Ever wonder how crisps are actually made?

The “cooking lab” in Oak Park is where new potato varieties are tested for their performance in the kitchen. The big test is for “fry colour” – that golden colour you like to see on your chips and crisps.

A light fry colour can be difficult to achieve when breeding a potato. Some of the varieties grown here in Ireland are not suited to processing because of their poor fry colours.

The result of this is that €10 million worth of processing potatoes are imported into this country every year.

One of the aims of the breeding programme in Teagasc Oak Park is to develop varieties with light fry colours, that can be grown in Ireland and can also be stored between 4-6°C without deterioration in fry colour.

Light fry colour is needed in the production of chips and crisps. However, many potato varieties grown in Ireland are susceptible to naturally high reducing sugar levels – the accumulation of natural sugars due to senescence and low temperature sweetening during cold storage. These traits result in dark fry colour.

DNA sampling

The sequencing of the potato genome in 2011 opened up the world of potato breeding and may contribute to lower potato imports in the future and the development of more Irish grown potatoes for processing.


Being able to track genetic markers for traits of interest can help to speed up and take the randomness out of potato breeding, which can traditionally take 12-15 years for one variety.

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By taking a small piece of leaf tissue from a potato plant, that plant’s DNA can be tested to see what genetic markers it has and this information can be factored into decisions about whether is should stay in the potato breeding programme or not.

At present, Teagasc is gathering information on potato genes, fry colour and other processing characteristics.

Teagasc researcher, Fergus Meade, explained how this information can help to improve the potato breeding programme in the future.

All of this information gets fed into a model, which we are improving each year. We hope that will help us to predict fry colour in the future, without having to go through the process of actually frying large numbers of candidate varieties coming through the programme.


The crop to crisp process

Meade gave his presentation on “Marker assisted selection for fry colour in potatoes” at Potato Day for Science Week in Teagasc, Oak Park. Once the scientific details were out of the way “the crop-to-crisp process”, which has 11 steps, was described by Amy O’Leary of Keogh’s Crisps.

The Keogh family grow a mix of Lady Rosetta and Lady Claire potatoes to make crisps for their family-run business. Lady Rosetta potatoes are used at harvest and Lady Clare potatoes keep well in the store for later use.

The majority of potatoes are grown on Keogh’s farm, but they also come from two other farms and all are checked for quality on arrival.

11 steps of crisping:
  1. Washing – potatoes are gently washed to prevent any damage;
  2. Peel and slice to 1.8mm thickness, no more no less;
  3. Cooking in high quality sunflower oil for 7-8 minutes;
  4. Resting – to remove any excess oil;
  5. Grading is carried out with an optical grading machine for size, air puffs and colour;
  6. Visual inspection for consistency;
  7. Sizing – crisp size is graded to make sure that bags are even;
  8. Flavouring – the flavouring machine seasons all crisps evenly;
  9. Bagging – scanned with a metal detector;
  10. Weight corrector – makes sure every bag is the correct weight;
  11. Case fill – getting the packets packed for sale.
Amy O’Leary of Keogh’s Crisps addressing the attendance at Potato Day for Science Week at Teagasc Oak Park