Lyophilized tomato plant material: Validation of a reliable extraction method for the analysis of vitamin C

Vitamin C is widely studied for its protective role in humans and plants, but its quantification in fresh vegetable matrices is delicate, especially because of the unstable nature of its reduced form. Facing this aspect and with unavoidable extraction constraints, we developed and validated a method for extracting vitamin C from the lyophilized powder of tomato fruits and leaves. Easy and quick to implement by removing most of the cold constraints needed for the use of fresh powder, this method proved to be precise, accurate, and linear at the same time, across a large vitamin C concentration range (160-740 mg 100 g(-1) for dried fruits; 190-1140 mg 100 g(-1) for dried leaves). A simultaneous quantification of total and reduced vitamin C levels was performed by spectrocolorimetry, using a microplate reader. The evaluation of the impact of the storage conditions of the lyophilized powders on the vitamin C concentrations made it possible to optimize certain parameters of the method and to evaluate its robustness as well as the remarkable biochemical stability of the lyophilized sample.