When producing high-quality aqua feed, oil coating technology plays a critical role in feed nutrition, pellet stability, appearance, and overall product value.

Many feed mills start with traditional drum coating systems because of their relatively low investment cost and simple operation. However, as feed quality requirements increase, especially in premium fish feed and shrimp feed production, more manufacturers begin upgrading from drum coaters to vacuum coating systems.

So what is the real difference between these two technologies?

A drum coater is a continuous coating system mainly used for spraying oils, fats, vitamins, and liquid additives onto the pellet surface after extrusion or pelleting.

The material rotates inside the drum while liquid is sprayed through nozzles to achieve surface coating.

Drum coaters are widely used because:

• Lower initial investment
• Simple structure
• Easy maintenance
• Suitable for standard feed production

In practical aqua feed production, drum coaters are commonly used for lower oil addition applications. Industry references generally show practical liquid addition ranges around 2–8% depending on pellet structure and process conditions.

As feed producers pursue higher energy density and premium feed quality, traditional drum coating systems begin facing several limitations:

When oil addition becomes too high, excess oil remains on the pellet surface instead of penetrating into the pellet core.

This may cause:

• Oily feed bags
• Poor feed appearance
• Oil leakage during storage
• Surface oil film in ponds

Traditional drum coating mainly relies on surface spraying and mechanical mixing, making it difficult to achieve deep and uniform oil absorption.

For high-end aqua feed, especially salmon feed, trout feed, shrimp feed, and premium marine fish feed, higher oil levels are often required.

Conventional coating systems become increasingly unstable at higher liquid addition levels.

Vacuum coating technology was developed specifically to solve the limitations of traditional coating systems.

Unlike drum coaters, vacuum coaters use vacuum pressure to force oils and liquid additives deep into the internal pores of the pellets.

When the vacuum is released, liquids are absorbed into the pellet core rather than remaining on the surface.

Vacuum coaters can achieve significantly higher liquid inclusion compared with traditional coating systems.

Some industrial systems can achieve oil addition levels above 20% depending on feed formulation and pellet structure.

Because oil penetrates into the pellet core, the pellet surface remains cleaner and more stable.

This improves:

• Product appearance
• Packaging cleanliness
• Storage stability

Vacuum coating improves:

• Oil absorption
• Nutritional consistency
• Feed palatability
• FCR performance
• Product value

Especially for high-end aquaculture feeds and pet food applications.

Vacuum coating is ideal for:

• Fish oil
• Enzymes
• Vitamins
• Probiotics
• Functional additives

because liquids are added after extrusion.

Not necessarily.

For standard poultry feed or low-oil products, drum coaters may still be an economical and practical solution.

However, for manufacturers pursuing:

• Premium aqua feed
• High-fat fish feed
• High-end shrimp feed
• Pet food
• RAS aquaculture feed
• Long-term product upgrading

vacuum coating technology becomes increasingly valuable.

The real question is not simply:

“Which machine is cheaper?”

The real question is:

“What feed quality and long-term production target do you want to achieve?”

For feed producers focusing only on low initial investment, traditional coating systems may still work.

But for companies pursuing stable high-quality production, better oil absorption, and premium feed value, vacuum coating is becoming the industry trend.

Both drum coaters and vacuum coaters have their own suitable applications.

The best solution depends on:

• Feed type
• Oil addition target
• Product positioning
• Production scale
• Long-term development plan

As aqua feed technology continues to evolve, vacuum coating is increasingly becoming a key technology for high-end feed manufacturing.