Methylxanthine and Flavonoid Contents from Guarana Seeds (Paullinia cupana): Comparison of Different Drying Techniques and Effects of UV Radiation

Abstract

Guarana seeds are typically processed using one of three drying methods: traditional sun exposure, greenhouse drying, or the alguidar oven technique. In our research, we evaluated the contents of methylxanthines and flavan‐3‐ols in sun‐ and alguidar‐dried guarana seeds from Bahia State’s Low Sul Identity Territory. Caffeine, theobromine, catechin, and epicatechin were determined by high‐performance liquid chromatography with UV‐visible detection (HPLC/UV‐vis). Statistical tools, including analysis of variance (ANOVA), Tukey’s test, and exploratory analysis, were employed to analyze the obtained data. Our findings indicated that the flavan‐3‐ols content in sun‐dried guarana samples was lower compared to those dried using the alguidar oven, possibly due to exposure to ultraviolet radiation from solar energy. Conversely, we observed no significant differences (p > 0.05) in the average contents of methylxanthines between the two drying methods. Our supplementary experiments involving UV‐A and UV‐C radiation lamps revealed a decreasing trend in methylxanthines and flavan‐3‐ols contents with increasing duration of UV radiation exposure.