Kh. Khristov

Bio: Kh. Khristov is an academic researcher from Bulgarian Academy of Sciences. The author has contributed to research in topics: Emulsion. The author has an hindex of 1, co-authored 2 publications receiving 13 citations.

Review on the Stability Mechanism and Application of Water-in-Oil Emulsions Encapsulating Various Additives

Abstract: Water-in-oil (W/O) emulsions can be used to encapsulate and control the release of bioactive compounds for nutrition fortification in fat-based food products. However, long-term stabilization of W/O emulsions remains a challenging task in food science and thereby limits their potential application in the food industry. To develop high-quality emulsion-based food products, it is essential to better understand the factors that affect the emulsions' stability. In real food system, the stability situation of W/O emulsions is more complicated by the fact that various additives are contained in the products, such as NaCl, sugar, and other large molecular additives. The potential stability issues of W/O emulsions caused by these encapsulated additives are a current concern, and special attention should be given to the relevant theoretical knowledge. This article presents several commonly used methods for the preparation of W/O emulsions, and the roles of different additives (water- and oil-soluble types) in stabilizing W/O emulsions are mainly discussed and illustrated to gain new insights into the stability mechanism of emulsion systems. In addition, the review provides a comprehensive and state-of-art overview of the potential applications of W/O emulsions in food systems, for example, as fat replacers, controlled-release platforms of nutrients, and delivery carrier systems of water-soluble bioactive compounds. The information may be useful for optimizing the formulation of W/O emulsions for utilization in commercial functional food products.

Thin Liquid Films: where Hydrodynamics, Capillarity, Surface Stresses, and Intermolecular Forces meet

Abstract: Thin liquid films arise in many technological applications and biological phenomena. They also present a fascinating object of study, because of a rich interplay between capillarity, hydrodynamics, interfacial transport phenomena and interfacial rheology, as well as the effects of interaction forces when films thin down to molecular thicknesses. Recent advances in experimental techniques have given further insights in the variety of physical phenomena, which can occur. These techniques are briefly reviewed. How these techniques can be utilised is illustrated by recent studies addressing the effect of interfacial rheological stresses on drainage, the interplay between capillarity and hydrodynamics during film retraction, and the solutocapillary stabilisation of films. Finally, we briefly discuss the challenges of conducting drainage measurements at high and varied capillary numbers and how these could be overcome by the combined use of experiments and simulations.

Viscosity of Water-in-Oil Emulsions from Different American Petroleum Institute Gravity Brazilian Crude Oils

Abstract: Water-in-oil (W/O) emulsions are very common in oil field operations and are formed as a result of energy input from turbulence caused by the flow in the production pipelines, pumps, and valves. Understanding emulsion rheological behavior is crucial to deal with flow assurance issues. This paper presents and discusses a series of rheological experiments carried out with synthetic emulsions formulated with 126 Brazilian crude oils with American Petroleum Institute (API) gravity ranging from 13° to 35°. This rheological study includes viscosity dependence upon the shear rate, temperature, and water volume fraction. The results show that crude oils with similar API gravity and viscosity can generate emulsions with very different viscosities (8–50 mPa s at 50 °C around 25° API gravity, for example) and different maximum water content limits. Besides, W/O emulsions that are prepared with either light (API gravity of >35°) or heavy (API gravity of <13°) crude oils are the emulsions observed to be the more diffi...

Properties and Performance of Newly Developed Demulsifiers in Oil Sands Froth Treatment

Abstract: Chemical demulsification with EO-PO block copolymers is widely employed to treat bitumen froth in oil sands operations. In this effort, the relation between demulsifier properties and demulsification efficiency was explored using three EO-PO block copolymer demulsifiers, DMO A, DMO B, and DMO C. The EO-PO block copolymers were categorized by their relative solubility number (RSN) and dynamic interfacial tension (IFT). The dewatering and solids removal efficiencies of EO-PO block copolymer demulsifiers were in the order DMO C > DMO B > DMO A from 0 to 50 ppm dosage at 30 min settling time. DMO C also showed superior performance with lower hydrocarbon losses to the underflow as compared to demulsifiers DMO A and DMO B at all the dosages studied. The direct correlation was observed between the RSN values and dewatering/solids removal performance while the IFT does not correlate to the dewatering/solids removal efficacy of the EO-PO block copolymer demulsifiers. The influence of operating conditions such as p...