Developing and designing french fry lines for more than 50 years

Preparation

As potatoes are received to the plant, they are sorted and pre-graded to correspond with the type of french fry or other product to be produced. Potatoes then enter the line and pass through the Cyclone destoner and pre-washing units before conveyed to the peeler. 

Steam peeling and inspection

In the Steam peeler, steam is injected during a short period, which makes the skin loosen from the potato flesh. Steam peeling is gentle and efficiently resulting in low peeling losses. The potatoes are directly conveyed to De-skinner, which removes the peel waste. This waste is pumped away. The potatoes are then washed clean prior to being inspected at the Roller Trimming Table and transported to the cutting process. 

Cutting

The cutting is performed by either a hydro-cutting or mechanical cutting system. The Hydro Cutting system uses water that is pumped together with the potatoes, through an exchangeable cutting block. In a Mechanical Cutter the potatoes can be cut into straight or crinkle cut, dices or other types. In the next step, the cut product passes a Sliver Remover, where small triangular shaped pieces are removed. A vibratory Nubbin Remover will sort out all short strips over exchangeable screens.  

Blanching

The potato strips pass through a blanching system, consisting of two Screw blanchers. Blanching is used to gelatinize starch, inactivate enzymes for colour and leak out sugar. The first blancher is designed for short time and high temperature and the second one for low temperature and long time. After blanching, the strips go through a SAPP-dipping unit before being pre-dried. 

Drying

During the drying process, the moisture content is reduced and will prepare the strips for the frying process so that the final texture and colour can be achieved. The new updated drying system from 2024 improve hygiene and cleanability which means longer production hours and saves energy with heat recovery. In the Belt Dryer, air with low temperature and high humidity will ensure even drying result of each strip. The Belt Dryer uses the counter–air–flow principle where the air flow covers the full width of the belts. Drying is used to maintain uniform colour, stabilize product quality, avoid weak and soggy products to get final crispy fries. Before entering the fryer, the dried strips are slowly conveyed on the Equilibration Belt to get an even and uniform moisture content. 

Multi Zone Frying

The Multi-Zone Frying System consists of; frying pan, drum oil filter, oil circulation pump and tube heat exchanger. The Frying pan with controlled oil flows together through multiple oil in- and outlets will give you the best tools to achieve the desired texture and colour. The frying belt lays directly on the pan bottom and with the belt return on the outside, it results in a very low total oil volume in the complete system. The drum oil filter continuously filters every drop of oil every 30 -45 seconds. The oil pump transfers the oil to the tube heat exchanger, where the vegetable oil is heated indirectly by steam or thermo oil. After frying the product will pass a de-fatting step, which can be a special designed de-oiling vibratory conveyor or an oil miser. For coated fries and other potato products, a batter applicator, settling belt and 1st stage-frying step is added before the normal frying system.

Read more about Rosenqvists coated french fry system here! 

Freezing & packing

After the de-fatting step the golden french fries will enter the freezer on their way to the packaging system. The line can also be equipped with a pre-cooler installed before the freezer if needed.