Conventional and emerging techniques for extraction of bioactive compounds from fruit waste

Antioxidant activity increased due to dynamic changes of flavonoids in orange peel during Aspergillus niger fermentation

“…This result suggested that A. niger in controlled fermentation contributes to the depolymerization of high molecular weight flavonoid. Interestingly, hesperidin content increased continuously before 72 h. One possible explanation for this might be that the fermentation‐induced structural breakdown of the OP cell walls promotes the release of flavonoids at the initial fermentation, and then the released flavonoid exposed chemical bonds that react with the enzymes (Santos & Santana, 2022).…”

Valorization of tropical fruit‐processing wastes and byproducts for biofuel production

“…This extraction technique has many advantages relative to solvent extraction, including high reaction rates, the absence of toxic solvents, the ability to adjust solvent power for accurate extraction of target components, and the production of pure crude oils that are not contaminated with solvents 153 . Ethanol, acetone, methanol, water, and carbon dioxide are common supercritical solvents that are predominantly used in these techniques due to their non‐toxicity, the fact that they are non‐explosive, and their ability to solubilize lipophilic substances and easily remove them from the final products 137,153 . Furthermore, the low viscosity, high diffusivity, dielectric constant, and density of these fluids make them easily penetrate the sample and increase the extraction activity.…”

“…In this regard, unconventional intensification techniques such as microwave‐assisted extraction (MAE) have been developed to improve the yield, extraction efficiency, and quality of solvent‐based processes. This operates under the principle of electromagnetic irradiation (with a frequency from 300 MHz to 300 GHz) of the polar solvent and the sample, which results in the superheating of the solid material, rupturing it 137 . Hazarudin and Razali 156 stated that the MAE techniques involve three steps that take place one after the other.…”

“…Hence, optimization of all process parameters enables better yield and quality. Despite having potential benefits, large‐scale (industrial) applications of enzymes are difficult because of the elevated cost of enzymes, 138 and their application is limited by environmental conditions 137 …”

“…153 Ethanol, acetone, methanol, water, and carbon dioxide are common supercritical solvents that are predominantly used in these techniques due to their non-toxicity, the fact that they are non-explosive, and their ability to solubilize lipophilic substances and easily remove them from the final products. 137,153 Furthermore, the low viscosity, high diffusivity, dielectric constant, and density of these fluids make them easily penetrate the sample and increase the extraction activity. For non-polar compounds, supercritical carbon dioxide is the most efficient solvent, whereas ethanol, methanol, acetyl chlorides, and an azeotropic mixture of hexane and ethanol extract polar compounds effectively.…”