Biovalorization of brewers’ spent grain for the production of laccase and polyphenols

Abstract

Brewers’ spent grain (BSG) is the main solid by‐product of the brewing process and is typically disposed of as cattle feed. In this study, BSG was evaluated as a substrate for the production of polyphenols and the lignin‐degrading enzyme laccase using fungal solid‐state fermentation by Trametes versicolor. Laccases are finding increasing applications in the food industry and polyphenols have benefits for human health. After 14 days of fermentation with T. versicolor, there was a 3.4‐fold increase in the extraction of total polyphenols compared with untreated BSG. Using BSG as the sole source of carbon and nitrogen, maximum laccase activity was achieved after seven days of treatment with an activity of 560 U/L. Based on these results, BSG is suggested to be a good lignocellulose waste material to produce value‐added products such as the enzyme laccase and polyphenols. Copyright © 2018 The Institute of Brewing & Distilling

Proximate analysis of cold‐press oil cakes after biological treatment with Trametes versicolor and Humicola grisea

“…The fructose content, during the biotreatment with T. versicolor, increased from 0.48 up to 20.9 mg/g db. This is in agreement with our previous study, where it was shown that T. versicolor has higher affinity towards glucose than fructose [43,45].…”

“…During the biotreatment, the sucrose content decreased continuously, and after 10 days of cultivation, the amounts of sucrose were 3.73 mg/g db and 0.29 mg/g db for the hull-less pumpkin oil cake in case of the bio-treatment with T. versicolor and H. grisea, respectively. This is in agreement with our previous study, where it was shown that T. versicolor has higher affinity towards glucose than fructose [43,45]. In the first two days of flaxseed oil cake bio-treatment, the sucrose was not recorded.…”

“…In those experiments, the amount of ash, free fats, and protein content increased, while carbon to nitrogen ratio decreased. Some other materials were also used as substrates (sugar beet pulp, brewers' spent grains) for the cultivation of T. versicolor by our group, with the aim of producing laccase and manganese-peroxidase, or polyphenolic compounds [41,43].…”

“…T. versicolor is known to be a good producer of lignolytic enzymes such as laccase [27] and was chosen for this study due to our previous experience with its solid-state cultivation on corn silage [28,29] and brewery spent grains [30]. The study aims to identify the possible pathways for the utilization of hull-less pumpkin, flax, and hemp oil cakes, before and after biological treatment.…”

“…The study aims to identify the possible pathways for the utilization of hull-less pumpkin, flax, and hemp oil cakes, before and after biological treatment. T. versicolor is known to be a good producer of lignolytic enzymes such as laccase [27] and was chosen for this study due to our previous experience with its solid-state cultivation on corn silage [28,29] and brewery spent grains [30]. On the other hand, there is scarce literature data on the use of H. grisea in solid-state fermentation.…”