Micromechanical Behavior of Potato Tissue by Scanning Electron Microscopy: Effect of Storage Time, Impact Energy and Curvature Radius of Impact Location

ماشین های کشاورزی

Article 9, Volume 8, Issue 2 - Serial Number 16, 2018, Pages 347-363   

Document Type: Research Article

DOI: 10.22067/jam.v8i2.62599

Authors

S. Youneji¹; E. Ahmadi^{* 1}; A. Alavi Nia²

¹Department of Biosystem Engineering, Faculty of Agriculture, Bu-Ali Sina University, Hamedan, Iran

²Department of Mechanical Engineering, Faculty of Engineering, Bu-Ali Sina University, Hamedan, Iran

Abstract

Introduction
The mechanical impacts occur mainly during harvesting and post-harvesting operations, lead to the breaking of cell membranes in cellular structure that dependS on impact intensity. Furthermore, turgor pressure of potato tissue is influenced by the micromechanical and the physiological changes in the storage duration. Micromechanical changes of potato tissue due to the mechanical impact need to be monitored by microscopic images during storage. Scanning electron microscopy (SEM) is a high-resolution technique used to investigate the micromechanical behavior of potato tissue.

Materials and Methods
Potato samples (‘Sante’ cultivar), were stored at 5 ± 0.5°C and 85% relative humidity for 16 weeks. By 2-week intervals, potatoes were removed from the storage and then the impact test was done. Experimental factors were impacted energy at three levels of control (no impact was done), impact energy 1 (0.031 ± 0.002 J) and impact energy 2 (0.320± 0.020 J) and the radius of curvature at two levels of (35 and 45 mm). Water content was measured by drying thin slab samples in an oven at 70°C to a constant weight. The cell turgor pressure of potato tissue at 2-week intervals was estimated from the linear regression between turgor values of each mannitol solution (0–0.6 M) and relative volume change. The microstructural changes of impact location on the potato tubers were analyzed by SEM images at 2-week intervals during storage period. The surface and depth sections cutting from the impact location were immediately immersed in 2.5% glutaraldehyde in 0.1 M sodium phosphate buffer (2 h) at 4± 0.5°C. The specimens were then rinsed 3 × 10 min in 0.1 M sodium phosphate buffer (pH 7.2), and dehydrated through an ethanol series, 25, 50, 70, 90 and 100% dry, 15 min each step, 2 × 100%. In this study the HMDS as a high-quality chemical drying was investigated. The sample preparation for SEM observation then followed by chemical drying via HMDS, under a laboratory hood overnight. Analysis of variance test based on completely randomized design (CRD) was considered for all of the data using SPSS 23.

Results and Discussion
Superior preservation of potato microstructure was obtained by hexamethyldisilazane (HMDS) drying during sample preparation for SEM observation. The MIP software was used for quantitative analysis of SEM images and the microstructural features of potato tissue at the impact location were determined. So that each cell outline was manually separated by drawing the lines along the visible contours of cell walls. Measurement of the impact damage dimensions was done by MIP software for the surface section (major and minor width, w1 and w2) and the depth section (depth, d and major width, w1). The results indicated the significant differences between water content, cell turgor pressure, cell area and cell perimeter over 16 weeks storage. Generally, by increasing impact intensity the water content, cell turgor pressure, cell area and cell perimeter significantly decreased. Also interaction effect of storage time, impact level and radius of curvature for impact damage of potato tissue was significant.

Conclusion
The cell turgor pressure at the impact location on the potato tubers had the similar trend with the water content. SEM investigation showed that potato parenchyma, which was high preserved by HMDS drying, had consisted of the pentagon and hexagonal thin-wall cells with the average cell area of 23.14 × 103 ± 0.178 μm2, the average cell perimeter of 564.98 ± 2.008 μm at week 0. The higher impact damage was at week 16 of storage, impact level 2 and the radius of curvature of 35 mm compared to the other treatment.

Keywords

Cell turgor pressure; Impact damage; Micromechanical behavior; Scanning electron microscopy (SEM); Storage time

References

1. Abedi, Gh., and E. Ahmadi. 2014. Bruise susceptibilities of golden delicious apples as affected by mechanical impact and fruit properties. Journal of Agricultural Science 152: 439-447.

2. Afshari, H., S. Minaei, M. Almasi, and P. Abdolmaleki. 2008. Evaluation of potato damage under dynamic loading. Quarterly of Food Science and Technology 5 (2): 69-76. (In Farsi).

3. Ahmadi, E., and H. Barikloo. 2016. Mechanical property evaluation of apricot fruits under quasi-static and dynamic loading. Journal of Agricultural Machinery 6 (1): 139-152. (In Farsi).

4. Alvarez, M. D., D. E. J. Saunders, and J. F. V. Vincent. 2000. Effect of turgor pressure on the cutting energy of stored potato tissue. European Food Research and Technology 210: 331-339.

5. Al-Weshahy, A., M. El-Nokety, M. Bakhete, and V. Rao. 2013. Effect of storage on antioxidant activity of freeze-dried potato peels. Food Research International 50: 507-512.

6. Asmamaw, Y., T. Tekalign, and T. S. Workneh. 2010. Specific gravity, dry matter concentration, pH, and crisp-making potential of ethiopian potato (Solanum tuberosum L.) cultivars as influenced by growing environment and length of storage under ambient conditions. Potato Research 53: 95-109.

7. Baheri, M. 1997. Development of a method for prediction of potato mechanical damage in the chain of mechanized potato production, Ph.D. Thesis Nr. 342, Faculty of Agricultural and Applied Biological Sciences, KU Leuven.

8. Bajema, R. W., and G. M. Hyde. 1998. Instrumented pendulum for impact characterization of whole fruit and vegetable specimens. Transactions of the American Society Agricultural Engineers 41 (5): 1399-1405.

9. Baritelle, A., and G. Hyde. 2001. Commodity conditioning to reduce impact bruising. Postharvest Biology and Technology 21: 331-339.

10. Bentini, M., C. Caprara, and R. Martelli. 2006. Harvesting damage to potato tubers by analysis of impacts recorded with an instrumented sphere. Biosystems Engineering 94 (1): 75-85.

11. Bentini, M., C. Caprara, and R. Martelli. 2009. Physico-mechanical properties of potato tubers during cold storage. Biosystems Engineering 104: 25-32.

12. Berger, L. R. R., N. P. Stamford, L. G. Willadino, D. Laranjeira, M. A. B. De Lima, S. M. M. Malheiros, W. J. De Oliveira, and T. C. M. Stamford. 2016. Cowpea resistance induced against fusariumoxysporum f. sp. tracheiphilum by crustaceous chitosan and by biomass and chitosan obtained from cunninghamellaelegans. Biological Control 92: 45-54.

13. Blahovec, J. 2005. Impact induced mechanical damage of Agria potato tubers. Research in Agricultural Engineering 51 (2): 39-43.

14. Brook, R. C. 1993. Impact testing of potato harvesting equipment. American Potato Journal 70: 243-256.

15. Brusewitz, G. H., R. E. Pitt, and Q. Gao. 1989. Effects of storage time and static preloading on the rheology of potato tissue. Journal of Texture Studies 20 (3): 267-284.

16. Danila, D. M. 2015. Assessing the potato impact response using a pendulum controlled and designed by computer. Bulletin of the Transilvania University of Braşov. Series II: Forestry, Wood Industry, and Agricultural Food Engineering 8 (57): 65-70.

17. FAOSTAT. 2014. www.fao.org/faostat/en.

18. Gancarz, M., and K. Konstankiewicz. 2007. Changes of cellular structure of potato tuber parenchyma tissues during storage. Research in Agricultural Engineering 53 (2): 75-78.

19. Gibson, L. J. 2012. The hierarchical structure and mechanics of plant materials. Journal of the Royal Society Interface 9 (76): 1-18.

20. Haman, J., K. Konstankiewicz, and A. Zdunek. 2000. Influence of water potential on the failure of potato tissue. International Agrophysics 14: 181-186.

21. Kaack, K., L. Kaaber, E. Larsen, and A. K. Thybo. 2002. Microstructural and chemical investigation of subsurface hardened potatoes (Solanum tuberosum L.). Potato Research 45: 9-15.

22. Karcz, J., T. Bernas, A. Nowak, E. Talik, and A. Woznica. 2012. Application of lyophilization to prepare the nitrifying bacterial biofilm for imaging with scanning electron microscopy. Scanning 34: 26-36.

23. Konstankiewicz, K., K. Pawlak, and A. Zdunek. 2001a. Influence of structural parameters of potato tuber cells on their mechanical properties. International Agrophysics 15: 243-246.

24. Konstankiewicz, K., K. Pawlak, and A. Zdunek. 2001b. Quantitative method for determining cell structural parameters of plant tissues. International Agrophysics 15: 161-164.

25. Konstankiewicz, K., and A. Zdunek. 2001. Influence of turgor and cell size on the cracking of potato tissue. International Agrophysics 15: 27-30.

26. Laza, M., M. G. Scanlon, and G. Mazza. 2001. The effect of tuber pre-heating temperature and storage time on the mechanical properties of potatoes. Food Research International 34: 659-667.

27. Lin, T. T., and R. E. Pitt. 1986. Rheology of apple and potato tissue as affected by cell turgor pressure. Journal of Texture Studies 17: 291-313.

28. Lu, F., Y. Ishikawa, H. Kitazawa, and T. Satake. 2010. Measurement of impact pressure and bruising of apple fruit using pressure-sensitive film technique. Journal of Food Engineering 96: 614-620.

29. Mahto, R. and M. Das. 2014. Effect of gamma irradiation on the physico-mechanical and chemical properties of potato (Solanum tuberosum L.), cv. ‘kufriSindhuri’, in non-refrigerated storage conditions. Postharvest Biology and Technology 92: 37-45.

30. Maricle, B. R., N. K. Koteyeva, E. V. Voznesenskaya, J. R. Thomasson, and G. E. Edwards. 2009. Diversity in leaf anatomy, and stomatal distribution and conductance, between salt marsh and freshwater species in the c4 genus spartina (poaceae). New Phytologist 184: 216-233.

31. Mohsenin, N. N. 1996. Physical characteristics: Physical properties of plant and animal materials. New York, Gordon and Breach Science Publishers.

32. Molema, G. J., B. R. Verwijs, J. V. Van Den Berg, and H. Breteler. 1997a. Effect of repetitive impacts on subcutaneous tissue discoloration in potato tubers. Netherlands Journal of Agricultural Science 45: 187-200.

33. Molema, G. J., J. J. Klooster, B. R. Verwijs, M. M. W. B. Hendriks, and H. Breteler. 1997b. Effect of impact body shape on subcutaneous tissue discoloration in potato tubers. Netherlands Journal of Agricultural Science 45: 407-421.

34. Molema, G. J., P. C. Struik, B. R. Verwijs, A. Bouman, and J. J. Klooster. 2000. Impact measured by an instrumented sphere. Potato Research Journal 43: 225- 238.

35. Noble, R. 1985. The relationship between impact and internal bruising in potato tubers. Journal of Agricultural Engineering Research 32: 111-121.

36. Pathan, A. K., J. Bond, and R. E. Gaskin. 2010. Sample preparation for SEM of plant surfaces. Materials Today 12: 32-43.

37. Parker, C. C., M. L. Parker, A. C. Smith, and K. W. Waldron. 2001. Pectin distribution at the surface of potato parenchyma cells in relation to cell-cell adhesion. Journal of Agricultural and Food Chemistry 49: 4364-4371.

38. Praeger, U., W. B. Herppich, C. Konig, B. Herold, and M. Geyer. 2009. Changes of water status, elastic properties and black spot incidence during storage of potato tubers. Journal of Applied Botany and Food Quality 83: 1-8.

39. Praeger, U., J. Surdilovic, I. Truppel, B. Herold, and M. Geyer. 2013. Comparison of electronic fruits for impact detection on a laboratory scale. Sensors 13: 7140-7155.

40. Pieczywek, P. M., A. Zdunek, and M. Umeda. 2011. Study on parameterisation of plant tissue microstructure by confocal microscopy for finite elements modeling. Computers and Electronics in Agriculture 78: 98-105.

41. Scanlon, M. G., C. H. Pang, and C. G. Biliaderis. 1996. The effect of osmotic adjustment on the mechanical properties of potato parenchyma. Food Research International 29 (5-6): 481-488.

42. Skrobacki, A., J. L. Halderson, J. J. Pavek, and D. L. Corsini. 1989. Determination potato tuber resistance to impact damage. American Potato Journal 66: 401-416.

43. Singh, N., L. Kaur, R. Ezekie, and H. S. Guraya. 2005. Microstructural, cooking and texture characteristics of potato (Solanum tuberosum L.) tubers in relation to physicochemical and functional properties of their flours. Journal of the Science of Food and Agriculture 85: 1275-1284.

44. Singh, F., V. K. Katiyar, and B. P. Singh. 2014. Analytical study of turgor pressure in apple and potato tissues. Postharvest Biology and Technology 89: 44-48.

45. Strehmel, N., U. Praeger, C. Konig, I. Fehrle, A. Erban, M. Geyer, J. Kopka, and J. T. Van Dongen. 2010. Time course effects on primary metabolism of potato (Solanum tuberosum) tuber tissue after mechanical impact. Postharvest Biology and Technology 56: 109-116.

46. Talbot, M. J., and R. G. White. 2013. Methanol fixation of plant tissue for scanning electron microscopy improves preservation of tissue morphology and dimensions. Plant Methods 9 (36): 1-7.

47. Uwins, P. J. R., M. Murray, and R. J. Gould. 1993. Effects of four different processing techniques on the microstructure of potatoes: comparison with fresh samples in the ESEM. Microscopy Research and Techniue 25: 412-418.

48. Van Zeebroeck, M., E. Tijskens, P. Van Liedekerke, V. Deli, J. De Baerdemaeker, and H. Roman. 2003. Determination of the dynamical behaviour of biological materials during impact using a pendulum device. Journal of Sound and Vibration 266: 465-480.

49. Van Canneyt, T., E. Tijskens, H. Ramon, R. Verschoore, and B. Sonck. 2003. Characterisation of a potato-shaped instrumented device. Biosystems Engineering 86 (3): 275-285.