Impact of Food Processing on Quality

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

EU project EVITHERM
European Virtual Institute for Thermal
Metrology www.evitherm.org
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Food processing

• Significant effect on food properties
• hence
• Significant impact on food quality

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Food - becoming a global commodity

• Legislation
• Competition

Food - connection to Health

• Beneficial v. Detrimental (Elixir of Life)
• Functional foods
• Smart foods

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

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What is the Food Quality ? -gt 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)

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Convenience - Ready Meals

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

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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)

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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

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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
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Benefits of ingesting food
Building of body component during growth

• Energy

FOOD
Prevention or reduction of RNA / DNA damage
anti-mutagens
DNA / RNA Repair
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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
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Other reasons for Food Processing

• Other safety reasons
• Destruction of toxins
• Improving properties
• physico-chemical
• sensory
• aesthetic

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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

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Thermal processing

• 95 of staple foods require cooking
• Processing by heating is as old as fire
• Domestic cooking
• Half of the worlds population uses solid fuel as
  source of heating for food

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Pasteurisation

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

Pasteur
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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 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  
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Sterilisation

• Heating for 3s between 135C and 150C
• 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 0,30
B2 (mg) 16,30 1,48
B6 (mg) 6 0,39
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Quality Retention during sterilisation
n log ( N0 / N )
Time
n 6
n 9
Vitamin B1 destruction
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Micro-Organism Inactivation
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Temperature
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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
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To Refrigerate (4 - 8 C)

• Slow down the development of
• micro organisms
• bio-chemical degradation reactions

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Modelling microbial growth
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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

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Cell damage during freezing

• high solute concentration (low aw)
• membrane shrinkage and damage
• intracellular ice (?)

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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

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Inactivation of micro-organisms
Inactivation of enzymes
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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
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Electric pulses

• Same action high pressure and heating
• Disruption of the cell membrane
• Electroporation

Schematic configurations of the three most used
PEF treatment chambers
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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

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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
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Anti Oxidants

• Diseases
• Cancer
• Cardiovascular
• Neurological
• Antioxidants
• L-ascorbic acid
• Carotenoids
• Flavonoids other polyphenolic compounds

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Examples of widely used preservatives in the EU
E-Number Substance / class Some foodstuffs in which they are used
E 200-203 Sorbic acid and sorbate compounds Cheese, wines, dried fruit, fruit sauces, toppings
E 210-213 Benzoic acid, Pickled vegetables, low sugar jams and jellies, candied fruits, semi preserved fish products, sauces
E 210-213 and benzoate Pickled vegetables, low sugar jams and jellies, candied fruits, semi preserved fish products, sauces
E 220-228 Sulphur dioxide and sulphite Dried fruits, fruit preserves, potato products, wine
E 220-228 compounds Dried fruits, fruit preserves, potato products, wine
E 235 Natamycin Surface treatment of cheese and sausage
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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

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Additive Free Foods

• Salt mainly as a flavour enhancer in western
  world
• Nitrites
• Phosphates
• Monosodium Glutamate

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Packaging

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

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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

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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.
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Sensors for Food Quality

• Imaging (computer vision)
• Classification, Inspection
• Density
• Viscosity
• Spectroscopic Techniques
• Biosensors / Immunosensors

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Bio-processing Added Value Products

• Functional Foods
• Interface to Pharmaceuticals
• Bio-separation of biomolecules
• Immunoglobulins
• Purification of proteins from blood serum

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

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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

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• Thank you for your
• attention

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