With increasing demand for ready-to-eat food items and pressure to reduce food wastage, commercial kitchens require advanced food preparation and preservation equipment. Blast chillers have emerged as one of the most effective solutions for commercial kitchens to quickly chill or freeze cooked foods while maintaining high food quality and safety standards.
What are Blast Chillers?
Blast chillers, also known as shock freezers or blast freezing tunnels, are industrial food preparation appliances that allow rapid and precise cooling of cooked foods using a blast of cold air. They help reduce the temperature of hot foods cooked in commercial kitchens from +90°C to +3°C or below in a very short span of 90-120 minutes. This rapid cooling prevents the proliferation of harmful bacteria in the 'danger zone' between +5°C and +63°C, where bacteria multiply quickly.
Working Mechanism of Blast Chillers
Blast Chillers have a refrigeration system that circulates chilled air at very low temperatures, usually between -35°C to -40°C, inside an insulated chamber. The hot food is placed on mobile racks or mobile containers that are loaded inside this cold chamber. Fans inside the chamber ensure uniform circulation of cold air around the food at very high velocities, typically 5-10 meters/second. This blast of cold air enables ultra-fast extraction of heat from the surface and core of the food via two methods - convection and respiration. Within 1-2 hours, the core temperature of the largest food item drops below +3°C, making it safe for storage from a food safety perspective.
Food Quality Benefits of Blast Chilling
Apart from ensuring food safety, blast chilling also helps maintain high food quality in several ways:
- Retains nutrients, flavours and texture: The flash freezing effects during blast chilling prevent food dehydration, nutrients loss and texture changes.
- Stops enzymatic actions: Rapid chilling arrests enzymatic and microbial actions that can cause loss of texture, consistency and visual appeal over time in refrigerator storage.
- Increases shelf life: Proper blast chilling doubles or triples the normal refrigerator shelf life of cooked foods allowing better planning and utilization.
- Maintains appearance and colour: Slow cooling in a refrigerator causes condensation on food surface leading to discoloration but blast chilling prevents this.
Types of Blast Chillers
Based on design and application, commercial blast chillers come in various types:
Compression-System Chillers: Most common types used for small to medium kitchens. Rely on traditional vapour-compression refrigeration cycles.
Absorption-System Chillers: Eco-friendly options that use water as a refrigerant. Better for large scale production areas with high energy costs.
Pass-Through Tunnel Chillers: Efficient continuous processing models ideal for high volume catering businesses requiring rapid throughput.
Hydrostatic Chillers: Unique blast chilling through partial immersion of food in cold water. Useful for delicate items like bakery products, fruits etc.
Modular Chillers: Customizable modular units that can be joined together for varying capacity needs of restaurants and hotels.
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