First choose your potato

The method and length of cooking potatoes affects both griddle cake dough and other uses for potatoes. The aim is to find the best cooking method for different variations of dry matter and starch content, for example. Besides being an important food product in itself, the potato is the most important ingredient in griddle cakes, many snack foods and chips. The large variations in the constituents of potatoes can be a challenge for the producers. A recently developed measuring method allows better control of the important quality parameters.

Contact person
Portrettbilde av Nils Kristian Afseth
Nils Kristian Afseth

Senior Scientist
Phone: +47 958 40 641
nils.kristian.afseth@nofima.no

The method and length of cooking potatoes affects both griddle cake dough and other uses for potatoes. The aim is to find the best cooking method for different variations of dry matter and starch content, for example.
The method and length of cooking potatoes affects both griddle cake dough and other uses for potatoes. The aim is to find the best cooking method for different variations of dry matter and starch content, for example.

Besides being an important food product in itself, the potato is the most important ingredient in griddle cakes, many snack foods and chips. The large variations in the constituents of potatoes can be a challenge for the producers. A recently developed measuring method allows better control of the important quality parameters.

"It is now quicker and easier to measure dry matter content, for example, which provides us with new opportunities for understanding how different content levels affect quality," explains Nils Kristian Afseth, a research scientist at the Nofima food research institute. He has been working with Ph.D. student Trygve Helgerud on developing the new method, which is based on near-infrared spectroscopy.

No two potatoes are alike
The constituents of a potato and its suitability for industrial processing depend on many different circumstances, such as potential diseases, time of year, growth, weather and storage.

"The potato is something of a biochemical factory. For this reason there are enormous variations in the nutritional content of potatoes between harvests, within the same harvest and even between the tubers on a single plant," says Afseth.

Even if in an ideal world we could be able to control cultivation and storage conditions right down to the individual tuber, there would always be natural biological variation.

The potato industry needs correct information about dry matter content
Dry matter content says a great deal about potato quality. The higher the dry matter content, the less water and the higher the price per kilo for the potato producers. The commonest method used by the industry to determine dry matter content is called underwater weight. This is found by weighing a sample in air and then weighing it immersed in water.

"What is actually being calculated is the density of the tubers, and this is then used to estimate the dry matter content," says Helgerud.

There are several advantages to this method. It is cheap, user-friendly and relatively accurate for the sample that is taken. The problem is that it is impossible to characterise an entire batch and only small spot-checks of five kilograms are taken.

"We have been working on a method based on a technology called near-infrared spectroscopy to estimate the dry matter in raw, unpeeled potatoes on the processing line. The aim is to be able to measure the dry matter of every single potato on the line or when sorting beforehand. This means the producers could exclude extreme variation and sort the potatoes better. In this way, they could achieve a more uniform product quality," says Nils Kristian.

The properties of a griddle cake dough are determined by potato quality
At Buer Lompe og Lefsebakeri in Askim, they want to achieve the most stable potato quality possible and it is the most experienced bakers who have the job feeling what the dough needs; this is a craft that demands knowledge. Getting even better quality control has been a top priority for a long time.

"It is possible to correct a dough that has become too sticky, but it affects the flavour. So predictable quality and monitoring of quality are important to us. The tests we have carried out together with Nofima mean that we now have a better understanding of the processes, which means we can make the necessary adjustments earlier in the production process," says Bjørn Olav Drabløs, owner and general manager of Buer AS.

The properties of griddle cake dough are determined by many different factors. Variations in the potatoes become multiplied along the way and greatly affect the final quality. In order to understand what affects dough quality in different recipes and process conditions, we measure the material properties of the dough using rheology.  

"Here we can compare doughs of different compositions with what the bakery defines as the optimum. This helps us to understand the key factors that give the optimum dough. As far as I am aware, this is the first time that any scientific research has been done on griddle cakes on behalf of the Research Council of Norway," says research scientist Simon Ballace of Nofima. He has the primary responsibility for building expertise in the new rheology system being used in the project.

Looking for answers to why some potatoes are more suitable than others
The method and length of cooking potatoes affects both griddle cake dough and other uses for potatoes. The aim is to find the best cooking method for different variations of dry matter and starch content, for example.

Investigating griddle cake dough is just one part of the potato quality research at Nofima. The researchers are also looking at things like how sugar and starch in potatoes affects other finished potato products. They have been looking at what is important in potatoes for crisps and chips, and now they are looking at the factors that give the best ready-cooked potato products. For crisps and chips, it is especially important to be able to control the glucose level, from the point of view of both acrylamide and colour.

"At the moment, there is no commercial system for measuring the dry matter content of intact potatoes on the line, but developments so far have been extremely promising and we are now working on also developing this technology further in other projects at Nofima," concludes Nils Kristian.

Raw materials and process optimisation  

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