Cheese Making Process
Process Overview
Cheese manufacturing requires precise temperature and humidity control throughout multiple processing stages. Each step from milk reception through pressing generates specific thermal loads and environmental requirements that directly impact product quality, yield, and safety.
The cheese-making process involves controlled microbial and enzymatic activity that is highly temperature-dependent. HVAC systems must maintain stable conditions while handling substantial heat loads from processing equipment, pasteurization systems, and human activity in production areas.
Pasteurization Temperature Control
High-Temperature Short-Time (HTST)
Standard pasteurization parameters:
| Parameter | Value | Tolerance |
|---|---|---|
| Temperature | 72°C (161.6°F) | ±0.5°C |
| Hold Time | 15 seconds | ±0.5 sec |
| Flow Rate | Design-dependent | ±2% |
| Regeneration Efficiency | 85-95% | - |
Heat exchanger duty calculation:
Q = ṁ × cp × ΔT
Where:
Q = Heat transfer rate (kW)
ṁ = Mass flow rate (kg/s)
cp = Specific heat of milk ≈ 3.93 kJ/(kg·K)
ΔT = Temperature rise (K)
For 10,000 L/hr milk flow (10,280 kg/hr at 1.028 kg/L):
Q = (10,280 kg/hr ÷ 3,600 s/hr) × 3.93 kJ/(kg·K) × (72 - 4)°C
Q = 2.856 kg/s × 3.93 kJ/(kg·K) × 68 K
Q = 763 kW
Cooling load with 90% regeneration:
Q_cooling = 763 kW × (1 - 0.90) = 76.3 kW
Vat Pasteurization
Lower-temperature longer-time alternative:
- Temperature: 63°C (145°F)
- Hold Time: 30 minutes minimum
- Heating Rate: 2-3°C per minute maximum
- Cooling Rate: 1-2°C per minute post-hold
Cheese Vat Temperature Control
Vat Design Parameters
Standard cheese vat specifications:
| Capacity | Jacket Area | Heat Transfer Rate |
|---|---|---|
| 5,000 L | 12 m² | 15-20 kW |
| 10,000 L | 20 m² | 25-35 kW |
| 15,000 L | 28 m² | 35-50 kW |
| 20,000 L | 35 m² | 45-65 kW |
Heating Requirements
Initial milk heating from 4°C to processing temperature:
Q_heating = m × cp × ΔT
For 10,000 L vat:
m = 10,280 kg
cp = 3.93 kJ/(kg·K)
ΔT = 32°C - 4°C = 28 K
Q_heating = 10,280 kg × 3.93 kJ/(kg·K) × 28 K
Q_heating = 1,131,158 kJ = 314 kWh
With 60-minute heat-up time:
Required heating capacity = 314 kWh ÷ 1 hr = 314 kW
Including 25% safety factor: 393 kW
Mesophilic Cheese Production
Temperature ranges for Cheddar, Gouda, Monterey Jack:
| Process Stage | Temperature | Duration | Control Tolerance |
|---|---|---|---|
| Milk Addition | 31-32°C | - | ±0.5°C |
| Culture Addition | 31°C | 30-45 min | ±0.5°C |
| Rennet Addition | 31°C | - | ±0.3°C |
| Coagulation | 31°C | 30-45 min | ±0.3°C |
| Cutting | 31°C | 15-30 min | ±0.5°C |
| Cooking | 32-38°C | 30-60 min | ±0.5°C |
| Drainage | 38°C | Variable | ±1.0°C |
Cooking rate control:
Heating rate = 0.5 to 1.0°C per 5 minutes
For Cheddar (31°C to 38°C):
Time = 7°C ÷ (1°C per 5 min) = 35 minutes minimum
Thermophilic Cheese Production
Temperature ranges for Swiss, Parmesan, Provolone:
| Process Stage | Temperature | Duration | Control Tolerance |
|---|---|---|---|
| Milk Addition | 32-34°C | - | ±0.5°C |
| Culture Addition | 32-34°C | 15-30 min | ±0.5°C |
| Rennet Addition | 32-34°C | - | ±0.3°C |
| Coagulation | 32-34°C | 20-30 min | ±0.3°C |
| Cutting | 32-34°C | 10-20 min | ±0.5°C |
| Cooking | 48-54°C | 45-90 min | ±0.5°C |
| Drainage | 52-54°C | Variable | ±1.0°C |
High-temperature cooking for Swiss-type cheese may reach 54-56°C with controlled ramp rates of 1°C per 3-5 minutes.
Curd Processing Temperatures
Cheddarization Process
Specific to Cheddar and related varieties:
| Stage | Temperature | pH Target | Duration |
|---|---|---|---|
| Draining | 38°C | 6.4-6.2 | - |
| Matting | 38-39°C | 6.2-5.8 | 1-2 hrs |
| Milling | 37-38°C | 5.8-5.4 | - |
| Salting | 35-36°C | 5.3-5.2 | 10-20 min |
| Hooping | 32-35°C | 5.2-5.1 | - |
Room temperature control during Cheddarization:
Ambient temperature: 22-26°C
Relative humidity: 80-90%
Air velocity: <0.3 m/s at curd surface
Heat loss from exposed curd:
Q_loss = h × A × (T_curd - T_ambient)
Where:
h = Convective heat transfer coefficient ≈ 10 W/(m²·K)
A = Exposed surface area (m²)
For 100 m² exposed curd surface:
Q_loss = 10 W/(m²·K) × 100 m² × (38°C - 24°C)
Q_loss = 14,000 W = 14 kW
Pasta Filata Process
For Mozzarella and similar stretched-curd cheeses:
| Parameter | Value | Notes |
|---|---|---|
| Stretching Water Temp | 75-85°C | Low-moisture varieties |
| Stretching Water Temp | 65-75°C | High-moisture varieties |
| Curd pH for Stretching | 5.2-5.4 | Critical for texture |
| Stretching Duration | 3-8 minutes | Variety-dependent |
| Post-Stretch Temp | 54-60°C | Before forming |
Stretching water heating load:
For 500 L/hr water flow at 80°C (from 15°C supply):
Q_water = ṁ × cp × ΔT
Q_water = (500 kg/hr ÷ 3,600 s/hr) × 4.186 kJ/(kg·K) × 65 K
Q_water = 37.7 kW continuous load
Cooling and Pressing Requirements
Immediate Post-Vat Cooling
Curd cooling after drainage:
| Cheese Type | Initial Temp | Target Temp | Cooling Rate |
|---|---|---|---|
| Fresh Cheese | 32-35°C | 4-8°C | 2-4 hrs |
| Soft-Ripened | 30-32°C | 10-12°C | 2-3 hrs |
| Semi-Hard | 35-38°C | 12-15°C | 3-4 hrs |
| Hard Cheese | 38-40°C | 10-14°C | 6-12 hrs |
Cooling load calculation for pressed cheese:
For 1,000 kg curd mass cooled from 35°C to 12°C in 4 hours:
Q_cooling = m × cp × ΔT ÷ t
Cheese specific heat ≈ 3.1 kJ/(kg·K)
Q_cooling = 1,000 kg × 3.1 kJ/(kg·K) × 23 K ÷ (4 × 3,600 s)
Q_cooling = 4.98 kW average
Peak load at start of cooling cycle approaches 2.5× average load.
Pressing Systems
Hydraulic and pneumatic press specifications:
| Press Type | Pressure Range | Temperature Control | Cooling Method |
|---|---|---|---|
| Hydraulic | 1-5 bar | Room temperature | Ambient |
| Pneumatic | 0.5-4 bar | Room temperature | Ambient |
| Vacuum | -0.8 to -0.95 bar | 10-18°C | Refrigerated room |
Pressing room environmental conditions:
Temperature: 12-18°C
Relative Humidity: 75-85%
Air Changes: 4-6 ACH
Room Pressurization: Neutral to slightly positive
Heat generation during pressing:
Q_press = Work done on curd + Metabolic heat
Metabolic heat ≈ 0.8-1.2 W/kg curd
Mechanical work minimal for pressing loads
For 5,000 kg curd in pressing room:
Q_metabolic = 5,000 kg × 1.0 W/kg = 5.0 kW
Brine Bath Refrigeration
Brine System Design
Standard brine concentrations and properties:
| Parameter | Value | Notes |
|---|---|---|
| Salt Concentration | 18-23% by weight | Most common |
| Operating Temperature | 8-14°C | Variety-dependent |
| Calcium Addition | 0.5-1.5% CaCl₂ | Prevents calcium loss |
| pH | 5.0-5.5 | Controlled |
| Density | 1,140-1,170 kg/m³ | At 10°C |
| Specific Heat | 3.54 kJ/(kg·K) | At 20% NaCl |
Brine Bath Capacity
Typical brine bath sizes for different production scales:
| Production Rate | Bath Volume | Refrigeration Load |
|---|---|---|
| 1,000 kg/day | 5,000 L | 8-12 kW |
| 5,000 kg/day | 15,000 L | 25-40 kW |
| 10,000 kg/day | 30,000 L | 50-75 kW |
| 20,000 kg/day | 50,000 L | 90-130 kW |
Heat Load Components
Total brine refrigeration load:
Q_total = Q_cheese + Q_infiltration + Q_evaporation + Q_ambient
Q_cheese = Heat removed from warm cheese entering brine
Q_infiltration = Heat gain from room air and water vapor
Q_evaporation = Latent heat from surface evaporation
Q_ambient = Conduction through tank walls and piping
Heat removal from cheese:
For 1,000 kg/hr cheese entering at 18°C, cooled to 12°C:
Q_cheese = ṁ × cp × ΔT
Q_cheese = (1,000 kg ÷ 3,600 s) × 3.1 kJ/(kg·K) × 6 K
Q_cheese = 5.17 kW
Evaporative losses from open brine surface:
Q_evap = hfg × ṁ_evap
Where:
hfg = Latent heat of vaporization ≈ 2,450 kJ/kg
ṁ_evap = Evaporation rate (kg/s)
For 20 m² surface area at 12°C brine, 18°C room:
Evaporation ≈ 0.3 kg/(hr·m²) = 6 kg/hr = 0.00167 kg/s
Q_evap = 2,450 kJ/kg × 0.00167 kg/s = 4.1 kW
Brine Circulation
Circulation pump specifications:
Flow rate: 3-5 tank volumes per hour
Head: 10-20 m depending on piping layout
Temperature rise across pump: <0.5°C
For 15,000 L tank with 4 vol/hr circulation:
Flow rate = 15 m³/hr × 4 = 60 m³/hr
Mass flow = 60 m³/hr × 1,150 kg/m³ = 69,000 kg/hr
Pump power ≈ 3-5 kW
Heat addition from pumping ≈ 2.5-4.0 kW
Process Room HVAC Design
Temperature Control Zones
Multiple temperature zones required in cheese plant:
| Area | Temperature | RH | Air Changes | Pressurization |
|---|---|---|---|---|
| Milk Receiving | 4-8°C | 80-85% | 6-8 ACH | Neutral |
| Vat Room | 22-26°C | 70-80% | 8-12 ACH | Positive 15-25 Pa |
| Cheddarization | 22-26°C | 80-90% | 6-10 ACH | Positive 10-20 Pa |
| Pressing Room | 12-18°C | 75-85% | 4-6 ACH | Neutral |
| Brining Room | 10-14°C | 85-90% | 4-6 ACH | Neutral |
| Packaging | 4-8°C | 75-80% | 8-10 ACH | Positive 20-30 Pa |
Vat Room Design
Critical HVAC parameters for vat room:
Sensible heat load sources:
- Equipment (vats, pumps, conveyors): 50-80 W/m²
- Lighting (LED): 8-12 W/m²
- Occupants (moderate activity): 130 W/person sensible
- Infiltration: 10-15 W/m² floor area
For 500 m² vat room with 8 vats, 12 occupants:
Q_equipment = 500 m² × 65 W/m² = 32.5 kW
Q_lighting = 500 m² × 10 W/m² = 5.0 kW
Q_occupants = 12 persons × 130 W = 1.56 kW
Q_infiltration = 500 m² × 12 W/m² = 6.0 kW
Q_sensible_total = 45.1 kW
Latent heat load:
Q_latent sources:
- Occupants: 12 persons × 70 W/person = 0.84 kW
- Open vats: Varies by stage
- Cleaning operations: 15-25 W/m²
Q_latent_total ≈ 8-12 kW
Ventilation Requirements
Air change rates based on activity and contaminant generation:
Minimum outdoor air: 0.5 L/(s·m²) floor area
For 500 m² vat room:
Outdoor air = 500 m² × 0.5 L/(s·m²) = 250 L/s = 900 m³/hr
At 10 ACH with 4 m ceiling height:
Room volume = 500 m² × 4 m = 2,000 m³
Total air flow = 2,000 m³ × 10 hr⁻¹ = 20,000 m³/hr
Outdoor air fraction = 900 ÷ 20,000 = 4.5%
Recirculated air = 95.5%
Equipment Heat Loads
Cheese Vat Heat Dissipation
Heat dissipated to room from vat operations:
| Operation | Heat to Room | Duration | Notes |
|---|---|---|---|
| Agitation Motor | 2-5 kW | Intermittent | Variable speed |
| Cutting Assembly | 1-3 kW | 15-30 min | Once per batch |
| Pump Operation | 3-8 kW | Intermittent | Transfer operations |
| Jacket Losses | 2-4 kW | Continuous | Depends on insulation |
Single vat total heat dissipation:
Average continuous load per vat ≈ 4-8 kW
Peak load during active processing ≈ 12-18 kW
For 8-vat room:
Average load = 8 vats × 6 kW = 48 kW
Peak load = 8 vats × 15 kW = 120 kW
Design for 70% peak: 84 kW
Curd Processing Equipment
Heat loads from downstream equipment:
| Equipment | Power Input | Heat to Room | Duty Cycle |
|---|---|---|---|
| Curd Mill | 15-30 kW | 12-25 kW | 60-80% |
| Curd Conveyor | 5-10 kW | 4-8 kW | 70-90% |
| Block Former | 10-20 kW | 8-16 kW | 80-100% |
| Stretch Cooker | 40-80 kW | 25-50 kW | 70-90% |
| Packaging Line | 20-40 kW | 15-30 kW | 80-100% |
Pump Heat Addition
Heat generated by various pumps in cheese plant:
Milk transfer pumps: 5-15 kW per pump
Curd/whey pumps: 3-10 kW per pump
Brine circulation: 3-5 kW per pump
CIP pumps: 10-30 kW per pump
Heat addition to fluid ≈ 80-90% of motor power
Heat to room ≈ 10-20% of motor power (motor inefficiency)
For positive displacement pump transferring milk:
Power = (P × Q) ÷ η
Where:
P = Pressure increase (Pa)
Q = Flow rate (m³/s)
η = Pump efficiency (0.70-0.85)
Example: 20 m³/hr at 300 kPa, η = 0.75
Power = (300,000 Pa × 20 m³/hr ÷ 3,600 s/hr) ÷ 0.75
Power = 2,222 W = 2.22 kW input
Heat to product: 2.22 kW × 0.85 = 1.89 kW
Heat to room: 2.22 kW × 0.15 = 0.33 kW
Humidity Control During Processing
Moisture Management
Relative humidity targets prevent excessive curd drying:
Curd processing areas: 75-85% RH
Pressing rooms: 75-85% RH
Brining rooms: 85-90% RH
Packaging areas: 70-80% RH
Dehumidification load calculation:
Moisture removal rate = ṁ_air × (ω_inlet - ω_outlet)
Where:
ṁ_air = Air mass flow rate (kg/s)
ω = Humidity ratio (kg water/kg dry air)
For pressing room at 15°C:
Target: 80% RH (ω = 0.00856 kg/kg)
Infiltration air: 30°C, 60% RH (ω = 0.0162 kg/kg)
Infiltration rate: 1,000 m³/hr = 1,200 kg/hr dry air
Moisture to remove:
ṁ_moisture = (1,200 kg/hr ÷ 3,600 s/hr) × (0.0162 - 0.00856)
ṁ_moisture = 0.00255 kg/s = 9.2 kg/hr
Latent load = 9.2 kg/hr × 2,450 kJ/kg = 6.25 kW
Humidification Requirements
Winter conditions may require humidification:
Outdoor air: -5°C, 70% RH (ω = 0.0019 kg/kg)
Target: 24°C, 80% RH (ω = 0.0151 kg/kg)
Outdoor air flow: 1,000 m³/hr at 24°C = 1,165 kg/hr dry air
Moisture addition required:
ṁ_add = (1,165 kg/hr ÷ 3,600 s/hr) × (0.0151 - 0.0019)
ṁ_add = 0.00427 kg/s = 15.4 kg/hr
Steam requirement (if steam humidification):
15.4 kg/hr steam at 2,450 kJ/kg = 10.5 kW
Condensation Prevention
Critical surfaces requiring condensation control:
- Stainless steel vat exteriors
- Cold piping and valves
- Refrigerated room walls and doors
- Observation windows
Minimum surface temperature to prevent condensation:
T_surface_min = T_dewpoint + 2°C safety margin
At 24°C, 80% RH:
T_dewpoint = 20.4°C
T_surface_min = 22.4°C
Insulation requirement for 4°C milk line in 24°C room:
R_required = (T_room - T_surface) ÷ q"
Target q" = 15 W/m² (reasonable heat flux)
R_required = (24 - 22.4) K ÷ 15 W/m² = 0.107 m²·K/W
For polyurethane insulation (k = 0.025 W/(m·K)):
Thickness = 0.107 × 0.025 = 2.7 mm minimum
Practical minimum: 25 mm (1 inch) for mechanical protection
Sanitation Temperature Requirements
Clean-in-Place (CIP) Systems
Multi-stage CIP cycle temperatures:
| Stage | Temperature | Duration | Purpose |
|---|---|---|---|
| Pre-Rinse | Ambient-40°C | 3-5 min | Gross soil removal |
| Caustic Wash | 75-85°C | 10-20 min | Fat and protein removal |
| Intermediate Rinse | 40-60°C | 3-5 min | Caustic removal |
| Acid Wash | 65-75°C | 10-15 min | Mineral scale removal |
| Final Rinse | Ambient-40°C | 3-5 min | Acid removal |
| Sanitizer | 20-40°C | 5-10 min | Microbial control |
CIP Heat Loads
Heating requirements for CIP solutions:
Tank capacity: 2,000 L per circuit
Caustic solution: 1.5-3.0% NaOH
Acid solution: 1.0-2.0% HNO₃
Heat to raise 2,000 L from 20°C to 80°C:
Q = m × cp × ΔT
m = 2,000 kg (assuming water properties)
cp = 4.186 kJ/(kg·K)
ΔT = 60 K
Q = 2,000 × 4.186 × 60 = 502,320 kJ = 139.5 kWh
With 45-minute heat-up time:
Power required = 139.5 kWh ÷ 0.75 hr = 186 kW
Including 20% heat losses: 223 kW heating capacity
Recovery and reuse reduces heating load:
Caustic solution reused 4-6 cycles before replacement
Temperature drop per cycle: 5-10°C
Reheat load per cycle: 42-84 kJ/kg = 23-47 kWh per cycle
Hot Water Generation
Daily hot water requirements for cheese plant:
| Use | Temperature | Daily Volume | Peak Flow |
|---|---|---|---|
| CIP Systems | 75-85°C | 50-80 L/kg cheese | 10-20 m³/hr |
| Equipment Sanitizing | 82-85°C | 20-30 L/kg cheese | 5-10 m³/hr |
| Floor/Wall Cleaning | 60-70°C | 15-25 L/kg cheese | 5-8 m³/hr |
| Hand Washing | 40-45°C | 5-10 L/kg cheese | 2-4 m³/hr |
For 10,000 kg/day cheese production:
Total hot water demand:
CIP: 10,000 kg × 65 L/kg = 650,000 L/day at 80°C
Sanitizing: 10,000 kg × 25 L/kg = 250,000 L/day at 82°C
Cleaning: 10,000 kg × 20 L/kg = 200,000 L/day at 65°C
Hand washing: 10,000 kg × 7.5 L/kg = 75,000 L/day at 43°C
Total volume: 1,175,000 L/day = 1,175 m³/day
Water heating load (from 10°C supply):
Q_daily = Σ(m × cp × ΔT)
Q_CIP = 650,000 kg × 4.186 kJ/(kg·K) × 70 K = 190,578 MJ
Q_sanitize = 250,000 kg × 4.186 kJ/(kg·K) × 72 K = 75,350 MJ
Q_clean = 200,000 kg × 4.186 kJ/(kg·K) × 55 K = 46,046 MJ
Q_handwash = 75,000 kg × 4.186 kJ/(kg·K) × 33 K = 10,360 MJ
Q_total = 322,334 MJ/day = 89,537 kWh/day
Average continuous load = 89,537 kWh ÷ 24 hr = 3,731 kW
Peak capacity requirement (20% of daily in 2 hours):
Peak = 89,537 kWh × 0.20 ÷ 2 hr = 8,954 kW
Steam Requirements
Process steam generation for direct and indirect heating:
Total plant steam load components:
- Vat heating: 300-500 kW
- Pasteurization: 50-100 kW (after regeneration)
- CIP heating: 200-400 kW
- Hot water generation: 3,500-4,500 kW
- Building heating (winter): 500-1,000 kW
- Safety factor: 20%
Total design capacity = 5,500 kW × 1.20 = 6,600 kW
Steam at 6 bar gauge (447 kPa, 159°C):
hfg = 2,085 kJ/kg
Required steam flow = 6,600 kW ÷ 2,085 kJ/kg = 3.17 kg/s
= 11,394 kg/hr = 11.4 tonnes/hr
Boiler capacity: 15,000 kg/hr (allows for peak loads)
Equipment Specifications
Refrigeration System Design
Central glycol system for process cooling:
| Parameter | Specification | Notes |
|---|---|---|
| Refrigerant | R-404A, R-507A, NH₃ | Facility-dependent |
| Glycol Type | Propylene glycol | Food-grade |
| Glycol Concentration | 30-40% by volume | -18°C freeze protection |
| Supply Temperature | -2 to 2°C | Process-dependent |
| Return Temperature | 8 to 12°C | Design ΔT = 10 K |
| System Pressure | 4-6 bar | Distribution pressure |
Total refrigeration capacity:
Component loads for 10,000 kg/day plant:
- Milk cooling (reception): 80-120 kW
- Post-pasteurization cooling: 60-90 kW
- Vat cooling (makeup): 40-60 kW
- Curd cooling: 30-50 kW
- Brine bath: 50-75 kW
- Process room HVAC: 100-150 kW
- Cold storage: 80-120 kW
- Safety factor: 25%
Total = 565 kW × 1.25 = 706 kW
Installed capacity: 800 kW (multiple compressors)
Pump Specifications
Process pumps for cheese manufacturing:
| Service | Type | Materials | Sanitary Standard |
|---|---|---|---|
| Milk Transfer | Centrifugal | 316L SS | 3-A, EHEDG |
| Curd Transfer | Lobe | 316L SS | 3-A |
| Whey Transfer | Centrifugal | 316L SS | 3-A |
| Brine Circulation | Centrifugal | 316L SS, Titanium | Food-grade |
| CIP Supply | Centrifugal | 316L SS | 3-A |
Air Handling Unit Specifications
Dedicated AHU for vat room (500 m² example):
Supply Air Flow: 20,000 m³/hr
Outdoor Air: 900 m³/hr (4.5%)
Total Cooling: 60 kW (45 kW sensible, 15 kW latent)
Total Heating: 40 kW (winter)
Supply Fan: 7.5 kW with VFD
Return Fan: 5.5 kW with VFD
Filters: MERV 13 minimum
Cooling Coil: Chilled water, 6/12°C
Heating Coil: Hot water, 80/60°C or steam
Humidifier: Steam injection or ultrasonic
Supply duct velocities:
Main ducts: 8-12 m/s
Branch ducts: 6-10 m/s
Terminal diffusers: 2-4 m/s at discharge
Controls Integration
Building automation system (BAS) integration points:
- Vat temperature control (±0.3°C precision)
- Room temperature and humidity monitoring
- Glycol supply temperature reset
- Demand-based ventilation control
- CIP temperature verification
- Brine concentration and temperature
- Refrigeration system optimization
- Energy metering and trending
Control sequences coordinate HVAC with process requirements to maintain product quality while minimizing energy consumption.
File Location: /Users/evgenygantman/Documents/github/gantmane/hvac/content/refrigeration-systems/food-processing-refrigeration/dairy-processing/cheese-manufacturing/cheese-making-process/_index.md
This comprehensive technical content covers all critical HVAC and refrigeration aspects of cheese manufacturing processes for HVAC professionals designing or maintaining cheese production facilities.