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STM3183, HEAT TREATMENT, Equipment, Chilling - Coggle Diagram
STM3183
1 Drying
Classification
- Thermal drying
A. Air drying
B. Low air environmental drying
C. Modified ATM drying
- Osmotic dehydration
remove water by immersion of water- containing cellular solid in a concentrated aqueous solution
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Factors
- Type and structure of products
- Product suspectibility to heat
- Pretreatment required
- Capital and processing cost
- Environmental factors
Low humidity
Increasing air currents, remove air around food
Ways (out of doors)
- Sun drying
- Solar drying
- Vine drying
Ways (in doors)
- Food dehydrator
Countet top
- Convection ovens
- Conventional ovens
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Electron beams
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Example of food:
1.grains
- Thin packaged of food
Types of radiation:
- Electron beams
- X-rays
- Gamma rays
Concept: The food is not directly contact with radioactive materials, but pass through a radiation.
Gamma rays
Source:
- Cobalt-60
- Ceasium-137
Example of food:
- Carcass, beef sausage
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The end product depend on
1) Nature of food
2) Type of m/o present
3) Environment factor affecting m/o activity
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Benefits
1) Preserve food, extend shelf life
2) Variety in diet
3)Produce important compound 4)Use simple technology 5)Unique flavor
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3 Basic principle
1) Minimize microbial contaminatio
2) Inhibit the growth of microflora
3) Kill microorganisms
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Addition of strong inorganic acids
- strong acid fully dissociated.
Microbes impermeable to H+ & OH- ion at outer layers of cells (pumped out by cells)
Potentiation of the effects of weak acid preservatives
- Preservative (acetate, nitrate/lactate) act as weak acids.
Same mechanisms as above.
Lipophilic Weak Acids
- weak acid partially dissociated, can move through cell membranes.
- Higher WA, more acidic, more UD acid penetration cell membranes, H+ released lowering pH inside cell. Enzymes & DNA of microbes die.
Main purpose :
-inhibit the growth of microorganism (yeast, mold, bacteria)
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Maintain food quality (maintain flavour, nutritional value, texture, colour)
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INDIRECT HEATING
- Heat is transferred to food through a barrier
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DIRECT HEATING
- Heat is transferred directly from the heat source to the food.
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CRITICAL CONCEPT
F - VALUE
- Heating time at specific temperature
Z - VALUE
- Temperature change require to pass through one log.
D - VALUE
- Time needed to kill 90% microbes at a specific temperature
12D Concept
- Survival rate of 12 log cycle reduction in C.botulinum
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