(178h) Oleogels As Future Trans fat Alternative: A Mathematical Model for an Unsolved Conundrum in Gelation during Scale up Process

Authors: 
Sagiri, S. S. - Presenter, The City College of New York,CUNY
Samateh, M., The City College of New York,CUNY
Pan, S., The City Colelge of New York
Maldarelli, C., Levich Institute, City College of New York
John, G., The City College of New York,CUNY
Molecular oleogels are supramolecular soft gels, in which vegetable oil is immobilized within the self-assembled network of low molecular weight gelators. Oleogels have found applications in various fields, namely, food, pharmaceutics, cosmetics, petrochemical, tissue engineering and art. Though extensive research has been carried out on oleogels, their industrial usage is still in its infancy. Experimental studies have shown that gelation fail to occur when larger volumes (5ml, 10ml, 15ml and 20ml) were prepared based on the minimum gelator concentration (MGC) that was determined using the smallest oil volume (1ml), a general laboratory scale practice. Gelation failure at larger volumes was evident when tested by two independent studies; vial inversion and rheological studies. This observation was consistent with all the studied molecular gelators, sorbitol dioctanoate (S8), mannitol dioctanoate (M8), and 12-hydroxy stearic acid (12HSA). These results foresee a constraint during fabrication of oleogels at industrial scale; that is to achieve consistency in physical properties during scale up. To understand and predict the gelation behaviour of molecular gelators in vegetable oil of any volume, a mathematical model was developed based on the fact that self-assembly and propagation of gelator networks is governed by rate of cooling. The model indicates that maintenance of minimal thermal gradient from boundaries to center of the vial is necessary to achieve uniform gel propagation across the vial. This provides uniform heat dissipation and gelation times in the vial so that the self-assembled fibers can extend and form network prior to the sedimentation. With these predictions, we hypothesized and confirmed that maintenance of the correct surface area to volume (S/V) ratio which minimizes thermal gradients irrespective of volume of oleogels could result in identical gelation times during scale up. Under this condition, in addition to gelation time, MGC and other physical properties of the gel remained consistent regardless of the sizes of the gel prepared; the other physical properties were melting temperature (Tm), melting enthalpy (ΔHm), yield stress (Ys), solid phase content (SPC) and oil binding capacity (OBC).