Adsorption of Dark Colored Compounds in Apple Juice – Effects of Initial Soluble Solid Concentration on Adsorption Kinetics and Mechanism

Abstract

Adsorption of dark colored compounds onto adsorbent resin was studied for different adsorbent resin concentrations (1.5, 2.0, 3.0, 5.0, 10.0, 15.0 g resin/L apple juice) and different °Brix ratios of apple juice (10, 20, 30 °Brix). The equilibrium data obtained fitted well to Langmuir isotherm. The maximum adsorption capacity was found 0.124 1/g resin at 30C for apple juice having a °Brix ratio of 10. The adsorption of dark colored compounds from apple juice onto adsorbent resin followed pseudo‐second‐order kinetic model. The adsorption rate constants decreased as the °Brix ratio of apple juice increased. As it was confirmed by Bangham's equation, the rate‐limiting step was intraparticle diffusion. This study showed that using adsorbent resin to improve color had no effect on organic acid and sugar composition of apple juice. PRACTICAL APPLICATIONS Browning during processing and storage adversely affects the commercial acceptability of apple juice concentrate. Adsorption is considered as a viable process to improve apple juice color. The present study shows the adsorption behavior, kinetics and mechanism of dark colored compounds in apple juice. From a practical application point of view, initial soluble solid content of apple juice is considered as an important parameter that should be taken under control to improve the adsorption efficiency. After the adsorption process, the level of main constituents such as sugar and organic acids remain constant so this adsorption process appears to be effective for apple juice process.

Recovery, concentration and purification of phenolic compounds by adsorption: A review

“…Conventional techniques include flocculation with gelatin and bentonite , and adsorption (Qiu et al, 2007), as it has been proposed for phenolics from apple peels and cores (Haddad et al, 2003), juice (Schieber et al, 2003) and mango peels (Berardini et al, 2005). Resins are suited for processing apple pomace (Schieber et al, 2003) and juice (Gökmen and Serpen, 2002;Ataç and Gökmen, 2009). Polymeric phenolics responsible for the brown colour of apple juices can be more hydrophobic than low-molecular weight phenolics, resulting in different degrees of interaction with resins .…”

Equilibrium, Kinetic, and Thermodynamic Studies for Crude Structured-Lipid Deacidification Using Strong-Base Anion Exchange Resin

“…Although our results were poorer than those obtained by Doboni et al in their study, 30 the maximum capacity of D202 resin in the nonaqueous system was larger than those of the various absorbents used in metal ion eliminations in aqueous systems, which may be attributed to the absorbents characteristics, including their specific surface area, functional group ionization, and pore size. 19,26,28,29 As shown in Table 2, the R 2 values of the linear and nonlinear Freundlich and Langmuir theoretical isotherms were 0.9063 and 0.9283, and 09676 and 0.9902, respectively; thus, the Langmuir isotherm better describes the adsorption behavior of FFAs onto anion exchange resin D202 in crude SL/hexane solution. Therefore, the ion exchange adsorption between D202 resin and the FFAs may be considered monolayer adsorption.…”

“…Commonly, a value of n ranging between 1 and 10 indicates that the adsorption process is favorable, whereas an n less than 0.5 means that the adsorbent is unable to adsorb the adsorbate well. 6,16,19,26,27 The linear plot of log q e versus logC e provided K and n values of 3.074 and 1.16, respectively (Figure 2a, Table 2), whereas the values were 5.120 and 1.39 when the experimental data were fitted to the Freundlich theoretical model using the nonlinear method (Figure 2b, Table 2). Both the linear and nonlinear regression analyses afforded n values that were greater than 1, which suggests that the sorption of FFAs onto the resin in this nonaqueous system is favorable.…”