The origins of ice cream can be traced back to at least the 4th century B.C. Early references include the Roman emperor Nero (A.D. 37-68) who ordered ice to be brought from the mountains and combined with fruit toppings, and King Tang (A.D. 618-97) of Shang, China who had a method of creating ice and milk concoctions. Ice cream was likely brought from China back to Europe. Over time, recipes for ices, sherbets, and milk ices evolved and served in the fashionable Italian and French royal courts. After the dessert was imported to the United States, it was served by several famous Americans. George Washington and Thomas Jefferson served it to their guests. In 1700, Governor Bladen of Maryland was recorded as having served it to his guests. In 1774, a London caterer named Philip Lenzi announced in a New York newspaper that he would be offering for sale various confections, including ice cream. Dolly Madison served it in 1812. First Ice Cream Parlor In America - Origins Of English NameThe first ice cream parlor in America opened in New York City in 1776. American colonists were the first to use the term "ice cream". The name came from the phrase "iced cream" that was similar to "iced tea". The name was later abbreviated to "ice cream" the name we know today.
Making of ice cream
There's nothing like a bowl of homemade ice cream with its cold, creamy texture balanced with that fresh taste. If you crave making your own homemade ice cream all you need is a good ice cream freezer, a great recipe, the best ingredients and these tips.
1. Be familiar with the directions of your ice cream maker prior to choosing a recipe.
2. Make sure ice cream base is cold before putting it in the machine. Refrigerating overnighty is preffered but at least an hour or two will suffice.
3. Chill ice cream machine bowl and dashers/beaters prior to adding the ice cream base. This depends on your ice cream machine model and make.
4. Only fill ice cream container 3/4 full. Air is incorporated while mixing the ice cream base and it will rise to the top of the container.
5. Fruit should be ripe prior to adding it to the ice cream base. Puree or mash at least half, if not all of the fruit, for a deeper fruit flavor. Adding a little fruit extract will also enhance the flavor.
6. Additives such as chocolate, cookies, whole fruit and/or nuts should be in small chunks and pre-frozen before adding to ice cream.
7. Don’t add those ingredients until the very end of mixing. This keeps them from sinking to the bottom of the container. Mixing by hand prior to putting in the proper freezer container is preferred.
8. Pre-chill or freeze container to be used for ice cream.
9. Place ice cream in freezer for a couple of hours prior to serving, if possible.
10. Allow the ice cream to sit at room temperature for 10 minutes prior to serving. Serve your ice cream in chilled bowls, preferably glass.
Structure of ice cream
Ice cream structure is both fascinating and confusing. The way we perceive the texture of ice cream when we consume it (smooth, coarse, etc.) is based on its structure, and thus structure is probably one of its most important attributes. Ice cream is both an emulsion and a foam. The milkfat exists in tiny globules that have been formed by the homogenizer. There are many proteins that act as emulsifiers and give the fat emulsion its needed stability. The emulsifiers are added to ice cream to actually reduce the stability of this fat emulsion by replacing proteins on the fat surface, leading to a thinner membrane more prone to coalescence during whipping. When the mix is subjected to the whipping action of the barrel freezer, the fat emulsion begins to partially break down and the fat globules begin to flocculate or destabilize. The air bubbles which are being beaten into the mix are stabilized by this partially coalesced fat. If emulsifiers were not added, the fat globules would have so much ability to resist this coalescing, due to the proteins being adsorbed to the fat globule, that the air bubbles would not be properly stabilized and the ice cream would not have the same smooth texture (due to this fat structure) that it has.
Effect of emulsifier on fat destabiization in ice cream 17KB
This fat structure which exists in ice cream is the same type of structure which exists in whipped cream. When you whip a bowl of heavy cream, it soon starts to become stiff and dry appearing and takes on a smooth texture. This results from the formation of this partially coalesced fat structure stabilizing the air bubbles. If it is whipped too far, the fat will begin to churn and butter particles will form. The same thing will happen in ice cream which has been whipped too much.
Ice Cream Meltdown
One of the important manifestations of ice cream structure is its melt-down. When you put ice cream in an ambient environment to melt (as in a scoop on a plate), two events occur; the melting of the ice and the collapse of the fat-stabilized foam structure. The melting of the ice is controlled by the outside temperature (fast on a hot day) and the rate of heat transfer (faster on a hot, windy day). However, even after the ice crystals melt, the ice cream does not "melt" (collapse) until the fat-stabilized foam structure collapses, and that is a function of the extent of fat destabilization/partial coalescence, which is controlled mostly by the emulsifier concentration, for reasons we have just described above.This is shown in the diagram below, which shows ice cream sitting on a mesh screen at ambient temperature:You can see above the increased amount of shape retention and slowness of melt that comes from the added emulsifiers, particularly polysorbate 80.
Also adding structure to the ice cream is the formation of the ice crystals. Water freezes out of a solution in its pure form as ice. In a sugar solution such as ice cream, the initial freezing point of the solution is lower than 0° C due to these dissolved sugars (freezing point depression), which is mostly a function of the sugar content of the mix. As ice crystallization begins and water freezes out in its pure form, the concentration of the remaining solution of sugar is increased due to water removal and hence the freezing point is further lowered. This process is shown here, schematically. This process of freeze concentration continues to very low temperatures. Even at the typical ice cream serving temperature of -16° C, only about 72% of the water is frozen. The rest remains as a very concentrated sugar solution. Thus when temperature is plotted against % water frozen, you get the phase diagram shown below. This helps to give ice cream its ability to be scooped and chewed at freezer temperatures. The air content also contributes to this ability, as mentioned in discussing overrun.Also critical to ice cream structure is ice crystal size, and the effect of recrystallization (heat shock, temperature fluctuations) on ice crystal size and texture. A primer on the theoretical aspects of freezing will help you to fully understand the freezing process. Please see the discussion and diagram on ice crystallization rate, as shown on that page, to fully understand this process. Recrystallization (growth) of ice is discussed elsewhere in the context of shelf life. Thus the structure of ice cream can be described as a partly frozen foam with ice crystals and air bubbles occupying a majority of the space. The tiny fat globules, some of them flocculated and surrounding the air bubbles also form a dispersed phase. Proteins and emulsifiers are in turn surrounding the fat globules. The continuous phase consists of a very concentrated, unfrozen solution of sugars. One gram of ice cream of typical composition contains 1.5 x 10exp12 fat globules of average diameter 1µ m that have a surface area of greater than 1 square meter (in a gram!), 8 x 10exp6 air bubbles of average diameter 70 µ m with a surface area of 0.1 sq. m., and 8 x 10exp6 ice crystals of average diameter 50 µ m with a surface area of another 0.1 sq. m. The importance of surface chemistry becomes obvious!
Microscopy
Before we leave ice cream structure, I want to draw your attention to the following address: "Foods Under the Microscope". This is a link to an absolutely marvellous website developed by my good friend Dr. Milos Kalab, with many high-quality images of the structure of milk and dairy products obtained during Dr. Kalab's long and outstanding career as a food microscopist with Agriculture and Agri-Food Canada in Ottawa. Dr. Kalab asked me to contribute microscopic images of ice cream structure as a guest microscopist. You can find my (Doug Goff) first contribution under "Guest microscopists", and I have also copied it here. Subsequent to that submission, I have prepared another one for D. Kalab that focuses on the use of cryo-fixation and TEM for visualization of fat and air structures in ice cream. One of my graduate students, Alejandra Regand, also made a contribution, based on her M.Sc. thesis work, focussing on the structure of polysaccharides in frozen solutions.
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