Optimization of the process parameters for extruded commercial sinking fish feed with mixed plant protein sources

Abstract

The aim of the investigation was to optimize extrusion process parameters for processing commercial sinking fish feed with mixed plant protein sources in a pilot‐scale twin‐screw extruder equipped with a preconditioner. It has been found out that the bulk density of feed pellets increased with the moisture content in the range of 22–27% (wt), then decreased with the moisture content from 27 to 32%. Meanwhile, increasing moisture content (22–32%) resulted in a decrease of pellet hardness, water solubility, and specific mechanical energy (SME), and an increase of pellet hydration time. There was a significant decrease (p <.05) in SME, bulk density, and hydration time when the die temperature was increased from 90 to 140°C. Increasing the screw speed (180–300 rpm) led to an increase in SME, water solubility index (WSI), and water solubility, but a decrease of water solubility index (WAI). The optimal process parameters for processing the sinking feed pellets were moisture content: 26.6%, screw speed: 180 rpm, and die temperature: 113°C. These operation parameters provide a reference for the industrial production of fish feed with mixed plant protein sources.Practical applicationsIn recent years, plant protein has been increasingly developed as an aquatic feed source, but this has resulted in quality fluctuations for fish feed pellets. Sinking pellets require sufficient gelatinization but should avoid floating due to excessive swelling. Thus, it is important to control the parameters of the extrusion process during sinking feed production. Contrary to conventional laboratory studies, this study used a pilot extrusion line (capacity: 70–150 kg/hr) equipped with a steam adding preconditioner and an automatic data acquisition system for parameter optimization. Moreover, we defined satisfactory products through the targeted evaluation of key indicators such as water solubility and hydration time. The results of this study provide a reference for the industrial production of sinking feed with mixed plant proteins.

Effects of Clostridium autoethanogenum protein inclusion levels and processing parameters on the physical properties of low-starch extruded floating feed

“…The increase in moisture content resulted in a decrease in bulk density in this study. Consistent with the present study, Wang et al (2021a) reported that the bulk density of commercial sinking fish feed decreased as the moisture content increased from 27% to 32%. Under high temperature and high moisture content conditions, the superheated water in the extruder promoted bubbles formation and decreased the viscosity of the melt, resulting in a decrease in the bulk density (Samray et al, 2019).…”

“…In this study, the hardness of feeds increased with the decrease in moisture content. Consistent with our study, Wang et al (2021a) reported that the moisture content had an adverse effect on the hardness of extruded commercial sinking fish feed. The above discussion mentioned that at high temperatures, the high moisture content could promote extrudate expansion in our study.…”

Effects of native and pregelatinized starches on feed physical properties, digestibility, growth, nutrient utilization and histology of liver and intestine of juvenile tinfoil barb ( Barbonymus schwanenfeldii , Bleeker 1853)

“…According to Riaz (2009), BD of neutral buoyancy pellets ranges from 480 to 520 g/L for freshwater. After considering optimal condition for extrusion mixture with plant‐based feedstuffs, Wang et al (2021) suggested a minimum density of 560 g/L for sinking pellets. On the whole, tinfoil barb diets appeared to be a slow‐sinking extrudate with no marked differences in ER and BD among the pre‐cooked and native starch sources.…”

Comparison of growth performance, non-specific immunity, and intestinal microbiota of olive flounder (Paralichthys olivaceus) fed with extruded pellet and moist pellet diets under field conditions in South Korea

“…Over the last two decades, aquaculture scientists have sought to identify low-cost alternatives to fish meal and fish oil from alternative sources such as plants, microbes, seaweeds, and insects (Belghit et al, 2019;Wang et al, 2021). Feed formulation strategies, nutrient stability, leaching in water, and raw material properties are also limiting factors that affect the nutritional profile of supplemented diets, which in turn affects aquaculture profitability (Draganovic et al, 2011).…”