Surface activity of saponin from Quillaja Bark at the air/water and oil/water interfaces

Kamil Wojciechowski

Abstract

Surface activity of Sigma's Quillaja bark saponin (QBS) was studied by means of dynamic interfacial tension and surface dilational rheology at three fluid/fluid interfaces with the polarity of the non-aqueous phase increasing in the order: air/water, tetradecane/water and olive oil/water. The equilibrium interfacial tension isotherms were fitted to the generalized Frumkin model with surface compressibility for the air/water and tetradecane/water interfaces, whereas the isotherm for the third interface displays a more complex shape. Upon fast compression of a drop of concentrated "Sigma" QBS solution immersed in olive oil, a clearly visible and durable skin was formed. On the other hand, no skin formation was noticed at the air/water interface, and only a little at the tetradecane/water interface. Addition of a fatty acid, however, improved slightly the skin-formation ability of the QBS at the latter interface. The surface behavior of the QBS from Sigma was compared with that from Desert King, Int. ("Supersap"), employed in a recent study by Stanimirova et al. [22]. The two products exhibit different areas per molecule in the saturated adsorbed layer (0.37nm(2) vs. 1.19nm(2) for "Sigma" and "Supersap", respectively). Also their surface rheology is different: although both QBSs form predominantly elastic layers, for "Sigma" the surface storage modulus, εr=103mNm(-1), while for "Supersap" εr=73mNm(-1) at 10(-3)moll(-1) (i.e., around their cmc). The two saponin products exhibit also different ionic character, as proven by the acid-base titration of their aqueous solutions: QBS from Sigma is an ionic surfactant, while the "Supersap" from Desert King is a non-ionic one.
Author Kamil Wojciechowski (FC / IBC / DM)
Kamil Wojciechowski,,
- Department Of Microbioanalytics
Journal seriesColloids and Surfaces B-Biointerfaces, ISSN 0927-7765
Issue year2013
Vol108
Pages95-102
Publication size in sheets0.5
Keywords in EnglishSaponins; Adsorption; Ionic surfactants; Air–water; Olive oilwater; Tetradecane–water
ASJC Classification1505 Colloid and Surface Chemistry; 1606 Physical and Theoretical Chemistry; 3110 Surfaces and Interfaces; 2700 General Medicine; 1305 Biotechnology
DOIDOI:10.1016/j.colsurfb.2013.02.008
URL http://www.sciencedirect.com/science/article/pii/S0927776513001288
Languageen angielski
File
1-s2.0-S0927776513001288-main.pdf 796.5 KB
Score (nominal)35
Score sourcejournalList
ScoreMinisterial score = 30.0, 01-01-2020, ArticleFromJournal
Ministerial score (2013-2016) = 35.0, 01-01-2020, ArticleFromJournal
Publication indicators WoS Citations = 42; Scopus SNIP (Source Normalised Impact per Paper): 2013 = 1.573; WoS Impact Factor: 2013 = 4.287 (2) - 2013=4.226 (5)
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