The Importance of Efficient Drying in Aqua Feed Production

Understanding the Drying Process in Aqua Feed Mills

Drying is the largest and most energy-consuming process in the aquafeed mill, according to Progressus facilitator Joe Kearns. Pellets typically enter the dryer at approximately 22% moisture. The targeted moisture content for dry aqua feed pellets in Asia is usually between 8-12%. Therefore, the dryer must effectively remove about 10-15% moisture from the pellets.

Achieving the industry standard of drying within ±0.5% of the target moisture content is critical. It ensures that moisture is evenly distributed across each pellet. This uniformity allows all pellets to absorb oil uniformly, ensuring they sink at the same speed.

Factors Affecting Moisture Uniformity

Joe Kearns discussed several key factors that influence the moisture uniformity of aquafeed exiting the dryer:

Pellet Size

Smaller pellets have a higher surface area to volume ratio, which facilitates quicker moisture evaporation during drying. This means that smaller pellets can dry more efficiently than larger ones, reducing both drying time and energy consumption. However, variations in size can lead to uneven drying. Smaller pellets may dry out too quickly, while larger ones may retain moisture longer, leading to potential spoilage or quality issues.

Pellet Structure

The structure of the pellets affects their porosity, which in turn influences how moisture is retained and released during drying. Floating feed pellets typically have a loose and porous structure that allows for better water stability. However, this same structure can facilitate rapid moisture release during the drying process.

Bulk Density

The bulk density of the pellets plays a significant role in drying efficiency. Pellets with lower density tend to have more air pockets, enhancing airflow during drying and improving moisture removal rates. Conversely, denser pellets may restrict airflow, slowing down the drying process.

Drying Temperature

Increasing the drying temperature generally accelerates moisture removal from extruded aqua feeds. However, excessively high temperatures can lead to over-drying. This results in a final product with very low moisture content, negatively affecting pellet texture and nutritional quality. Typically, temperatures between 80-120°C are recommended for effective drying without compromising nutritional value or causing degradation of sensitive ingredients like proteins and vitamins.

Drying Time

Longer drying times generally result in lower moisture content in extruded aqua feeds. While extended drying can effectively reduce moisture content, there is a need to balance this with the risk of over-drying. Over-drying can lead to brittleness and reduced water stability, making pellets more prone to breaking apart when submerged in water.

Air Flow

All pellets must be exposed to the same air flows. Poor air distribution can create dead zones where moisture removal is inefficient, resulting in inconsistent product quality. If pellets are not spread evenly across the dryer bed, air will take the path of least resistance. This can lead to over-drying in areas where air passes quickly and under-drying in areas where air passes slowly, or not drying the feed at all.

“It is not an exaggeration to say that a company's profitability on an extrusion line can be made or lost at the dryer,” stressed Joe.

The Consequences of Inadequate Drying

Inadequate drying can have several negative consequences for aquafeed production. These include:

• Quality Issues: Poorly dried pellets may spoil faster and lose their nutritional value.

• Operational Costs: Inefficient drying processes can lead to higher energy costs.

• Market Competitiveness: Companies that fail to optimize their drying processes may struggle to compete in the market.

  
  

Solutions for Improved Drying Efficiency

If uniformly drying extruded aqua feed is a challenge for your feed mill, consider the following solutions:

1. Invest in Advanced Drying Technology: Upgrading to more efficient drying systems can significantly improve moisture removal rates and reduce energy consumption.

2. Regular Maintenance: Ensure that drying equipment is well-maintained to avoid inefficiencies.

3. Training and Education: Attend workshops and training sessions, such as the upcoming 2025 In-Person AgriSchool – Aqua Feed Milling Management, to stay updated on best practices.

   
   

In conclusion, optimizing the drying process in aquafeed production is crucial for maintaining product quality and ensuring profitability. By understanding the factors that influence drying efficiency, feed mills can implement strategies to improve their operations and meet industry standards.