Air paths inside fruit

Microscopically small structures inside pears and apples allow them to "breathe". Researchers at the Catholic University of Leuven and the European Synchrotron Radiation Facility (ESRF) have visualized these pathways for the first time, therefore proving their previously hypothesized existence and allowing a better understanding of how fruit degrades after harvest. The structures appear as irregular cavities between cells in apples, and as tiny interconnected channels in pears. The three-dimensional images of the fruit help to determine and explain the gas exchange rates, oxygenation, and when the fruit cells start to die and browning starts. The Leuven team used the ESRF in Grenoble, France, to perform tomographic imaging of fruit samples, with 3-D images that are accurate below 1/1000th of a millimetre. It is still unclear how the airways develop and why they are different in apples and pears but the results help explain that pears are very prone to decay during storage: the microchannels are so small that oxygen supply is very limited.