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Upcycling of brewing by-products using bio-processing technology and an analysis of their functional and nutritional characteristics
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Date
2024
Authors
Jaeger, Alice
Journal Title
Journal ISSN
Volume Title
Publisher
University College Cork
Published Version
Abstract
This thesis focuses on the upcycling of brewing by-products; specifically brewer’s spent yeast (BSY) and a protein isolate produced from brewer’s spent grain (BSG). Although high in nutrients, the unappealing sensory characteristics and unstable nature of these products has made it difficult to valorise these materials to date. Spent yeast was extensively characterised and a process was developed focused on alcohol removal, standardisation, autolysis, and lactic acid bacteria fermentation using L. amylovorus FST 2.11. As a result of this process, sensory characteristics were significantly improved regarding reduced bitterness and an increase in fruity flavours. Techno-functional properties were also altered, with major changes in pH and protein composition. In addition, the effects of this processing on protein digestion, using the in-vitro INFOGEST protocol, and on the gut microbiome, using an in-vitro colon model were examined, yielding increased amino acid bio-availability and indicators of prebiotic potential. As well as BSY, the potential of BSG as a sustainable nutrition source was examined, particularly regarding the functional and digestive properties of a spent grain protein isolate (BRP). BRP was shown to have superior functionality to many plant proteins, in particular regarding solubility, and also displayed good digestibility characteristics as determined using the tiny-TIM in-vitro model.
This research explores the enormous potential to be found within brewing by-products and the benefits of processing to achieve palatable, functional and highly nutritious food ingredients to form a part of a more sustainable and circular future food system.
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Keywords
Brewing by-products , Spent grain , Spent yeast
Citation
Jaeger, A. B. 2024. Upcycling of brewing by-products using bio-processing technology and an analysis of their functional and nutritional characteristics. PhD Thesis, University College Cork.