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ARS Home » Plains Area » Brookings, South Dakota » Integrated Cropping Systems Research » Research » Publications at this Location » Publication #258541
Title: Twin screw extrusion processing of distillers dried grains with solubles (DDGS)-based Yellow Perch (Perca flavescens) feeds

Author
item AYADI, FEROUZ - South Dakota State University
item Rosentrater, Kurt
item MUTHUKUMARAPPAN, K - South Dakota State University
item BROWN, MICHAEL - South Dakota State University

Submitted to: Food and Bioprocess Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 2/5/2011
Publication Date: N/A
Citation: N/A

Interpretive Summary: This study investigated the feed processing aspects of diets for juvenile yellow perch. Five isocaloric (~ 3.06 kcal/g) ingredient blends, adjusted to a target protein content of 36.7% db, were formulated with 0, 10, 20, 30, and 40% distillers dried grains with solubles (DDGS). Additionally, fish meal, fish oil, whole wheat flour, corn gluten meal, and vitamin and mineral premixes were used. Extrusion processing was performed with a pilot-scale twin-screw extruder at screw speeds between 226 and 298 rpm using a 1.9 mm die. After processing, the resulting extrudates were analyzed for moisture content, water activity, unit density, expansion ratio, compressive strength, compressive modulus, pellet durability index, water stability and color, in order to quantify the effects of DDGS content on the extrudates. There were significant changes in brightness (L), redness (a) and yellowness (b) among the final products when increasing the DDGS content of the blends. Expansion ratio and compressive strength of the extrudates were low, but all blends exhibited high pellet durability. Overall, it was determined that DDGS could successfully be included at rates up to 40% of the feed blend and viable extrudates could be produced for all blends.

Technical Abstract: Increases in global aquaculture production, compounded with limited availabilities of fish meal for fish feed, has created the need for alternative protein sources. Twin-screw extrusion studies were performed to investigate the production of nutritionally-balanced feeds for juvenile yellow perch (Perca flavescens). Five isocaloric (~ 3.06 kcal/g) ingredient blends, adjusted to a target protein content of 36.7% db, were formulated with 0, 10, 20, 30, and 40% distillers dried grains with solubles (DDGS) at an initial moisture content of 5-7% db, with appropriate amounts of fish meal, fish oil, whole wheat flour, corn gluten meal, and vitamin and mineral premixes. During processing, varying amounts of steam (6.9-9.7 kg/h) were injected into the conditioner and water (6.7-13.1 kg/h) into the extruder to modulate the cohesiveness of the final extrudates. Extrusion cooking was performed at 226-298 rpm using a 1.9 mm die. Mass flow rate and processing temperatures generally decreased with progressively higher DDGS content. Moisture content, water activity, unit density, bulk density, expansion ratio, compressive strength and modulus, pellet durability index, water stability, angle of repose, and color were extensively analyzed to quantify the effects of varying DDGS content on the physical properties of the final extrudates. Significant differences (P<0.05) among the blends were observed for color and bulk density for both the raw and extruded material, respectively, and for the unit density of the extruded product. There were also significant changes in brightness (L), redness (a) and yellowness (b) among the final products when increasing the DDGS content of the blends. Expansion ratio and compressive strength of the extrudates were low. On the other hand, all extruded diets resulted in very good water stability properties and nearly all blends achieved high pellet durability indices. In summary, each of the ingredient blends resulted in viable extrudates.