Tag: Colloidal suspension

According to the U.S. Food and Drug Administration (FDA), tomato juice is officially defined as a "liquid extracted from mature tomatoes". However, its thick texture often raises questions about its classification, especially when compared to simpler liquids like water.

Nearly 90% of milk is water, but its opaque, white appearance is due to a special colloidal system known as an emulsion. This means milk is an oil-in-water emulsion, a stabilized mixture of two immiscible liquids where fat is the dispersed phase and water is the continuous medium.

While milk is famously composed of approximately 87% water, this familiar liquid is not technically water from a chemical standpoint. Instead, it is a complex, nutrient-rich biological fluid containing fats, proteins, carbohydrates, vitamins, and minerals, all suspended or dissolved in an aqueous solution.

Raw, unhomogenized milk will naturally separate, with a layer of cream rising to the top due to the lower density of fat. So, what prevents the separation of fat from milk that you buy at the store? The answer lies in a combination of mechanical processing and unique biological structures that create and maintain a stable emulsion.

Jelly is a perfect example of a gel, which is a type of colloid consisting of a liquid suspended within a solid network. This unique structure is why jelly doesn't act like a simple liquid or a solid, leading many to question its true state of matter. Understanding if jelly is considered a fluid requires delving into the fascinating field of rheology.