TECHNOLOGY
Understanding drying and cooling processes for pelleted shrimp feed Albert Wang, IDAH Co., Ltd.
Development of shrimp feed A few decades ago, a Japanese scientist Dr. Motosaku Fujinaga (also known as Dr. Hudinaga), became a pioneer in the technology of shrimp spawning and larval rearing. This technology development is an important milestone that marks the start of in-land shrimp cultivation. In the 1970s, commercial shrimp feed was sold to the public. These pellets are fast sinking and water-stable (Chamberlain, 2010). Pelleted feed production in the early days Early day formulation of shrimp feed incorporated a high percentage of an aquatic animal protein source, such as fishmeals or squid meal, which was readily digestible for the shrimp digestive tract (higher FCR) (Yun et al., 2017). The early pelleting process only incorporated a small amount of moisture and no significant drying process was needed. The limitation and rising price of the animal-based feed source promoted the usage of a reasonable amount of plant-based protein, such as soybean meal as a protein source substitute (Hasan, 2001; Suárez et al., 2009). The incorporation of plant-based meals induced the need for a better ingredient cooking process because the cooking process can denaturate these plant proteins and promote starch cooking. The first generation of shrimp feed pelleting system The first-generation (G1) of shrimp feed production machine, popular from the 1980s until the 2010s, consisted of a pellet mill, a post-conditioner, and a cooler. This machine setup can prolong the mash cooking while taking out a small amount of moisture. The pre-conditioner system with direct steam spraying incorporated into the pelleting system in the 1980s helped increase the moisture content of the mash by around 2-3% (wb). The higher moisture
Figure 1. The third-generation (G3) shrimp feed pelleting system development offers total moisture control and saves drying energy. (IDAH, Taiwan)
improvement can increase the feed stability in water. The following post-conditioning and cooling process will remove approximately 1-2% moisture from the feed, resulting in the finished product with a moisture content of 10-11%, a shelf-stable pelleted feed moisture content during storage.
Incorporation of the carousel dryer to shrimp feed pelleting lines Even though the G1 technology is still a popular option in many Asian countries, there is a growing demand to increase the incorporation of sustainable plant-based protein while keeping the water stability (Bae et al., 2020). One way to improve the water stability of plantbased protein is by adding moisture to the mash. The benefits of increasing the moisture content during mash cooking are the increase of starch cooking and
Aquafeed: Advances in Processing & Formulation Vol 14 Issue 3 2022
