Magnetic resonance imaging for nondestructive analysis of wine grapes.

Magnetic resonance imaging (MRI) was used to study the growth and ripening of grape berries for three varieties. The results show that this technique allows the visualization of internal characteristics of berries using noninvasive procedures in order to obtain the volume and degrees Brix distribution within a cluster. Samples of Cabernet Sauvignon, Carmenère, and Chardonnay varieties collected over the 2002 season were analyzed. Calibration models were developed to correlate soluble solids (degrees Brix) against spin-lattice relaxation time t(1) and spin-spin relaxation time t(2). The correlation of degrees Brix and t(1) was R(2) = 0.75 for Cabernet Sauvignon, R(2) = 0.8 for Carmenère, and R(2) = 0.65 for Chardonnay. In the case of t(2) the correlation was significantly lower. Reconstruction techniques for the three-dimensional representation of clusters were developed, allowing an interactive visualization of the bunches. The method also provides volume measurements of single berries and their distribution within the cluster with an accuracy of 3% and R(2) = 0.98. These results show the potential of MRI in the wine industry for both monitoring and research. Not only does it provide quantitative information about the berries such as volume and degrees Brix distributions, but it can also be used to support the sampling procedures by providing a better cluster characterization.