Influence of extraction solvents on the recovery of antioxidant phenolic compounds from brewer’s spent grains

Abstract

This study evaluated the efficacy of different solvents (methanol, ethanol, acetone, hexane, ethyl acetate, water, methanol:water mixtures, ethanol:water mixtures, and acetone:water mixtures) for extracting antioxidant phenolic compounds from brewer's spent grains (BSGs). The extracts were characterized regarding the contents of total phenols, flavonoids, proteins and reducing sugars. Antioxidant activity was determined by the 2,2-diphenyl-1-picrylhydrazyl (DPPH) free radical, and the ferric reducing antioxidant power (FRAP) assay. The solvents had different efficiencies for extraction of antioxidant phenolic compounds. All the produced extracts showed antioxidant activity, but the extract produced with 60% v/v acetone had the most elevated content of total phenols and antioxidant potential by the two methods. BSG was demonstrated to be a valuable source of antioxidant phenolic compounds, and solid-to-liquid extraction using 60% v/v acetone was a low cost and quite efficient method to recover these value-added compounds.

Brewer's spent grain from different types of malt: Evaluation of the antioxidant activity and identification of the major phenolic compounds

“…Recently, Meneses et al (2013) also evaluated the efficiency of different solvent compositions (methanol, ethanol, acetone, hexane, ethyl acetate, water, methanol:water mixtures, ethanol:water mixtures, and acetone:water mixtures) for extracting antioxidant phenolic compounds from BSG and reported that the extract produced with 60% v/v acetone had the highest content of total phenols (9.90 mg GAE/g). Again a higher phenolic content was found in the pilsen BSG used in this work when compared with the results of Meneses et al (2013). The higher values of phenolic content determined in the present work when compared with those from others works can be extensively discussed.…”

“…Although, it is possible to conclude that the pilsen BSG sample studied in this work and the extraction procedure are responsible for the highest values of phenolic content determined in this type of samples. In fact, the extraction technique is probably the most influential factor since BSG is a lignocellulosic material which contains significant amount of phenolic acids esterified to the cell-wall, making their recovery harder (Meneses et al, 2013;Moreira et al, 2012). Generally, the conventional extraction techniques, such as mechanical agitation solvent extraction, Soxhlet extraction, enzymatic and alkaline hydrolysis extractions (Dvorakova et al, 2008;Mussatto et al, 2007;Szwajgier, Waśko, Targoński, Niedźwiadek, & Bancarzewska, 2010), applied for the recovery of these compounds are time and solvent consuming, submitting polyphenols to thermal degradation and decreasing the phenolic content of the extracts.…”

“…The most common bioactive compounds include secondary metabolites such as antibiotics, mycotoxins, alkaloids, food grade pigments, plant growth factors, and phenolic compounds (Martins et al, 2011;Meneses, Martins, Teixeira, & Mussatto, 2013;Routray & Orsat, 2012). Particularly, phenolic compounds are of considerable interest to scientists, manufacturers and consumers due to their importance in food quality, with protective and preventive roles in certain types of cancer and several other chronic diseases (Barbosa-Pereira, Angulo, Paseiro-Losada, & Cruz, 2013;Krishnaswamy, Orsat, Gariépy, & Thangavel, 2013;Naczk & Shahidi, 2004).…”

Stabilization of Neem Oil Biodiesel with Corn Silk Extract during Long-term Storage

“…The type of phenolics soluble in each of the extracting solutions tested is mainly different, because the phenolics include one or more of hydroxyl groups polar side attached directly to an aromatic ring non polar side . This stereochemistry differentiates phenolics according to their polarity variance, which affects the recovery of phenol from natural sources, when accomplished with solvent extraction, being the yield of the process depends strongly on the nature of the solvent 47 . In particular, methanol alcohol has been demonstrated to be more efficient in extraction of polyphenols with lower molecular weight while flavones with the higher molecular weight are better extracted with aqueous acetone 48 50 .…”

“…In particular, methanol alcohol has been demonstrated to be more efficient in extraction of polyphenols with lower molecular weight while flavones with the higher molecular weight are better extracted with aqueous acetone 48 50 . Acetone has also been found to be more efficient than other organic solvents for the extraction of phenolics from different raw materials such as brewer s spent grains 47 , Syzygium cumini 51 Acetone: water mixtures 50-95 v/v have been reported to be one of the most effective solvents for extraction of phenolics from different natural sources, especially from protein matrices, since this mixture is able to degrade polyphenol-protein complexes 52 . These differences could be attributed to the different methods of extraction and standards used, but also to different varieties, genomics and harvest season of the samples all these parameter affect the synthesis and accumulation of phenolics in some parts of the plant 41,53 .…”