Optimization of Brewing Waste’s (Trub) Phenolic Compounds Extraction by Ultrasound Assisted Using Response Surface Methodology

Abstract

The brewing waste, also known as trub, is an abundant by-product of the brewing industry. Such material presents high levels of phenolic compounds, which promote antioxidant, antimicrobial and antifungal effects, turning the trub economically attractive. In this study, the trub’s phenolic compounds were extracted by ultrasound-assisted extraction technology. Such experiments were conducted according to a central composite rotatable design (CCRD), with the evaluated parameters being ethanol concentration, solid-liquid ratio and extraction temperature. Response surface methodology (RSM) described the effect of process’ variables through second order polynomial models, adjusted appropriately for such analysis, and optimized the operating conditions, aiming to obtain the maximum extraction of phenolic compounds through the proposed technique. The extraction’s optimal conditions for the evaluated variables were ethanol concentration of 58%, solid-liquid ratio of 1 g per 32 mL, and extraction temperature of 36 ºC, during a 30 minute process. Considering such experimental conditions, the total amount of phenolic compounds was equal to 7.23 mg of gallic acid g-1 trub, indicating that a great concentration of phenolic compounds can be extracted from this material through the proposed technique. Thus, this indicates that trub might be a promising by-product that can be used in different industrial fields.

Grape Pomace as a Natural Source of Phenolic Compounds: Solvent Screening and Extraction Optimization

“…Figure 2 b shows the good predictive capacity of the multivariate model since the experimental data are close to the diagonal line. The regression model is considered statistically significant when the calculated F -value is at least three to five times greater than the F -critical [ 38 ]. In this study, since F -value = 516.85 and F -critical = 2.11, the former is 244.95 times higher than the F -critical, indicating the statistical significance of the obtained model (with p < 0.0001).…”

Green Methods to Recover Bioactive Compounds from Food Industry Waste: A Sustainable Practice from the Perspective of the Circular Economy

“…Finally, Gandolpho et al made use of UAE to extract phenolic compounds from hot trub (the second main solid waste after BSG) [ 109 ]. The extraction’s optimal conditions consist of using 58% ethanol in water, a solid–liquid ratio of 1:32 ( w / v ) and 36 °C for 30 min, and this protocol resulted in a total phenolic content of 7.23 mg GAE/g [ 109 ].…”

Sustainable food processing: single and interactive effects of type and quantity of brewers' spent grain and of type of sweetener on physicochemical and sensory characteristics of functional biscuits

“…The phenolic component was analysed to evaluate the functional potential of the enriched biscuits. The phenolic component was extracted from previously ground cereal mixtures, BSGs, and biscuits according to Gandolpho et al (2021), analysed using the Folin-Ciocalteu reagent (Almeida da Rosa et al, 2017), and expressed as mg of gallic acid/g of dry weight. The total phenolic content was also determined on Manitoba flour 0, honey, brown sugar, and extra-virgin olive oil used in biscuit production.…”