1. A method of producing a multi-component product comprising a product attribute profile, the method comprising providing a first and second component of the product, each component having a component attribute profile; supplying to a product formulation zone the first component and the second component in desired amounts and combining the first and second components together to provide the product or a precursor thereof to yield a target product attribute profile; responsive to a change or predicted change in at least one component attribute profile, supplying information concerning the attribute change to a data processing apparatus and calculating with respect to that change an adjustment in the amounts to reduce the deviation of one or more attributes of the product attribute profile from the target product attribute profile.