Protein enrichment of brewery spent grain from Rhizopus oligosporus by solid-state fermentation

Abstract

Brewery spent grain represents approximately 85 % of total by-products generated in a brewery. Consisting of carbohydrates, fiber, minerals and low amounts of protein, the use of brewery spent grain is limited to the feeding of ruminants; however, its potential use should be investigated. The reuse of this by-product using microorganisms by solid-state fermentation process as the case of protein enrichment by single-cell protein incorporation is an alternative to ensure sustainability and generate commercially interesting products. In this context, the aim of this study was to grow Rhizopus oligosporus in brewery spent grain under different initial moisture contents and nitrogen sources to increase the protein content of the fermented material. After 7 days of fermentation, increase of 2-4 times in the crude protein and soluble protein content was verified, respectively, compared to unfermented brewery spent grain. The kinetics of protein enrichment demonstrated the possibility of application of this technique, which can be a great alternative for use in diets for animals.

Lipase production by solid‐state fermentation of olive pomace in tray‐type and pressurized bioreactors

“…also observed an increase of 107% using A. uvarum by SSF using mixture of winery by‐products and OP. Canedo et al . found a 100% increase in crude protein content after 7 days of SSF in the fermented wastes of brewery spent grain using Rhizopus oligosporus .…”

“…Salgado et al 25 also observed an increase of 107% using A. uvarum by SSF using mixture of winery by-products and OP. Canedo et al 24 found a 100% increase in crude protein content after 7 days of SSF in the fermented wastes of brewery spent grain using Rhizopus oligosporus. The use of A. ibericus in SSF is safe as mycotoxins are not produced, 26 it provides a protein concentrate, and may give an alternative use of the by-products from the olive mill industry as animal feed.…”

“…[20][21][22][23] SSF of agro-industrial residues is a promising alternative to improve the nutritional value of these by-products, allowing its use for animal feed. 24 In addition to producing enzymes such as lipases, the fungus growth may increase protein content of the residues; it may increase the biodegradability facilitating the digestibility by ruminant animals; and it may reduce the content of polyphenols, which can affect the palatability of the residues. 25 In this way, all fractions after SSF can be exploited by agro-food industries.…”

Bioprocessing of common beans in diets for tilapia: in vivo digestibility and antinutritional factors

“…In our study, dehulling reduced tannins and fiber in beans. Several reports indicate that enzymatic inhibition caused by tannins decreases the digestibility of nitrogenous nutrients, thus causing low protein digestibility . Levels of tannins higher than 0.63 mg g −1 significantly affect digestibility of dry matter, proteins and lipids in tilapia .…”

“…Bioprocessing of ingredients by solid‐state fermentation is a low‐cost technique for preparing diets. Rhizopus oligosporus has been used as producer of fermented foods in solid form and the bioconversion of agro‐industrial by‐products . The genus Rhizopus is especially important for the production of proteins with high digestibility, preventing the formation of toxic substances and being considered safe for application in the food industry …”