Decolorization of soybean oil by acid‐activated Ca‐Bentonite (EL Gnater, Central Tunisia)

Abstract

In the central Atlas of Tunisia, numerous outcrops of the upper Eocene provide smectitic clays. A representative sample (A) which was collected from the El Gnater region round El Ala underwent mineralogical and physicochemical analyses (granulometry, DRX, BET, FT-IR, etc.). This clay showing percentage of the order of 80% in smectite were activated with hydrochloric acid to improve its physicochemical properties, and consequently to increase their decolorization power for soybean oils. The best results were obtained using clay, activated with 3 N hydrochloric acid for 3 h at 75 C (AA2). Indeed, the specific surface area increased from 44 to 119 m 2 /g. The characterization of physicochemical properties was carried out on the samples (A: raw, AA: activated at different acid concentrations 1.5, 3 and 4.5 N at 75 C during 3 h). Under optimal conditions, the decolorization power of AA2 clay (60.15%) was found to be better than that obtained by a bleaching earth imported from Germany (57.27%). These encouraging results allow the reduction or permanently stopping of these materials imports.

Removal of Minor Components From Vegetable Oils by a Multistage Chromatography Column in a Specific Order

“…The first adsorption stage was short in the first 10 min, followed by a slow process until equilibrium was attained after 40 min of reaction, which indicated that the maximum sorption of β-carotene occurred after 40 min of decolorization, which was in line with previous reports [35]. In the first stage, mainly β-carotene molecules react with the surface of activated clay; specifically, β-carotene is fixed to the clay surface by forming hydrogen bonds with Bronsted sites in the activated clay or by forming coordination bonds with Lewis sites [36]. In addition, the protonated AlOH 2 + structure can serve as an effective binding site for β-carotene in vegetable oil [37].…”

Effect of Chemical Refining on the Reduction of β-Carboline Content in Sesame Seed Oil

“…Oil refining usually consists of degumming, deacidification, decolorization and deodorization steps, of which decolorization is one of the important processes in edible oil refining. Some studies have reported that solid adsorbents (e.g., clay and activated carbon) used in the decolorization process can bind to small molecules (e.g., pigments) in oils via physical adsorption [16,17]. Recently, it has been shown that decolorization is a key process to reduce some harmful compounds (e.g., BaP) [18][19][20].…”