Spent Grain from Malt Whisky: Assessment of the Phenolic Compounds

Abstract

In order to extract antioxidant phenolic compounds from spent grain (SG) two extraction methods were studied: the ultrasound-assisted method (US) and the Ultra-Turrax method (high stirring rate) (UT). Liquid to solid ratios, solvent concentration, time, and temperature/stirring rate were optimized. Spent grain extracts were analyzed for their total phenol content (TPC) (0.62 to 1.76 mg GAE/g SG DW for Ultra-Turrax pretreatment, and 0.57 to 2.11 mg GAE/g SG DW for ultrasound-assisted pretreatment), total flavonoid content (TFC) (0.6 to 1.67 mg QE/g SG DW for UT, and 0.5 to 1.63 mg QE/g SG DW for US), and antioxidant activity was measured using 2, 2-diphenyl-2-picrylhydrazyl (DPPH) free radical (25.88% to 79.58% for UT, and 27.49% to 78.30% for UT). TPC was greater at a high stirring rate and high exposure time up to a certain extent for the Ultra-Turrax method, and at a high temperature for the ultrasound-assisted method. P-coumaric acid (20.4 ± 1.72 mg/100 SG DW for UT, and 14.0 ± 1.14 mg/100 SG DW for US) accounted for the majority of the phenolic found compounds, followed by rosmarinic (6.5 ± 0.96 mg/100 SG DW for UT, and 4.0 ± 0.76 mg/100 SG DW for US), chlorogenic (5.4 ± 1.1 mg/100 SG DW for UT, and non-detectable for US), and vanillic acids (3.1 ± 0.8 mg/100 SG DW for UT, and 10.0 ± 1.03 mg/100 SG DW for US) were found in lower quantities. Protocatechuic (0.7 ± 0.05 mg/100 SG DW for UT, and non-detectable for US), 4-hydroxy benzoic (1.1 ± 0.06 mg/100 SG DW for UT, and non-detectable for US), and caffeic acids (0.7 ± 0.03 mg/100 SG DW for UT, and non-detectable for US) were present in very small amounts. Ultrasound-assisted and Ultra-Turrax pretreatments were demonstrated to be efficient methods to recover these value-added compounds.

Quality Characteristics of Spelt Pasta Enriched with Spent Grain

“…Chemical composition of spelt flour was (%w/w, dry basis): 3 ± 0.01% lipids, 8 ± 0.05% fiber, 14 ± 0.09% protein, 64 ± 1.15% carbohydrates, 2.11 ± 0.04% ash, 11.26 ± 0.08% moisture, 313 ± 1.14 s falling number, 32.73 ± 2.14% wet gluten, 2 ± 0.02 mm gluten deformation index, and 74 ± 1.54% hydration capacity. Spent grain flour had the following characteristics (%w/w, dry basis): moisture (5.04 ± 0.42%), ash (3.47 ± 0.02%), protein (18.88 ± 0.37%), lipids (7.11 ± 0.39%), and fibers (22.67 ± 0.42%), as we obtained from previous study [20]. The addition of spent grain in pasta formulation was analyzed on rheological properties of dough, and on dry and cooked pasta.…”

Valorisation of Spent Grain from Malt Whisky in the Spelt Pasta Formulation: Modelling and Optimization Study

“…The linear and quadratic models that were fitted on each response were evaluated. The chemical composition of spelt flour is described in Table 1, which we obtained from a previous study [39]. The mathematical models were significant and presented the responses accurately; in all cases, the F-value was significant (p < 0.01), and R 2 values were more than 0.87, according to the ANOVA results presented in Table 2.…”

Bioactive compounds extraction from oak chips into rice spirit: New application of ultrasound

“…Moreover, Zhang et al (2015) reported that DPPH was correlated to TPC during ultrasonic treatment. In contrast, Chetrariu and Dabija (2021) reported that an ultrasound-assisted method could increase the DPPH of the samples. It was also reported that DPPH has a positive trend with the duration of alcoholic beverage maturation (Fraser & Francis, 2021).…”

“…The samples' DPPH scavenging activity was measured following a previously published work (Chetrariu & Dabija, 2021). The 2 ml sample was mixed with 2 m of DPPH (SIGMA‐ALDRICH, Co, USA) and 0.1 mM in methanol (Fine Chemicals, USA).…”