Food processing

a) ≤ 0.65 (RH=65%) b) ≤ 0.3

Surface area (+) Temperature (+) Humidity (-) Atmospheric pressure (-)

Lag phase - Fast; water lost from surface Constant (fast) rate - Dry layer on outside forms– insulation barrier; solute conc. increases Falling rate - Reaching a normal equilibrium in RH

Vitamin C Thiamine (B1) Protein quality » all decreased Pre-hydration steps (e.g. cooking, blanching); high temp; slow drying

Colour – browning reactions (enzymatic* & non-enzymatic) Flavour – loss of volatile compounds Taste – mostly intensified Texture – altered in rehydrated products *inactivate enzymes 1st by pasteurising/blanching

Improved (linked to preservation) But good hygiene is needed Sun-drying – slower process & can  risk of bacterial spoilage > Use of smoke/salt as further preservative agents evolved

80-90%

Transfer by contact & molecules vibrating against one another Reduces with density (solids>liquids>gases) Thermal conductivity depends on type of material

Transfer by movement of a heated fluid Natural vs. forced (uses fan)

Occurs through empty space or via electromagnetic energy Energy absorbed at particular wavelengths (e.g. microwave cooking)

Blanching and pasteurisation (mild) Sterilisation (severe)

Inactivated endogenous enzymes to avoid spoilage, e.g. Polyphenol oxidase (PPO) catalyses browning in peeled apples/potatoes Useful before canning/freezing Applied to: fruits & veg | Temp-time: 95oC, 5 min

Destruction of pathogenic bacteria to remove health hazard; 3 temp-time combinations: -Low temp 63oC, 30 min -High temp-short time (HTST) 75oC, 15s -Ultra-high temperature (UHT) 150oC, 1-3s Applied to: liquid foods e.g. milk, beer, juices, sauces, liquid egg, marinades, soups

Complete destruction of microorganisms – objective to eliminate C botulinum spores Applied to: canned/bottled foods Temp-time: 121oC, 15-30 min

decimal reduction time (time to reduce bacteria by 10-fold) at specified temp 12D process = food safety D-value @ 63°C  2.5 min (12*2.5) = 30 min

temp requires to increase the D-Value by 10-fold

• Modified Atmosphere Packaging (MAP) • High Pressure Processing (HPP) • Food Irradiation • Chemical Preservatives

Definition: a one-time change in the atmosphere within a food package or storage area in order to extend shelf life Uses gas mixtures for food preservation MAP vs CAP = one time vs continual attempts (Controlled Atmosphere Packaging) Extends product shelf-life (x2-5 fold @ 1°C storage) Preserve SNSS characteristics Improve food supply chain distribution (↓ losses at POS) Improves manufacturing efficiency by enabling longer production runs (↓ # deliveries)

Normal air = 78% N2, 21% O2, 0.035% CO2) >30% CO2 for meat, poultry & seafood ~10% CO2 for fruits & vegetables CO2 is antimicrobial agent: Alters cell membrane & nutrient uptake Inhibits food enzymes Denatures protein Changes pH inside cells N2 is a passive filler (avoids package collapse)

Kills all pathogens, e.g. Lysteria monocytogenes, E. coli, Leaves no residues Low cost (~ 1-pence) / lb of food Endorsed by WHO, IFT and American Medical Association Moderate or no loss of nutrients at < 3kGray 1 gray (Gy) = 1J/ per kg of food material Low dose applications (up to 1 kGy) Sprout inhibition, delay fruit ripening, destroy insects Medium dose applications (1 – 10 kGy) Kill spoilage microbes in meat Kill pathogenic microbes in fresh and frozen meat

Food is subjected to very high pressures (liquid/solid foods) 100-200 MPa Kills pathogens Colours and nutrients retained Mild SNSS changes

GENERAL STANDARD FOR FOOD ADDITIVES CODEX STAN 192-1995 any substance not normally consumed as a food by itself and not normally used as a typical ingredient of the food – whether or not it has nutritive value* intentional addition to food for a technological (including organoleptic) purpose

Food additives REGULATION (EU) No. 1333/2008 Food labelling REGULATION (EU) No. 1169/2011 Must be named in list of ingredients (main) functional class and specific name or E number e.g. ‘Preservative: Sodium Nitrite’ or ‘Preservative: E250’ Additives for same function in a food can be grouped together No requirement to label some additives not considered an ingredient Carry-over from an ingredient (e.g. preservatives in fruit puree > yoghurt) Processing aids (e.g. ascorbic acid to prevent discolouration of fruit > pie making, but has no effect in fruit pie - cooked off) Other substances used in the quantities strictly necessary as solvents or media for additives or flavouring

Mostly weak acids that “short circuit” membrane H+ gradient, e.g. Poly(3-hydroxybutyrate (PHB) Sorbic Acid, Benzoic acids Propionic, acetic acid Sulphite, sulphur dioxide