Effects of process parameters on the extraction of total anthocyanins from purple sweet potatoes by ultrasound with wide frequency and its kinetics study

Abstract

To obtain a better insight into comprehending the unusual role of ultrasound frequency and enhance the extraction yield of total anthocyanins (TA) from purple sweet potatoes (PSPs), an approach of wide frequency‐based ultrasound‐assisted extraction (WF‐UAE) was applied to evaluate the influence on the extraction of TA under process parameters at different levels, ultrasound frequency (20–84 kHz), ethanol concentration (20–65%), solvent to solid ratio (10–70 ml/g), ultrasound power (50–280 W), temperature (30–70°C), particle size (0.147–0.908 mm), and treatment time. The results showed that ultrasound frequency has more influence on the extraction yield, followed by temperature, treatment time, and other extraction parameters. The maximum yield of 0.567 ± 0.005 mg/g of TA was obtained at optimized parameters, which was significantly higher than Soxhlet extraction where only 0.324 ± 0.002 mg/g was achieved at 98°C for 720 min, as well as higher than ultrasound‐assisted extraction where only 0.465 ± 0.006 mg/g was obtained at 300 W and 20 kHz for 45 min. The extraction kinetics were performed at different levels of process parameters by Peleg's model. Model constants and equilibrium concentration for different process parameters were predicted. Model validation was done by depicting predicted and experimental values from extracted TA. The obtained values of regression coefficient (R2 > 0.972) and root mean square deviation (RMSD < 0.218) indicated that this model has a good agreement with the experimental results. Novelty impact statement This work is the first to evaluate the effects of ultrasound frequency span a wide range from 20 to 84 kHz and other process parameters on the extraction of TA from PSPs by using an approach of WF‐UAE that was based on a frequency search device with eight extraction tanks controlled by a computer. The application of WF‐UAE technology could not only efficiently extract TA from PSPs, but also be promising for extracting active components from different natural materials in the industry.

Extraction of phenolics and anthocyanins from purple eggplant peels by multi-frequency ultrasound: Effects of different extraction factors and optimization using uniform design

“…After that, both extraction yields slightly decreased as the ultrasonic power was further increased. Similar results were reported in other research for MUAE of anthocyanin from strawberry fruit [60] , and UAE of total anthocyanins from purple sweet potatoes [61] . This may be due to the mechanical effect, thermal effect, and cavitation effect are all strengthened with the increase of ultrasonic power.…”

Ionic liquid-based ultrasonic-assisted extraction coupled with HPLC to analyze isoquercitrin, trifolin and afzelin in Amygdalus persica L. flowers

“…Ultrasonic-assisted extraction had been proved to significantly shorten the extraction time and improve the extraction yield in the process of assisting plant extraction. In the process of ultrasonic application, cavitation and mechanical effects would be produced, which made it easier for solvents to penetrate into plant raw materials, destroy plant cell walls and promote the release of active components [ 19 – 21 ]. Ionic liquid-based ultrasonic-assisted extraction was a green extraction technology with high efficiency and energy saving, which combines the characteristics of high efficiency cavitation effect generated by ultrasound and high solubility of ionic liquid [ 22 ].…”

Recovery of phenolic compounds from purple onion peel using bio‐based solvents: Thermal degradation kinetics and color stability of anthocyanins

“…The main constituents of flavonoids are flavonols and anthocyanidins, responsible for quercetin and anthocyanins, respectively, both present in purple onion peel (Bordin Viera et al, 2021; Ren et al, 2020). Several polyphenol extraction techniques are reported, such as maceration (Oliveira & Antelo, 2020; Santos et al, 2021; Viera et al, 2017), enzymatic‐assisted extraction (Araújo et al, 2021), reflux (Saptarini & Herawati, 2018), and ultrasound‐assisted extraction (Liao, Peng, et al, 2022; Liao, Xue, et al, 2022), the conventional method is the most used due to the low operational cost.…”

“…Several studies have been carried out to evaluate better conditions for green extraction of bioactive compounds from several matrices (Dairi et al, 2021; Drăghici et al, 2018; Liao, Peng, et al, 2022; Viera et al, 2017), mainly using nontoxic and low‐cost solvents (e.g., bio‐based solvents). The bio‐based solvents (e.g., ethanol, ethyl acetate, acetic acid, etc.)…”