Our love affair with ice cream is centuries old. The ancient Greeks, Romans, and Jews were known to chill wines and juices. This practice evolved into fruit ices and, eventually, frozen milk and cream mixtures. In the first century, Emperor Nero reportedly sent messengers to the mountains to collect snow so that his kitchen staff could make concoctions flavored with fruit and honey. Twelve centuries later, Marco Polo introduced Europe to a frozen milk dessert similar to the modern sherbet that he had enjoyed in the Far East. The Italians were especially fond of the frozen confection that by the sixteenth century was being called ice cream. In 1533, the young Italian princess Catherine de Medici went to France as the bride of the future King Henry II. Included in her trousseau were recipes for frozen desserts. The first public sale of ice cream occurred in Paris at the Café Procope in 1670.
Frozen desserts were also popular in England. Guests at the coronation banquet of Henry V of England in the fourteenth century enjoyed a dessert called cremefrez. By the seventeenth century, Charles I was served creme ice on a regular basis. Eighteen-century English cookbooks contained recipes for ice cream flavored with apricots, violets, rose petals, chocolate, and caramel. Other early flavorings included macaroon and rum. In early America, George Washington and Thomas Jefferson were especially fond of ice cream. Dolley Madison was known to serve it at White House state dinners.
Because ice was expensive and refrigeration had not yet been invented, ice cream was still considered a treat for the wealthy or for those in colder climates. (In a note written in 1794, Beethoven described the Austrians’ fear that an unseasonably warm winter would prevent them from enjoying ice cream.) Furthermore, the process of making ice cream was cumbersome and time-consuming. A mixture of dairy products, eggs, and flavorings was poured into a pot and beaten while, simultaneously, the pot was shaken up and down in a pan of salt and ice.
The development of ice harvesting and the invention of the insulated icehouse in the nineteenth century made ice more accessible to the general public. In 1846, Nancy Johnson designed a hand-cranked ice cream freezer that improved production slightly. The first documented full-time manufacturing of ice cream took place in Baltimore, Maryland, in 1851 when a milk dealer named Jacob Fussell found himself with a surplus of fresh cream. Working quickly before the cream soured, Fussell made an abundance of ice cream and sold it at a discount. The popular demand soon convinced him that selling ice cream was more profitable than selling milk.
However, production was still cumbersome, and the industry grew slowly until the industrialization movement of the early twentieth century brought electric power, steam power, and mechanical refrigeration. By the 1920s, agricultural schools were offering courses on ice cream production. Trade associations for members of the industry were created to promote the consumption of ice cream and to fight proposed federal regulations that would call for selling ice cream by weight rather than volume, and the disclosure of ingredients.
The Prohibition era proved to be very profitable for the ice cream industry. Denied alcoholic beverages, many people ate ice cream instead. Breweries were often converted to ice cream factories, although it is likely that some of the plants were merely fronts for illegal liquor sales. Although the repeal of Prohibition in 1933 and the ensuing depression slowed ice cream sales, the industry continued to grow. The movie industry was especially instrumental in the promotion of ice cream and scenes depicting stars enjoying the frozen concoctions were plentiful. Ice cream parlors sprang up in every town and the parlor employee, the so-called soda jerk, developed into a cultural icon.
After World War II, with raw materials readily available again, the ice cream industry produced over 20 qt (19 1) of ice cream for each American per year. During the 1950s, competition sprang up between the ice cream parlor and the drug store that sold packaged ice cream. It was during this time that usage of lesser quality ingredients increased. Many producers were adding very low percentages of butterfat and pumping large quantities of air into the ice cream to fill out the carton.
The 1970s saw the development of gourmet ice cream manufacturers with an emphasis on natural ingredients. People also became interested in making ice cream at home. Upscale restaurants offer homemade ice cream on their dessert lists.
Ice cream is a frozen blend of a sweetened cream mixture and air, with added flavorings. A wide variety of ingredients are allowed in ice cream, but the minimum amounts of milk fat, milk solids (protein + lactose + minerals), and air are defined by Standards of Identity in the U.S. Code of Federal Regulations (CFR), section 21 CFR 135.110 for ice cream, 21 CFR 135.115 for goat’s milk ice cream, and 21 CFR 135.140 for sherbet.
Ice cream must contain at least 10% milk fat, and at least 20% total milk solids, and may contain safe and suitable sweeteners, emulsifiers and stabilizers, and flavoring materials. The finished ice cream must weigh at least 4.5 pounds per gallon and there must be at least 1.6 pounds of total solids (fat + protein + lactose + minerals + added sugar) per gallon, thus limiting the maximum amount of air (called overrun) that can be incorporated into ice cream. There are well-defined labeling requirements for the types of flavors used (natural and/or artificial) and for the presence of egg yolks in the finished product (ice cream can be called custard or “French” if the content of egg yolks is at least 1.4%). Ice cream may also be labeled as reduced fat (25% less fat than the reference ice cream), light (50% less fat than the reference), lowfat (less than 3 g fat/serving), or nonfat (less than 0.5 g fat/serving).
Ice cream is sold as hard ice cream or soft serve. After the freezing process only a portion of the water is actually in a frozen state. Soft ice cream is served directly from the freezer where only a small amount of the water has been frozen. Hard ice cream is packaged from the freezer and then goes through a hardening process that freezes more of the water in the mix.
There is a wide range of ingredients and formulations (recipes) that can be used in ice cream. The basic types of ingredients and their functions are briefly described below. For a more detailed explanation of ingredient function see literature references by Marshall et al. (2003) and the website by Goff, www.foodsci.uoguelph.ca/dairyedu/icecream.html.
Milk fat provides creaminess and richness to ice cream and contributes to its melting characteristics. The minimum fat content is 10% and premium ice creams can contain as much as 16% milk fat. Sources of milk fat include milk, cream, and butter.
The total milk solids component of ice cream includes both the fat and other solids. The other milk solids consist of the protein and lactose in milk and range from 9 to 12% in ice cream. The nonfat solids play an important role in the body and texture of ice cream by stabilizing the air that is incorporated during the freezing process. Sources of nonfat solids include milk, cream, condensed milk, evaporated milk, dry milk, and whey.
Sweeteners are used to provide the characteristic sweetness of ice cream. Sweeteners also lower the freezing point of the mix to allow some water to reamin unfrozen at serving temperatures. A lower freezing point makes ice cream easier to scoop and eat, although the addition of too much sugar can make the product too soft. Sweeteners used include sugar (sucrose) and corn syrups.
Stabilizers are proteins or carbohydrates used in ice cream to add viscosity and control ice crystallization. Over time during frozen storage small ice crystals naturally migrate together and form larger ice crystals. Stabilizers help to keep the small crystals isolated and prevent the growth of large crystals, which causes ice cream to be coarse, icy and unpleasant to eat. Stabilizers used include alginates (carrageenan), gums (locust bean, guar), and gelatins.
Emulsifiers are used to help keep the milk fat evenly dispersed in the ice cream during freezing and storage. A good distribution of fat helps stabilize the air incorporated into the ice cream and provide a smooth product. Emulsifiers used in ice cream include egg yolks and mono- and diglycerides.
A wide range of flavorings are used in ice cream. Flavorings include natural and artificial flavors, fruit, nuts, and bulky inclusions such as chocolate chunks and candies.
General Manufacturing Procedure
The following discussion provides a general outline of the steps required for making ice cream. For a more detailed explanation see the literature references by Marshall et al. (2003), Walstra et al. (1999), and the website by Goff, www.foodsci.uoguelph.ca/dairyedu/icecream.html.
General Ice Cream Processing Steps
Add Liquid Flavors and Colors
Add Fruits, Nuts, and Bulky Flavorings
1. Blend the Ice Cream Mixture
The milk fat source, nonfat solids, stabilizers and emulsifiers are blended to ensure complete mixing of liquid and dry ingredients.
2. Pasteurize Mix
Ice cream mix is pasteurized at 155°F (68.3°C) for 30 minutes or 175°F (79.4C) for 25 sec. The conditions used to pasteurize ice cream mix are greater than those used for fluid milk because of increased viscosity from the higher fat, solids, and sweetener content, and the addition of egg yolks in custard products.
Ice cream mix is homogenized (2500 to 3000 psi) to decrease the milk fat globule size to form a better emulsion and contribute to a smoother, creamier ice cream. Homogenization also ensures that the emulsifiers and stabilizers are well blended and evenly distributed in the ice cream mix before it is frozen.
4. Age the Mix
Ice cream mix is aged at 40°F (5°C) for at least 4 hours or overnight. Aging the mix cools it down before freezing, allows the milk fat to partially crystallize and gives the proteins stabilizers time to hydrate. This improves the whipping properties of the mix.
5. Add Liquid Flavors and Colors
Liquid flavors and colors may be added to the mix before freezing. Only ingredients that are liquid can be added before the freezing, to make sure the mix flows properly through the freezing equipment.
The process involves freezing the mix and incorporating air. Ice cream mix can be frozen in batch or continuous freezers and the conditions used will depend on the type of freezer. Batch freezers consist of a rotating barrel that is usually filled one-third to one-half full with ice cream mix. As the barrel turns, the air in the barrel is incorporated into the ice cream mix. Ice cream freezers designed for home use are batch freezers. Continuous freezers consist of a fixed barrel that has a blade inside that constantly scrapes the surface of the freezing barrel. The ice cream mix is pumped from a bulk tank to the freezing barrel and the air is incorporated with another pump just before it enters the freezing barrel. The continuous freezing process is much faster than the batch freezing process.
The addition of air is called overrun and contributes to the lightness or denseness of ice cream. Up to 50% of the volume of the finished ice cream (100% overrun) can be air that is incorporated during freezing. The overrun level can be set as desired to adjust the denseness of the finished product. Premium ice creams have less overrun (approximately 80%) and are more dense than regular ice cream.
At the point of discharge from the freezer (draw temperature), only about 50% of the water in ice cream is frozen. Soft serve ice cream is generated at this point in the freezing process.
7. Add Fruits, Nuts and Bulky Flavorings (candy pieces, etc.)
Fruits, swirls, and any bulky type of flavorings (nuts, candy pieces, etc.) are added at this point. These ingredients can not be added before freezing or they would interfere with the smooth flow of the mix through the freezer. The ice cream at this point is soft and it is easy to mix in the bulky flavorings so they are uniformly distributed throughout the ice cream. Mixing in bulky flavorings after freezing also prevents damage to the pieces and allows them to remain whole or in large chunks.
As desired, depending on the product.
The ice cream is cooled as quickly as possible down to a holding temperature of less than -13°F(-25°C). The temperatures and times of cooling will depend on the type of storage freezer. Rapid cooling will promote quick freezing of water and create small ice crystals. Storage at -13°F(-25°C) will help to stabilize the ice crystals and maintain product quality. At this temperature there is still a small portion of liquid water. If all the water present in the ice cream were frozen, the ice cream would be as hard as an ice cube.
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