Document Type

Thesis - Open Access

Award Date

2023

Degree Name

Master of Science (MS)

Department / School

Agronomy, Horticulture, and Plant Science

First Advisor

Melanie Caffe

Abstract

Oats, rich in lipids, lipase, and unsaturated fatty acids, can develop bitterness from triglyceride hydrolysis and unpleasant aromas through unsaturated fatty acid oxidation. To counteract these effects, the processing of hulled oats includes kilning, a step aimed at inactivating the enzymes responsible for lipid degradation. Kilning plays a crucial role in preserving the quality of oats by preventing undesirable flavors development linked to lipid breakdown. Despite the benefits of free threshing and absence of a dehulling requirement in naked oats, assessing lack of enzyme inactivation during processing is crucial for potential storage rancidity issues. Our aim was to determine the extent of rancidity development during naked oats storage and assess genotype effects. Two experiments were conducted. The first involved storing grain samples, from several naked oat genotypes grown in 2021 and 2022, at 18-20°C and 25-50% RH in cotton cloth bags for a year. The second experiment assessed the impact of mechanical damage on rancidity by subjecting oat grain samples from four genotypes to physical treatment with a Codema dehuller. In both experiments, rancidity was monitored over 2, 6, 8, and 12 months, measuring free fatty acids, peroxide value, hexanal, and oxidative stability index. There were notable variations among the genotypes for fat contents, total phenolics, and antioxidant activity. Paul and ND040341 had the highest fat contents, total phenolics, and antioxidant activity in 2021 and 2022, respectively. Genotypes and storage time influenced rancidity development. Despite varying levels of lipid hydrolysis among genotypes, the free fatty acid content remained consistently low for ND040341 in both years, possibly due to lower lipase activity and lower genetic susceptibility to hydrolysis. The higher degree of unsaturated fatty acid correlated with lower oil stability with Streaker being the most susceptible genotype. However, the overall oxidative rancidity was minimal, possibly due to genetic factors, active antioxidants, and proper storage. Surprisingly, dehulling-induced mechanical damage had no effect on observed rancidity parameters, likely due to limited grain damage and favorable storage conditions. These findings benefit oat growers and the food industry, indicating minimal rancidity in naked oats under proper storage conditions, preserving product quality within the first year.

Library of Congress Subject Headings

Oats -- Storage.
Oats -- Quality.
Oats -- Genetics.
Rancidity.

Publisher

South Dakota State University

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Rights Statement

In Copyright