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ARS Home » Plains Area » Brookings, South Dakota » Integrated Cropping Systems Research » Research » Publications at this Location » Publication #229720
Title: Effect of Starch Sources and Protein Content on Extruded Aquaculture Feed Containing DDGS

Author
item KANNADHASON, SANKARANANDH - SOUTH DAKOTA STATE UNIV
item MUTHUKUMARAPPAN, KASIVISWANATHAN - SOUTH DAKOTA STATE UNIV
item Rosentrater, Kurt

Submitted to: Food and Bioprocess Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/16/2008
Publication Date: 1/21/2009
Citation: Kannadhason, S., Muthukumarappan, K., Rosentrater, K.A. 2009. Effect of Starch Sources and Protein Content on Extruded Aquaculture Feed Containing DDGS. Food and Bioprocess Technology. pp.1-13. DOI: 10.1007/s11947-008-0177-4.

Interpretive Summary: Distillers dried grains with solubles (also known as DDGS) is a potential protein source for aquaculture feeds, but much work remains in order to effectively process this ingredient into a complete feed. A 3x3 completely randomized design was used to investigate the extrusion cooking and resulting product characteristics of DDGS-based aquafeeds. Cassava, corn, and potato starches with varying levels of DDGS (20, 30, and 40% wb) were formulated to contain three different proportions of protein (28, 30, and 32% wb); these blends were then extruded using a laboratory-scale single screw extruder. Extrusion cooking was performed at a constant feed moisture content of 20% wb, barrel temperature of 120 oC, and screw speed of 130 rpm (13.6 rad/sec). Extrudate properties, including expansion ratio (ER), unit density (UD), sinking velocity (SV), color (L*, a*, and b*), water absorption and solubility indices (WAI & WSI), and pellet durability index (PDI), were determined to examine the quality of the extrudates. For all three starch sources, increasing the DDGS level resulted in an increase in sinking velocity, redness (a*), and blueness (b*), and resulted in a decrease in brightness (L*). With an increase in DDGS and protein level, a noticeable increase was observed for unit density and pellet durability for cassava and potato starch-based extrudates. The extrudates produced from cassava starch with lower proportions of DDGS (20%) and protein (28%) levels exhibited better expansion and floatability. The extrudates produced from corn starch with higher levels of DDGS (40%) and protein (32%) were more durable, but sank. Results from this study show the importance of experimentally determining the effects of feed ingredients and process variables when developing aquafeeds from various materials. Even though this study has provided information about extrusion processing of DDGS with feed ingredients, work still remains in order to optimize aquafeeds from this protein source.

Technical Abstract: A 3x3 completely randomized design was used to investigate the extrusion cooking and product characteristics of DDGS, protein levels, and various starch sources in a laboratory scale single screw extruder. Cassava, corn, and potato starches with varying levels of DDGS (20, 30, and 40% wb) were extrusion cooked with three different proportions of protein levels (28, 30, and 32% wb). The extrusion cooking was performed at a constant feed moisture content of 20% wb, barrel temperature of 120 oC, and a preset screw speed of 130 rpm (13.6 rad/sec). Extrudate properties like expansion ratio (ER), unit density (UD), sinking velocity (SV), color (L*, a*, and b*), water absorption and solubility indices (WAI & WSI), and pellet durability index (PDI) were determined to judge its suitability for specific variety of fishes. For all three starch bases, increasing the DDGS levels exhibited a significant increase in sinking velocity, redness (a*), and blueness (b*), and showed a decrease in brightness (L*). With the increase in DDGS and protein levels, a noticeable increase was observed on unit density and pellet durability indices for cassava and potato starch extrudates. The DDGS based extrudates produced from cassava starch with lower proportions of DDGS (20%) and protein (28%) levels used in our study exhibited better expansion and floatability. Also, the extrudates produced from corn starch with higher levels of DDGS (40%) and protein (32%) levels were more durable and possessed sinking characteristics.