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Impact of Food Processing on Quality

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Presentation on theme: "Impact of Food Processing on Quality"— Presentation transcript:

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


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