A process for obtaining a tannin extract isolated from whole grape seeds is provided. The process is performed in as a one-pot reaction and in a single extraction step, wherein the seeds are processed without grinding or milling. Also provided is a tannin extract with improved antioxidant and light fastness properties obtained from whole grape seeds that includes a mixture of tannins and non-tannins, in which the content of tannins or polyphenols is higher than 50%. Ise, the tannin extract isolated from whole grape seeds can include a coloring agent.