Modelling and optimisation of ultrasound-assisted extraction of roselle phenolic compounds using the surface response method

Abstract

Extracts from Hibiscus sabdariffa L. (roselle) have been used traditionally as a food, in herbal medicine, in hot and cold beverages, as flavouring or coloring agent in the food industry. In vitro and in vivo studies and trials provide evidence, but roselle is poorly characterised phytochemically due to the extraction processes. The optimization of the extraction of phenolic compounds and their antioxidant activities is still a hot topic. In this study, the effect of solute/solvent ratio (33, 40 and 50 mg/mL), extraction temperature (40, 50 and 60 °C) and extraction time (30, 60 and 90 min) was evaluated through the content of phenolic compounds and antioxidant activity. A response surface methodology through a Box–Behnken design was applied and model fit, regression equations, analysis of variance and 3D response curve were developed. The results showed that TPC, TFC, DPPH and FRAP were significantly influenced by temperature, extraction time and solvent/solute ratio. Thus, TPC, TFC, DPPH and FRAP varied from 5.25 to 10.58 g GAE/100 g DW; 0.28 to 0.81 g QE/100 g DW; 0.24 to 0.70 mg/mL; 2.4 to 6.55 g AAE/100 g DW respectively. The optimal experimental condition (41.81 mg/mL; 52.35 °C and 57.77 min) showed a significant positive effect compared to conventional methods. The experimental values at this extraction condition show that this optimization model is technologically, financially and energetically viable as it requires a reasonable concentration, time and temperature.

Ultrasound-Assisted Extraction of Bioactive Compounds from Broccoli By-Products

“…These results fitted to the Peleg kinetic model, which has been used in similar studies [31,32], although our results seem to follow a cubic model, to which they are better adapted (>R 2 ), as also reported by other researchers [33,37,46]. These facts are due to the lower concentrations found, as previously reported in several works [38][39][40]. Future studies must elucidate the use of mathematical and kinetic models that can justify this behavior in the UAE in broccoli byproducts.…”

“…In fact, the concentrations of such biocompounds were not high enough to be modelled in the present work, for which they did not have a good adaptation to the studied models. This is the main limitation of the present research, as other previous researchers assessed [38][39][40]. In this sense, as R 2 was lower than 0.5 for both statistical models of the cited variables, their representation is not shown in the present work, although obtained results from those analyses are shown in Tables 2 and 3.…”

Enhancing phytochemical parameters in broccoli through vacuum impregnation and their prediction with comparative ANN and RSM models

“…Initially, 0.5 g of fresh broccoli florets were combined with an 80% methanolic solution and subjected to centrifugation at 553.41 G for 20 min using a C 24 Remi Group Laboratory Instruments centrifuge (India). The resulting supernatant was obtained by filtering the methanolic extract through qualitative filter paper (100,125 R, AXIVA SICHEM BIOTECH, India) 9 , 10 . The methanolic extract was further used for the TPC, TFC and FRSA analysis.…”

“…The second-order polynomial model was developed for each dependent variable to interpret the individual and interactive effect of the independent variables 10 . The adequacy of the developed model was checked through the estimation of model parameters like F test ( p ≤ 0.05), coefficient of determination (R 2 ), lack-of-fit, and coefficient of variation (c.v. 10%).…”

Optimization of Ultrasonic Extraction Parameters for the Recovery of Phenolic Compounds in Brown Seaweed: Comparison with Conventional Techniques

“…This results in a stronger interaction between the solvent and free phenolic compounds that are polar in nature, thus causing the greater solubilization of the free phenolics into the solvent [21]. According to Fick's law, the higher concentration gradient between the cell wall content and extraction medium drives the yield of bioactive compounds [27]. Indeed, based on the ANOVA analysis in Table 2, the effect of the solvent:seaweed ratio is statistically significant (p < 0.05) compared to the other factors supporting it as a major variable during the free phenolic extraction process.…”