Document Type

Thesis - Open Access

Award Date


Degree Name

Master of Science (MS)

Department / School

Dairy Science

First Advisor

Padmanaban G. Krishnan


defatting solvents, food grade distiller's dried grains, nutrient composition, processing method, toxicology


Introduction: Distillers Grains represent a major co-product of corn ethanol production. At the production rate of 44 million tons/year and a price of $95/ton, this co-product has potential as a food ingredient (solvent-treated dried products) owing to its high protein content (38%) and high fiber content (40%TDF). The aim of the research was to determine the composition, quality and safety of several initial moisture types of distiller’s grains – distiller’s grains without solubles (DG) and distiller’s grains with solubles (DGS) in wet and freeze-dried form (FrD) from 2017 and 2018.
Method: Processing methods were optimized for raw DG & DGS by employing food grade solvents namely: a) Ethanol b) Ethyl acetate + Ethanol and c) Hexane + Ethanol on the wet and FrD raw material to reduce pigments, odor, and oils to improve compositional quality and shelf stability. The resulting solvent-treated dried product was ground to 0.5mm and heat-sterilized. Linear models were generated, and analysis of variance was used to compare proximate composition, total phenolic content (TPC) and mycotoxin content of raw DG & DGS - wet, FrD form and their corresponding solvent-treated dried products. The mycotoxins were determined through controlled spiking studies and using rapid mycotoxin detection test kits and LC-MS technique. Particle size distribution (PSD) was determined using a series of stacked sieves (40, 60, 80, 100 & 200 mesh) and correlated with solvent-treated dried product color parameters. Results: Raw DG and DGS - wet and FrD from 2017 and 2018 were significantly different from each other in terms of composition. Use of defatting solvents - Hexane and ethyl acetate reduced the fat content from ~11% to ≤1% for solvent-treated dried products. Maximum retention with 150-180μm particle size (PS) range was seen for finished products obtained using wet and FrD DG whereas 250-400μm PS range was seen for finished products obtained using wet and FrD DGS. The mycotoxin content was found to be below the FDA guidance levels of 20ppb (aflatoxins) and 2ppm (fumonisins) for solvent-treated dried products. Solvent treatment of wet & FrD DG & DGS yielded TPC ranges of 250-400mgGAE/100gm and 30-250mgGAE/100gm, respectively.
Significance: Processing treatments enhanced the food functionality traits of solventtreated dried products. This food grade product was found to be odorless, tasteless, color neutral, gluten-free with minimal oil content and consistent PS. A material specification sheet was developed to highlight the characteristics of a food grade distillers dried grains product.

Library of Congress Subject Headings

Distilling industries -- By-products.
Food -- Quality.
Corn products.
Food -- Analysis.



Number of Pages



South Dakota State University

Included in

Food Science Commons



Rights Statement

In Copyright