Cold Storage at −18 °C for Butter & Cream – A Practical Case Study

 

Cold Storage at −18 °C for Butter & Cream – A Practical Case Study

Introduction

Butter and cream are highly sensitive dairy products that require strict temperature control to preserve quality, texture, and shelf life. Any deviation in storage temperature can lead to fat separation, flavor degradation, or microbial growth. For long-term storage, −18 °C cold rooms are widely used in dairy plants to ensure product stability and food safety.

This case study explains how we designed and implemented a −18 °C cold storage facility for butter and cream, focusing on refrigeration design, insulation, moisture control, and operational reliability.

Project Overview

  • Application: Frozen storage of butter & cream

  • Design Temperature: −18 °C (±1 °C)

  • Product Form: Cartons / blocks / tubs on pallets

  • Storage Duration: Medium to long term

  • Operational Pattern: 24/7 operation

  • Key Objectives:

    • Maintain consistent low temperature

    • Prevent quality deterioration

    • Ensure hygiene and audit compliance

    • Minimize energy consumption

The client required a robust system that could operate continuously with minimal downtime and high reliability.

Why −18 °C Is Required for Butter & Cream

Although butter and cream are not frozen solid like ice cream, storing them at −18 °C offers several benefits:

  • Slows oxidation of milk fat

  • Prevents microbial growth

  • Maintains flavor and texture

  • Extends shelf life significantly

  • Meets export and regulatory requirements

Maintaining temperature uniformity is critical to avoid partial thawing and refreezing, which damages product quality.

Key Design Challenges

Designing a −18 °C cold storage for dairy products presented several challenges:

  • High heat load during product loading

  • Frequent door openings

  • Moisture ingress and frost formation

  • Condensation at doorways

  • Energy consumption at low temperatures

  • Hygiene and cleaning requirements

Each of these had to be addressed in the system design.

Step 1: Heat Load Calculation

Accurate load estimation was the foundation of the design.

Heat Load Components

  • Product load (incoming butter & cream temperature)

  • Transmission load through walls, floor, and ceiling

  • Infiltration load due to door openings

  • Internal load from lighting and personnel

  • Equipment and fan motor heat

Peak load conditions were calculated based on worst-case loading scenarios to ensure system stability.

Step 2: Refrigeration System Selection

A low-temperature refrigeration system was selected to maintain −18 °C efficiently.

Key Design Features

  • Industrial-grade compressors suitable for low suction temperatures

  • Proper refrigerant selection for low-temperature operation

  • Multiple compressors for capacity staging

  • Redundancy to ensure continuous operation

This configuration ensured both reliability and energy-efficient part-load operation.

Step 3: Evaporator & Air Distribution Design

Uniform temperature distribution was critical.

Design Considerations

  • Ceiling-mounted low-temperature evaporators

  • Adequate air throw to cover the entire storage volume

  • Avoidance of direct air blast on products

  • Even air circulation to prevent hot spots

Evaporator selection balanced cooling capacity with minimized dehydration of dairy products.

Step 4: Insulation & Cold Room Construction

Thermal insulation quality directly impacts energy consumption.

Construction Details

  • High-density insulated panels for walls and ceiling

  • Insulated flooring with vapor barrier

  • Proper sealing of all joints and penetrations

Insulation thickness was selected to minimize heat ingress while preventing condensation on external surfaces.

Step 5: Door Design & Infiltration Control

Doors are a major source of heat and moisture ingress.

Measures Implemented

  • Insulated, airtight cold room doors

  • Self-closing mechanisms

  • Air curtains or strip curtains

  • Operational discipline for door usage

These measures significantly reduced infiltration load and frost formation.

Step 6: Frost & Defrost Management

At −18 °C, frost buildup on evaporator coils is unavoidable.

Defrost Strategy

  • Controlled electric or hot-gas defrost cycles

  • Scheduled defrost during low-load periods

  • Drain pan heating to prevent ice blockage

Proper defrost control ensured efficient heat transfer and stable room temperature.

Step 7: Temperature Monitoring & Controls

Precise control was essential for product safety.

Control Features

  • Digital temperature controllers

  • Multiple temperature sensors within the room

  • High- and low-temperature alarms

  • Data logging for audit compliance

Continuous monitoring ensured traceability and early fault detection.

Step 8: Hygiene & Food Safety Considerations

Dairy storage requires strict hygiene standards.

Design Measures

  • Smooth, cleanable interior surfaces

  • Proper drainage to avoid water accumulation

  • Easy access for cleaning and inspection

  • Separation from raw material or processing areas

The system was designed to support regular sanitation without compromising insulation or equipment.

Commissioning & Performance Validation

Before handover, the system was thoroughly tested.

Commissioning Activities

  • Pull-down test from ambient to −18 °C

  • Temperature uniformity mapping

  • Door opening recovery tests

  • Defrost performance verification

All parameters were recorded and documented for client validation.

Results & Operational Performance

After commissioning:

  • Stable temperature maintained at −18 °C ±1 °C

  • Uniform cooling across storage zones

  • No condensation or excessive frost issues

  • Improved product shelf life and quality

  • Energy consumption within projected limits

The cold storage met both operational and regulatory expectations.

Key Lessons Learned

  • Accurate heat load calculation prevents oversizing

  • Infiltration control is critical at −18 °C

  • Insulation quality directly affects operating cost

  • Proper defrost management ensures long-term efficiency

  • Monitoring and alarms are essential for dairy safety

Why This Design Works for Dairy Cold Storage

For butter and cream, reliability and consistency matter more than rapid freezing. This design focused on steady low-temperature operation, hygiene, and energy efficiency—ensuring product integrity and operational peace of mind.

Conclusion

Designing a −18 °C cold storage facility for butter and cream requires careful coordination of refrigeration engineering, insulation design, airflow management, and hygiene practices. This project demonstrated that with the right approach, it is possible to achieve stable low temperatures, protect dairy quality, and operate efficiently over the long term.

In dairy cold-chain infrastructure, temperature stability is quality assurance.


For More Information Visit Our Website: www.wcsipl.com // www.wcsipl.net

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