Freezing on a Large Scale
Of the available preservation technologies, freezing has long been recognized as an excellent method of preserving the quality characteristics of bakery products. However, physical parameters such as specific volume, moisture, hardness, gas cell distribution and size are all influenced by the freezing rate.
Too quick freezing will impact yeast activity but too slow will result in large water crystal formation and moisture loss. It is critical to find a moderate freezing rate, depending on the product, and a uniform airflow across the product zone.
The Right Solution
Cryogenic systems are not adapted to bread and more generally to bakery processes as Nitrogen or CO2 generates very low temperatures below -70°C which burn product surface. In addition temperature control is challenging with cryogenic freezing.
“The solution to get the right product quality is still mechanical refrigeration allowing for a wide range of temperature levels and accurate temperature control. Refrigerant and refrigeration systems are designed to ‘feed’ the process equipment heat exchangers with the right temperature and with minimum energy consumption.
Inline solutions provide the best quality in regards to accurate temperature control versus batch solutions where door openings during product loading and unloading are generating temperature and moisture variations”, representatives of GEA cooling specialist told us.
As a provider in automated equipment and production lines for industrial bakeries and pastry-making activities, MECATHERM also develops cooling and freezing solutions.
Jérémy Hogrel, Soft & Pastry Sales Support Manager explained for European Baker & Biscuit that their freezing solutions rely on a mechanization system to transport the products to be cooled or frozen surrounded by an isothermal enclosure. Inside of it, a set of heat exchangers combined with blowing fans are ensuring products temperature lowering to reach a correct cooling and freezing state after a specified time ensured.
Spiral or Vertical
During cooling and freezing phase, two types of transporting products through the line are available:
“The first solution consists in a spiral mechanization system, and another solution is based on vertical trays with a handling mechanization. The most current technology used in the industrial bakery is the spiral technology. Well-known, easy to install, it’s a reliable equipment. In parallel a real alternative based on a vertical mechanization system exists. This system can be used with baking trays or with dedicated cooling / freezing trays. It’s a disruptive solution with multiple and applicable benefits during production but also outside the production hours,” he explains.
The choice between these two solutions depends on three elements: on the products, on the range of SKUs to be handled in the cooler and / or freezer and lastly on the expectations of the process step itself in terms of efficiency, maintenance, and flexibility.
At first sight, working all day long on a production line, on a mono-type product and on a spiral solution seems simpler than manipulating trays, which may appear inconvenient or more complex. In fact, the opposite is true: trays are one of the most interesting points of this solution, enabling the operator to also wash the handling support during production.
Using trays during other process phases has also other advantages: it allows stationary operations for the decoration or personalization of products or gives the opportunity to buffer in the event of downstream stoppage.
You can read the rest of this article in the May-June Issue of European Baker & Biscuit magazine, which you can access by clicking here.