Cocrystals to tune oily vitamin E into crystal vitamin E

d-α-tocopherol (d-αToc), the most biologically active form of natural Vitamin E, is oily in appearance and unstable to oxygen. Esterification and encapsulation are generally needed to stabilize and solidify d-αToc for the purpose of its expanding applications. In this study, we propose a more effective way to stabilize and solidify d-αToc oil in one step. By cocrystallization, the melting point of d-αToc is significantly increased, such that the oily d-αToc is successfully transformed into solid form at room temperature. The single crystal structure of d-αToc was firstly uncovered and the molecular interaction in cocrystals was revealed. Crystalline Vitamin E shows high stability to light and temperature. Its spherical crystallization affords good powder flowability, which is extremely important as food or feed additives. Moreover, cocrystal Vitamin E remains the original form of tocopherol without esterification and thus has a great advantage on higher bioavailability. Cocrystallization of oily d-αToc spares the use of acetic ester and a mass of excipients, which is of great environmental importance and greatly reduces the production cost.