Brewer's spent grain (BSG) is a main by-product of beer manufacturing and is rich in nutrients including 15-30% protein, making it a potentially valuable protein source for human food. Current challenges of extracting protein from BSG include low yields and high manufacturing costs, but the rising trend of plant-based diets for environmental and health reasons increases BSG's appeal. This research proposes an innovative extraction process utilizing wet fractionation and enzymatic purification that targets fiber to effectively separate proteins form BSG. Additionally, the feasibility of BSG protein as a food ingredient is explored, offering a unique approach that limits harsh processing commonly used for protein extraction. The choice of the enzyme (CTec 2 and Viscozyme L), enzyme dose, and incubation time (1, 3, 6, 9, and 24 hrs) were investigated to maximize protein content and recovery and further evaluate processing effects on protein functionality. Following wet fractionation, there was a notable reduction in fiber from 48.6% in the BSG to 22.5% in the filtrate (PRF) on a dry basis. Additionally, the protein content increased from 22.8 to 40.0% from the BSG to the PRF, respectively. The coarse fiber (CF) had an average protein content of 6.30%, highlighting the effectiveness of wet fractionation in enhancing protein recovery from BSG. The optimal enzymatic treatments condition identified was using CTec 2 to degrade fiber at a dose of 6.00% (g enzyme/g solid) for 24 hours. The enzymatic fiber hydrolysis proved to be able to remove lignocellulosic biomass from BSG resulting in a defatted protein concentrate (DPC) with a high protein content (52.8%) along with a high recovery rate (63%). All treatments resulted in protein functionality similar to the two control treatments. Varying fiber hydrolysis conditions did not have a significant effect on the functional properties. Several functional properties were improved using limited hydrolysis (LH) using proteases. LH had negative impacts on foaming stability and emulsifying properties; however, it improved the solubility, foaming capacity, WHC, and OHC of the BSG protein. Potential applications for the DPC include low moisture applications such as protein bars or granola. The DPCs could also have potential use in meat alternatives due to the high WHC and OHC and the need for varying protein solubility in meat alternatives. The LH protein has greater potential in applications such as protein beverages due to the high solubility. This process presents a promising protein extraction approach from BSG, offering producers the flexibility to tailor it to their specific application needs. After obtaining the protein concentrate, additional steps like defatting or limited hydrolysis can be applied to improve the purity and functionality of the result protein. Notably, this approach contributes to sustainable food production by addressing food waste and meeting the rising demand for sustainable protein sources to support the nutritional needs of a growing global population. / Master of Science in Life Sciences / Brewer's spent grain (BSG) is a by-product of beer manufacturing with rich nutrients, including 15-30% protein. It holds potential as a valuable protein source for human food. Current challenges of extracting protein from BSG include low yields and high costs, but the rising trend of plant-based diets for environmental and health reasons increases BSG's appeal. Its abundant availability year-round makes it an attractive option for human food. In this study, an innovative process to extract protein from BSG was explored using wet fractionation to separate the BSG by size. Enzymes were then used to remove remaining fiber. Various enzymes and times were tested to optimize extraction and achieve a high protein content and recovery rate. The protein's physicochemical and functional properties were then evaluated for potential uses in human food. After wet fractionation, nearly half the fiber was removed, and the protein content increased by 17.2%. Using an enzyme called CTec 2 for 24 hours worked best, resulting in a protein concentrate with a high protein content (52.8%) and good recovery (63.0%). Changes in enzyme treatments did not have a significant effect on the protein functional properties. Potential applications for the protein concentrates include low moisture applications such as protein bars or granola due to the poor solubility. The protein concentrates could also have potential use in meat alternatives due to the water and oil holding properties. The low solubility of the protein concentrates was improved using a process called limited hydrolysis making it possible to apply to products like protein beverages. This research highlights BSG's potential as a valuable protein source for protein bars, meat alternatives, and protein beverages. These findings provide a promising approach to utilize BSG as a valuable plant protein source for a healthier and more environmentally friendly food production.
| Identifer | oai:union.ndltd.org:VTETD/oai:vtechworks.lib.vt.edu:10919/116162 |
| Date | 29 August 2023 |
| Creators | Allen, Jordan |
| Contributors | Food Science and Technology, Huang, Haibo, Yin, Yun, Chu, Hyun Sik Stephano, Feng, Yiming |
| Publisher | Virginia Tech |
| Source Sets | Virginia Tech Theses and Dissertation |
| Language | English |
| Detected Language | English |
| Type | Thesis |
| Format | ETD, application/pdf |
| Rights | Creative Commons Attribution 4.0 International, http://creativecommons.org/licenses/by/4.0/ |
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