Optimization of an Ultrasound-Assisted Extraction Condition for Flavonoid Compounds from Cocoa Shells (Theobroma cacao) Using Response Surface Methodology

Abstract

This study investigates the ultrasound-assisted extraction of flavonoids from Malaysian cocoa shell extracts, and optimization using response surface methodology. There are three variables involved in this study, namely: ethanol concentration (70–90 v/v %), temperature (45–65 °C), and ultrasound irradiation time (30–60 min). All of the data were collected and analyzed for variance (ANOVA). The coefficient of determination (R2) and the model was significant in interaction between all variables (98% and p < 0.0001, respectively). In addition, the lack of fit test for the model was not of significance, with p > 0.0684. The ethanol concentration, temperature, and ultrasound irradiation time that yielded the maximum value of the total flavonoid content (TFC; 7.47 mg RE/g dried weight (DW)) was 80%, 55 °C, and 45 min, respectively. The optimum value from the validation of the experimental TFC was 7.23 ± 0.15 mg of rutin, equivalent per gram of extract with ethanol concentration, temperature, and ultrasound irradiation time values of 74.20%, 49.99 °C, and 42.82 min, respectively. While the modelled equation fits the data, the T-test is not significant, suggesting that the experimental values agree with those predicted by the response surface methodology models.

Optimization of Ultrasound-Assisted Extraction of Flavonoids from Celastrus hindsii Leaves Using Response Surface Methodology and Evaluation of Their Antioxidant and Antitumor Activities

“…When a maximum TFC was obtained, a further increase in ethanol concentration induced a decrease in the TFC, which is consistent with the result of the flavonoids extraction from cocoa shells [31], Dendrobium officinale [32], and Bombyx batryticatus [7]. Studies have shown that ethanol concentration is one of the most important factors affecting the extraction of flavonoids [7,31,32]. Changing the ethanol concentration adjusts the polarity of the extraction solvent and alters the solubility of flavonoids, thus affecting the efficiency of the flavonoids extraction [32].…”

“…is result is consistent with the ultrasound-assisted extraction of flavonoids from olive leaves [16] and cocoa shells [31], polysaccharides extraction from A. selengensis [21], and the ultrasound-assisted extraction of phenolic from Trapa quadrispinosa [15].…”

“…Increasing the extraction time significantly increased the TFC at any extraction temperature. Nevertheless, extended extraction time led to a reduction in the TFC due to the degradation of flavonoids [16,31], which is similar to that obtained for flavonoids extraction from olive leaves [16] and cocoa shells [31]. In addition, the result is similar to the polysaccharides extraction from A. selengensis [21] and phenolic extraction from T. quadrispinosa [15].…”

“…e TFC is significantly enhanced with the increase in extraction temperature at any extraction time. is was attributed to the positive effect of temperature on the extraction [16,31]. However, a higher temperature caused a reversal of the aforementioned trend.…”

“…is could be because flavonoids are sensitive to temperature and therefore high temperature causes degradation of flavonoids [16,31]. Similar to temperature, the extraction time also had a significant effect on the TFC.…”