Using MALDI-TOF q-MSI for detailed comparison of varietal and tissue regional differences in strawberries

Detailed quantitative histochemical distribution of the components in fruits has not yet been clarified. To verify the availability of using the serial section method of matrix-assisted laser desorption/ionization time-of-flight quantitative mass spectrometry imaging (MALDI-TOF q-MSI) in evaluating fruit qualities, the distributions of soluble carbohydrates, organic acids and ascorbic acid in the fruits of 6 strawberry cultivars were examined. Simultaneous analysis of the compounds was successfully achieved by applying 1,5-diaminonaphthalene as a matrix. Quantitative digital images showing the distribution of each compound were created, along with a virtual image of soluble carbohydrates and organic acids as an index of taste. It was confirmed that the concentration of citric acid was lower ( P < 0.05), but that of hexose was higher ( P < 0.10) in the pith than those in the cortex regardless of the cultivar. Mean values and standard deviations clearly showed varietal differences in component distribution, which would be useful for evaluating fruit quality. • Distribution of phytochemicals in strawberry fruit was examined using MALDI-TOF q-MSI. • Simultaneous analysis was achieved by using 1,5-diaminonaphthalene as a matrix. • Quantitative digital images on distribution of the compounds were created. • Varietal and tissue regional differences of the compounds were shown statistically. • It was demonstrated that MALDI-TOF q-MSI will be useful for evaluating fruit quality.