Tyagi G, Torquato LMG, Ahmad Z, Fong R, Cabral JT. How triacylglycerol thermal history impacts film removal by surfactant solution.
J Colloid Interface Sci 2024;
670:540-549. [PMID:
38776689 DOI:
10.1016/j.jcis.2024.05.069]
[Citation(s) in RCA: 0] [Impact Index Per Article: 0] [Reference Citation Analysis] [Abstract] [Key Words] [Track Full Text] [Journal Information] [Subscribe] [Scholar Register] [Received: 01/10/2024] [Revised: 05/02/2024] [Accepted: 05/09/2024] [Indexed: 05/25/2024]
Abstract
HYPOTHESIS
The physical and mechanical properties of triacylglycerols (TAGs), or 'fats', depend on their composition and thermal history which, in turn, impact crystal structure and morphology. We examine whether thermal history can be mechanistically related to film removal by a surfactant solution.
EXPERIMENTS
Model TAG mixtures, comprising triolein:tripalmitin:tristearin 0.5:0.3:0.2, were subjected to a range of cooling profiles from the melt (0.5-80°C/min, Newtonian and annealed), and the resulting solid films characterised by microscopy, X-ray diffraction, infrared spectroscopy, and contact angle measurements. Film removal from a model glass substrate by an aqueous surfactant solution of sodium dodecylsulphate and dodecyldimethylamine oxide at room temperature fixed at 25°C was examined under quiescent flow conditions.
FINDINGS
Quantitative relations are established between TAG cooling profile, crystal structure and morphology, surface energy γSFE, and removal (or 'cleaning'). In general, films cooled slowly from the melt yield heterogeneous morphologies with predominantly β1' phase, higher polar γSFE, and faster removal timescales. By contrast, rapid cooling results in homogeneous films, rich in β2' phase, low polar γSFE, and long removal times. Our results elucidate the non-trivial impact of TAG thermal history, connecting the multiscale semi-crystalline structure to surface energy, and eventually to film delamination by micellar solutions.
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