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Biorefining of Bilberry (Vaccinium myrtillus L.) Pomace Using Microwave Hydrodiffusion and Gravity, Ultrasound-Assisted, and Bead-Milling Extraction

Ravi, Harish Karthikeyan, Breil, Cassandra, Vian, Maryline Abert, Chemat, Farid, Venskutonis, Petras Rimantas
ACS sustainable chemistry & engineering 2018 v.6 no.3 pp. 4185-4193
Vaccinium myrtillus, anthocyanins, antioxidant activity, bilberries, biorefining, ethanol, gallic acid, gravity, linoleic acid, linolenic acid, lipophilicity, milling, oils, polyphenols, pomace, prediction, quercetin, solubility, solvents, ultrasonic treatment
Biorefining of bilberry pomace using innovative technologies such as microwave hydrodiffusion and gravity extraction (MHG) and ultrasound-assisted extraction (UAE) with different concentrations of ethanol/water as the solvent was established. Bead milling was also utilized in this sequential extraction scheme to remove the lipophilic fraction. The solubility index of target polyphenols was predicted using a computational tool (COSMO-RS) and compared to experimental results obtained by in vitro antioxidant activity assessments. MHG extracts obtained using microwave power of 2 W/g had the highest Folin–Ciocalteu reducing capacity (43.46 ± 0.48 mg gallic acid equivalent (GAE)/g of extract), total flavonoid (4.17 ± 0.04 mg quercetin equivalents (QE)/g of extract), total monomeric anthocyanin content (12.19 ± 0.13 mg delphinidin-3-O-glucoside equivalents (D3GE)/g of extract), and radical scavenging capacity (22.64 ± 2.23 mg trolox equivalents (TE)/g of extract). In UA ethanol/water extracts, the highest flavonoid (10.41 ± 0.08 mg QE/g of extract) and anthocyanin content (12.19 ± 0.51 D3GE mg/g of extract) was present in ethanol (100%), these results were in good correlation with computational predictions. The lipid fraction recovered from pomace using bead-milling extraction was mainly composed of oil rich in polyunsaturated linoleic and linolenic acids.