Optimization of ultrasound-assisted extraction of polyphenols from globe artichoke (Cynara scolymus L.) bracts residues using response surface methodology.

BACKGROUND: The globe artichoke (Cynara scolymus L.) is a rich source of phenolic compounds which may be extracted by ultrasound technology and used as a medicinal alternative. The objective of this work was to determine the radiation amplitude (%), ethanol concentration (%), and time extraction (min) required to guarantee an elevated content of polyphenol compounds. METHODS: The optimal extraction conditions were assessed through the Box-Wilson design and by applying Composite Face Centered (CCFC) and total phenolic compounds (TPC) as the response variables. RESULTS: A quadratic model was adequate, with R2 = 0.993. The optimal conditions were a radiation amplitude of 97%, an ethanol concentration of 53%, and an extraction time of 9.7 min. The optimized extract of artichoke bracts (Cynara scolymus L.) showed a TPC of 25.13 (±0.030) mg GAE/g, an antioxidant activity DPPH of 39.79 (±0.014) mmol Trolox equivalents (TE), and an antioxidant capacity TEAC of 33.98 (±0.03) mmol Trolox equivalents. CONCLUSIONS: The results showed values closely related to the expected values, indicating that the models were well-developed.

Optimization of the ultrasoud-assisted extraction of saponins from quinoa (Chenopodium quinoa Wild) using response surface methodology.

BACKGROUND: Quinoa grain has a bitter tasting layer in the pericarp called saponin, a triterpenoid glycoside with industrial potential. Traditionally, quinoa saponins are extracted with a large amount of water, which is why ultrasound technology constitutes an emerging technological alternative which is considered efficient and profitable compared to traditional extraction methods. The objective of this research was to determine the amplitude, time, and concentration of ethanol that guarantee a higher content of saponin through extraction assisted by ultrasound. METHODS: To find the optimal extraction conditions, the response surface methodology was used using the Box Behnken design with 5 central points, taking as a response the content of saponins (expressed in oleanolic acid as it is the most abundant sapogenin). RESULTS: According to the results obtained, the R2 values were in agreement with the adjusted R2, showing that the data fit the model well. The results showed that ethanol concentration has a significant effect (p < 0.05) on the saponin content in the extract. Optimization showed that the optimal extraction conditions were 70% ethanol, 59% amplitude and an exposure time of 12 min. These values were obtained experimentally to compare theoretical values and found residual error percentages less than 3%. The emulsifying activity was evaluated, reporting a value of 52,495 units of emulsion activity per milliliter (UAE/mL), and the foaming stability indicated that 87.54% of the initial foam was maintained after 5 min, indicating high stability. CONCLUSIONS: The parameters of ethanol concentration, amplitude and time were optimized in the extraction of saponins, assisted by ultrasound. Furthermore, the extract obtained had good foaming and emulsifying characteristics, suggesting its suitability for use in industry.