Food Emulsions: an Important Mix
Food emulsions are everywhere in today’s food industry. From the milk poured with a bowl of cereal in the morning to the margarine used to flavor rolls at dinner, food emulsions are something that an individual will encounter on a daily basis. By formal definition, a food emulsion is defined as, “a colloidal dispersion of two liquids, usually oil and water, that are immiscible.” (Murano 2003). To better understand what this definition is stating, a colloidal dispersion must also be defined. A colloidal dispersion is a dispersion of food colloids, a dispersed phase, into a continuous phase such as water or oil. Keep in mind, however, that a colloidal dispersion is not a solution, and the two liquids are said to be immiscible, meaning unmixable. Food colloids are too large to be dissolved into a solution and are thus suspended in a continuous phase, similar to a mixture, but the particles are still small enough that they will not settle out like in a suspension. In a colloidal dispersion, the food colloids are each approximately 10 – 100nm in diameter, smaller than food particles contained in a suspension, but larger than those that can dissolve into a solution (Murano 2003). Some people regard foams as a type of emulsion, but this is not true. Foams are similar to emulsions, but occur when a gas is dispersed in a liquid, such as in whipped cream. Other dispersions similar to emulsions are gels, which are a liquid dispersed in a solid, and sols, which are solids dispersed in a liquid, an example being gravy.
The history of food emulsions starts with milk. Milk is the oldest known food emulsion and can be dated back to 8000 BC with the domestication of sheep and cows in India, the Middle East, and Sub-Saharan Africa. The classification of oil-in-water and water-in-oil emulsions originated from a 1910 paper by Wolfgang Ostwald (Becher 1991). Milk, butter, and cheese were the pioneering emulsions and were created long before other
References: Aveyard R, Binks BP, Clint JH. 2003. Emulsions stabilized solely by colloidal particles. Advances in Colloid and Interface Science [serial online]. Available from [http://sciencedirect.com]. Posted March 31, 2003. Becher P. 1991. Microemulsions and Emulsions in Food. Washington, DC: American Chemical Society. 268 p. Jiang ZM, Zhang SY, Wang XR, Yang NF, Zhu Y, Wilmore D. 1993. A comparison of medium-chain and long-chain triglycerides in surgical patients. Annals of Surgery [serial online]. 217:175-184. Available from [http://ncbi.nlm.nih.gov]. Posted February 1993. Murano PS. 2003. Understanding food science and technology. Belmont, CA: Wadsworth. 449 p. Reece D. 2000. Unilever takes new shot: bid for Bestfoods expected to rise to US$70 a share. National Post [serial online]. Available from Lexis Nexis (http://lexisnexis.com) Posted May 29, 2000. South Mountain Creamery: About Us [Internet]. Middletown, MD: South Mountain Creamery; c2010 [Accessed 2010 Nov 18]. Available from: http://southmountaincreamery.com/pages.php?pageid=3 Thompson S. 2003. Kraft counters Unilever launch; major TV hike for Miracle Whip brand. Advertising Age [serial online]. Available from Lexis Nexis (http://lexisnexis.com) Posted August 25, 2003. Yahoo! Finance: Unilever Company Profile [Internet]. Santa Clara, CA: Yahoo! Finance; c2010 [Accessed 2010 Nov 18]. Available from: http://biz.yahoo.com/ic/41/41850.html