Brewer’s Spent Yeast (BSY), an Underutilized Brewing By-Product

Abstract

The repurposing of by-products and the reduction of waste from food processing streams is an ever-increasing area of interest. Brewer’s spent yeast (BSY) is a prevalent by-product of the brewing industry. The spent yeast cells are removed at the end of the bulk fermentation. A small amount of it is used to start the next batch of fermentation; however, the majority of the spent yeast is discarded. This discarded yeast is high in nutrients, in particular proteins, vitamins and minerals, as well as containing functional and biologically active compounds such as polyphenols, antioxidants, β-glucans and mannoproteins. At present, BSY is mainly used in animal feed as a cheap and readily available source of protein. This review explores alternative, value-added applications for brewer’s spent yeast including nutritional ingredients, functional food additives as well as non-food applications. A major challenge in the utilization of BSY in food for human consumption is the high level of RNA. An excess of RNA in the diet can lead to an increase in uric acid in the bloodstream, potentially causing painful health conditions like gout. This issue can be overcome by RNA degradation and removal via additional treatment, namely heat treatment and enzymatic treatment. There is potential for the use of BSY ingredients in various food applications, including meat substitutes, bakery products and savory snacks.

More than just a beer—the potential applications of by-products from beer manufacturing in polymer technology

“…According to Vieira et al [218], the most common amino acids in spent yeast are alanine (even over 9%), arginine, aspartic acid, and cysteine. At the same time, Jaeger et al [219] indicated that glutamic acid is the most abundant one (~ 15%), followed by histidine, alanine, arginine, and aspartic acid. Such an effect may be associated with the differences between particular Saccharomyces cerevisae strains applied worldwide [220].…”

“…The ribonucleic acid is metabolized to the uric acid in the human body, which can cause gout [225]. Generally, the spent yeast application in animal and human nutrition was comprehensively discussed in dedicated review works [219,[226][227][228][229].…”

Yeast Cells in Microencapsulation. General Features and Controlling Factors of the Encapsulation Process

“…Firstly, they have a sustainable and low-cost origin. Since viability of yeast is not crucial for encapsulation [ 31 ], under-utilized by-products such as spent yeast from beer making [ 40 ] can be employed. Secondly, they can be seen as safe and consumer-friendly products.…”

Value-Added Products from Ethanol Fermentation—A Review

“…Spent yeast is another by-product from the brewing and biofuels industry. The spent yeast is typically removed at the end of the fermentation, although a small amount can be retained for subsequent fermentation batches [131]. Due to its protein content, discarded yeast is typically used as inexpensive animal feed materials [131].…”

“…The spent yeast is typically removed at the end of the fermentation, although a small amount can be retained for subsequent fermentation batches [131]. Due to its protein content, discarded yeast is typically used as inexpensive animal feed materials [131]. However, spent yeast also contains valuable nutrients, such as vitamins (e.g., vitamins B 1 , B 2 , B 3 , B 6 , B 9 , and B 12 ) [132][133][134], minerals (e.g., Na, K, Ca, Mg, Fe, Mn, Zn, Cu, Se, Cr, and Mo) [134,135], proteins (e.g., mannoproteins and hydrolysates) [135], carbohydrates (e.g., β-glucans) [135], antioxidants (e.g., glutathione) [136], and phenolic compounds (e.g., gallic acid and (±)-catechin) [132].…”