STUDY OF A GREEN AND SUSTAINABLE PROCESS FOR EXTRACTING PROTEIN FROM BREWER'S SPENT GRAIN

Food science and technology are increasingly aligning with green and sustainable practices in their production and industrial processes. In this sense, the study of new processes aligned with these perspectives becomes necessary in the fight against hunger (SDG 2) and to corroborate the health and well-being of the population through solutions that can bring some kind of improvement to food (SDG 3). This work aims to propose a green and sustainable method for extracting proteins from brewer's spent grain (BSG), an agro-industrial residue generated after beer fermentation, with a view to achieving greater efficiency.  The BSG, donated by the Invicta brewery (Ribeirão Preto, SP), was characterized in terms of its centesimais composition (moisture, ash, lipid, protein, and carbohydrate content). A 24-1 fractional factorial design was carried out at three levels (-1, 0, and 1) to study the effects of temperature (from 25 to 45°C), time (1 to 5 hours), salt addition (10 to 30 g/100 g of BSG), and NaOH concentration (1 to 4%), using the efficiency of the protein extraction process (precipitate 1 and precipitate 2) and the relative losses of the process as responses. The centesimal characterization of BSG revealed that this by-product has a low moisture content (3.41±0.02%). The ash and lipid content were 3.32±0.09% and 9.54±0.08%, respectively. This residue has a significant protein (23.21±0.02%) and carbohydrate (60.52±0.21%) content. Thus, fractional planning indicated that the best extraction conditions were at a temperature of 25°C, for 1 hour, with 10g/100g of salted BSG and 1% NaOH (equivalent to point -1, -1, -1, -1). At this point, there was a protein recovery of 32.89±1.10% from precipitate 1 and 50.06±0.00% from precipitate 2, with a total process efficiency (precipitate 1 + 2) of 74.64%. It was noted that lower concentrations of NaOH have a significant effect (p<0.05) on all response variables, confirming that low concentrations of NaOH extract greater amounts of protein and lead to greater process efficiency, making it a greener and more sustainable alternative that is easily scalable for food industries, as it is a simple process that takes advantage of agro-industrial waste, in line with the principles of the circular economy, as well as being a potential new source of protein for food production.