The 2011 ASHS Annual Conference

In this study, water status of fresh fruit cortical tissue of apple (Malus ×domestica) was manipulated with a centrifuge method and then the flesh sample mechanical properties were determined with a computer-controlled biological test device. Fruit tissue firmness, estimated by the maximum rupture force, declined with decreases in bulk elastic modulus (y = 10.025x - 15.77, R² = 0.940), pressure potential (y = 7.6391x + 5.0271, R² = 0.933), water potential (y = 5.7632x + 13.794, R² = 0.903), relative water content (y = 31.643x - 17.96, R² = 0.803), and osmotic potential (y = 22.262x + 39.246, R² = 0.770). Bioyield force, an estimate of fruit tissue crispness, was also more closely related to pressure potential (y = 3.2113x + 4.0632, R² = 0.935), water potential (y = 2.4217x + 7.7484, R² = 0.904), and elastic modulus (y = 4.1171x - 4.4109, R² = 0.899) than to relative water content (y = 13.276x - 5.5756, R² = 0.802) and osmotic potential (y = 9.3401x + 18.426, R² = 0.768). A linear relationship between the fruit tissue firmness and the bioyield force was observed (y = 2.3636x - 4.5327, R² = 0.985) in the range of water status tested. The measured elastic modulus appeared in close relation with the pressure potential (y = 0.7398x + 2.0946, R² = 0.935) and relative water content (y = 3.2216x - 0.28, R² = 0.890) of apple cortical tissue. The results indicate that fruit water relation parameters were important when one is analyzing the mechanical properties of fruit flesh tissue.