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
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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

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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
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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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