A statistical approach for proton transfer reaction mass spectrometry (PTR-MS) data aimed at a qualification of fruits based on VOC emissions

Due to the high degree of sensitivity and the large amounts of data obtained by Proton Transfer Reaction Mass Spectrometry (PTR-MS), an appropriate method of data handling, analysis and interpretation is required. The experiments that we have carried out show a strong dependence of the measured Volatile Organic Compound (VOC) emissions from a large number of parameters that characterize a fruit. We have' studied the preservation of Malus domestica 'Red Delicious' under Initial Low Oxygen Stress (ILOS) treatment and we have considered as co-variant parameters the weight and skin attributes such as hue, saturation and lightness. We have developed an approach based on a causal network model with respect to sets of parameters prior, intervening and consequent respectively. Through the statistical analysis of VOC emissions measured by PTR-MS, we have identified the masses of the VOC that best correlate to the different properties of the apples over the whole period of preservation and for shelf-life of about two weeks.[...]