Fat spreads are composed of liquid oil, fat crystals and water. The fat crystals in these products give the product the required consistency and stabilize the water droplets. Shortenings are waterfree products , the rheology of which depends on the solid fat content and interactions between fat crystals. Size and interaction between crystals is influenced by both composition and processing. Crystals form a three - dimensional network. Recrystallization phenomena, especially formation of large beta- crystals , can create product defects like sandiness. Margarines and halvarines are water- in - oil emulsions and have a relatively simple product structure. Because of the wettability of fat crystals, part of the solids are present in the water/oil interface, and influence the stability of the emulsion. Depending on the type of application, tropical margarines, table margarines, halvarines , puff-pastry, c reaming margarines, etc. , the ratio of solidlliquid and water content can be varied. No essential differences exist in the microstructure of products for different applications. Butter differs in its microstructure from margarines because of different processing and raw materials. Butter still contains a number of fat globules (derived from the cream) in its final product structure. These globules are dispersed in a matrix of fat crystals and oil desc ending from fat globules that were broken during churning. Also the moisture is present in different forms ranging from droplets to "free moisture". Differences in microstructure can be introduced by different processing regimes.
Juriaanse, A. C. and Heertje, I.
"Microstructure of Shortenings, Margarine and Butter - A Review,"
Food Structure: Vol. 7
, Article 8.
Available at: http://digitalcommons.usu.edu/foodmicrostructure/vol7/iss2/8