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Proposal for Soybean Association to Reduce the Sterol Glucoside Content in Soy-based Biodiesel. By Haiying Tang. Structures. Plant Sterols exist as free sterols, steryl esters, steryl glycosides, and acylated steryl glycosides.
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Proposal for Soybean Association to Reduce the Sterol Glucoside Content in Soy-based Biodiesel By Haiying Tang
Structures • Plant Sterols exist as free sterols, steryl esters, steryl glycosides, and acylated steryl glycosides.
Toivo et al(Determination of sterols in foods: Recovery of free, esterified, and glycosidic sterols. Journal of Food Composition and Analysis 2001;14(6):631-643) Corn meal and onion contain an appreciable amount of steryl glycosides Rapeseed oil did not contain steryl glycosides. Verleyen et al ( Influence of the vegetable oil refining process on free and esterified sterols. JAOCA, Vol.79, no.10, 2002) Water degumming did not affect the sterol content or its composition. A significant reduction in the free sterols during neutralization; a gradual reduction in the total sterol content as a function of temperature (220-260 0C) during deodorization A considerable increase in sterol ester fraction during physical refining; a slight increasing in the free sterols during acid degumming and bleaching Results:
Continued • Kochhar (Influence of Processing on Sterols of Edible Vegetable-Oils. Progress in Lipid Research 1983;22(3):161-188.) • Sterol occur in free and esterified form in refined vegetable oil process. • Conventional refining has minor effects on the sterols; however, high temperature physical (steam) refining of oil does affect the sterol composition. • Reduction in the levels of sterols during degumming, neutralization,bleaching, hydrogenation, deodorization,and steam refining. • The rate of reduction was depended on • The amount of sodium hydroxide, • Type of bleaching earth, • Conditions of hydrogenation • Time and temperature of steam deodorization • Physical deacidification • Loss of sterols of between 10-70%
Continued: Sterol Glucosides • Sterol glycosides are removed during the oil refining process. • Degumming vegetable oils effectively removes sterol glucosides. • Fully refined oils are invariably free from sterol glucosides; • Alkali refines removes a portion of the sterol; • Both steam deodorization and physical refining further reduce the sterol glucosides.
Wedel( Quantitative studies of the pHLip Test Kit for B100, AOCS presentation, May 2007)
Critical Issue • No ASTM standard on the analytical methods to determine sterol glucosides in biodiesel; • The effect of refining and processing strategy on sterol glucoside content in biodiesel has not been fully elucidated; • Few studies on reducing the sterol glucoside content in biodiesel blends.
Objectives • Evaluate different refining and processing strategy to reduce the sterol glucoside content in soy-based biodiesel • The effect of vacuum distillation on the sterol glucoside content in biodiesel; • The effect of cold filtering on the sterol glucoside content in biodiesel and blends • Using filter membrane • Using gravity to settle out, and separate
Chemical refining • Water degumming • Chemical neutralization • Bleaching • Deodorization • Physical refining • Acid degumming • Bleaching • Deordorization
Process • Water degumming: oil 70 oC at 175 rpm+water(3%) ----at 250 rpm for 30 min----Centrifuging-----supernatant • Chemical neutralization: water-degummed oil at 55oC + NaOH (10%) at 175 for 40 min----heated to 75 oC----centrifuge----oil was collected and washed with water. • Acid degumming:oil 60 oC+0.15% citric acid at 10000rpm for 1 min__ 60min at 40oC--- cnetrifuging • Bleachinng: The degummed oil at 95oC under reduce pressure (50 mbar)+ bleaching earth --- mixed at 85 rpm for 30 mil--- filter • Depdorization: at 240oC (2 mbar) with injection of 1.5 and 1% steam, respectively.
Sterol Glycosides • Crude soy oil: 2300ppm SG • 19300 ppm SG in gum • Hydrolysis may be carried out by the application of steam and alkali or acid: biodiesel made from acid oil can have high levels of SG
Analysis method • Total sterols were analyzed by acid and alkaline hydrolysis, hydrolysis, derivatisation to trimethylsilyl(TMS)-esters and anlysis using GC-FID. • The steryl glucosides were isolated by solid phase extraction (SPE), and then was hydrolysed with acid to release the free sterols