Ultrasound‐assisted extraction of anthocyanin from black rice bran using natural deep eutectic solvents: Optimization, diffusivity, and stability

Abstract

The present study was aimed to establish a green extraction method for anthocyanins from black rice bran using natural deep eutectic solvents (NADES) coupled with ultrasound-assisted extraction (UAE). Initially, five NADES were used and lactic acid: fructose was screened as an efficient extractant for anthocyanin from black rice bran.The extraction condition was optimized using an artificial neural network-genetic algorithm and the best condition was found to be time 11.25 min, water 12.63%, solventto-solid ratio 18.75 ml/g, amplitude 21.31%. The UAE-NADES extraction kinetics of anthocyanin was suitable for the pseudo second order model (0.94 ≤ R 2 ≤ 0.99).The UAE-NADES showed higher effective diffusivity (1.14 × 10 -12 m/s 2 ) of anthocyanin than the conventional extraction process. The enthalpy, entropy, and Gibbs free energy were negative irrespective of temperature. The stability of anthocyanin in NADES was higher than aqueous medium. This result indicates that the proposed method is an excellent alternative for the extraction and stabilization of anthocyanin. Practical applicationsAnthocyanin pigments are used as food colorants, antioxidants, and anticancer agents.However, anthocyanin is sensitive to processing factors, and the majority of regularly used extractant solvents are hazardous to the environment and reduce anthocyanin stability. The present study demonstrated that using a natural deep eutectic solvent to extract anthocyanin minimizes pollutants, lowers expenses, and improves extraction efficiency. Moreover, the study also demonstrated the non-thermal extraction as well as valorization of black rice bran.

Comparison of pulse electric field, microwave and ultrasonic pretreatment prior to black rice extraction on antioxidant and sirtuin1 enzyme stimulating activities

“…The results exhibited that the amount of anthocyains extracted from UAE was less than that obtained by PEF and MAE under similar extraction time. Ultrasound waves during UAE are attributed to mechanical effects of cell disruption on black rice pericarp, and increased solvent diffusion leading to enhance ultrasonic capillary effect (Thakur et al, 2022). These effects are similar to the effects UAE on other plant materials (Yin et al, 2022;Zhong & Wang, 2010).…”

Comparison of Different Extraction Methods for Bioactive Compounds from Kao-Kum Doi-Saket (Oryza sativa L.)

“…This phenomenon, known as cavitation, leads to tiny bubbles' formation and rapid collapse. The collapse of these bubbles generates intense local pressures and temperatures, disrupting cell walls or breaking molecular bonds, facilitating the release of desired compounds [13][14][15][16]29]. Whereas the PEF method involved the use of electric current, caused structural changes in the cell membranes, and induced severe cracking in the cell walls of the Kao-Kum Doi-Saket.…”

Green Extraction of Polyphenols via Deep Eutectic Solvents and Assisted Technologies from Agri-Food By-Products

“…As shown in Table 4, these by-products are major sources of natural rutin, flavonoids, and anthocyanins. As a green and sustainable extraction medium, DESs have extracted polyphenols from wheat barn [73] and brewer spent grain [72], anthocyanin from black rice bran [74], and rutin from tartary buckwheat hull [75]. The polyphenol-rich NADESs extract from foxtail millet bran was mainly composed of coumaric acid, apigenin-C-dihexoside, and p-coumaroylspermidine, and showed high acetylcholinesterase inhibitory activity [76].…”

“…Fick's model successfully forecasted the extraction kinetics of tannic acid using an ultrasound-assisted DESs extraction method and revealed that diffusivity was the controlling factor [57]. Kinetic studies showed that the extraction diffusivity of anthocyanin in NADESs (1.063 × 10 −12 ) was markedly higher than in water (0.835 × 10 −12 ) [74]. Moreover, it has been reported that DESs extracted more polyphenols with higher molecular weights and more diverse phenolic compounds than methanol from mangosteen peel [43].…”

“…The extraction conditions (namely solid-to-liquid ratio, water content, temperature and time, and technical parameters of assisted technologies) are usually optimized to maximize the extraction yield of polyphenols. The optimization process can be experimentally conducted and optimized using the response surface method (RSM) and/or artificial neural network (ANN) methods [32,74].…”