Skip to main content
ARS Home » Plains Area » Brookings, South Dakota » Integrated Cropping Systems Research » Research » Publications at this Location » Publication #216255
Title: EXTRUSION STUDIES OF AQUACULTURE FEED USING DISTILLERS DRIED GRAINS WITH SOLUBLES AND WHEY

Author
item CHEVANAN, NEHRU - SOUTH DAKOTA STATE UNIV
item MUTHUKUMARAPPAN, K - SOUTH DAKOTA STATE UNIV
item Rosentrater, Kurt

Submitted to: Food and Bioprocess Technology
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/6/2007
Publication Date: 12/10/2007
Citation: Chevanan, N., Muthukumarappan, K., Rosentrater, K.A. 2007. Extrusion studies of aquaculture feed using distillers dried grains with solubles and whey. Food and Bioprocess Technology. DOI 10.1007/s11947-007-0036-8.

Interpretive Summary: Aquaculture feed is a potential use for DDGS, but to date has not been thoroughly explored. Three feed blends were formulated to contain 3.5 kcal/g and 28% (wb) protein, and contained 20, 30, and 40% (wb) DDGS. The blends also contained soy flour, corn flour, fish meal, mineral and vitamin mix, in order to produce balanced feed rations. Additionally, whey was incorporated at 5% (wb) as a binding agent. These blends were then extruded in a single screw laboratory extruder at 15, 20, and 25% (wb) moisture content, and at 130 and 160 rpm screw speeds. The durability and unit density of the extrudates were found to increase substantially by the addition of whey to the blends. Increasing the DDGS content from 20 to 40% resulted in a 6.5%, 8.0%, and 5.2% decrease in moisture content, water activity, and brightness, respectively, as well as an 8.5% and 4.2% increase in redness and yellowness, respectively, of the extrudates. Increasing the moisture content of the ingredient blends from 15 to 25% resulted in a 15.4%, 4.1%, 19.9%, 22.6%, and 8.4% decrease in moisture content, water activity, brightness, redness, and yellowness, respectively, of the extrudates. Changing the screw speed had no significant effect on most of the properties of the extrudates studied in our experiments, except for durability, unit density, and moisture content. Additionally, we observed an increase in fiber content of 31.8%, an increase in fat content of 66.0%, and a decrease of 7.3% in Nitrogen Free Extract in the extrudates when the DDGS content was increased from 20 to 40%. As demonstrated in this study, ingredient moisture content and screw speed affect both processing conditions, as well as final extrudate quality.

Technical Abstract: Three isocaloric (3.5 kcal/g) ingredient blends containing 20, 30 and 40% distillers dried grains with solubles (DDGS) along with 5% whey were prepared with a net protein content adjusted to 28%. Other ingredients in the blends included soy flour, corn flour, fish meal, vitamin and mineral mix. These blends were extruded in a single screw extruder at 15, 20, and 25% (wet basis - wb) moisture content and at 130 and 160 rpm screw speeds. The durability and unit density of the extrudates were found to increase substantially by the addition of whey to the blends. Increasing the DDGS content from 20 to 40% resulted in a 6.5%, 8.0%, and 5.2% decrease in moisture content, water activity, and brightness, respectively, as well as an 8.5% and 4.2% increase in redness and yellowness, respectively, of the extrudates. Increasing the moisture content of the ingredient blends from 15 to 25% resulted in a 15.4%, 4.1%, 19.9%, 22.6%, and 8.4% decrease in moisture content, water activity, brightness, redness, and yellowness, respectively, of the extrudates. Changing the screw speed had no significant effect on most of the properties of the extrudates studied in our experiments, except for durability, unit density, and moisture content. Additionally, we observed an increase in fiber content of 31.8% and an increase in fat content of 66.0%. We also observed a decrease of 7.3% in Nitrogen Free Extract in the extrudates when the DDGS content was increased from 20 to 40%. As demonstrated in this study, ingredient moisture content and screw speed are critical considerations when producing extrudates with ingredient blends containing DDGS.