processing factor

What are 3 methods to keep microbes away

1. Maintain good hygiene and good source of the product

2. Kill the microbes through different process methods High T hugh pressure or radiation

3. Keep microbes from growing by combining different microbial growth factor

What are the 3 hype of radiación used in the food processing

I microware, uv gamma ray

How dos microwave inactivate microbes

1. microwave indirectly inactivate microbes through heat generation

2. The dipolar water molecules will align themselves with the field of microwaves

3. Then when microwaves is on it will reverse the polarity of water molecules

4. As a result the vibration of water molecule will transmit to the surrounding area and generate heat

5. This will increase the temperature of the food product

6. Food product with high salt concentration will vibrate more and cause faster surface heating

What is the advantage of microware heating

It is fasts and quick

What is the disadvantage of using microwave

1) the heating is non-uniform

I will cause consumption if adequate heated food

2.Presence of the cold spot

in the microwave it might have the presence of cold spot

At these cold spot microbes cannot be elimine

How does UV inhibit the microbes

1.UV will cause formation of covalent bond between the thymine base in DNA

2. UV will cause failure of key metabolic reaction failure in the microbes

What is the advantage of UV

There is no change in quality of the product

Disadvantage of UV

1. UV radiation it self have low penetration to medium

  Due to this reason, the application of UV is limited to disinfection of air, surface and water only.

2.   Microbial resistance

Resistance order: Gram-negatives < Gram-positives ~ yeasts < bacterial spores<mould spores < <viruses.

3. Induce non-microbial spoilage

-              UV may induce spoilage of product contain unsaturated fatty acid accelerate the rancidit

4. Harmful to workers

What is the bacteria resistance to the UV light

virus>mould>spore>yeast>gram positive>gram negative

How does gamma ray effect microbes

1. Direct damage of the key molecule of the microbes

2. Radiolysis of water

   • water will produce reactive molecules such as hydrogen peroxide hydroxyl radical and hydrogen radical etc

   • These radicals will react with key molecules in the cell such as DNA and plasma membrane protein enzymes etc

What are the factors make cells more resistant to the gamma ray

1. Absence of water no production of reactive water molecules by product

2. Absence of oxygen

   
   

What is the resistance of cell

Virus>yeast>spore>gram positive>gram negative

What is the advantage of gamma ray

1. Instant deep and uniform process

2. Can maintain the quality of the food product

3. better sensory quality of the product, if the product is being treated under frozen state.

4. Reduce the virulence of pathogens

What is the disadvantage of gamma ray

1. Consumer resistance

2. Hard to predict if the food is treated with ionizing radiation or not

3. Production of radioactive waste

4. Harmful to the workers

What is radiation pasteurization

Radicidation：elimination of pathogen

Radurization: prolong shelf life by reducing the spoilage pathogen

What is pascalization

• it is a batch process

• It uses the high hydrostatic pressure to reduce the microbial load

What are the 2 factors enhance the effect of pascalization

It will be enhanced by low pH or temperature higher or lower than the ambient temperature

what are the 2 components in the microbes that will be effected by the high pressure

Plasma membrane

Protein

How does high pressure affect the plasma membrane

Increase pressure will cause lipid membrane to stack together and the physical volume of the membrane is also reduced

As a result the fluidity of the microbes will be reduced

It will be harder for molecules to pass through the lipid bilayer

How does the high pressure affect the protein structure

1. the high hydrostatic pressure will affect the non-covalent bond in protein

2. As a result the secondary and the tertiary protein will lose it’s structure

3. Since the protein lose its structure the subsequent functionality will also be affected

What is the effect of pressure on starch

1. The pascalizednstarch will lose its structural conformation

2. As a result it will be digested easily by the amylase

Effect of pascalization on different microbes

1. Vegetative cell

   400mpa for 5 min reach 1 log reduction

2. Spore

   it is more resistance to pressure and harder to be removed

What is the solution to remove spore

1. We can use high temperature to induce spore germination first

2. Once the spores are germinated it will loss its resistance thus they can be killed

What is the advantage of pascalization

1. Uniform and instant heating to the food product

2. Maintain the quality of food product

3. Positive consumer feedback

4. Can applied to different type of food product (meat)

   Losen the muscle of oyster make it easier to peel

what is the disadvantage of pascalization

1. It mainly used to eliminate mould and yeast

2. Microbial spore is more resistant to the pressure than vegetative cell

3. Other hurdle require to inhibit the growth of microbes

   eg. low acid product, inhibit mould yeast and spores

what is pasteurisation

heat treatment between temperature range of 60-80 degree for a few minutes

what is the function of pasterisation

1. eliminate the target microbes

2. legal requirement for certain product (milk)

3. elimination of large spoilage microbes to extend the shelf-life of the product

what is the advantage of pasteurization process

1.        It can also eliminate other organism with similar heat sensitivity (salmonella)

what is the 3 disadvantage of pasteurisation

1. some microbes can survive the mild heat treatment

2. pasterization need to be combined with other hurdle factors to extend the shelf-life

what is appertization

: organism that survive appertization process are mostly non-pathogenic and are incapable of developing in the ambient temperature environment

what is the advantage of appertisation

1. long storage under ambient temperature

what is the disadvantage

1.        Appertization is not sterilization, it is not completely free of microbes.

2.        They can still grow under ambient T.

what is the heat order

UHT>commericial sterilization <steam treatment <blanhing<pasterurization <pre-pasterusation <sou-vide cooking<hot room

what is UHT

Condition:

T: 135–150°C

Time :1-10 s

Effect:

-similar with commercial sterilization

-but higher temperature will shorter time can better maintain the quality of the product

commericial sterlization

T: 120

Time: few minutes

Effect : -only non-pathogenic survivors that cannot develop in the product

-under normal codition no spoilage occur

steam treatment

T: 100-120

Time: s-minutes

effect

-inactivation of microorganism on spices

blanching

T: 90-100

Time: few minutes

Effect

decontamination of sliced veg

-enzyme inactivation

-surface decontamination

pasteurisation

T: 60-80

Time: few minutes

Effect

-inactivate of some pathogen

-elimination of spoilage microbes, extend the shelf-life

-legal requirement

pre-pasteruisation

T: 60

Time: few seconds

Effect

-to pre kill some of the microbes, then storage and waiting for the actual pasterisation process

sou-vide cooking

T: 90

Time: 10 minutes

effect

-mainly for French cuisine

-multiple hurdle is used, first vacumm then boil it under 90 degree, finally storage in the fridge

hot-room

T: 50-55°C

Time:days

-mainly used for egg powder to prevent denaturation of the protein.

what is pulsed electric field

-              Rapid change of the high voltage over microbes (50kV and high frequence of 2 microseconds)