Cryogenic or mechanical freezing –
what's best for your production line?
The Covid-19 pandemic, followed by a cost-of-living crisis resulted in a sharp increase in demand for frozen food products from consumers. In fact, data from the British Frozen Food Federation shows that volume sales for frozen food continue to grow as price-conscious consumers look for more affordable options. We're increasingly working with food manufacturers looking to introduce new frozen ranges or scale up existing operations in response.
One question that often comes up is whether mechanical or cryogenic freezing is best. The answer depends on several factors, not least the type of product being handled and the required production rate, the factory layout, and the need for flexibility and speed. The most sensible starting point is to really understand the key differences between mechanical and cryogenic freezing.
Spot the difference!
Mechanical freezers were the first to be used in the food industry and are currently used in the majority of freezing lines. They function by circulating a common refrigerant around, which withdraws the heat from the food product. Mechanical freezers typically operate in the temperature range of -30 to -40°C.
By contrast, cryogenic systems can operate at much lower temperatures, for long periods, using the cold properties of cryogenic gases – namely liquid nitrogen or liquid carbon dioxide to freeze food to temperatures as low as -120 °C.
The biggest difference between the two methods is the time that the product spends in the critical freezing zone where the ice crystals are generated. Typically, mechanical freezing results in larger crystal sizes, which can have a knock-on impact on texture, quality, and rate of drip loss at the defrosting stage. But there are other differences too, which all need to be considered when choosing the right technology for your production process.
Speed of freeze
With cryogenic freezing, food items can be rapidly chilled and frozen to a sustainable temperature and shelf environment within minutes. Why is speed important? Well, other than maximising product output, the faster a product is frozen, the faster it becomes microbiologically stable as the growth of bacteria is dramatically slowed. For frozen foods, -18°C delays chemical reactions and puts any bacteria that may be present on pause. Both mechanical and cryogenic freezing can deliver here, but cryogenic processes, depending on the product, can typically freeze five times faster than mechanical freezers.
Floor space
Cryogenic freezers take up significantly less factory floor space when compared with more traditional mechanical freezers while delivering the same outputs. So, in larger factory environments, where space is not an issue, then mechanical or cryogenic freezing could be an option, whereas cryogenic freezing would be preferable when there is a need to maximise available space for production and operator efficiency.
Product flexibility
Equally, the type of product you're manufacturing matters too. Mechanical freezing is best suited to environments which run one base food product consistently, at the same production speed.
On the other hand, cryogenic freezing is a better option for manufacturing environments where there are multiple, higher value products running at different production speeds, or where there are seasonal variations in activity.
In this environment, manufacturers are also likely to have a heightened interest in the sort of data and insight that digital monitoring can offer. Cryogenic freezing allows for the addition of Freshline® Smart Technology, a system that offers improved efficiency and safety by using diagnostic sensors and wireless communications technology to investigate, record and review freezer performance data and production data in real time.
We're seeing a real appetite for this sort of data, and increasingly our customers are finding it can inform key strategic decisions about production lines and product processing.
Cost
Last, but not least, we need to consider cost. The initial capital costs for mechanical freezers tend to be higher, but ongoing running costs are lower. By contrast, cryogenic freezers incur lower capital costs (as they are typically leased) but cost more to run, but when you take into consideration all the other benefits the overall costs can be similar.
