Polysaccharide blended whey protein isolate-(WPI) hydrogels: A physicochemical and controlled release study

Characterization of Emulsion Stabilization Properties of Gum Tragacanth, Xanthan Gum and Sucrose Monopalmitate: A Comparative Study

Emulsification effect of gum tragacanth (GT) obtained from Astragalus species is gaining particular interest in recent years. In this study, stabilization effect of GT, xanthan gum (XG), and sucrose monopalmitate (SMP) was investigated by keeping their concentration constant (0.5% w/v) for the oil-in-water emulsions containing 20% (v/v) sun flower oil and 2% (w/v) whey protein isolate. Emulsification was achieved by using high shear homogenization. Particle size and T₂ (spin-spin relaxation time) measurements were performed for the characterization and repeated over the course of 28 days. Emulsion stability index (ESI [%]) was measured and rheological characterization was also performed. The lowest particle size was found for the XG emulsions and this was attributed to the pseudoplastic behavior of xanthan compared to GT (n_Xanthan = 0.188 ≪ n_GT = 0.721). Xanthan emulsions thinned out dramatically when sheared during homogenization, and consequently, floccules formed could have been disrupted more resulting in smaller particle size. Result of rheological experiments showed that SMP emulsions were fit to Newtonian model, while XG and GT showed shear thinning behavior and fit to a power law model. Apparent viscosity of XG emulsions was found significantly higher than the GT ones. The most stable emulsions were the ones prepared by XG and they remained stable during 28 days. Although GT emulsions could not protect their stability during 28 days, ESI (%) results were found similar with XG indicating promising emulsification effect of GT. PRACTICAL APPLICATION: Gum tragacanth, xanthan gum, and sucrose monopalmitate have been used to formulate oil-in-water emulsions. The final formulated products can be used in emulsion-based food products to increase their stability and shelf life.

Design of gel structures in water and oil phases for improved delivery of bioactive food ingredients

Gels are viscoelastic systems built up with a liquid phase entrapped in a three-dimensional network, which can behave as carriers for bioactive food ingredients. Many attempts have been made to design gel structures in the water phase (hydrogels, emulsion gels, bigels) or oil phase (organogels, bigels) in order to improve their delivery performances. Hydrogels are originated from proteins or polysaccharides, which are suitable for the delivery of hydrophilic ingredients. Organogels are mainly built up with the self-assembling of gelator molecules in the oil phase, and they offer good carriers for lipophilic ingredients. Emulsion gels and bigels, containing both aqueous and oil domains, can provide accommodations for lipophilic and hydrophilic ingredients simultaneously. Gel structures (e.g. rheology, texture, water holding capacity, swelling ratio) can be modulated by choosing different gelators, modifying gelation techniques, and the involvement of other ingredients (e.g. oils, emulsifiers, minerals, acids), which then alter the diffusion and release of the bioactive ingredients incorporated. Various studies have proved that gel-based delivery systems are able to improve the stability and bioavailability of many bioactive food ingredients. This review provides a state-to-art overview of different gel-based delivery systems, highlighting the significance of structure-functionality relationship, to provide advanced knowledge for the design of novel functional foods.

Development of pH Sensitive Alginate/Gum Tragacanth Based Hydrogels for Oral Insulin Delivery

Insulin entrapped alginate-gum tragacanth (ALG-GT) hydrogels at different ALG replacement ratios (100, 75, 50, 25) were prepared through an ionotropic gelation method, followed by chitosan (CH) polyelectrolyte complexation. A mild gelation process without the use of harsh chemicals was proposed to improve insulin efficiency. Retention of almost the full amount of entrapped insulin in a simulated gastric environment and sustained insulin release in simulated intestinal buffer indicated the pH sensitivity of the gels. Insulin release from hydrogels with different formulations showed significant differences ( p < 0.05). Time domain (TD) NMR relaxometry experiments also showed the differences for different formulations, and the presence of CH revealed that ALG-GT gel formulation could be used as an oral insulin carrier at optimum concentrations. The hydrogels formulated from biodegradable, biocompatible, and nontoxic natural polymers were seen as promising devices for potential oral insulin delivery.

Physico-Chemical Changes of Composite Whey Protein Hydrogels in Simulated Gastric Fluid Conditions

Polysaccharide blended whey protein isolate (WPI) hydrogels were developed for the delivery of black carrot ( Daucus carota) concentrate as bioactive agent in simulated gastric fluid (SGF). Pectin (PC), gum tragacanth (GT), and xanthan gum (XG) were blended as additional polymers to modulate the release characteristics of the WPI hydrogels. Experiments showed that sole whey protein (C), XG, and GT blended hydrogels possessed restricted release profiles 67%, 61%, and 67%, respectively, whereas PC samples attained higher release rates (83%) ( p < 0.05). Interactions between polymers and aqueous medium were analyzed by nuclear magnetic resonance relaxometry. C (82 ms) and GT (84 ms) hydrogels attained higher T₂ values than PC (74 ms) and XG (73 ms) samples in SGF. Hardness of only XG hydrogels increased from 1.9 to 4.1 N after gastric treatment. Physicochemical changes within hydrogels during release were also investigated, and hydrogels were proved to be appropriate for desired delivery purposes.