Document Type

Dissertation - Open Access

Award Date

2023

Degree Name

Doctor of Philosophy (PhD)

Department / School

Agricultural and Biosystems Engineering

First Advisor

Zhengrong Gu

Abstract

Glucosinolates in canola meal decrease its inclusion rate in animal feed diets. Recovering the glucosinolates, while minimizing protein solubilization, is an effective strategy to producing a high protein animal feed. Washing with an acid aqueous phase showed benefit to extracting GS (16.03 μmol GS per g CM) but minimizing SP solubilization (3.93 mg SP per g CM) was best with the phosphate buffer. The breaking point was after 3 washes there appeared to be negligible GS extraction. Thus, an acidic solution was used for the next iteration of experiments. Temperature (10oC and 20oC) and pH (2.0 – 4.5) were also tested as major factors for GS recovery. The temperature 10oC had higher GS recovery than 20oC for all pHs and peaked at 10oC, pH 4.5 (13.88μmol GS per g CM). Also, SP solubilization was decreased at 10oC, compared to 20oC, and was lowest at pH 3.5 for 10oC (3.85mg SP per g CM). Since different pHs at the same temperature gave different desirable parameters, using a unique combination of pHs was tested to optimize the desired performance. However, using pH combinations at 10oC, such as 3.5, 3.0, 4.5; 3.5, 4.0, 4.5; 4.5 4.0, 4.0; and 4.5, 4.5, 4.0 on wash steps 1, 2, and 3, respectively, did not show significant improvement in GS extraction or SP solubilization. Particle size was also a major variable for both the GS extraction and SP solubilization. For all particle sizes, GS appeared to have reached equilibrium within the first 10 minutes of washing, but SP solubilization increased linearly over the entire 30 minute trial. The smaller particles of 50-100 mesh had the best GS extraction (7.23μmol GS/g CM) but also the highest SP loss (6.54mg SP/g CM). The lowest GS extraction from the CM was at the 16-25 mesh particle size (5.99μmol GS/g CM) and the lowest SP loss from >16 mesh at (3.58mg SP/g CM). The raw CM was in between the extremes for both GS extraction and SP loss from the CM (7.01μmol GS/g CM) and (5.88mg SP/g CM), respectively. This underscores the importance of mass transfer characteristics for bioprocess optimization. The geometric design of the vessel, mixer head, and angular velocity of the mixer head also played a significant role in GS extraction parameters. As a comparison, a leaching bed without any agitation peaked at 11.42 μmol GS/ g CM and 10.82 mg SP/g CM. Using the high-shear mixer at 200rpm the high-form vessel had a maximum of 9.99μmol GS/g CM and 0.82 mg SP/g CM. Using a low-form vessel with the same mixer head at the same speed yielded 13.72 μmol GS/g CM and 13.68 mg SP/g CM. Switching the mixer head for low-shear impeller head, the LF vessel had a maximum of 3.30μmol GS/g CM and 0.60 mg SP/ g CM 160rpm. Using an HF vessel, the impeller head yielded 11.33 μmol GS/ g CM 0.60 mg SP/ g CM at 200rpm. A 13.3% SLR of raw CM to water yielded 11.50μmol GS/g CM and 1.91mg SP/g CM. Using an SLR of 8% the extraction yielded 15.82μmol GS/g CM and 3.08mg SP/g CM. Overall, the higher SLRs yielded a higher product concentration in the liquid phase and the lower loading rates yielded a lower product concentration. Conversely, higher loading rates yielded less product per gram of feedstock and lower loading rates yielded more product per gram of feedstock. Future directions of research would be utilizing the GS free canola meal for swine feeding trials or as a protein-rich feedstock for fermentation.

Library of Congress Subject Headings

Canola meal as feed.
Proteins in animal nutrition.
Proteins -- Purification.
Glucosinolates.
Oilseed plants.
Value added.

Publisher

South Dakota State University

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