General Steps of Ice Cream Processing
A frozen mixture of milk a-nd rice was used in China around 200 BC. The Chinese may be credited with inventing a device to make sorbets a-nd ice cream. They poured a mixture of snow a-nd saltpetre over the exteriors of containers filled with syrup, for, in the same way as salt raises the boiling-point of water, it lowers the freezing-point to below zero.
Before the development of modern refrigeration, ice cream was a luxury reserved for special occasions. It was made by ha-nd in a large bowl placed inside a tub filled with ice a-nd salt. This was called the pot-freezer method. In the pot-freezer method, the temperature of the ingredients is reduced by the mixture of crushed ice a-nd salt. The salt water is cooled by the ice, a-nd the action of the salt on the ice causes it to (partially) melt, absorbing latent heat a-nd bringing the mixture below the freezing point of pure water. The immersed container can also make better thermal contact with the salty water a-nd ice mixture than it could with ice alone.
The development of industrial refrigeration by German engineer Carl von Linde during the 1870s eliminated the need to cut a-nd store natural ice, a-nd, when the continuous-process freezer was perfected in 1926, commercial mass production of ice cream a-nd the birth of the modern ice cream industry was underway.
In ice cream plant, general ice cream processing steps includes: Blend ingredients, Pasteurize mix, Homogenize, Age the mix, Add colors a-nd liquid flavors, Freeze, Add nuts, fruits a-nd bulky flavorings, Package, a-nd Harden.
1. Blend Ingredients
The milk fat source, nonfat solids, stabilizers a-nd emulsifiers are blended to ensure complete mixing of liquid a-nd dry ingredients.
2. Pasteurize Mix
Ice cream mix is pasteurized at 68.3°C (155°F) for 30 minutes or 79.4C (175°F) for 25 Seconds. 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, a-nd sweetener content, a-nd the addition of egg yolks in custard products.
3. Homogenize
Ice cream mix is homogenized (2500 to 3000 psi) to decrease the milk fat globule size to form a better emulsion a-nd contribute to a smoother, creamier ice cream. Homogenization also ensures that the emulsifiers a-nd stabilizers are well blended a-nd evenly distributed in the ice cream mix before it is frozen.
4. Age the Mix
Ice cream mix is aged at 5°C (40°F) for at least 4 hours or overnight. Aging the mix cools it down before freezing, allows the milk fat to partially crystallize a-nd the gives the proteins stabilizers time to hydrate. This improves the whipping properties of the mix.
5. Add Colors a-nd Liquid Flavors
Colors a-nd Liquid Flavors 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 machines.
6. Freeze
The process involves freezing the mix a-nd incorporating air. Ice cream mix can be frozen in batch or continuous freezers a-nd 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 freezing barrel. The ice cream mix is pumped from a bulk tank to the freezing barrel a-nd 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 a-nd 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 s-e-t as desired to adjust the denseness of the finished product. Premium ice creams have less overrun (approximately 80%) a-nd are more dense than regular ice cream. At the point of disc-h-arge 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 Nuts, Fruits a-nd Bulky Flavorings
Fruits, swirls, a-nd any bulky type of flavorings (ca-ndy pieces, nuts, a-nd 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 a-nd 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 a-nd allows them to remain whole or in large chunks.
8. Package
As desired, depending on the product.
9. Harden
The ice cream is cooled as quickly as possible down to a holding temperature of less than -25°C(-13°F). The temperatures a-nd times of cooling will depend on the type of storage freezer. Rapid cooling will promote quick freezing of water a-nd create small ice crystals. Storage at -25°C(-13°F) will help to stabilize the ice crystals a-nd 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.
Before the development of modern refrigeration, ice cream was a luxury reserved for special occasions. It was made by ha-nd in a large bowl placed inside a tub filled with ice a-nd salt. This was called the pot-freezer method. In the pot-freezer method, the temperature of the ingredients is reduced by the mixture of crushed ice a-nd salt. The salt water is cooled by the ice, a-nd the action of the salt on the ice causes it to (partially) melt, absorbing latent heat a-nd bringing the mixture below the freezing point of pure water. The immersed container can also make better thermal contact with the salty water a-nd ice mixture than it could with ice alone.
The development of industrial refrigeration by German engineer Carl von Linde during the 1870s eliminated the need to cut a-nd store natural ice, a-nd, when the continuous-process freezer was perfected in 1926, commercial mass production of ice cream a-nd the birth of the modern ice cream industry was underway.
In ice cream plant, general ice cream processing steps includes: Blend ingredients, Pasteurize mix, Homogenize, Age the mix, Add colors a-nd liquid flavors, Freeze, Add nuts, fruits a-nd bulky flavorings, Package, a-nd Harden.
1. Blend Ingredients
The milk fat source, nonfat solids, stabilizers a-nd emulsifiers are blended to ensure complete mixing of liquid a-nd dry ingredients.
2. Pasteurize Mix
Ice cream mix is pasteurized at 68.3°C (155°F) for 30 minutes or 79.4C (175°F) for 25 Seconds. 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, a-nd sweetener content, a-nd the addition of egg yolks in custard products.
3. Homogenize
Ice cream mix is homogenized (2500 to 3000 psi) to decrease the milk fat globule size to form a better emulsion a-nd contribute to a smoother, creamier ice cream. Homogenization also ensures that the emulsifiers a-nd stabilizers are well blended a-nd evenly distributed in the ice cream mix before it is frozen.
4. Age the Mix
Ice cream mix is aged at 5°C (40°F) for at least 4 hours or overnight. Aging the mix cools it down before freezing, allows the milk fat to partially crystallize a-nd the gives the proteins stabilizers time to hydrate. This improves the whipping properties of the mix.
5. Add Colors a-nd Liquid Flavors
Colors a-nd Liquid Flavors 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 machines.
6. Freeze
The process involves freezing the mix a-nd incorporating air. Ice cream mix can be frozen in batch or continuous freezers a-nd 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 freezing barrel. The ice cream mix is pumped from a bulk tank to the freezing barrel a-nd 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 a-nd 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 s-e-t as desired to adjust the denseness of the finished product. Premium ice creams have less overrun (approximately 80%) a-nd are more dense than regular ice cream. At the point of disc-h-arge 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 Nuts, Fruits a-nd Bulky Flavorings
Fruits, swirls, a-nd any bulky type of flavorings (ca-ndy pieces, nuts, a-nd 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 a-nd 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 a-nd allows them to remain whole or in large chunks.
8. Package
As desired, depending on the product.
9. Harden
The ice cream is cooled as quickly as possible down to a holding temperature of less than -25°C(-13°F). The temperatures a-nd times of cooling will depend on the type of storage freezer. Rapid cooling will promote quick freezing of water a-nd create small ice crystals. Storage at -25°C(-13°F) will help to stabilize the ice crystals a-nd 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.
