BIOSYSTMe Bio S Turgor Objective BIOSYSTMe Bio S

BIOSYST-Me. Bio. S Turgor

Objective BIOSYST-Me. Bio. S To investigate the influence of turgor on micromechanical properties of apple parenchyma To investigate the relation between micromechanical properties and cellular deformations in tensile and compression tests Development of detailed mathematical models to predict behaviour of fruits under mechanical loading

BIOSYST-Me. Bio. S www. biw. kuleuven. be Influence of Turgor on Micromechanical and Structural Properties of Apple Tissue M. Oey, E. Vanstreels, J. De Baerdemaeker, E. Tijskens, H. Ramon, B. Nicolaï

Materials and Methods BIOSYST-Me. Bio. S Apple cultivar: Jonagored fresh/stored (15 apples each) Samples: green side, radial orientation Tensile 11 x 5 x 2 mm Testing speed: 5 mm/s 3 x 11 x 5 mm Testing speed: 2 mm/s Compression

Turgor manipulation BIOSYST-Me. Bio. S Manipulating of turgor by overnight soaking in Isotonic solution (0. 65 M) no change of turgor Hypotonic solution (0. 45 M) turgor increases as cells take up water Hypertonic solution (0. 85 M) turgor decreases as cells release water

BIOSYST-Me. Bio. S Mechanical tests Miniature tensile stage Staining of samples Tensile and compression tests until rupture, 3 cycles Simultanous recording of cell deformations

Data analysis – micromechanical parameters Force-deformation data stress-strain data BIOSYST-Me. Bio. S σmax E 2 E 1 εmax Maximum stress (σmax) Strain at failure (εmax) Initial modulus (E 1) Modulus at 80% stress (E 2)

BIOSYST-Me. Bio. S Data analysis – image processing Area Aspect Perimeter Roundness Length Width

BIOSYST-Me. Bio. S Video – Tensile Test

BIOSYST-Me. Bio. S Results: Typical curves

Results: Micromechanical Parameters BIOSYST-Me. Bio. S Influence of storage in tensile tests

Results: Micromechanical Parameters BIOSYST-Me. Bio. S Influence of turgor in tensile tests

Results: Micromechanical Parameters BIOSYST-Me. Bio. S Influence of turgor in compression tests

Results: Cell Parameters BIOSYST-Me. Bio. S 170µm Initial Parameters 190µm Area: 22. 500 µm² Perimeter: 557 µm Aspect: 1, 12 Roundness: 1, 16 Not influenced by apple or firmness Not influenced when turgor is manipulated

170µm Results: Cell Deformations - Tensile 190µm Stored Apples Fresh Apples +6, 8% BIOSYST-Me. Bio. S High Turgor -4, 9% +8, 7% +4, 1% -1, 2% +13, 8% Normal Turgor -10, 5% Low Turgor -16, 8% +15, 8% +20, 2% +19, 5% +4, 6% +14, 4% -6, 9% -11, 3% +12, 3% +15, 3% +14, 6%

170µm Results: Cell Deformations - Compression 190µm Fresh Apples -12, 9% High Turgor BIOSYST-Me. Bio. S Stored Apples +4, 1% -33, 1% +0, 3% -13, 5% Normal Turgor +7, 0% Low Turgor +7, 1% -36, 5% -16, 5% -46, 1% +5, 4% -5, 9% -16, 6% -11, 3% -24, 1% -22, 1% +5, 5% -34, 7%

Conclusions Micromechanical parameters Strongly affected by test method and firmness Turgor BIOSYST-Me. Bio. S has effect on tissue extensibility and initial stiffness but influence on firmness and stiffness at higher strains is not clear Initial cell parameters Not affected by turgor manipulation Cell deformations Turgor has influence on deformations in length, width and aspect Cell deformations are closely related to micromechanical deformations

BIOSYST-Me. Bio. S Thank you!