Faculty of Food Engineering, Stefan cel Mare University of Suceava, 720229 Suceava, Romania.
Molecules. 2021 May 27;26(11):3236. doi: 10.3390/molecules26113236.
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.
为了从废麦糟中提取抗氧化酚类化合物，研究了两种提取方法：超声辅助法（US）和 Ultra-Turrax 法（高搅拌速率）（UT）。优化了液固比、溶剂浓度、时间和温度/搅拌速率。对废麦糟提取物进行总酚含量（TPC）（Ultra-Turrax 预处理为 0.62 至 1.76mgGAEgSGDW，超声辅助预处理为 0.57 至 2.11mgGAEgSGDW）、总类黄酮含量（TFC）（UT 为 0.6 至 1.67mgQE/gSGDW，US 为 0.5 至 1.63mgQE/gSGDW）和抗氧化活性的分析，采用 2,2-二苯基-2-苦基肼（DPPH）自由基（UT 为 25.88%至 79.58%，US 为 27.49%至 78.30%）。对于 Ultra-Turrax 法，在一定程度上，高搅拌速率和高暴露时间下 TPC 较高，而对于超声辅助法，在高温下 TPC 较高。对香豆酸（UT 为 20.4±1.72mg/100SGDW，US 为 14.0±1.14mg/100SGDW）占发现的酚类化合物的大部分，其次是迷迭香酸（UT 为 6.5±0.96mg/100SGDW，US 为 4.0±0.76mg/100SGDW）、绿原酸（UT 为 5.4±1.1mg/100SGDW，US 为不可检测）和香草酸（UT 为 3.1±0.8mg/100SGDW，US 为 10.0±1.03mg/100SGDW）含量较低。原儿茶酸（UT 为 0.7±0.05mg/100SGDW，US 为不可检测）、4-羟基苯甲酸（UT 为 1.1±0.06mg/100SGDW，US 为不可检测）和咖啡酸（UT 为 0.7±0.03mg/100SGDW，US 为不可检测）含量非常低。超声辅助和 Ultra-Turrax 预处理被证明是回收这些高附加值化合物的有效方法。
