DAIRY FOODS MARKET: ICE CREAM
ICE CREAM MANUFACTURING PROCESS
Ice cream, frozen desserts and related products are made of milk fat (butterfat) 12%, nonfat milk solids 11 %, sugar 15%, stabilizers 0.2%, emulsifiers 0.2%, small trace of vanilla, and the rest is water. Typical total solids are 38.4% ; plus the possible additions of flavors, fruits, nuts, chocolate, and eggs.
Step 1. Mix Liquids and Solid Ingredients:
The steps of the manufacturing process are to mix liquid ingredients in vat at 43*C, add sugar & dry ingredients until they dissolve in mix, add air, pasteurize, homogenize, age the ice cream and then finally harden the ice cream.
Step 2. Adding Air Into the Ice Cream Mix ; also called the Ice Cream “Overrun”:
“Overrun” is a term used in the Dairy Industry to measure how much air is whipped (added) into the ice cream. In other words, “overrun” is a volumetric (how much space it occupies) measure of the density (total mass divided by total volume) of an aerated product such as ice cream or whipped cream. Air is added to the ice cream mix by whipping it in the mixing container, which incrementally adds air during the mixing process over time.
In order to calculate the overrun of any ice cream, you need to melt the ice cream and remove the air bubbles from the mix. There is a formula to figure this amount out, and the equation to calculate the amount of overrun.
“Overrun Formula” is the following:
(Volume of ice cream – volume of mix) / volume of mix x 100 = Percent Overrun (% of air whipped into ice cream)
Here’s how the “Overrun Formula” is figured out:
a) The volume of the ice cream is the volume of the container (full gallon, full quart, full pint).
b) The volume of the mix can be estimated by melting the full container of ice cream (it must be full) and removing the air bubbles. The foam can be collapsed to remove the air by stirring the melted liquid ice cream with a spoon or other stirring device. Once you have removed all of the air bubbles that were entrapped in the ice cream, you need to measure the volume of the remaining liquid. This final measure will be the “volume of mix” value which you plug into the formula. This gives your overrun percentage for that specific brand; and remember every brand of ice cream will usually have a different amount of overrun.
Step 3. There are two PASTEURIZING methods:
- “Batch Method” = Heat at 71 *C for 30 minutes, or
- “HTST” (High Temperature / Short Time) at 82*C for 25 seconds. This is also known as “Flash Pasteurization”.
Step 4. “HOMOGENIZE” the Ice Cream:
The ice cream is then Homogenized and cooled to 4.4*C . Homogenization is a process designed for liquid dispersions(this one contains: water, fat, protein and enzymes) which will prevent the small particles from agglomerating (clumping together). Inclusions additions occurs after the homogenization process during the cooling phase.
Homogenization Click here for more info on Homogenization
Inclusions (aka. Variegates) Click here for more info on Inclusions (aka. Variegates)
Step 5. “AGE” the Ice Cream:
The ice cream is “AGED” for 3 to 24 hours to solidify melted fat, hydrate stabilizers (plant gums), hydrate milk proteins, and viscosify (or thicken) the mix. The “Aging Stage” pertains to being stored in a refrigerated room but not nearly as cold as the temperature in the “Hardening Stage”. The larger ingredients (fruits, nuts, etc … ) were added at the cooling point prior to “aging”. See next section for more on dairy “inclusions”.
Step 6. “HARDEN” the Ice Cream:
Then the Ice cream is “HARDENED” when it is put into cold refrigerated storage rooms and held at – 34* C for a minimum of several hours to a period of time that may last for days before shipping.