Structural changes of potato tissue during French fries production

The purpose of the study was to determine some changes in the structure of potato tissue and the contents of non-starch polysaccharides and lignin in potatoes at particular stages of French fries production. The samples for laboratory studies were taken from potato tubers, strips and French fries collected from six locations of the technological line. Immediately after the samples were collected from the processing line, the texture of potatoes was determined using an Instron 5544. Structural changes in the tissue were determined using a Leo-435VP scanning electron microscope. Dry matter and non-starch polysaccharide contents were determined in the samples of processed potatoes. It was found that the texture of potato was changing during the technological process due to water losses and damages of potato tissue and consequent changes in non-starch polysaccharides and lignin. The greatest changes in potato tissue resulted from thermal processes: blanching, pre-drying and frying. Increases of non-starch polysaccharide and lignin contents were observed during these processes, owing to water losses in potato strips. The ultimate texture of French fries was developed during frying, by penetration of fat primarily into the external layer of strips.