1. Food preservation

Preservation methods

• Traditional methods

• Thermal methods

• Concentrating

• Packaging

• Combinations/other

Process concepts

• Fluid flow

• Reactions-Reactors

• Heat transfer

How to control microorganisms and enzymes

• Slow down deterioration reactions

• Change conditions for undesired m.o.

• Remove m.o.

• Inactivate m.o. and enzymes

Food Preservation mechanisms

Food preservation mechanisms for milk, fruit juices & alcholic drinks

PEF = pulse electric field

Food preservation mechanisms for semi-solid foods

(Heat treatments) Thermisation

• Gets rid of psychrotrophic bacteria

• 65-72 C, 15-22 seconds

(Heat treatments) LTLT, low temperature; long time

• 62-65 C, for at least 30 min

(Heat treatments) Pasteurization

• 72-75 C, for 15-40 seconds

(Heat treatments) Flash pasteurization

• 85 C

• 1-2 seconds

(Heat treatments) UHT, ultra-high temperature

• Sterilization

• 135-140 C, for 1-2 seconds

Aim of bactofugation & bactocatch

• Used for milk/dairy

• Aim:

  • prolonged shelf life

  • Preserve taste and nutritional value

  • Remove Clostridia sporeformers from milk for cheesemaking

• Can be achieved by doing this instead of heat treatments

Process of bactofugation

1. Increase temp for fat removal

2. Centrifugation: separation of fat fraction

3. Bactofugation: separate stream with bacteria 

4. Sterilization of stream with bacteria

5. Recombining + mild pasteurization of recombined stream

Process of bactocatch

• used for ESL milk-milk with extended shelf life

• Membrane process; Microfiltration (membrane 1.4 micrometer)

• Separation based on size

Effect of treatment on product

• The effect can be tested, for example the protein nativity is an indicator for heat treatment

• Or measure beta lactoglobulin nativity

Packaging for preservation

• Post package treatment (cans)

  • You have to heat the can

• Aseptic packaging

  • Product is sterilized first, followed by filling disinfected containers under sterile, enclosed conditions

Three categories of operations

1. Separations: including cleaning, fractionation and purification

2. Conversions and structuring: such as fermentation, enzymatic/microbial inactivation, and changing ingredient positioning

3. Stabilizations: involving a preservation treatment to reduce deterioration risk and packaging