Food Production Chains – Part A
How to analyse a food production chain:
- Make a flow diagram
- Analyse mass flows (raw material use efficiency & water consumption)
- Make a Sankey diagram
Mass balances:
Law of conservation of mass – mass can be neither created nor destroyed
Mass balance: accumulation = in – out + production
Often: production = 0
Continuous steady state process: accumulation = 0
Mass balance becomes: in = out
Example mass balance: m1 + m2 = m3 + m4
Example component balance: xA1m1 + xA2m2 = xA3m3 + xA4m4
Mass fraction: xA = (mA)/(mA + mB …)
Mass ratio: XA = mA / mB
Different processes:
Batch process – no input and output
Semi-batch – continuous feed and discharge of discrete packs of material
Continuous – input and output are introduced and removed continuously throughout the proces
Steady state – process variables (e.g. T, flow rate) are independent of time (continuous)
Transient – process variables change in time ((semi-)batch processes)
Procedure mass balance calculation:
1. Make a drawing of the process
2. Select a basis for calculation
3. Write the equations for the components of interest (including the total mass balance)
4. Solve the equations
5. Write an appropriate answer and evaluate this answer
Mass flow analysis (for continuous processes):
Mass flow
𝜙𝑖𝑛 = 𝜙𝑜𝑢𝑡1 + 𝜙𝑜𝑢𝑡2 …
Unit operations in food processing:
- Pasteurisation, blanching, sterilisation
- Cooling, freezing
- Evaporation, drying
- Mixing
- Separation, filtration
- Baking, roasting, frying
- Fermentation, enzyme technology
- packaging
Evaporation – removing water from a liquid feed to produce a
concentrated liquid product
! xw,D is 1 because the vapour only consists of water
Drying – removing water from a feed by using (hot) air
Cabinet (tray) driers, belt driers – e.g. vegetables, fruit products, breakfast cereals
Spray driers – e.g. milk powder and instant coffee (liquid to powder)
How to analyse a food production chain:
- Make a flow diagram
- Analyse mass flows (raw material use efficiency & water consumption)
- Make a Sankey diagram
Mass balances:
Law of conservation of mass – mass can be neither created nor destroyed
Mass balance: accumulation = in – out + production
Often: production = 0
Continuous steady state process: accumulation = 0
Mass balance becomes: in = out
Example mass balance: m1 + m2 = m3 + m4
Example component balance: xA1m1 + xA2m2 = xA3m3 + xA4m4
Mass fraction: xA = (mA)/(mA + mB …)
Mass ratio: XA = mA / mB
Different processes:
Batch process – no input and output
Semi-batch – continuous feed and discharge of discrete packs of material
Continuous – input and output are introduced and removed continuously throughout the proces
Steady state – process variables (e.g. T, flow rate) are independent of time (continuous)
Transient – process variables change in time ((semi-)batch processes)
Procedure mass balance calculation:
1. Make a drawing of the process
2. Select a basis for calculation
3. Write the equations for the components of interest (including the total mass balance)
4. Solve the equations
5. Write an appropriate answer and evaluate this answer
Mass flow analysis (for continuous processes):
Mass flow
𝜙𝑖𝑛 = 𝜙𝑜𝑢𝑡1 + 𝜙𝑜𝑢𝑡2 …
Unit operations in food processing:
- Pasteurisation, blanching, sterilisation
- Cooling, freezing
- Evaporation, drying
- Mixing
- Separation, filtration
- Baking, roasting, frying
- Fermentation, enzyme technology
- packaging
Evaporation – removing water from a liquid feed to produce a
concentrated liquid product
! xw,D is 1 because the vapour only consists of water
Drying – removing water from a feed by using (hot) air
Cabinet (tray) driers, belt driers – e.g. vegetables, fruit products, breakfast cereals
Spray driers – e.g. milk powder and instant coffee (liquid to powder)
