The Brewer’s Spent Grain Cellulose Lignin Complex Sorption Capacity Study
Authors: Gribkova Irina N. , Lazareva Irina V. 
Published: December 2024

Introduction. The development of low-waste technologies in any industry, including the food industry, is an urgent task for researchers. The raw materials composition study allows us to develop directions for its deep processing of directed action. 80% of the secondary raw material resource for brewing production is brewer's spent grain, which consist of carbohydrate, protein, lipid and phenolic complex of compounds that perform their functions and are connected with each other by complex interactions. Lignocellulosic structures are of value in terms of sorption capacity when properly processed. Therefore, it seems possible to process grain structures to create free carboxyl -COOH groups, alcohol and phenolic hydroxyls -OH, silanol groups -Si-OH, acting as active centers on the sorption surface of brewer’s spent grain insoluble compounds. The brewer’s spent grain sorption abilities can be studied on the basis of alcoholic hop extracts, which are a complex of phenolic, ester compounds and bitter resins, which are of interest in brewing technology.

Purpose: The sorption properties study of the brewer’s spent grain cellulose-lignin complex to assess the possibility of creating a carrier of flavoring components on a plant basis.

Materials and Methods: 2 types of processed brewer’s spent grain were used by different physicochemical methods. The sorption capacity was determined by the difference in the content of 2 types hop compounds (bitter and aromatic) in alcohol extracts. The evaluated hop compounds were bitter resins (α-acid), polyphenolic and aromatic compounds determined according to GOST.

Results: The studied samples of the brewer’s spent grain cellulose-lignin complex showed sorption capacity for bitter resins, phenolic compounds and essential oils with different degrees of efficiency, which indicates the achievement of the goal of the study.

Conclusion: The conducted studies indicate that the physical methods of brewer’s spent grain processing (excessive atmospheric pressure, ultrasound) in the presence of ECA-activated water contribute to the formation of free bonds within the cellulose-lignin complex, which are the sites of reversible binding of hop compounds. As a result of sorption-desorption processes of brewer’s spent grain two samples study, it was found that, regardless of the processing methods the structure of the brewer’s spent grain (excessive pressure or ultrasound), polyphenols are sorbed by 22.6-28.0% of the treated pellet No. 1, and 13.6- 21.4% processed shot No. 2; bitter α-acids are sorbed by 14.9-20.2% with pellet No. 1 and by 9.6-15.1% with pellet No. 2; essential oils are sorbed by 11.1-12.0% and 6.7-8.9% of pellets No. 1 and No. 2, respectively, from the initial content in the extract. The polyphenolic compounds desorption occurs by 2/3, and bitter and ester compounds - by ½ of the amount of sorbed ones, regardless of either the type of hop or the brewer’s spent grain type. Research on the conditions for carrying out the processes of sorption and desorption will be continued.