Comparison of Conventional Microwave and Focused Microwave-assisted Extraction to Enhance the Efficiency of the Extraction of Antioxidant Flavonols from Jocote Pomace (Spondias purpurea L.)

Abstract

Jocote (Spondias purpurea L.) is rich in phenolic compounds which have antioxidant properties. The focused microwave-assisted extraction (FMAE) was compared with the conventional microwave-assisted extraction (MAE) to obtain flavonols from jocote pomace. The effects of parameters such as the extraction time, the temperature and the composition of the solvent mixture (i.e., the ethanol to water ration) were evaluated and optimized using a statistical experimental design approach. Response surface methodology (RSM) was applied to determine the important effects and interactions of these independent variables on the extractive yield and quantification of some flavonoids. In addition, the antioxidant activity was analyzed. The total phenolic and flavonoid content was determined according to the Folin-Ciocalteu and aluminum chloride methods, respectively. The free radical scavenging activity of the extract was evaluated according to the DPPH assay. The results showed that the optimum extracting parameters used FMAE with extraction time of 20 min, temperature of 68 °C and ethanol composition of 80% in water. Under these conditions, a yield of 3.42% was obtained. Rutin and quercetin were quantified (0.19 mg/mL and 0.024 mg/mL, respectively) through HPLC-DAD. The total phenol and flavonoid contents were found to be 0.897 g GAE/g and 1.271 g QE/g, respectively. In the DPPH scavenging assay, the IC50 value of the extract occurred at 43.10 μg/mL. This study shows that FMAE is suitable as an efficient extraction procedure for the extraction of flavonols from jocote pomace.

Siriguela peels provide antioxidant compounds‐rich extract by solid–liquid extraction

“…These results were different from those reported by Reis et al (2015), which extracted bioactive compounds from siriguela peels using microwave‐assisted conventional extraction. These authors found that the best result was obtained when a solution containing 80% ethanol in water was employed in the extraction process of phenolic compounds (flavonols).…”

“…Our results showed that 30% ethanol was the best solvent solution to recover antioxidant compounds from siriguela peels, being different from the Reis et al (2015) data, which obtained better results using 80% ethanol at 68°C. In that study, the authors extracted antioxidant compounds (flavonols) from siriguela peels by focused microwave‐assisted extraction.…”

“…The siriguela peels have already been studied by Reis, Carneiro, Branco, and Branco (2015). These authors evaluated the recovery of phenolic compounds mainly flavonols and the antioxidant capacity of the fruit peels through conventional microwave, and focused microwave‐assisted extraction.…”

Progress in the Valorization of Fruit and Vegetable Wastes: Active Packaging, Biocomposites, By-Products, and Innovative Technologies Used for Bioactive Compound Extraction

“…This approach has been used to extract high-quality pectin with biomasses such as mango peels [ 155 ], citrus mandarin peels [ 156 ], fig skin [ 157 ], orange peel, apple pomace, mango peel, carrot pulp [ 158 ], pumpkin biomass [ 148 ], and banana peels [ 159 ]. The study conducted by Zin et al [ 160 ] showed that the highest microwave power used on the fruit waste (sour cherry pomace) was 700 W. Other biochemical compounds can also be obtained using this technique, such as antioxidants from black carrot pomace [ 161 ], pitaya peel [ 153 ], and mango seed kernels [ 162 ]; flavonoids from Jocote pomace [ 163 ]; anthocyanins from grape juice waste [ 164 ] and sour cherry pomace [ 165 ]; and essential oil from lemon peels waste [ 166 ]. Casas et al [ 167 ] also showed the potential of cocoa butter produced from mango kernel butter by extracting discarded seed kernels.…”

“…For optimum yield extraction of the targeted compound, focused microwave-assisted extraction is preferred to conventional or household microwave ovens, as the parameters, namely the pressure and temperature, can be monitored [ 163 ]. A previous study showed that the combination of MAE with other methods could help produce high-yield compounds.…”