A milk products are categorized as sweetened condensed milk if the protein content is 6.8 - 10% and 8-10% for fat.
Manufacturing Process of Sweetened Condensed Milk
There are two types of sweetened condensed milk manufacturing process:
- Traditional method
- Modern method
- The raw milk is transported from the dairy farm to the plant in refrigerated tank trucks. At the plant, the milk is tested for odor, taste, bacteria, sediment, and the composition of milk protein and milk fat. The composition of protein and fat is measured by passing the milk under highly sensitive infrared lights.
- The milk is piped through filters and into the pasteurizers. Pasteurization process in used to increase the milk's stability, decrease the chance of coagulation during storage, and decrease the bacteria level. There are two method :
· High Temperature Short Time (HTST) heat the milk to of 161 °F (71.6°C) for 15 seconds
· Ultra High Temperature (UHT) heats the milk to 280°F (138°C) for two seconds.
- The warm milk is piped to an evaporator. Through the process of vacuum evaporation, (exposing a liquid to a pressure lower than atmospheric pressure) the boiling point of the milk is lowered to 104-113°F (40-45°C). As a result, the milk is concentrated to 30-40% solids.
- The milk is then homogenized by forcing it under high pressure through tiny holes. This breaks down the fat globules into minute particles, improving its color and stability. Pre-measured amounts of a stabilizing salt, such as potassium phosphate, are added to the milk to make it smooth and creamy. This stabilization causes the milk to turn a pale tan.The milk is passed under a series of ultraviolet lights to fortify it with Vitamin D.
- The milk is piped into pre-sterilized cans that are vacuum-sealed. The milk is flash-heated to about 185°F (85°C) for several seconds. It is then piped to the evaporator where the water removed.
- The milk is then concentrated under vacuum pressure until it measures between 30-40% solid. It now has a syrupy consistency.The milk is cooled and then inoculated with approximately 40% powdered lactose crystals. The milk is then agitated to stimulate crystallization. It is this sugar that preserves the condensed milk.The milk is piped into sterilized cans that are then vacuum-sealed.
- The raw material used is water or fresh milk (if semi-recombination) and powdered ingredients such as skim milk powder, whey powder (sweetened condensed cream many uses whey powder because it is cheaper), sugar and cocoa powder (for chocolate), last one is fat. All of this material should be mixed at a temperature of 50-55oC in high-speed mixer (turbo-mixers) because the total solids in the mixing stage has reached 68-70%.
- Homogenization process is done in single stage homogenizer machine to break down fat globula be sized up to 2 microns. The pressure applied in this homogenization process varies according to the formulation and fat content but generally range between 700-1100 psi (lbs/inch2). Then the mixture is pasteurized at a temperature of 85-900C for 30 seconds.
- Evaporation process carried out in vacuum, when lactose is added to grain for seeding. The process of seeding lactose should be at the right temperature, the temperature at the time of crystallization of lactose due to supersaturated (supersaturated). Lactose granules used should be the maximum size of 10 microns, so that the crystallized lactose in milk does not form clusters but is spread evenly throughout the product, is carried by grains of fine lactose earlier. To get the maximum grain size of 10 micron lactose, usually sweetened condensed milk producers do grinding lactose prior to use. But, now there micronised lactose with the desired size without having to be grinding first.
- Evaporation is done until the final total solids in the product reaches 72-74%. The process of aging is the process of lactose crystallization refinement and distribution, which is a waiting process while stirring for 2-3 hours so that the entire crystalline lactose spread evenly throughout the product.