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Impact of Food Processing on Quality

Impact of Food Processing on Quality. Paul Nesvadba The Robert Gordon University Aberdeen, Scotland, UK. CHISA 2004, Prague, 23 August 2004. Robert Gordon University St Andrew Street, Aberdeen. Physicist - Food processing - Food Physics. EU project EVITHERM.

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Impact of Food Processing on Quality

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  1. Impact of Food Processing on Quality Paul Nesvadba The Robert Gordon University Aberdeen, Scotland, UK CHISA 2004, Prague, 23 August 2004

  2. Robert Gordon University St Andrew Street, Aberdeen

  3. Physicist - Food processing - Food Physics EU project EVITHERM European Virtual Institute for Thermal Metrology www.evitherm.org

  4. Food processing Significant effect on food properties hence Significant impact on food quality

  5. Food - becoming a global commodity • Legislation • Competition Food - connection to Health • Beneficial v. Detrimental (“Elixir of Life”) • “Functional” foods • “Smart” foods

  6. Food Production - Components Generation of Bio-mass Recycling Human Consumption Products resulting from Agriculture Waste Live-stock Process and transformation Storage Packaging Storage Distribution Quality Control Advertising

  7. Why are most foods processed? • To increase digestibility, nutritive and health value • To attract & satisfy the consumers, to develop the food market • To preserve foods • To maintain or enhance the quality

  8. What is the Food Quality ? -> “Fitness for purpose” Hygienic ( Ex: No salmonella) Chemical ( Ex: No toxin) FOOD QUALITY Sensory ( Ex: Pleasant flavour) Physical ( Ex: Good texture ) Energy, Nutrition, Health Promotion (Ex: Vitamins ) Consumerchoice Convenient (Ex : prepared meals)

  9. Convenience - Ready Meals • Convenience • Less time for preparation • Economical for single person or small families • Reduced wastage • Demographic trend • Use of the Internet

  10. How to ensure Food Quality / Safety? Quality control from “farm” to “fork” • HACCP (Hazard Analysis and Critical Control Point) • Appropriate processing methods • Traceability and labels(Linked to Real-time delivery / inventory control / management)

  11. Meeting the Requirements • Safety and preservation • Pasteurisation, Appertisation and Sterilisation • Screening for physical and chemical contaminants • Adding chemical conservatives • Modification • Novelty, “added” properties • Digestibility, Nutritive value

  12. Modifying Food Properties • Agriculture • Genetic Modification of plants DNA • Food Processing • Production of bio-molecules and bio-polymers by modified genetic organisms; transformation • Incorporation of additives • Enhancing nutritive and health benefits

  13. Benefits of ingesting food Building of body component during growth Energy FOOD Prevention or reduction of RNA / DNA damage – “anti-mutagens” DNA / RNA Repair

  14. What is Preservation ? • Destruction of micro-organisms and spores • Inactivation of enzymes Salmonella • Slowing the rate of chemical reactions such as oxidation Browning of an apple due to oxidation

  15. Other reasons for Food Processing • Other safety reasons • Destruction of toxins • Improving properties • physico-chemical • sensory • aesthetic

  16. How to produce safe foods ? • Thermal processing • Diminution of the water activity by • - Drying and Freezing • - Adding molecules ( e.g: NaCl) • High pressure • Ultraviolet light • Ozone • Electric pulses • Incorporation of additives

  17. Thermal processing • 95% of staple foods require cooking • Processing by heating is “as old as fire” • Domestic cooking • Half of the world’s population uses solid fuel as source of heating for food

  18. Pasteurisation • First time used by Pasteur in the 19th century. • Heating 30 minutes at 63°C or 12 seconds at 72°C • Destruction of the pathogen, food deteriorating floras. • Destruction of deteriorating enzymes • Conservation of the nutritious properties (vitamins, proteins, flavour...) Pasteur

  19. Appertisation Comparison of the protein composition in Fish flesh • Nicolas Appert invented it in 1810 • In general, Heating between 110 and 130 degrees during 20min to an hour, in glass or aluminium cans • The results are the same as for Pasteurisation but the time of conservation is longer

  20. Sterilisation • Long time of conservation • Heating for 3s between 135°C and 150°C • Destruction of all the micro organisms and enzymes • Destruction of some interesting nutritious properties

  21. Quality Retention during sterilisation n = log ( N0 / N ) Time n = 6 n = 9 Vitamin B1 destruction 10% Micro-Organism Inactivation 3% Temperature

  22. COSTHERM, a computer program for the prediction of Thermophysical properties -Temperature range : -40 to 40 degrees -Accuracy: 10% Modelling of the effect of Heating • Input Data • = contents of: • Water • Protein • Fat carbohydrates • Minerals • Density • Initial freezing point Output: Specific Heat, Enthalpy, Thermal Conductivity, Ice fraction Temperature Model Micro- or kinetic model

  23. What happens in a non-packaged product To Refrigerate (4 - 8 C) Slow down the development of • micro organisms • bio-chemical degradation reactions

  24. Modelling microbial growth

  25. To freeze (-18 to -40 C) • Decrease the temperature below -18 C in a few minutes, the quickest possible. • Stop food degradation reactions • Prevent the development of micro organisms • Long time of conservation

  26. Cell damage during freezing • high solute concentration (low aw) • membrane shrinkage and damage • intracellular ice (?)

  27. High pressure • Covalent bonds are not strongly affected - vitamins preserved • Inactivation of enzymes • Some enzymes are modified, “hardened” • Inactivation of micro-organisms • Disruption of cell membrane cells - “lysis” • Spores are resistant • Thermodynamic effects • Pressure shift freezing and thawing

  28. Inactivation of micro-organisms Inactivation of enzymes

  29. Ionisation • Creation of ions in the irradiated food, by an gamma or electron beams • Maximum dose: 10 kGy • Destruction of the pathogen, food deteriorating floras. • Destruction of deteriorating enzymes • Conservation of the nutritious properties(vitamins,proteins, flavour, except lipids...) • Consumer resistance Logo of ionized food

  30. Electric pulses • Same action high pressure and heating • Disruption of the cell membrane • Electroporation Schematic configurations of the three most used PEF treatment chambers

  31. Dependence of microbial survival fraction on the A) electric field and B) treatment time. Curves a correspond to resistant micro-organisms and curves b to sensitive micro-organisms S, survival fraction; N, microbial count; E, electric field; b, kinetic constant; t, time. Subscripts: 0, initial; c, critical; t, time; e, electric field

  32. Incorporation of additives • butylated hydroxytoluene (in some potato chips, salted peanuts, breakfast cereals and many other things) • calcium disodium ethylene diamine tetra acetate (in salad dressings and some drinks) • sodium L-ascorbate (a form of vitamin C) • E-numbers

  33. Incorporation of Salt - NaCl • Ubiquitous • natural presence and a major additive • Preservation by lowering Aw • Possible raising of blood pressure • Tendency to decrease salt content • High Pressure Treatments can assist NaCl Structure

  34. Anti Oxidants • Diseases • Cancer • Cardiovascular • Neurological • Antioxidants • L-ascorbic acid • Carotenoids • Flavonoids & other polyphenolic compounds

  35. Examples of widely used preservatives in the EU

  36. Anti oxidant properties • Relatively unstable • Processing or storage can improve antioxidant activity – e.g. polyphenols at an intermediate oxidation state can scavenge radicals more than in non-oxidised state

  37. Additive Free Foods • Salt – mainly as a flavour enhancer in western world • Nitrites • Phosphates • Monosodium Glutamate

  38. Packaging • Most foods are packaged • Hygiene • Stability of the product • Storage container • Presentation to the consumer • Discarded packaging • Waste • Recycling

  39. Edible packaging • Film and coatings based on: • Polysaccharides • Cellulose, starches, gums • Lipids • Cocoa butter, waxes • Proteins • From milk, soya, cereals • Functions • barrier for moisture, oxygen, fat (b. layers) volatiles • Can carry antioxidants and antimicrobials

  40. Example of specific packagings • For the food degraded by oxidation (Ex: Fruits) • Packaging with modified atmosphere: • Less oxygen • More carbon dioxide • Well defined humidity • Packaging with controlledatmosphere( All the parameters are well known and are monitored) • Vacuum Packaging( No Oxidation) Modified atmosphere packaging to extend shelf life.

  41. Sensors for Food Quality • Imaging (computer vision) • Classification, Inspection • Density • Viscosity • Spectroscopic Techniques • Biosensors / Immunosensors

  42. Bio-processing – Added Value Products • Functional Foods • Interface to Pharmaceuticals • Bio-separation of biomolecules • Immunoglobulins • Purification of proteins from blood serum

  43. Example - Functional Foods • - Purdue University • By changing chicken feed supplements • developed • Eggs that include more of two”good” fats, • conjugated linoleic acid (CLA) and • docosahexaenoic acid, a type of omega-3 fatty acid.

  44. Conclusions • Food processing • Essential for human well-being and health • Influenced by the state of the society • Driven by • consumer demand • Understanding of the connection between food, nutrition and health • New physico-chemical processes • Genetic modification

  45. Thank you for your attention

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