Articles
Micromechanics of apple and pear tissues for fruit growth modeling
Article number
1382_17
Pages
131 – 138
Language
English
Abstract
Fruit firmness is an important factor in fruit quality, and is largely determined by the mechanical properties of the composing tissues.
The composition and structure of cell walls change considerably during growth, storage and shelf life.
The study of the mechanical properties at the cellular level of fruit tissues could aid in determining the impact of cell wall structure changes.
To this end, a hydromechanical model based on discrete element modeling (DEM) is under development, for which quantitative measures of the cellular stiffness were be obtained.
To quantify the stiffness of pome fruit tissues, atomic force microscopy (AFM) was performed on apple (Malus domestica Borkh.) and pear (Pyrus communis L.) tissues.
The Youngs modulus was identified from tissue samples of 3 different maturities: young fruits (60 to 70 days after full bloom), mature fruits (130 to 140 days after full bloom) and mature fruits kept in shelf life conditions (20°C, 12 days). The Sneddon model was used for extracting the Youngs modulus from the indentation curves.
The results showed an exponentially decaying distribution of Youngs modulus values for all time points.
For apple, the AFM measurements suggest an increase in stiffness of the cells from the early stage toward maturity, and a softening after shelf life conditions.
For pear on the other hand, the average Youngs modulus decreased until maturity, and decreased rapidly even further during shelf life.
These results provide physiological parameters for use in hydromechanical models of pome fruit tissues during growth and postharvest handling.
The composition and structure of cell walls change considerably during growth, storage and shelf life.
The study of the mechanical properties at the cellular level of fruit tissues could aid in determining the impact of cell wall structure changes.
To this end, a hydromechanical model based on discrete element modeling (DEM) is under development, for which quantitative measures of the cellular stiffness were be obtained.
To quantify the stiffness of pome fruit tissues, atomic force microscopy (AFM) was performed on apple (Malus domestica Borkh.) and pear (Pyrus communis L.) tissues.
The Youngs modulus was identified from tissue samples of 3 different maturities: young fruits (60 to 70 days after full bloom), mature fruits (130 to 140 days after full bloom) and mature fruits kept in shelf life conditions (20°C, 12 days). The Sneddon model was used for extracting the Youngs modulus from the indentation curves.
The results showed an exponentially decaying distribution of Youngs modulus values for all time points.
For apple, the AFM measurements suggest an increase in stiffness of the cells from the early stage toward maturity, and a softening after shelf life conditions.
For pear on the other hand, the average Youngs modulus decreased until maturity, and decreased rapidly even further during shelf life.
These results provide physiological parameters for use in hydromechanical models of pome fruit tissues during growth and postharvest handling.
Authors
B. Dequeker, H. Van Cauteren, P. Pieczywek, A. Zdunek, P. Verboven, B. Smeets, B. Nicolaï
Keywords
apple, pear, AFM, nanoindentation, Youngs modulus, biomechanics, cell wall, texture, Sneddon, modeling
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