Question: How do commercial bakeries use lard to introduce air bubbles?
About the article "Cake", section "Cake decorating".

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 decorating.
A finished cake is often enhanced by covering it with icing, or frosting, and toppings such as sprinkles, which are also known as "jimmies" in certain parts of the United States and "hundreds and thousands" in the United Kingdom.
Frosting is usually made from powdered (icing) sugar, sometimes a fat of some sort, milk or cream, and often flavorings such as vanilla extract or cocoa powder.
Some decorators use a rolled fondant icing.
Commercial bakeries tend to use lard for the fat, and often whip the lard to introduce air bubbles.
This makes the icing light and spreadable.
Home bakers either use lard, butter, margarine or some combination thereof.
Sprinkles are small firm pieces of sugar and oils that are colored with food coloring.
In the late 20th century, new cake decorating products became available to the public.
These include several specialized sprinkles and even methods to print pictures and transfer the image onto a cake.
Special tools are needed for more complex cake decorating, such as piping bags or syringes, and various piping tips.
To use a piping bag or syringe, a piping tip is attached to the bag or syringe using a coupler.
The bag or syringe is partially filled with icing which is sometimes colored.
Using different piping tips and various techniques, a cake decorator can make many different designs.
Basic decorating tips include open star, closed star, basketweave, round, drop flower, leaf, multi, petal, and specialty tips.
Royal icing, marzipan (or a less sweet version, known as almond paste), fondant icing(also known as sugarpaste) and buttercream are used as covering icings and to create decorations.
Floral sugarcraft or wired sugar flowers are an important part of cake decoration.
Cakes for special occasions, such as wedding cakes, are traditionally rich fruit cakes or occasionally Madeira cakes, that are covered with marzipan and iced using royal icing or sugar-paste.
They are finished with piped borders (made with royal icing) and adorned with a piped message, wired sugar flowers, hand-formed fondant flowers, marzipan fruit, piped flowers, or crystallized fruits or flowers such as grapes or violets.
Lard is pig fat in both its rendered and unrendered forms.
Lard was commonly used in many cuisines as a cooking fat or shortening, or as a spread similar to butter.
Its use in contemporary cuisine has diminished; however, many contemporary cooks and bakers favor it over other fats for select uses.
The culinary qualities of lard vary somewhat depending on the part of the pig from which the fat was taken and how the lard was processed. 
Zubbles is a commercial name for colored soap bubbles.
Zubbles claim to fame is that they are the first colored soap bubbles that do not leave stains.
Instead they fade away with exposure to air, pressure, and water.
"Popular Science" named Zubbles the "Innovation of the Year" for 2005.
"Reader's Digest" agreed, saying they were one of the "Best Innovations" of the year in 2006. 
The Continental Baking Company was one of the first bakeries to introduce fortified bread.
It was the maker of the Twinkie and Wonder bread.
Through a series of acquisitions and mergers it became part of Interstate Bakeries Corporation. 
Protein skimming removes certain organic compounds, including proteins and amino acids found in food particles, by using the polarity of the protein itself.
Due to their intrinsic charge, water-borne proteins are either repelled or attracted by the air/water interface and these molecules can be described as hydrophobic (such as fats or oils) or hydrophilic (such as salt, sugar, ammonia, most amino acids, and most inorganic compounds).
However, some larger organic molecules can have both hydrophobic and hydrophilic portions.
These molecules are called amphipathic or amphiphilic.
Commercial protein skimmers work by generating a large air/water interface, specifically by injecting large numbers of bubbles into the water column.
In general, the smaller the bubbles the more effective the protein skimming is because the surface area of small bubbles occupying the same volume is much greater than the same volume of larger bubbles.
Large numbers of small bubbles present an enormous air/water interface for hydrophobic organic molecules and amphipathic organic molecules to collect on the bubble surface (the air/water interface).
Water movement hastens diffusion of organic molecules, which effectively brings more organic molecules to the air/water interface and lets the organic molecules accumulate on the surface of the air bubbles.
This process continues until the interface is saturated, unless the bubble is removed from the water or it bursts, in which case the accumulated molecules release back into the water column.
However, it is important to note that further exposure of a saturated air bubble to organic molecules may continue to result in changes as compounds that bind more strongly may replace those molecules with a weaker binding that have already accumulated on the interface.
Although some aquarists believe that increasing the contact time (or dwell time as it is sometimes called) is always good, it is incorrect to claim that it is always better to increase the contact time between bubbles and the aquarium water.
As the bubbles increase near the top of the protein skimmer water column, they become denser and the water begins to drain and create the foam that will carry the organic molecules to the skimmate collection cup or to a separate skimmate waste collector and the organic molecules, and any inorganic molecules that may have become bound to the organic molecules, will be exported from the water system.
In addition to the proteins removed by skimming, there are a number of other organic and inorganic molecules that are typically removed.
These include a variety of fats, fatty acids, carbohydrates, metals such as copper and trace elements such as iodine.
Particulates and other detritus is also removed, along with phytoplankton and bacteria.
This removal is highly desired by the aquarist and is often emphasized by the placement of the skimmer before other forms of filtration; lessening the burden of the filtration system as a whole.
There is at least one published study that provides a detailed list of the export products found in protein skimmer skimmate.
Protein skimmers are used to harvest algae and phytoplankton gently enough to maintain viability for culturing or commercial sale as live cultures.
Alternative forms of water filtration have recently come into use, including the algae scrubber, which leaves food particles in the water for corals and small fish to consume, but removes the noxious compounds including ammonia, nitrite, nitrate, and phosphate that protein skimmers do not remove.