Processing vs food components

Art Hill

Department of Food Science

University of Guelph

www.foodscience.ca

Department of Food Science | University of Guelph | Guelph, Ontario

Review: what is Food Science?

Food Science means to know (discover) the

chemical, biological, and physical properties

of food and how those properties change

during food processing.

The application of that knowledge is food

technology, which is about food process and

food product development. A key word in

food product development is differentiation.

Department of Food Science | University of Guelph | Guelph, Ontario

Why not just eat unprocessed foods?

• ?

•

•

•

•

•

•

•

•

Department of Food Science | University of Guelph | Guelph, Ontario

Why not just eat raw foods?

• Preservation

• Flavour

• Texture

• Health

• Nutrition

• Safety

• Sustainability

• Convenience

• Differentiation www.primaverakitchen.com

Dairy Family Tree

Dairy E-book, University of

Guelph

Department of Food Science | University of Guelph | Guelph, Ontario

Preservation Processes (unit operations)

• Heating

• Modified atmosphere

• Ultraviolet radiation

• Electric pulse

• Microfiltration

• Packaging

• High pressure

• Ozone

• Hydrogen peroxide

• Cold plasma

• Finely dispersed w/o

emulsion.

• Cooling and freezing

• Drying

• Osmotic pressure

• Acidification

• Antioxidants

• Antibiotics

• Antifungal agents

• Biocontrol

• Fermentation

• Ionizing irradiation, γ-rays,

and x-rays

Department of Food Science | University of Guelph | Guelph, Ontario

Pasteurization: HTST

Department of Food Science | University of Guelph | Guelph, Ontario

Thermal Processing (milk)

Process(s) Temp Duration WPC Purpose

Raw or sub-

pasteurized milk <65ºC < 1 min <5%Full flavoured ripened

cheese

Vat

pasteurization63ºC 30 min 10%

Destroy all pathogens.

Reduce spoilage

HTST

pasteurization73ºC 16 s <5%

Destroy all pathogens

Reduce spoilage

Ultra-high

temperature140ºC <4 s 10%

Destroy all

microorganisms

Yogurt milk85-

90ºC4 – 6 min 80%

Denature whey proteins;

thicken yogurt

Department of Food Science | University of Guelph | Guelph, Ontario

Direct vs Indirect UHT

Department of Food Science | University of Guelph | Guelph, Ontario

Retort Sterilization

• Normally 121ºC

• Target 12 log reduction of

microbes (quadrillion to

one)

• Pouches and cans

• Denatures proteins,

deactivates vitamins and

enzymes.

• Alters pigments

• Softens many food

matrices

Department of Food Science | University of Guelph | Guelph, Ontario

Raw Milk

Separator

Cream Skim

Microfilter

Recombine Retentate

UHT Standardize Permeate

Pasteurize

Microfilter

Microfiltration Flow Chart

• Physical process

• Few chemical

changes

• Minimal effects on

enzymes and

vitamins

Department of Food Science | University of Guelph | Guelph, Ontario

High Pressure Processing

• High pressure transmitted

by water

• 3000– 6000 Bar

• Destroys vegetative cells

but not all spores and may

induce germination of

spores

• Denatures some proteins

including some enzymes.

• Accelerates cheese

ripening

Department of Food Science | University of Guelph | Guelph, Ontario

Spray Drying

• Spray drying

• Air inlet ≈ 125 -160ºC

• Air outlet ≈ 70 - 80ºC

• Product protected from

heat damage by heat of

vaporization.

Department of Food Science | University of Guelph | Guelph, Ontario

Vacuum/Microwave Drier

• Low temperature

drying achieved by

drying under vacuum to

lower boiling point.

• Energy for vaporisation

provided by

microwaves.

Department of Food Science | University of Guelph | Guelph, Ontario

Fermentation: bacteria, yeast, moulds

Department of Food Science | University of Guelph | Guelph, Ontario

Fermentation

• Enhance Food Safety and Extend

Shelf Life• Compete for nutrients

• Acidify

• Create anaerobic conditions

• Release antimicrobials

• Reduce water activity

• Promote Health• Probiotics

• Vitamins, bioactive peptides,

• Modify texture

• Create an endless diversification

of flavours.

Department of Food Science | University of Guelph | Guelph, Ontario