A mathematical model for the development of mealiness in apples

Mealiness in apples (Malus domestica Borkh.) is an internal quality defect which is characterised by a dry and crumbly texture. It is related to the relative strength of the cell wall and the middle lamella. A mathematical model has been built to relate changes in the texture attributes juiciness, tensile strength and hardness, which are associated with mealiness, to the development of the turgor pressure of the tissue and the degree of hydrolysis of the middle lamella. The latter, in turn, are described in terms of properties which are meaningful from the physiological point of view, such as starch content, soluble solids content, non-hydrolysed and hydrolysed middle lamella, water in the symplast, and water in the apoplast. Biochemical reactions as well as water transfer processes are incorporated in the model. The parameter values of the model are estimated using experimental data from a storage experiment. The model fits the three texture characteristics adequately. The correlation coefficients between the parameters were below 0.96, which indicates that the model does not overfit the data

On-line MRI sequences for the evaluation of apple internal quality.

On-line dynamic MRI, which is oriented to industrial grading lines, requires high-speed sequences with motion correction artefacts. In this study two different types of motion correction sequences have been used and have been implemented in real-time (FLASH and UFLARE). They are based on T2* and T2 respectively and their selection depends on the expected contrast effect of the disorder: while watercore enhances bright areas due to higher fluid mobility, internal breakdown potentiates low signal due to texture degradation. For watercore study, five different apple cultivars were used (Normanda-18-, Fuji-35-, Helada-36-, Verde Doncella-54-, Esperiega-75-) along two seasons (2011 and 2012). In total 218 fruits were measured under both, static conditions (20 slices per fruit) and under dynamic conditions (3 repetitions without slice selection). For internal breakdown, Braeburn cultivar has been studied (in total 106 fruits) under both static (20 slices per fruit) and dynamic conditions (3 replicates with slice selection). Metrological aspects such as repeatability of dynamic images and subsequent histogram feature stability become of major interest for further industrial application. Segregation ability among varying degrees of disorder is also analyzed

Effect of harvest and delaying controlled atmosphere storage conditions on core breakdown incidence in 'conference' pears

A logistic regression model was built to describe the effect of picking time and the most relevant commercially applied storage factors on the incidence of core breakdown in pears (Pyrus communis L. cv. Conference). The statistical analysis showed that the probability of core breakdown depended on several variables in a more complicated way than assumed before. In general, more mature fruit, stored at lower O-2 and higher CO2 concentrations, at a higher temperature and for longer times are more susceptible to core breakdown. However, delaying the controlled atmosphere (CA) conditions for 21 days decreased the core breakdown incidence efficiently even for late-picked fruit. Together with a proper delay of CA, a sufficiently high O-2 concentration during CA was most important. The model was validated with data of 16 orchards gathered over five harvest seasons in two countries which gives it a wide validity range and a high practical relevance. (C) 2002 Silsoc Research Institute. Published by Elsevier Science Ltd. All rights reserved