The selection and design is dependent upon operational requirements as well as product condition. There is no single type of freezer that is best for all food freezing applications.
In practice, the food manufacturer must carefully balance the capital cost, operating cost, throughput and product quality, when deciding on which systems to install. However, advances in both technologies are reducing these distinctions. Fast freezing rate, smaller footprint, and lower capital costs are usually cited as the main benefits of a cryogenic system, while high cryogen cost is often cited as the main disadvantage. In many ways this debate has been to the benefit of all sides leading to advances and improvements in all systems. There has been a constant debate in the industry between the relative merits of mechanical versus cryogenic systems.
Both systems can freeze the food using various freezer designs, including tunnel, spiral, fluidised bed, impingement, spray, immersion, etc. There are two main types of freezing system: mechanical (which use a circulating refrigerant to reduce the temperature of air or a liquid which is passed over the food) and cryogenic (which use the direct application of liquid nitrogen or carbon dioxide onto the food). Although not true for all foods, minimising freezing times can be advantageous in also reducing energy consumption, increasing throughput, and improving yield. There is a general view that fast freezing, and the formation of small ice crystals, offers some quality advantages.
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