Measurements of Protein Content in Aqueous and Alkaline Extracts from Brewer's Spent Grains (bsg): Insights Into the Extraction Kinetics and Energy Consumption

The brewers’ spent grain (BSG) is a rich biomass matrix containing several compounds of interest that require urgent and suitable valorisation strategies, due to its high production volume in the brewing industry. Among the most widespread approaches is the preparation of extracts, targeting particular compounds or soluble and/or insoluble fractions, after operating pre-treatment processes. In the present study, extraction experiments are carried out with fresh untreated BSG, under very gentle extraction conditions (room temperature and moderate agitation, in the 0-5 h interval), and using different solvents: deionized water, 0.1 M NaOH and 0.5 M NaOH in a 1:5 m/v solid-to-solvent ratio. The extraction dynamics were followed by monitoring the dry matter (DM) content obtained in the extracts after a centrifugation step. The protein content is estimated in each case by means of two different methods: direct measurements of absorbance at 280 nm (using bovine serum albumin, BSA, and commercial whey protein isolate as standards) as well as using the Bradford colorimetric method and BSA standard; the consistency of these measurements is contrasted against the DM values. The apparent extraction kinetics were studied, using a saturation model; the coefficients and their range of uncertainty were obtained. Extraction efficiencies in the range 14.24%-53.60% gDM ext/gDM BSG are achieved, which correspond to extraction yields of 38.88-150.09 gDM ext/kg fresh BSG. In addition, the energy footprint of the process is estimated at laboratory scale

Repurposing Tempeh Fermentation: a Promising Protein Source Using Food Residues and Edible Filamentous Fungi

Brewers' spent grains (BSG) are the main by-product of the brewery industry, accounting for more than 80 % of total produced by-products. Although this matrix is primarily composed of hemicellulose, cellulose, protein and lignin, the current end-of-life scenario for BSG is as livestock feed. In the present study, a valorisation approach for BSG that uses an edible fungus (Rhizopus oligosporus) in solid state fermentations (SSF) is proposed. First, a microbiological characterization is performed, to shed light on the indigenous microorganisms that are present in the BSG matrix. Then, an appropriate technology approach is used for the SSF that can be conducted both at laboratory and household levels. In the SSF experiments, different temperature (30-35 °C), mass of BSG substrate, inoculum ratio (10 and 15 % v/m) and drilling patters for the aeration of the systems are investigated. The fermentation products were characterized by preparing homogenized samples; it was registered an increase in protein content (5-64%), a slight acidification (ΔpH=0.1-1.2), a decrease of °Brix and the loss of organic matter (and water). The formation of the tempeh cakes was variable, and the differences are analyzed in terms of the operational parameters of each studied batch

Design guidelines for fixed-bed photocatalytic reactors

This paper summarizes the results of a work aimed at the design of pilot and industrial size photocatalytic reactors for waste waters treatment. The work is based on the findings of previous lab-scale experiments and model development. The physical reactor model was used to simulate the performance of the photocatalytic system in various configurations and different operating conditions. The cost of the water treatment was determined by considering both the energy consumption and the periodic renewal of commercial UV lamps. The results of this work show that the optimal conditions for a photocatalytic purification unit remarkably depend on the kinetics of the pollutants degradation. In the case of fast degradation reactions low-power UV sources and low absorption catalysts are preferable. On the contrary the use of high-power lamps and dense catalysts can reduce sensibly the treatment cost when the degradation processes is slow

Photocatalytic Oxidation of Organic Acids in Aqueous Media by a Supported Catalyst

15 INTERNATIONAL SYMPOSIUM ON CHEMICAL REACTION ENGINEERIN