Project
Protein from Residual Microbial Cells (PROMESS)
Food production in general, both from animal and plant sources, contributes significantly to environmental footprints. Alternative ways to produce food, such as upgrading of underutilized side streams, can effectively reduce the excessive pressure on natural resources. Brewers’ Spent Yeast (SY) is a high-protein (45 – 60% w/w) side product of beer brewing that represents 15% of the total residual stream associated with this process, with an annual magnitude of nearly 1 million tons in Europe alone in 2018. Despite its wealth of constituents (proteins, glucans, etc.), Brewers’ SY is currently significantly underutilized, mainly as feed. The primary reason for this underutilisation is the intrinsic (compositional and morphological) hurdles preventing the isolation of functional food ingredients from Brewers’ SY. Another yeast, Baker’s yeast, is grown for a broad range of purposes. Extracts from this yeast are produced for their high content of protein, peptides, amino acids, B-vitamins, essential minerals and other growth factors. They are used as versatile, added-value feedstock in industrial fermentation processes, but extract production generates a large amount of Baker’s Spent Yeast (Bakers’ SY) material, β-glucans and protein, that is currently underutilized in feed like Brewers’ SY.
The overarching objective of PROMESS is to create a solid fundamental knowledge basis on the functional performance of spent yeast (and their components) in food products, and how the functional performance can be altered by existing and novel processing techniques. This fundamental knowledge basis will be translated into guidelines for a tangible, applied biorefinery process to isolate functional (high-protein) food ingredients from spent yeast (Brewers’ and Bakers’ SY). The PROMESS consortium will identify a target food ingredient and will develop a biorefinery process to isolate that fraction from spent yeast with its specific functionality and hurdles as point of departure. PROMESS will focus on the relation between (isolated) fraction functionality and biorefinery process in an iterative value chain and back-engineering approach. A range of cell disruption and biorefinery techniques will be assessed prior to choosing the most optimal processing strategy that will subsequently be further developed. The PROMESS approach will aim at maximum feedstock use by focussing on functional fractions that comprise other yeast constituents beside protein (and minimal processing), rather than focussing on maximum purity (and limited functionality).