"Value Addition of Distillers Dried Grains with Solubles (DDGS) Using E" by Sankaranandh Kannadhason

Document Type

Thesis - University Access Only

Award Date

2009

Degree Name

Master of Science (MS)

Department / School

Agricultural and Biosystems Engineering

Abstract

This research study was done with a broad intention of enhancing the value of Distiller's Dried Grains with Solubles (DDGS) in aquaculture feeds for the production of floating and sinking feed using extrusion technology. The various ingredients used in the preparation of balanced blends included DDGS, soybean meal, starch sources (tapioca, com, and potato), fish meal, whey, and vitamin and mineral mixes. The equipment used in the production of DOGS based extrudates were single screw extruder and a twin screw extruder. The feed parameters in the various experimental studies included: Starch sources (tapioca, com, and potato), DDGS levels (17.5 to 60% db), feed moisture content (15 to 35% db), and net protein content (28 to 35% db). The extruder parameters included: Extruder screw speed (100 to 200 rpm) and extruder processing temperature (100 to 150 °C). The effect of feed composition and extruder parameters on the physical properties of the extrudates, extruder processing parameters, and nutrient composition were investigated. The physical properties of the extrudates determined were moisture content (MC,% db), expansion ratio (ER,(-)), unit density (UD, kg/m\ bulk density (BO, kg/m1), sinking velocity (SV, mis), color (L *, a*, and b*), water absorption index (WAI, (-)), water solubility index (WSI, %), and pellet durability index (POI,%). The extruder processing parameters investigated included moisture content at the die (% db), mass flow rate (MFR, g/min), apparent viscosity (Pas), extruder torque (N-m), die pressure (MPa), and specific mechanical energy (SME, J/g). The proximate composition of DOGS based extrudates included crude protein (% db), neutral detergent fiber (% db), crude fat (% db), and ash (% db). In the first study, the effect of various starch sources (tapioca, com, and potato), DDGS levels, feed moisture content, processing temperature, and screw speed on the resulting extrudate properties were determined. Increasing the DOGS levels from 20 to 60% resulted in decreased ER, WAI, and POI values for all the three starch extrudates. For all the three starch extrudates, a profound increase in ER and WAI values could be noticed for the change in the feed moisture content from 15 to 25%. Overall, tapioca starch extrudates were found to be more appropriate for the production of floating aquaculture feeds, where as com starch extrudates were more durable. As a second part of this research, the effect of DOGS levels and net protein content on the resulting DOGS based extrudates were analyzed. Increasing the DOGS levels from 20 to 40% decreased ER values for all the three starch extrudates but WAI and WSI values were found to decrease for com and potato starch extrudates. On the other hand, a noticeable increase in PDI values were observed with an increase in DOGS and protein levels from 20 to 40% and 28 to 32%, respectively. In the overall analysis, it was noticed that tapioca starch incorporated in a 20% DOGS diet resulted in a floating feed more appropriate for tilapia. The third part of the study was conducted with an intention of producing floating aquaculture feeds using a single screw extruder. Based on the previous experimental results, tapioca starch was used as the starch source in this study. Increasing the DOGS content from 20 to 30%, protein content from 30 to 32.5%, and temperature from 100 to 150 °C resulted in decreased ER, WAI, and POI values of the resulting DOGS based extrudates. Also, apparent viscosity, die pressure, and extruder torque decreased significantly with an increase in DOGS, protein levels, and processing temperature. As anticipated, mass flow rate increased with corresponding increase in extruder screw speed. The fourth part of this research study was carried out with the similar experimental conditions used in the third experiment with an exception of changing the starch source. Increasing the DDGS levels, net protein, feed moisture, and processing temperature decreased the ER values substantially where as screw speed was found to have a positive effect on ER values. Extruder torque value was found to decrease with an increase in net protein content, processing temperature, and screw speed. Corn starch was used in the fifth experiment along with other ingredients to produce a balanced aquaculture ration more appropriate for tilapia. The experimental conditions used in this study were the same as the third and fourth parts of this thesis. Experimental results revealed that an increase in processing temperature from 100 to 150 °C had a significant effect on all the extrudate properties studied. More interestingly, any changes in the DDGS levels and feed moisture content possessed a significant impact on all the extruder parameters studied. The final study was a pilot scale study that was conducted using a twin screw extruder for the production of floating fish feed by varying the levels of DOGS, die dimensions, and screw speed. For both the die/screw speed combination, increasing the DDGS levels from Oto 27.5% resulted in an increased density values (unit and bulk density), WSI, and MFR values. The control blend that possessed 0% DOGS resulted in highest ER values and lowest UD, BD, and SV values and hence floated, whereas extrudates produced using 20% and 27.5% DDGS were more durable and appropriate for the production of sinking aquaculture feeds. Our experimental results had shown that the optimal inclusion of DOGS for the production of aquaculture feed is 20% using a single and twin screw extruder.

Library of Congress Subject Headings

Fishes -- Feeding and feeds
Distillers feeds
Extrusion process
Distilling industries -- By-products

Format

application/pdf

Number of Pages

261

Publisher

South Dakota State University

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