Valorization of Brewers’ Spent Grains: Pretreatments and Fermentation, a Review

Abstract

Brewers’ spent grains constitute a valuable byproduct of the beer industry. They are characterized by a rich nutritional composition consisting of around 70% lignocellulosic fibrous material, 20% proteins, 10% lipids, in addition to vitamins, minerals, amino acids, and phenolic compounds. These spent grains are produced in large amounts all through the year, are cheap, and lack economically feasible applications. Nowadays, 70% of these spent grains are used as animal feed, 10% are used for biogas production, and the remaining 20% are disposed in landfills. Due to the aforementioned facts, alternative uses of the brewers’ spent grains are highly sought-after. In fact, this nutrient-rich industrial by-product makes it a very good candidate for valorization through biotechnological processing, particularly microbial fermentation. After applying the needed pretreatments, using brewers’ spent grains as a substrate in submerged and solid-state fermentation of different microorganisms leads to the production of various value-added compounds such as organic acids, amino acids, volatile fatty acids, enzymes, vitamins, second-generation biofuels and other products.

The future in the litter bin – bioconversion of food waste as driver of a circular bioeconomy

“…The production of 100 L of beer generates 20 kg of BSG which primarily comprises of lignocellulose fibers (around 70% dry weight basis) but is also rich in nutrients such as proteins (20% on a dry weight basis), minerals and vitamins ( 177 ). Today 70% of BSG is exploited as feed for animal such as cattle, chicken and poultry, 10% for the production of biogas, and the rest goes to landfills ( 178 ) ( Figure 6 ).…”

Phytochemical Characterization of Malt Spent Grain by Tandem Mass Spectrometry also Coupled with Liquid Chromatography: Bioactive Compounds from Brewery By-Products

“…The huge amount of this lignocellulosic bio-waste contains undegraded material, with bioorganic fractions rich in carbohydrates, proteins, lipids, along with small amounts of minerals, vitamins, phenolic compounds, and its nutritional potential is still very high, reason why the BSG is, up today, mainly used as animal feed, although the high content of water renders it a perishable food hard to store. Nonetheless, a large part of the BSG remains unused, and until recently, most of the investigation focuses on the conversion of the BSG biomass into bioenergy, by thermo-and bio-chemical methods, from combustion to anaerobic digestion, as recently reported [4] and widely reviewed [5,6]. Conversely, the high potential of BSG as renewable bio-source of value-added compounds is still waiting to be deeply explored.…”

Spent Grain: A Functional Ingredient for Food Applications

“…Agro-industrial processes generate substantial amounts of by-products with increased contents of organic compounds that have a significant impact on the environment [ 1 ]. On the other hand, the increased demand for food globally drives the discovery of substitute raw materials with affordable pricing and superior nutritional value.…”