Quality Optimization with State-of-the-Art Vacuum Cooling of Baked Goods

With 21 shops, Fleur de Pains is a medium-sized bakery and patisserie in western Switzerland that places great value on high-quality baked goods, patisserie and confectionery products. All the products are made by hand using traditional methods in Crissier near Lausanne, Switzerland. In addition to this craftsmanship, consistently high quality of the baked goods is also made possible by modern vacuum cooling, which very quickly cools the products after they are baked and prepares them for further processing or sale.

The production of all these goods is very much influenced by craftsmanship. All products are made fresh daily at the bakery in Crissier using only natural ingredients. Rolls are not crisped up at the individual shops. This seems to be a recipe for success because Fleur de Pains is on a growth trajectory and opens an average of two new shops per year. 2000 bread loaves of various types are baked and sold every day. The yearly flour requirement is 500 tons.

To guarantee consistently high quality of the baked goods, Managing Director Stéphane Simon invested considerable time and thought and kept testing and changing the manufacturing process. The most difficult aspect was creating a firm bread crust and consistent texture of rolls and croissants on humid days. The Aston Foods International AG company offered him a vacuum cooling system. This was to improve the quality of the baked goods and simultaneously dramatically reduce the baked goods' cooling time after baking. Stéphane Simon dared to try it and in August 2015, he installed a vacuum chamber (fig. 1) in his bakery.


Fig. 1: Vacuum chamber for a manually loaded transport rack

This vacuum chamber is connected to a vacuum pump located in a separate room (fig. 2). The vacuum chamber is designed so that it can accommodate a manually loaded transport rack. The baked goods are placed in the vacuum chamber immediately after baking. There, in a vacuum, they are cooled to 30 to 35 °C within one to three minutes. Afterwards they can be removed and almost immediately eaten or processed further. When the vacuum cooling system was introduced, Stéphane Simon deliberately did not inform customers or employees so he could test whether there would be a reaction from the consumers. Positive feedback quickly came from all shops. The customers praised the beautiful bread crust, its refined colour and more homogeneous formation of pores and the associated greater volume. These visual impressions reinforced customers' awareness that they were really able to enjoy a high quality product.


Fig. 2: The COBRA NC screw vacuum pump from Busch guarantees precise maintenance of the pressure profile during the cooling process

The principle of vacuum cooling of baked goods has been well-known for decades but was not able to be technically implemented in a satisfactory way in practice. The Swiss company, Aston Foods International AG, perfected vacuum cooling and, in the process, works closely with Busch AG in Magden in Aargau, Switzerland. Today, Aston Foods' cooling systems are equipped with dry COBRA screw vacuum pumps from Busch as standard. While oil-lubricated rotary vane vacuum pumps were often used while vacuum cooling systems were first being developed, Aston Foods had already switched to using COBRA screw vacuum technology two years ago. When compared to all other vacuum generators, this technology has substantial advantages. Firstly, COBRA vacuum pumps are operated entirely without oil or other operating fluid in the compression chamber. This means that water vapour that can be sucked into the system during the cooling process cannot mix with any operating fluids and condense in the vacuum pump in the process. Secondly, the high pumping speed of the vacuum pump in the low pressure range makes it possible to set up the vacuum pump 20 metres away from the actual vacuum chamber in an adjacent room. 

Due to the elimination of the oil and thus the risk of forming an emulsion with the condensate, all maintenance work required for oil-lubricated vacuum pumps in cooling processes, such as regular oil and filter changes, become unnecessary. Both COBRA vacuum pump screw rotors (fig. 3) avoid contact with both themselves and the housing. Thus there is no wear and there are no wearing parts to be exchanged. This is an important benefit for Stéphane Simon because, despite the improvement in quality, he has no additional costs. Maintenance of the entire vacuum cooling system is only performed once a year by service technicians from Aston Foods. Christian Vetterli, CEO at Aston Foods, confirmed that the yearly maintenance effort for the system takes between two and four hours. Although the system at Fleur de Pains operates in two-shift operation six working days per week every year, the only maintenance the vacuum pump requires is cleaning the inlet filter and exchanging the gear oil. 


Fig. 3: The contact-free screw profile of the COBRA vacuum pump enables an oil-free vacuum

For Fleur de Pains, converting to a vacuum cooling system also brings further advantages: The cooling time for the baked goods is reduced from several hours to one to two minutes, depending on the product. During conventional cooling, the baked goods are exposed to various environmental influences like humidity and ambient temperature, which have an uncontrollable influence on the quality. Today with vacuum cooling, the process after baking is precisely fixed and independent of all external conditions. "The process requirements for vacuum cooling are demanding," said Mr Vetterli, "but thanks to the integrated control and reliable vacuum technology it is perfectly manageable". Fleur de Pains installed a total of 150 programs for cooling its various products. In doing so, the exact procedure for the cooling process for each product is individually defined and can be replicated. The programs were finely adjusted together with the specialists from Aston Food during the initial phase and can now be easily started with the press of a button. 

The two deciding factors during the cooling process are the time and the progression of pressure in the vacuum chamber. The cooling process begins at atmospheric pressure and, after a predefined progression, reaches a vacuum of 30 to 50 millibars. This process can be repeated within the cooling period and, depending on the product, can pass through different vacuum levels. The COBRA screw vacuum pump also demonstrates itself to be the ideal vacuum generator here. It works reliably at all vacuum levels, from atmospheric pressure to far below one millibar. According to Christian Vetterli, "it is important that the predefined vacuum level and the pressure profile are precisely maintained. In the process, it is not a matter of achieving the highest possible vacuum. It is more about achieving the right vacuum level or precisely maintaining the predefined pressure profile." 

With the introduction of this state-of-the-art vacuum cooling system, Stéphane Simon was able to achieve a significant and consistent quality improvement for his baked goods. The genuinely positive reactions of customers in his shops are the best evidence of this.

About Fleur de Pains

Fleur de Pains was founded in 2005 and employs 200 staff, 50 of which work at the production company in Crissier. Various types of breads, baked goods like bread rolls, croissants, brioches, cakes or muffins and patisserie products are made here, as are snacks, salads and sandwiches. These are freshly delivered at least twice each day to the company's shops. A small portion also goes to hotels and other sales outlets.


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