RESUMEN
INTRODUCTION: During the processing of fresh plants, prolonged exposure to the air can cause rapid oxidative changes, and this is further accelerated if they have large surface areas. These changes can ultimately lead to losses in valuable ingredients and deterioration of the final product. Consequently, in the food, cosmetics, and pharmaceutical industries, oxidation and the use of antioxidant conservatives are major considerations during processing and production. However, similar considerations are not currently made for herbal medicines. The differences in the UV-Vis spectra of several commercial herbal mother tinctures were investigated here to determine if the oxidation process occurred and should thus be considered during their production. METHODS: The impact of air exposure on comminuted fresh Melissa officinalis and on the quality of the resulting mother tincture was evaluated using UV-Vis spectrophotometric analysis, antioxidant tests (potassium permanganate and FOLIN-Ciocalteu), and high-performance thin-layer chromatography. RESULTS: A time-dependent decrease in phenolic compounds, UV absorbance, and antioxidant capacity of the Melissa officinalis mother tincture were observed. Specifically, the antioxidant capacity of ground Melissa officinalis in the resulting herbal mother tincture was reduced by 40.47% and 55.52% after 5 and 30 min of air exposure, respectively. CONCLUSIONS: The results indicate that the Melissa officinalis mother tincture is affected if its comminuted starting material is exposed to air during the manufacturing process and that this should be considered when producing fresh herbal medicine plant products in the future.