The new mathematical model is reported to predict internal gas concentrations in fruit and vegetables, which may control the spoiling (browning) of stored foods. According to lead researcher Bart Nicolaï, while the model was designed for pears, it could be applied generally. Application to other fleshy fruit and plant organs would be relatively straightforward, when the tissue properties and the geometry had been measured. The model developed "is to our knowledge the most comprehensive model to date to simulate gas exchange in plant tissues," wrote the researchers in the journal PLoS Computational Biology. "It can be used to evaluate the effect of environmental stresses on fruit via in silico experiments and may lead to commercial applications involving long-term storage of fruit under controlled atmospheres." The new technology could be useful for food producers and manufacturers who often lose profit when fruit and vegetables become spoiled. The report explains that fleshy fruit are stored for commercial reasons under low oxygen, increased carbon dioxide, conditions to extend their storage life for up to nine months. If the oxygen concentration in the storage atmosphere is too low disorders such as internal browning may occur, leading to economic losses. This browning is known to be related to the mechanisms of gas exchange, respiration and fermentation in fruit. Until now further conclusions were difficult to make because of a lack of reliable methods to measure the gas concentrations in the fruit. The mathematical model predicts the internal gas concentrations, including permeation, diffusion and respiration and fermentation kinetics. (Diffusion was found to be the main driving force for gas exchange). Pear fruit was selected as a case study. The model was used to perform in silico (via computer simulation) experiments to evaluate the effect of, for example, fruit size or ambient gas concentration on internal oxygen and carbon dioxide levels. The model incorporates the shape of the fruit and was solved using fluid dynamics software. The researchers said that environmental conditions such as temperature and gas composition have a large effect on the internal distribution of oxygen and carbon dioxide in fruit. Also, the size of the fruit has an effect on local metabolic gas concentrations, so, depending on the size, local anaerobic conditions might result which could lead to physiological disorders. The researchers found that extremely low oxygen concentrations can occur in the core of the pear, which eventually may lead to cell death and browning. There report says that further advances are reliant on the investigation of the internal microstructure of the tissue to explain differences in gas exchange properties and to quantify the cellular and intercellular pathways for the gas exchange and the metabolic processes. Source: Public Library of Science Computational Biology The full report is available online Authors : Q.T. Ho, P. Verboven, B.E. Verlinden, J. Lammertyn, S. Vandewalle, B.M. Nicolaï
