Effect of Thermal Treatment on the Retention of Phenolic Compounds, Antioxidant Activity, and Vitamin C of Edible Plants (Mallow Leaf and Garambullo Flower)

Mexico has a wide variety of edible plants, such as mallow and garambullo flowers. Their composition is based on nutrients (carbohydrates, proteins, lipids, vitamins, minerals), as well as phytochemicals, organic or inorganic acids, etc. For the traditional consumption of these plants, they are boiled and then combined with other ingredients. However, after a thermal treatment, their nutritional and sensory qualities are affected. In this work, we study the effect of thermal treatment on the total phenolic compounds (TPC), antioxidant capacity, and vitamin C of two edible plants from Mexico. Both plants had a high amount of TPC as ferulic acid, p-coumaric acid, caffeic acid, quercetin, and apigenin. Both plants had a high amount of TPC as ferulic acid, p-coumaric acid, caffeic acid, quercetin, and apigenin. After thermal treatment, the samples showed a high antioxidant capacity analyzed by 2,2-Diphenyl-1-picrylhydrazyl (DPPH•), 2,2′-Azino-bis(3-ethylbenzothiazoline-6-sulfonic acid (ABTS●+), and ferric reducing antioxidant power (FRAP), associated with a high retention (78 and 89%) of phenolic compounds in the food matrix. Coumarin and ferulic acid were identified in both samples, while apigenin was only found in the mallow leaves and quercetin in the garambullo flowers after thermal treatment. Vitamin C content was higher on mallow leaves compared to garambullo flowers after thermal treatment. Further research is needed to characterize and evaluate the effect in both plants.