Storage-induced color change as an indicator of Cannabidiol degradation in MCT oil

Cannabidiol (CBD) is one of the major phytocannabinoids derived from Cannabis sativa L. Due to its lipophilic properties and bioavailability considerations, CBD is commonly formulated and provided to consumers as oil-based products. Oil-based CBD products frequently exhibit visible discoloration during storage, yet its relationship to CBD degradation and product quality remains unclear. The objective of this study was to systematically evaluate color stability and CBD content in medium-chain triglyceride (MCT) oil under different storage conditions, including light exposure (clear vials in complete darkness (Dark), amber vials under light (AL), and clear vials under light (CL)), air exposure (Sealed and Open-air), temperature variation (-18°C, 4°C, 23°C, and 40°C), and their combined effects over an extended storage period (1, 3, 6, 11, 23, 48, 96, and 192 days). Color was characterized using CIELab coordinates, and cumulative change was calculated as the area under the ΔE 2000 curve. Clear vials under light showed the largest overall CBD loss and color change, while air exposure notably accelerated discoloration but had limited impact on CBD loss. Low temperatures prevented both CBD degradation and perceptible color change, whereas room and elevated temperatures progressively increased discoloration. The combined effect was clearly observed when light and elevated temperature were applied simultaneously, leading to increases in both discoloration and CBD loss. CBD concentration showed a strong inverse relationship with yellowing (correlation coefficient = −0.79), indicating that increasing yellowing was closely associated with storage conditions that promote chemical degradation. These findings suggest that visually observable color changes cannot directly quantify CBD degradation or identify specific degradation products in MCT-based formulations but may serve as a potential indicator of improper storage conditions associated with CBD degradation.