Kinetics and thermodynamics of the solid-liquid extraction process of total polyphenols from barley

Abstract

The influence of the solvent concentration, pH, temperature, sampler solid ratio and extraction time on the extractability of total phenolic compounds from barley was investigated. The most effective solvent (30% aqueous ethanol solution with 5% HCl v/v) was used for modeling the solid-liquid extraction of total polyphenolic compounds at the solid-liquid ratio of 30 mL/g (the ratio of the solvent volume per gram of raw material). Total phenolic compounds in the barley extracts were determined spectrophotometrically using Folin-Ciocalteu method at 760 nm. The content of the phenolic compounds of extracts depends on the extraction conditions applied. The mechanism of the extraction is confirmed to occur in the following steps: first, the dissolution of the phenolic compounds near the particle surface (washing) and second, the diffusion from the solid particles to the bulk of the liquid extract (slow extraction). The process is described mathematically using two concepts of unsteady diffusion through the plant material and Ponomaryov's empirical equations. The data obtained are used to establish the kinetics and thermodynamics of the extraction process.

Extraction Kinetics of Total Polyphenols, Flavonoids, and Condensed Tannins of Lentil Seed Coat: Comparison of Solvent and Extraction Methods

“…Thus, typical extraction kinetics with a fast step of washing dominated by solute partition first and then a slow step of diffusion controlled by solute diffusion was observed. This is in line with most solid-liquid extraction curves [39][40][41]. Various mathematical simulations can prove this trend, and here, four empirical kinetic models for CSLE and UAE were applied to fit the experimental data for water, and ethanolic and methanolic extractions.…”

“…These models have been previously implemented for the extraction of bioactive compounds from several matrices such as Asteraceae plant, pomegranate peels, barley, and chicory roots by-products [41][42][43][44]. The yield of the phenolic compounds achieved from the nonlinear models was largely close to the experimental one.…”

Ultrasound‐assisted extraction (UAE) of bioactive compounds from coffee silverskin: Impact on phenolic content, antioxidant activity, and morphological characteristics

“…According to the results, the values of B 0 for control groups were significantly ( p < .05) higher than the values for UAE‐treated groups for both methanol–water and water extracts. The reason could be that the solid–liquid extraction includes two stages, which are: the dissolution of the phenolics around the matrix surface (washing), and then the diffusion from the matrix to the solvent (slow extraction) (Paunović, Mitić, Kostić, Mitić, & Stojanović, ). The yield increased rapidly at the first stage and then at a much slower rate at the second stage.…”

The estimation of kinetic parameters of the solid-liquid extraction process of the lavender flower (Lavandula x hybrida L.)

“…1 -4). The period of rapid increase of TPC, TDS, G, and DM at the beginning of the process, and their slow increase as the extraction process progresses (Paunović et al, 2014;Fan et al, 2015;Jurinjak Tušek et al, 2016). Since the extraction curves describing TPC, TDS, G, and DM in relation to the duration of the extraction process have similar shapes, the same mathematical models (Peleg's, Page's, and logarithmic) were used to analyse the extraction kinetics.…”