Modeling Single Screw Extrusion Processing Parameters and Resulting Extrudate Properties of DDGS-Based Nile Tilapia

Depletion of wild fisheries, coupled with rising demands for seafood items for human foods, offers resulted in increased aquaculture plastic sheet extruder production over the last several years. Dependant on the species and maturity, fish have huge dietary protein demands as high as 55%. Fish meal is among the main protein sources used in aquatic feeds; because of good amino acid equilibrium, high palatability, and growth performance, continually increasing demand for the limited way to obtain wild fish has steadily increased seafood meal prices. For example prices for fish meal for July 2010 were above $1370 per ton, compared to $600 per ton for July 2005. For several seafood species, feed costs only can represent up to 70% of the total production price for an aquaculture procedure.

Protein makes up about the major feed expense. Studies have shown that less expensive alternative protein resources can, at least partially, replace fish meal, satisfy protein requirements, and bring about good growth performance. These alternatives include various pet and plant sources. Ayadi et al. provided a thorough review of many of these feed elements. For instance, meat and bone meal has been found in salmonids feeds. Poultry by-product food has been used in commercial weight loss plans for sunshine bass and hybrid striped bass.

Soybean meal is among the most studied and widely used plant protein sources in professional aquatic feeds for many species, hybrid striped bass, such as tilapia, Atlantic salmon, rainbow trout and sunshine bass. Distillers dried grains with solubles is going to be another ingredient. It's the key nonfermentable coproduct of gas ethanol production, and is made from corn grain mostly. In comparison to other protein sources, such as for example SBM, DDGS is very competitive on a cost per unit necessary protein basis, highly palatable to fish, and does not contain anti-nutritional factors that are present in most pulses. In various studies, DDGS has been examined as a potential protein ingredient in fish feed for species such as for example Nile tilapia, channel catfish, and rainbow trout.

Nile tilapia started in Africa, and is the most crucial cultured fish species global. Global tilapia production has increased exponentially in the last 30 years. For example, in 1998, 0.7 million metric tonnes of Nile tilapia had been produced, in comparison to 2.3 million t in 2008, of which Asia is just about the major producer. For the US market, tilapia production increased from 15,521 t in 1998 to 81,130 t in 2008. It is the fifth most common seafood consumed in the US. Tilapia has fast development relatively, undemanding feed conditions, and physical hardiness. Despite the fact that Nile tilapia possesses been classified as herbivorous, it has been reported that Nile Tilapia may also feed on insects, algae, and potentially other fish. Protein requirements rely on maturity; they are often up to 45% for Nile tilapia fry.

Dietary components are only one aspect of fish feeding, however. The other is feed production. Top quality aquatic feeds are generally produced by extrusion processing, that may produce sinking or floating feeds and improve nutrient digestibility. Extrusion processing has become very popular in the food and feed industries due to high versatility, productivity, and product quality. Previous study by our group offers focused on several processing aspects of DDGS-based feeds. Single-screw and twin-screw extrusion have been used to produce feeds for tilapia, channel catfish, yellow perch, and rainbow trout. The effects of various levels of DDGS inclusion, ingredient moisture content, protein content screw rate, barrel temperature, and die dimension, on resulting extruder processing conditions and extrudate real estate have already been examined. Additionally, we have used these extruded feeds in feeding trials to test their efficacy. Most of these scholarly studies, however, were deterministic and empirical in nature. Follow-up modeling research on extrusion can help to predict output parameters predicated on extruder processing adjustments and/or formulations of the raw blends.

Extrusion food preparation involves many complex techniques which can be difficult to control due to interactions between mass, strength, and momentum transfer phenomena. Physicochemical changes effect extrudate properties, and can be problematic to predict. Some analysis has been conducted on modeling of extrusion operations and resulting product quality. For example, Meng et al. employed second-buy polynomial regression to version twin-screw extruder system parameters and physical properties of chickpea flour-based snack foods. An identical modeling study was accomplished by Ding et al. for rice-based expanded snacks. Chevanan et al. developed neural network and regression models of single-screw extrusion of aquaculture feeds containing DDGS; data collected from varied trials were mixed to predict extrudate real estate and extrusion processing parameters based on die dimensions, ingredient moisture articles, barrel temperatures, and screw acceleration. Wang et al. modeled twin-screw extrusion to regulate extrudate quality features. Multiple regression designs were developed by Ganjal et al. to relate the radial growth of extrudates to die nozzle dimensions and back pressure at the die for acetylated starch in a twin-screw extruder. Ali et al. designed a regression model to study the effects of screw and heat range acceleration on the radial, axial, and overall growth, as well as bulk density of extruded corn grits in a single-screw extruder.

In this analysis, the target was to model the consequences of various levels of DDGS, soybean meals, ingredient moisture content, screw rate, screw compression ratio, die dimension, and barrel temperature on resulting extrudate physical real estate and on resulting extruder processing conditions.

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