Freezing for French fries & Co
French fries, which actually originated as a Belgian specialty, are today famous around the world as a side dish or snack – but with a somewhat tarnished reputation for allegedly high fat content. These crispy delights, though, are better than their reputation. If properly prepared, their fat content is around 13 %. If consumers bake pre-deep fried and deep-frozen French fries in their own ovens, according to package instructions, they can enjoy a product with around 5 % fat. The type of fat being used, however, is crucial for effects on human health. By now, most manufacturers now use healthy vegetable oils such as sunflower-seed oil, rather than the earlier controversial hardened fats.
French-fry freezing tunnels typically handle capacities from 10 to 30 t / h, which amounts to an average of 6 million portions produced per day and per plant. French fries, at 200 °C / 392 °F in a deep-fryer, then proceed through a cooling and freezing tunnel that reduces the product temperature from 95 to - 18 °C / 203 to - 0.4 °F. Energy costs for freezing accounts for a large amount of the expenses arising for these deep-frozen potatoes. For companies of this size, methods for reduction of energy consumption are of course especially interesting. Cooling and freezing systems perfectly adapted to the various production processes – including predictive control systems provided by GEA – keep energy consumption to a minimum. An example of a GEA IQF tunnel for French fries can include various temperature zones from pre-cooling to freezing. The initial pre-cooling section includes a thermosyphon coil, which generally uses ammonia as refrigerant. After condensation in an evaporative condenser, the ammonia evaporates in the coil – which generates enough energy to cool the French fries from 95 to 50 °C / 203 to 122 °F, without the use of refrigerating compressors. This process is virtually energy-free! The following pre-cooling section includes a heat exchanger fed by water from the plant. During circulation in this coil, water is warmed from 15 to 22 °C / 59 to 71.6 °F while the French fries are cooled from 50 to 30 °C / 122 to 86 °F. This saves energy in the factory hot-water system. In addition, the waste heat produced during cooling and freezing in such plants can be used by heat-pump technology from GEA to heat water from 30 to 80 °C / 86 to 176 °F for use in other parts of the plant – resulting in energy savings of up to 30 %. For a production line for French fries with a capacity of 18 metric tons per hour, this means annual savings of around 500,000 euros.
But it’s not only sophisticated and energy-saving technology that helps to save money. Designs on the drawing boards already reveal savings potentials, in which developers direct their attention to simple maintenance and implementation of hygiene regulations. Freezers from GEA are designed such that cleaning is up to 40 % faster than with other types. Some reasons for this time saving are the smooth surfaces that are easy to clean, as well as the stainless steel structures, without joints and with welded connections throughout, where dirt hardly has a chance to collect. This involves the entire enclosure, including unit floor, as well as the inner structure. In addition, the floor of the unit is sloped and all structures are elevated on welded studs, so that liquids can run off without difficulty.
Pizza is the most evident synonym for frozen and convenience food itself – throughout the entire world. In the USA, for example, we are told that Americans eat about 40 hectares of pizza every day – the area of around 90 soccer fields. Its great success is based on its versatility. Whether topped with meat, vegetables, or seafood: there is something in a pizza for practically everyone. And you can say the same about systems provided by GEA – whatever pizza variations are included in your product portfolio, we’ll find the matching cooling and freezing technology.
Now and then, we are asked for a solution before production of these Neapolitan specialties actually begins. For example: for the harvest of broccoli, a popular pizza topping. Broccoli must be cooled still on the field since its great metabolic activity would otherwise quickly make it appear wilted. You can also relax while depending on our systems for the subsequent cooling processes with broccoli and other vegetable types in the food-processing industry: for example, GEA IQF tunnels with individually quick frozen technology (IQF). This technology guarantees the individual freezing of fruits and vegetables, so that vegetable topping can be easily weighed later by a machine and distributed over the pizzas. But before this stage, of course, the yeast dough must be kneaded, formed, pre-baked, and cooled again, to prevent the frozen vegetables or ground meat, for example, from immediately thawing. In the next step, the pizzas pass through the freezer, with entrance temperature between 45 °C / 113 °F and 100 °C / 212 °F, depending on the pizza. The temperature at the end of the production process, to be sure, is always - 18 °C / - 0.4 °F. The freezer cools the product down to - 25 °C / - 13 °F, to provide a “buffer”; otherwise, the light and thin convenience food could warm up above the specified - 18 °C / - 0.4 °F during packaging. In the pizza sector, production with large-capacity facilities and three working shifts a day are typical. Cost-effective work is of course possible under these conditions only with high-performance and long-life systems that are not easily susceptible to breakdowns. Two good examples of solutions here are our GEA E-Tec and GEA A-Tec double-drum spiral freezers, with output ratings of 12 tons per hour.
With such production volumes, down times mean great loss of money. Still, the most reliable systems need maintenance now and then. To allow the service team easy access, the drive systems are installed outside the equipment housing. In addition, GEA, if requested, can also deliver freezers with sequential defrosting functions (SD). With these solutions, the equipment can operate without interruption for six days. But cleaning must always be quickly and effectively possible. This begins with the basic design: dirt has no chance from the very beginning to adhere to smooth and jointless stainless-steel structures. The integrated, automatic Clean-in-Place (CIP) system ensures no-compromise hygiene – and in conjunction with a special recirculation system, it also saves water.
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