Spray drying of milk solids is an extensively used process in the dairy industry where liquid Milk can be converted into a powder form. It extends the shelf life of milk, cuts costs associated with transporting milk and makes it easier to handle and store. This includes steps like preparing milk and packing it into powdered form, to name a few. This article includes how a milk spray dryer operates, its equipment and the stages of the process.

The Need for milk spray dryer

Before getting in to the details of how milk spray dryer works, it is valued first to understand why milk processing tends towards this methodology. With around 87% water, liquid milk is highly prone to spoilage which limits its shelf life. Spray drying removes the moisture content of milk producing powder that can last without refrigeration for months, or even years. This is especially beneficial for manufacturers, retailers and consumers.

The milk spray dryer Process

Spray drying milk involves the following processes:

Milk Preparation

Step 1: Standardization — The first step is to standardize the milk content or fat & protein level. Eggnog is generally made from a blend of milk, and will sometimes be blended together with cream (perhaps removed or added back in), where you can have an eggless alternative.

Pasteurization : Then, the milk is pasteurized to kill off any potentially dangerous bacteria. Pasteurization is a vital process for food safety, and it essentially involves heating the milk to specific temperature limits during fixed hold periods.

Homogenisation: Following pasteurization, the milk is homogenised which reduces fat globule sizes so that cream separation does not occur and a uniform product results.

Concentration

This latent water must first be removed from the milk, making its way into pasteuriser and subsequently concentrated via evaporation prior to entry in a spray dryer. Typically, this is done via evaporators that extract most of the water so as to concentrate solids. Concentrated milk is skimed off and transferred to spray dryer.

Spraying

The milk concentrate then goes directly into the spray dryer where it is atomizing with a sprayer nozzle or rotating disc in fine droplets. The soaking process exposes a large surface area for drying, and moisture is quickly drawn out.

Drying

The atomized droplets are injected into a chamber with heated air. Hot air (normally heated to 150–200 °C approx.300-390°F) is passed through the notice board triggering fast evaporation of the water within droplets of milk. This drying time is very brief and generally comes in a matter of seconds thus maintaining the nutritional quality of milk.

The remaining solids become powder as the water evaporates. The air/powder mixture is then blown into a cyclone separator.

Separation

A cyclone separator separates the dried milk powder from exhaust air. Due to the centrifugal force, there will be separation of heavier powder particles from air while taking an exit causing them to fall in a collection chamber.

Cooling and Packaging

After the milk powder gathers in a collection system, it may be cooled to preserve its quality before packaging. Then, to prevent since absorption and for a smarter shelf life it can be kept in airtight bins.

What Equipment is Used for milk spray dryer

The milk spray dryer process utilises a range of specialist milk spray dryer:

Evaporators — These are employed to concentrate the milk (by removing water) before entering the spray dryer.

Spray Driers: The primary equipment that atomizes the milk and enables drying. The system has a drying chamber, an atomizer and air.

Cyclone Separators: These are needed for separating the air from dried powder.

Cooling Systems: The powdered milk needs to cool down enough before being packaged.

Packaging Machines: These machines are used to pack milk powder in bags / containers and seal it.

Advantages of Spray Drying

Spray drying has several advantages.

Maintains Nutritional Value: Since the drying process only takes a few minutes, milk proteins and vitamins are retained in their natural state.

Long Shelf Life - Dried milk powder has a long shelf life and can be stored without refrigeration.

Powdered milk: A very light convenient powder that is easy to carry and enjoy use in many ways, (baking time or bake the right way)Cooking Recipe formula.

Flexibility: Spray drying can be scaled in different sizes and used for other dairy products (e.g. whey protein, cheese powder).

Challenges and Considerations

While spray drying offers several benefits, it is also not without its challenges:

Consumption of energy: Heats the air and operates evaporators; it is a process that uses a lot of energy to accomplish this.

Quality Control: It is very important for a powder to have the same quality, that means it should be consistent and keep on having the same particle size (mesh), moisture content etc. this needs constant checking or measurements.

Financial investment in the downsides of spray drying: 1. High cost Eye-catching small Dairy processor may be hindered due to initial high equipment investment requirement.

In the dairy industry, milk spray dryer is an indispensable process to meet demand by converting liquid milk into powdered form. By first preparing the milk, then performing rigorous steps of atomization, drying and separating, spray driers efficiently produce high-quality shelf-stable milk powder. The process involves its limitations, but the pros it brings in terms of convenience and versatility as well as preservation forms a vital part in the dairy manufacturers across globe. While just like other food products, new technology innovations may improve spray drying processes to become even more efficient and enhance product quality so that powdered milk stays on kitchen tables and in production plants around the world.