Potato chips are one of the most popular and evergreen snacks in the world. According to Wikipedia, the earliest known recipe was published in a cookbook in 1817. For generations, potato chips remain one of the most popular snacks in the world.

    

In the supermarket shelves, we can typically find two types of fried potato chips. One type is the fresh cut potato chips and the other is the fabricated potato chips. Snacks manufacturers produced the fresh cut potato chips from raw potatoes while fabricated potato chips are produced from processed potato powders such as potato flakes/granules. Raw potatoes go through the following process to transform from a raw piece of potato to the finished product potato chips in a packet we find in the supermarket:

    

Wash -> peel -> slice -> starch reduction -> sugar reduction -> surface water reduction -> fry -> seasoning -> pack.

   

In this article, we look at Handyware Engineering’s fresh cut potato chips processing line.

   

Wash

Raw potatoes from the farm are transported to the first stage of the processing line, which is the washing machine to wash off the soil on the raw potatoes. The washing machine is a rotating drum with spray nozzles fitted in the drum. Raw potatoes are fed into the rotation drum via a mesh belt conveyor. There is a hopper at the conveyor to house the raw potatoes.

 

 

Picture 1 : Conveyor and Washing machine

  

Peel

After washing off the soil, the raw potatoes are sent for peeling. The washed potatoes are fed to the peeling machine via a conveyor. The peeling mechanism is based on centrifugal rotation of the potatoes against a rough wall. The potatoes rub against the rough wall to peel off the skin on the potatoes

 

 

 

Picture 2: Conveyor and Peeling machine

 

Inspection

After peeling, the potatoes are inspected before they are sent for slicing. During inspection, if the potatoes are oversized, they are manually chopped into smaller pieces. Oversized pieces might result in poorer cutting performance in the slicing machine.

 

 

Picture 3: Inspection belt

  

Slice

The peeled raw potatoes are fed into the slicing machine via a conveyor. The slicer houses a total of 8 sets of blades at the wall of slicing system. Centrifugal force rotation swings the potatoes against the 8 blades, slicing of pieces of flesh off the potatoes. Typically, the thickness of each piece of potato slice is about 1.5mm

  

 

Picture 4: Conveyor and Slicing machine

   

Starch Reduction

After the raw potatoes are sliced, they will be sent for starch reduction. Starch reduction is necessary to ensure product does not turn dark after fry. During this stage, the surface starch on each slice of potatoes is washed. In the washing machine, a mesh conveyor belt fetches the sliced potatoes through a tunnel. The top and bottom region of the tunnel is fitted with water spray nozzles across the width of the belt. During washing, water is sprayed at the potato slices from the top and bottom. A starch collection sink is positioned at the side of the washing machine. The rinsed water will flow into the collection sink. There is a filter inside the sink, filtering the water before they are recycled back into the washing machine. Operator may control the fresh and recycled ratio of water introduced into the washing machine.   

  

 

 

Picture 5: Starch Washing machine

  

Sugar Reduction

Similar to starch, the high amount of sugar in the potatoes will result in dark product after fry. Hence it is necessary to reduce the amount of sugar in the potatoes before fry. Sugar reduction is achieved using hot water blanching. During this process, potatoes are soaked in water about 70 Degree Celsius. This opens the membrane and sugar leaks from it. The hot water blancher has a rotating drum in the casing. Potatoes are fed into one end of the drum and leaves at the other end. Hot water (70 Degree Celsius) are fed into the drum to soak the potatoes. Temperature is maintained using an external heat exchanger.     

  

 

Picture 6: Hot Water Blancher

  

Surface Water Reduction

Throughout the previous stages of processes, water is sprayed on the potatoes. At this stage, water at the product surface will be reduced before they are sent into fryer for frying. The water reduction (dewater) machine utilizes blow and suction force to remove the moisture from the slices of potatoes.

   

   

Picture 7: Dewater machine

   

Frying

The frying system utilizes an external heat exchanger to maintain frying temperature. The heat exchanger design is coil type (CTHX). A hot oil pump continuously transports the oil from the frying pan to the heat exchanger to perform continuous heating. The heated oil be recycled back into the frying pan. At the frying pan, there are two oil inlets and one outlet.

   

 

 

Picture 8: Frying machine

 

Seasoning

After frying, the fried chips are sent into the seasoning system for seasoning application. The seasoning system includes seasoning applicators and seasoning drums. The seasoning applicator includes a seasoning hopper, screw feeder and vibration scraf. The product is fed into the rotating drum, and seasoning is applied on the product in the drum. The drum rotates slowly to ensure seasoning is uniformly applied onto the product surface.

   

  

Picture 9: Seasoning system