On the basis of publications in recent years, ideas about the deformation and strength properties of the flesh of potato tubers are being developed. The study is based on the analysis of experimental data on compression tests of cylindrical specimens cut from the flesh of potato tubers. The experiments were carried out taking into account the relaxation properties of the flesh. The diagrams of destruction of cylindrical samples by uniaxial compression revealed a number of features that made it possible to form an idea of the deformation-strength properties of potato pulp, taking into account the degree of its lethargy. Additional information is provided by experiments with intermediate unloadings, which start with ?> 0.1 MPa. A comparison of their graphs with the initial part of the diagram shows the absence of inelastic deformations within the limits of stresses in the samples from zero to values close to 0.1 MPa. Stresses ?> 0.1 MPa lead to the formation of inelastic deformations in the samples, which makes it necessary in the Hooke formula to abandon the use of the concept of a Young's modulus, which describes only elastic deformation. Instead of the Young's modulus, it was proposed to introduce a more general concept of the modulus of rigidity. Based on the analysis of the previously developed criteria for the rigidity of tubers of various flaccidity, two main ones were selected, which is associated with the simplicity of obtaining data for their calculation and sensitivity to changes in the flaccidity of tubers.

рotato, tuber, physical and mechanical properties, samples, stresses, strains, compression diagram, modulus of rigidity, rigidity criteria

1. Andreev N.R., Lukin D.N. Production of starch and starch products for import substitution. Pishchevaya promyshlennost'[Food industry]. 2014. no. 12. pp. 34–36. (in Russian)

2. Beer F.P., Johnston E.R., Dewolf Jr.J.T., Mazurek D.F. Mecanics of Materials. Sixth edition. New York, McGrau Hill, 2012. 758 p.

3. Abd el-Maksoud M.A., Gamea G.R., Abd el-Gawad A.M. Rheological constants of the four elements burgers model for potato tubers affected by various fixed loads under different storage conditions. Misr journal of agricultural engineering. 2009. vol. 26. no. 1. рp. 359–384.

4. Savrasova N.R. The results of the experimental determination of the modulus of elasticity and strength of the pulp of potato tuber. Vestnik ChGAA [Bulletin of the ChSAA]. 2012. vol. 60. pp. 80–82. (in Russian)

5. Zhukov V.G., Andreev N.R., Bezrukov D.V. Relaxation effect when testing potato samples with compression. Dostizheniya nauki i tekhniki APK [Achievements of Science and Technology of AICis]. 2016. vol. 30. no. 11. pp.121–122. (in Russian)

6. Zhukov V.G., Andreev N.R., Lukin D.N. The mechanism of compression deformation of a cylindrical sample of potato tuber. Dostizheniya nauki i tekhniki APK [Achievements of Science and Technology of AICis]. 2017. vol. 31. no. 6. pp.80–83. (in Russian)

7. Zhukov V.G., Andreev N.R., Bakulin V.A. et al. Three types of quantitative indicators of the degree of rigidity of potato tuber. Dostizheniya nauki i tekhniki APK [Achievements of Science and Technology of AICis]. 2017. vol. 31. no. 10. pp. 85–88. (in Russian)

8. Bentini, M., Caprara, C., Martelli, R. Physico-mechanical properties of potato tubers during cold storage. Biosystems Engineering. 2009. vol.104. pp. 25–32.

9. Miruna L. Mechanical properties affecting slicing performance of potatoes. Winnipeg, Manitoba, Food Science Departmerit University, 1999. 143 p.

10. Blahovec J., Vlckova M., Paprstein F. Static low-level bruising in pears. Research in Agricultural Engineering. 2002. vol. 48. no. 2. рр. 41–46.

11. Bentini M., Caprara C., Martelli R. Evaluation of the physical-mechanical properties of potatoes during conservation. Innovation Technology to Empower Safety, Health and Welfare in Agriculture and Agro-food Systems: International Conference. Ragusa, 2008, 7 p.