Spent Brewer's Yeast Lysis Enables a Best Out of Waste Approach in the Beer Industry

Abstract

Yeasts have emerged as an important resource of bioactive compounds, proteins and peptides, polysaccharides and oligosaccharides, vitamin B, and polyphenols. Hundreds of thousands of tons of spent brewer's yeast with great biological value are produced globally by breweries every year. Hence, streamlining the practical application processes of the bioactive compounds recovered could close a loop in an important bioeconomy value-chain. Cell lysis is a crucial step in the recovery of bioactive compounds such as (glyco)proteins, vitamins, and polysaccharides from yeasts. Besides the soluble intracellular content rich in bioactive molecules, which is released by cell lysis, the yeast cell walls β-glucan, chitin, and mannoproteins present properties that make them good candidates for various applications such as functional food ingredients, dietary supplements, or plant biostimulants. This literature study provides an overview of the lysis methods used to valorize spent brewer's yeast. The content of yeast extracts and yeast cell walls resulting from cellular disruption of spent brewer's yeast are discussed in correlation with the biological activities of these fractions and resulting applications. This review highlights the need for a deeper investigation of molecular mechanisms to unleash the potential of spent brewer's yeast extracts and cell walls to become an important source for a variety of bioactive compounds.

Keywords: antioxidant activity; chitin; elicitor; emulsifier; glucan; mannoprotein; taste enhancers; yeast cell walls; yeast extract.

Figure 1

Yeast cell lysis methods. Classification of cell lysis methods that are most commonly used for spent brewer’s yeast processing.

Figure 2

Illustration of the quality insurance system intended to compensate for the high variability of the raw material, the spent brewer’s yeast. This system also involves using a feed-forward system designed to adapt the parameters of the enzymatic-mechanical lysis technology to reduce bitter compound desorption from the yeast cell walls. The high-pressure liquid chromatography with mass spectrometry detector (HPLC-MS/MS) certifies the presence of kokumi peptides and supports a robust feedback (control) system.

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Network Visualization of the keywords co-occurrence.

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Overlay visualization of the keywords co-occurrence.