Turgor and temperature effect on fracture properties of potato tuber (Solanum tuberosum cv. Irga)
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Institute of Agrophysics, Polish Academy of Sciences, Doświadczalna 4, 20-290 Lublin, Poland
Institute of Fundamental Technological Research, Polish Academy of Sciences, Świętokrzyska 21, Warsaw, Poland
Plant Breeding and Acclimatization Institute, 05-140 Serock, Poland
Int. Agrophys. 2008, 22(1): 89–97
Fracture properties of plant tissue are important for consumers and industry. The mechanical properties of tissue depend on turgor and temperature. These two parameters can change significantly fracture properties by influencing on failure mode of a tissue. Tissue cracking during mechanical test can be analysed using contact acoustic emission (AE). The goal of the research is analysis of changes in fracture properties of potato tuber tissue in a function of turgor and temperature. In this research, a system for measuring acoustic signals within the audible frequency range is used. The AE is applied in two mechanical tests: texture profile analysis (TPA) and single edge notched bending (SENB). Samples of potato tuber tissue were treated in different concentration of mannitol for turgor control. For temperature control two methods were used in different temperature ranges; cooling for one day at temperatures 2-20°C and immersion in water for 10 min at temperatures 40-70°C. The experiment shows that fracture properties significantly change with turgor. Use of the acoustic emission shows that the cell wall rupturing is a dominant failure mode when cell-cell adhesion is relatively strong, for example for highly turgid samples in temperatures up to room temperature. The cell-cell debonding is dominant mode when adhesion decreases as a result of maceration or when low intracellular pressure decreases force between cells. In a future acoustic emission would be used for evaluation of texture attributes of plant tissue related to fracture properties, like crispness, crunchiness, juiciness and mealiness.