In the food refrigeration industry, choosing the appropriate cold storage temperature is crucial for maintaining product quality. This article explores the key differences in unit selection between low-temperature cold storage (below -30 ℃) and ordinary freezer (-18 ℃), as well as which one is more suitable for storing seafood and frozen food.

Temperature requirements and principles of food preservation

Ordinary freezer (-18 ℃): International standard freezing temperature, suitable for most frozen foods, can effectively slow down microbial growth and enzyme activity, and extend food shelf life.
Low temperature cold storage (-30 ℃ and below): provides a deeper freezing environment, which can quickly pass through the "maximum ice crystal generation zone", reduce the damage of ice crystals to food cell structure, and better maintain the original texture and flavor of food.

Analysis of Differences in Unit Selection

1. Compressor type and configuration

Low temperature cold storage: usually requires a two-stage or stacked compression system, using low-temperature dedicated compressors (such as Bitzer, Gulun and other brands' low-temperature series), with an evaporation temperature of up to -45 ℃ to -50 ℃
Ordinary freezer: A single-stage compression system can meet the requirements, with an evaporation temperature of about -25 ℃ to -30 ℃

2. Refrigerant selection

Low temperature cold storage: It often uses low-temperature refrigerants such as R404A, R507A, R23, etc., which have lower evaporation temperature characteristics
Ordinary freezer: commonly used R22 substitutes such as R407C, R410A, or natural refrigerants such as ammonia and carbon dioxide

3. Evaporator design

Low temperature cold storage: The fin spacing is larger (usually 6-12mm) to prevent frosting and blockage; Equipped with an efficient defrosting system
Ordinary freezer: standard fin spacing (usually 2-4mm), relatively low defrosting requirements

4. System efficiency and energy consumption

Low temperature cold storage: has a lower coefficient of performance (COP) and consumes 30-50% more energy than a regular freezer
Ordinary freezer: High energy efficiency and relatively low operating costs

5. Initial investment cost

Low temperature cold storage: equipment costs are 40-70% higher and installation is more complex
Ordinary freezer: lower cost, easier installation and maintenance

Storage suggestions for seafood and frozen food

Suitable for low-temperature cold storage (below -30 ℃):

High end sashimi and sushi grade seafood: require ultra-low temperature to maintain cell structure integrity
Seafood stored for a long time (over 6 months): below -30 ℃ can better maintain texture and flavor
Quick frozen prepared food: Quickly generate ice crystals to maintain the original taste of the food
High fat fish (such as salmon and tuna): Low temperature slows down fat oxidation, maintains color and nutrition

Suitable for ordinary freezer (-18 ℃):

Short term storage of seafood (consumption within 3-6 months)
Processed and cooked seafood products
Most frozen vegetables and fruits
Commercial frozen food with fast circulation speed

Industry Trends and Suggestions

As consumers demand higher food quality, many seafood suppliers are turning to low-temperature storage solutions. Japan and Nordic countries have already set -30 ℃ to -50 ℃ as the standard storage temperature for high-quality seafood.

Expert advice:

For the high-end seafood market and long-term storage, investing in low-temperature cold storage may have high initial costs, but it can significantly enhance product competitiveness
For regular retail and short-term turnover, a -18 ℃ freezer is still the most economical and practical choice
Hybrid solution: Large processing enterprises can be equipped with two systems simultaneously, which can be flexibly used according to different product requirements

Conclusion

The choice of cold storage system depends on the specific product type, storage time, quality requirements, and budget constraints. For seafood and frozen foods that pursue the highest quality, low-temperature cold storage below -30 ℃ can provide better preservation effect; For most commercial applications, a regular freezer at -18 ℃ is still the most cost-effective choice. Enterprises should comprehensively consider product characteristics, market demand, and investment returns when making decisions, and choose the refrigeration solution that is most suitable for their own business.