Colloidal stability, system undergoing

In this paper we propose a simple procedure whereby one can estimate the overall stability of a given colloidal system undergoing simultaneous creaming and flocculation. Since case (iii) has not been solved yet, we will focus our attention only on case (ii). As an example, we use this procedure to compare the net rates of particle loss due to creaming and gravity-induced flocculation when electrostatic repulsion is negligible. 

He have presented a simple procedure whereby one can estimate the stability of a colloidal system undergoing simultaneous creaming and gravity-induced flocculation. This procedure is by no means restricted to only this case. One can easily take into account other particle loss mechanisms, such as shear-induced flocculation or Brownian flocculation. What is required in these cases are the appropriate particle/particle collision kernels, which can be computed by solving the governing convective-diffusion equation. 

A mixture of emulsifiers can improve the stability of colloid food systems by strengthening the film membrane and by interaction between emulsifiers at the interface. Combinations of oil-soluble and water-soluble surfactants (Spans and Tweens) are often used in food formulations to produce more stable oil-inwater emulsions. Mixtures of phospholipids and proteins in foods undergo complex interactions during various thermal processing that can either promote or retard oxidation. At elevated temperatures phospholipids can produce antioxidant substances by the browning reaction, and proteins can denature to release reducing sulfhydryl groups that increase the oxidative stability of heated foods (e.g. evaporated milk). 

In the first place one should distinguish reversible and irreversible systems, that is to say, colloid systems which can undergo phase change or phase separation reversibly or otherwise. A thermodynamically definable stability difference is thus the basis of this classification. It is for this reason more logical than the old classification into lyophobic and lyophilic systems (and to a still greater degree than that into suspensoids and emulsoids). 

---