1. A method of sorting objects within a bulk of objects, having an inherent variation, from a heterogeneous population by separating from said bulk at least one class, having less variation than said inherent variation, which represents a quality of composition with reference to any organic material of said objects, wherein the method comprises the steps of (a) distributing each of said objects to be separated as a separate object in a sorting device; (b) exposing said separate object to energy from at least one energy source; (c) recording from at least one point of said separate object by means of at least one sensor a first multivariate signal; (d) predicting or classifying, by means of a multivariate calibration method previously performed on a subset of said population, between said first multivariate signal and said quality of composition, a second signal expressing the magnitude of at least one quality variable of univariate variation; and (e) separating said separate object from said sorting device to said at least one collected class in dependence on the magnitude of at least one quality variable of said second signal from said at least one point.