing techniques can help increase the shelf life of foods while maintaining nutritional value and fresh-like qualities. Some key techniques discussed in the document include: - Low temperature storage, which slows microbial growth and metabolic reactions through chilling. - Modified atmosphere packaging (MAP), which controls oxygen and carbon dioxide levels to slow spoilage. - High hydrostatic pressure processing, which inactivates enzymes and microbes through non-thermal high pressure without changing taste or nutrition. - Other techniques like oscillating magnetic fields, pulsed electric fields, and ozone treatment use non-thermal methods to eliminate microbes and extend shelf life minimally processed foods.
Minimal food processing
- 1. M i n i m a l F o o d P r o c e s s i n g V I R A J N A L I A P A R A
- 2. What is it? Increasing shelf life of food treated with: washing, sorting, trimming, cutting, slicing or dropping without changing in nutritional values and fresh like quality.
- 3. Why should people chose minimal processing over conventional processing? #Which factors do people/you consider when you chose any food? Factor Conventional food Minimally processed food Appearance Changes Almost remains same Taste Not that of fresh food Very little change or no change NutritionalValue Many nutritions are destroyed Almost no changes due to “cold” process Shelf life Longer than minimal Shorter but good for fresh product
- 5. Low Temp. Storage MAP/CAS High Hydrostatic pressure Oscillating Magnetic Field Ohmic Heating High Intensity Pulsed Electric field Pulsed Light Ozone Technology Aseptic Processing 𝐎 𝟑 Techniques For Minimal Processing
- 6. L OW T E M P E R AT U R E ST O R A G E WHY LOWTEMPARATURE STORAGE ? Low metabolic breakdown of cell tissues Many biological reactions, enzyme activity decreased Retards respiration of fresh foods Thus shelf life increases without much change in food Quality….. SOME DRAWBACKS Tropical and subtropical fruits subjected to chilling injury @ < 10-12“C Plus : discolouration, pitting, necrosis, and growth inhabitation
- 8. M A S / CAS WHAT IS MAP / CAS ? MAP (or gas flushing) is the introduction of an atmosphere, other than air, into a food package without further modification or control. In CAS, the concentrations of oxygen, carbon dioxide and sometimes ethylene (ethene) are monitored and regulated. 𝐶𝑂2 𝑂2 OR Retards senescence
- 9. For minimally processed products optimum 𝑂2 range of 2-8% and 𝐶𝑂2 range of 5-15% is recommended. Polyvinylchloride(PVC),Polypropylene(PP) and Polyethylene(EE) are widely used for MAP of minimally processed foods. Multi=layered films often with Ethylene Vinyl Acetate(EVA) can be manufactured with different gas transmission rates for MAP. Thus shelf life increases without much change in food Quality…..
- 10. Cabbage without MAP Stored in MAP
- 11. H I G H HY D R O ST AT I C P R E S S U R E T E C H N O L O GY TheTechnology As it’s name suggests, the product is packed in flexible package and placed in pressure chamber in which pressure will be applied through water in range of 4000-9000 Atm. for specific time How does it preserve food? When high pressures are applied to packages of food that are submerged in a water, the pressure is distributed instantly and uniformly throughout the food (i.e. it is ‘isostatic’). The high pressure causes destruction of micro-organisms.
- 13. At this much high pressure (4000-9000) enzymes and bacteria are inactivated by protein denaturation and cell wall rupture respectively, but the flavour and taste remain unaffected. Besides preservation it also improves rheological and functional properties of food. It extends shelf life of refrigerated products from 2 to 6 months @ 4“C. Pressure treatment of non pasteurized citrus juice are found to have “17 months” of shelf life plus no loss in taste and nutritions. Pressure can be lowered by using bacteriocins or high temp. with pulsed pressure application
- 14. O S C I L L AT I N G M A G N ET I C F I E L D TheTechnology Magnetic field usually generated by supplying current to electric coil A magnetic field of 5-50 tesla(T) with short pulses of 10-25 ohms-cm and frequency 5-50 Hz are required to inactivate microorganisms How does it preserve food? There are three theories about inactivation of microorganisms by magnetic field 1. By loosening of bonds b/w ion & protein. 2. By calcium vibration in calcium bound protein 3. breakdown of covalent bonds in the DNA
- 15. 1. By loosening of bonds b/w ion & protein. The first theory stated that a OMF could loosen the bonds between ions and proteins. Many proteins vital to the cell metabolism contain ions. In the presence of a steady background magnetic field such as that of the earth, the biological effects of OMF are more pronounced around particular frequencies, thus it stops metabolic activities of cells. 2. By calcium vibration in calcium bound protein A second theory considers the effect of SMF and OMF on calcium ions bound in calcium-binding proteins, such. The calcium ions continually vibrate about an equilibrium position in the binding site. A steady magnetic field causes the plane of vibration to rotate, or proceed in the direction of magnetic field. Adding a "wobbling" magnetic field at the cyclotron frequency disturbs the precision to such an extent that it loosens the bond between the calcium ion and the protein 3. breakdown of covalent bonds in the DNA the inactivation of microorganisms may be based on the theory that the OMF may couple energy into the magnetically active parts of large critical molecules such as DNA. Within 5-50 T range, the amount of energy per oscillation coupled to 1 dipole in the DNA is 10-2 to 10-3 eV. Several oscillations and collective assembly of enough local activation may result in the breakdown of covalent bonds in the DNA molecule and inhibition of the growth of microorganisms
- 16. O H M I C H E AT I N G ( J O U L E H E AT I N G OR E L E CT R O H E AT I N G ) TheTechnology Principle mechanisms of microbial inactivation in ohmic heating are thermal in nature. Electric currents are passed through foods and thus due to resistance heat generates internally in food and minor electroporation takes place How does it preserve food? The heat created inactivates the microorganisms plus minor electroporation helps in speeding up process by pore formation in cell walls This process to food reveal that there are no particular pathogenic strains with a unique resistance to technology.
- 19. Advantages of ohmic heating. Relatively rapid and uniform heating. Less use of total thermal energy compared to conventional process Conventional heat transfer technology problems overcome by ohmic heating No large temp. gradient in product (liquid plus particles both heated same time) No scale formation or burnt particles in end product. Product can be made to heat transfer more quickly by addition of ionic contents(salts etc..).
- 20. H I G H I NT E N S ITY P U L S E D E L E CT R I C F I E L D OR E L E CT R O P O R AT I O N TheTechnology Electric field is applied to fluid food in the form of short pulse and pulse duration ranging a few microseconds to milliseconds rather than using electricity directly. Food susceptible to dielectric breakdown are not suitable for this technology How does it preserve food? The electric field produces potential in cell membrane, when field strength exceeds 1v, pores form in cell membrane because of repulsive effect. Thus if the field strength is very great, the pores become irreversible and cell membranes are destroyed
- 21. For microorganisms the critical electric field strength is about 15 𝐾𝑉 𝑐𝑚 and the impulse lasts from 1-10 m second. This tech. is only useful for liquid foods because of their high dielectric breakdown points. It inactivates enzymes and spores but avoids changes like protein denaturation and vitamin denaturation. Generally high field strengths are more effective than low field strengths at short exposure of time.
- 22. P U L S E D L I G HT TheTechnology The intense burst of light in rapid pulses of tens per second is directed over the surface of the food or packaging material to be treated. The process is best suited to foods that have a smooth surface, and contain few fissures that could shield micro-organisms from the light. How does it preserve food? Pulsed light inactivates micro-organisms by a combination of photothermal and photochemical effects. The UV component of light has a photochemical effect, but photothermal: a large amount of energy is transferred rapidly to the surface of the food, raising the temperature of a thin surface layer sufficiently to destroy vegetative cells.
- 24. 𝑂3 O Z O N E T E C H N O L O GY TheTechnology Fresh foods are immersed in ozonised water or ozone gas is passed through foods. Ozone is highly unstable in nature so it should be produced on site. It is formed by high energy splitting of oxygen molecule How does it preserve food? Ozonization is non thermal method of killing microorganisms using ozone, through the oxidation of their cell membrane. Most of the pathogenic food borne microbes are susceptible to oxidizing effect
- 25. It is most powerful disinfectant than the most commonly used chlorine for deactivation of large no. of microorganisms It does not remain in water for a very long time thus much safer than other disinfectants Any by-product from ozone treatments are less likely to have dangerous health effect than chlorine.
- 26. A S E PT I C P A C K A G I N G TheTechnology As we know that in this technology: The product, the packaging material and the processing environment are sterile when the process is carried out. How does it preserve food? It does inactivate microorganisms by HTST process and heat treated food is filled in sterile package in sterile processing environment. Thus when product is packed there is no intrusion or formation of microbes inside the product, and shelf life increases by the minimal process
- 28. Y O U T H A N K