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

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 )
Consumer choice
Convenient (Ex : prepared meals)

9. Convenience - Ready Meals
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. Comparison of the protein composition in Fish flesh
Appertisation
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
Comparison of the protein composition in Fish flesh
acid amine
Original
Appertised
Isoleucine
5,6
Leucine
8,0
8,1
Lysine
9,0
9,1
Méthionine
3,1
3,0
Phénylalanine
3,8
3,9
Thréonine
5,1
5,2
Tryptophane
1,1
1,0
Valine
5,3

20. Milk without any heat treatment Milk after sterilisation
Heating for 3s between 135°C and 150°C
Destruction of all the micro organisms and enzymes
Long time of conservation
Destruction of some interesting nutritious properties
Vitamines
Milk without any heat treatment
Milk after sterilisation
A (mg)
4,04
0,55
D (µg) 21
0,30
C (mg)
132
0,8
B1 (mg)
3,80
B2 (mg)
16,30
1,48
B6 (mg) 6
0,39

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

22. Modelling of the effect of Heating
COSTHERM, a computer program for the prediction of Thermophysical properties
-Temperature range : -40 to 40 degrees
-Accuracy: 10%
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. To Refrigerate (4 - 8 C) Slow down the development of micro organisms
bio-chemical degradation reactions
What happens in a non-packaged product

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

29. Inactivation of micro-organisms
Inactivation of enzymes

30. 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

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

32. 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

33. 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

34. 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

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

36. Examples of widely used preservatives in the EU
E-Number
Substance / class
Some foodstuffs in which they are used E
Sorbic acid and sorbate compounds
Cheese, wines, dried fruit, fruit sauces, toppings E
Benzoic acid,
Pickled vegetables, low sugar jams and jellies, candied fruits, semi preserved fish products, sauces
and benzoate E
Sulphur dioxide and sulphite
Dried fruits, fruit preserves, potato products, wine
compounds
E 235
Natamycin
Surface treatment of cheese and sausage

37. 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

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

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

40. Edible packaging Film and coatings based on: Functions 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

41. 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 controlled atmosphere ( All the parameters are well known and are monitored)
Vacuum Packaging( No Oxidation)
Modified atmosphere packaging
to extend shelf life.

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

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

44. 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.

45. Conclusions Food processing New physico-chemical processes
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

46. Thank you for your
attention