Andrea Natolino

Towards multi-purpose biorefinery platforms for the valorisation of red grape pomace: production of polyphenols, volatile fatty acids, polyhydroxyalkanoates and biogas

The development of a multi-purpose four step-cascading biorefinery scheme for the valorization of red grape pomace (GP) was proposed. The consecutive processes were respectively dedicated to (a) the recovery of polyphenols by supercritical CO2 extraction, (b) the production of volatile fatty acids (VFAs) by anaerobic acidogenic digestion, (c) the exploitation of produced VFAs as the precursors for the biotechnological production of polyhydroxyalkanoates (PHAs) and (d) the production of a CH4-rich biogas by the anaerobic digestion of solid leftovers from the acidogenic process. More than 2.7 g of total polyphenols (as gallic acid equivalents) per 100 g of dry matter were extracted. A high content of valuable proanthocyanidins occurred in the recovered polyphenolic fraction. The dephenolized GP was anaerobically digested under batch acidogenic conditions, obtaining about 20 g L−1 of total VFAs in the liquid effluent. The latter matrix was employed to feed a pure culture of a Cupriavidus necator strain, which was induced to produce and store PHAs under nitrogen-limiting conditions. The process was carried out in 0.5 L-shake flasks by using a two-step production approach. In particular, pre-grown biomass was fed with different concentrations of the acidic effluent (20 or 40% v/v) in two sequential batch processes. Poly(3-hydroxybutyrate) was accumulated up to 63% of the cells dry weight when pre-grown biomass was fed with 40% of the acidic effluent. No inhibitory effects due to non-VFA compounds occurring in the actual acidogenic effluent were observed. Finally, the anaerobic digestion of the exhausted solid fraction from the acidogenic process allowed obtaining 113 mL of biomethane per gram of fed volatile solids.

Potential Oil Yield, Fatty Acid Composition, and Oxidation Stability of the Hempseed Oil from Four Cannabis sativa L. Cultivars

ABSTRACT The cultivation of four industrial hemp cultivars (Felina 32, Chamaeleon, Uso31, and Finola) was investigated for oil production in the north-east of Italy along two years. The oils of all cultivars resulted in rich amount of linoleic acid (ω-6) and α-linolenic acid (ω-3). Felina 32 and Chamaeleon oils exhibited the highest amount of linoleic acid (59%) and α-linolenic acid (18%). Finola and Uso31 oils resulted in the richest of γ-linolenic acid (5–6%). All hempseed oils presented high oxidation stability and an acceptable initial quality. It is suggested that these oils can be used to produce EFA dietary supplements high in ω-6 and ω-3 of vegetal origin.

Extraction kinetic modelling of total polyphenols and total anthocyanins from saffron floral bio-residues: Comparison of extraction methods

Analysis of the extraction kinetic modelling for natural compounds is essential for industrial application. The second order rate model was applied to estimate the extraction kinetics of conventional solid-liquid extraction (CSLE), ultrasound-assisted extraction (UAE) and microwave-assisted extraction (MAE) of total polyphenols (TPC) from saffron floral bio-residues at different solid-to-liquid ratios (RS/L)(1:10, 1:20, 1:30, 1:50 g ml-1), ethanol 59% as solvent and 66 °C temperature. The optimum solid-to-liquid ratios for TPC kinetics were 1:20 for CLSE, 1:30 for UAE and 1:50 for MAE. The kinetics of total anthocyanins (TA) and antioxidant activity (AA) were investigated for the optimum RS/L for each method. The results showed a good prediction of the model for extraction kinetics in all experiments (R2 > 0.99; NRMS 0.65-3.35%). The kinetic parameters were calculated and discussed. UAE, compared with the other methods, had the greater efficiency for TPC, TA and AA.

Application of a Supercritical CO2 Extraction Procedure to Recover Volatile Compounds and Polyphenols from Rosa damascena

Abstract A supercritical CO2 (Sc-CO2) extraction procedure to recover volatile compounds and polyphenols from Rosa damascena is investigated. It consists of two steps: the first by Sc-CO2 at 16 MPa and 313.15 K and on-line fractionation using two separators (S1: 7 MPa/ 298.15 K; S2: 5 MPa/ 288.15 K) for volatile compounds, the second by Sc-CO2 added with 10% ethanol-water mixture (57% v/v) at 8 MPa and 313.15 K for polyphenols. Sc-CO2 extract obtained in S2 resulted of high quality compared with essential oil. Polyphenol yield by SC-CO2 added with co-solvent resulted about 80 % of methanol extraction (3250 mg GAE/100 g dw).

Optimization of the extraction of phenolic compounds from red grape marc (Vitis vinifera L.) using response surface methodology

Abstract Optimization of the extraction of total polyphenols (TPC), flavanols (FL), total anthocyanins (TA) and total tannins (TT) from grape marc by the response surface methodology is important to improve the recovery of these high-value phytochemicals. The independent variables studied were ethanol concentration (% EtOH), extraction time (h) and liquid-to-solvent ratio (L/S). TPC, FL, TT and TA showed different patterns of extractability, with significant variation in the linear, quadratic and interaction effects of the independent variables. The optimal extraction conditions were determined and the quadratic response surfaces were drawn from the mathematical models. The optimal extraction conditions were: 57% EtOH, 17 h, 50:1 L/S for TPC; 57% EtOH, 13 h, 50:1 L/S for FL; 62% EtOH, 16 h, 50:1 L/S for TT and 52% EtOH, 6 h, 10:1 L/S for TA. These optimum conditions yielded: 24 mg GAE/g DM of TPC; 1.5 mg quercetin/g DM of FL; 18 mg catechin/g DM of TT and 6 mg malvidin/g DM of TA.