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 European Virtual Institute for Thermal Metrology www.evitherm.org

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

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

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

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

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)

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

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)

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

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

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

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

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

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

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

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

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  

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

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

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

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

Modelling microbial growth

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

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

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

Inactivation of micro-organisms Inactivation of enzymes

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

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

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

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

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

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

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 and benzoate E 220-228 Sulphur dioxide and sulphite Dried fruits, fruit preserves, potato products, wine compounds E 235 Natamycin Surface treatment of cheese and sausage

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

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

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

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

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.

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

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

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.

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

Thank you for your attention