Impact of Moisture, Temperature and Pressure on the Pelleting Process

Written by Anitox | Jan 14, 2022 4:38:42 PM

Creating high-quality pellets that support broiler performance requires the perfect balance of moisture, temperature and pressure. Temperature impacts the ability of feed to absorb moisture. Moisture acts as a conductor for thermal energy. Both temperature and moisture can impact the ability of pelleting equipment to use effective pressure to form pellets. Without moisture, heat applied and generated by equipment would burn and degrade nutrients found within the feed, and without heat, moisture would remain free in feed and lead to spoilage. Neither heat nor moisture will turn mash into a pellet without pressure forcing it into a form. The pelleting process is largely impacted by moisture, temperature and pressure. Variation in either one of these factors can impact the role each has to play in the production of high-quality pellets.

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Pelleting and Moisture

Animal feed is made in accordance with nutritionist-set target specifications, including specific moisture requirements. Not only is moisture essential to diets, but moisture also plays a critical role in the pelleting process. Adequate moisture supports the binding of feed particles, gelatinization, pellet quality, mill energy consumption and profitability. High moisture can cause “plug-ups” and reduced throughput within the mill, leading to heightened energy consumption and excessive microbial growth. In contrast, low feed moisture results in brittle pellets that lead to increased fines and poor feed utilization on the farm. Moisture management is fundamental to producer profitability. Even distribution and absorption of moisture prevent uncontrolled microbial load growth, supporting pellet quality and feed utilization while reducing production process loss and shrink. Moisture is a significant factor in determining high-quality pellets. To protect feed form, producers must ensure that moisture absorption occurs uniformly.

Pelleting Temperature

Temperature varies throughout the feed pelleting process. High temperature is used during conditioning to promote moisture absorption into feed. Researchers have found that temperatures between 50°C and 90°C improve pellet quality and enhance the digestibility of starch, dry matter and crude protein. Most

producers condition feed at 78 - 80°C, although this varies by type of feed, for example, high starch, fiber or protein, heat-sensitive and more. In this temperature range, moisture from steam is adequately absorbed by feed and facilitates starch gelatinization, particle binding, and digestibility is improved. Pressure is applied and occurs when feed is forced into the die. The resulting friction generates thermal energy that sometimes exceeds the heat applied during conditioning and impacts the feed's moisture content by flashing off any water not wholly absorbed.

Pressure as Part of Pelleting

Pressure exists in a few forms during the pelleting process. Firstly, steam is applied during conditioned via pressure. Pressurizing the steam decreases the droplet size of the moisture, making it more of a vapor. In this gaseous form, moisture is more readily absorbed. Secondly, pressure is applied to the feed when the conditioned mash is forced into the die. Moisture not absorbed by the feed will flash off due to the friction from the mechanical pressure within the die. However, die holes can become blocked if moisture is too high or too variable.

Pellet quality is dependent on moisture, temperature and pressure. However, temperature and pressure are in part controlled through adequate moisture management. Milling efficiency aids, such as Maxi-Mil, help feed producers achieve high-quality pelleted feed, reduce process losses and increase throughput.

Our milling efficiency experts are available to answer your moisture management and pellet quality questions today.

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