Deborha Decorti

Comparison of ultrasound-assisted extraction with conventional extraction methods of oil and polyphenols from grape (Vitis vinifera L.) seeds

Ultrasound-assisted extraction (US) carried out at 20 KHz, 150 W for 30 min gave grape seed oil yield (14% w/w) similar to Soxhlet extraction (S) for 6 h. No significant differences for the major fatty acids was observed in oils extracted by S and US at 150 W. Instead, K232 and K268 of US- oils resulted lower than S-oil. From grape seeds differently defatted (S and US), polyphenols and their fractions were extracted by maceration for 12 h and by ultrasound-assisted extraction for 15 min. Sonication time was optimized after kinetics study on polyphenols extraction. Grape seed extracts obtained from seeds defatted by ultrasound (US) and then extracted by maceration resulted the highest in polyphenol concentration (105.20mg GAE/g flour) and antioxidant activity (109 Eq αToc/g flour).

Ultrasound-assisted extraction coupled with under vacuum distillation of flavour compounds from spearmint (carvone-rich) plants: Comparison with conventional hydrodistillation.

Ultrasonically assisted extraction of flavour compounds from different varieties of Mentha spicata, using 70% ethanol, have been carried out for 5, 10 and 15min and coupled with under vacuum distillation. The ultrasound distilled extracts have been analysed by GC-MS and compared with essential oils obtained by hydrodistillation. The results have showed that ultrasonically assisted extraction in combination with under vacuum distillation have provided extracts with higher flavouring strength due to the increased concentration of desirable oxygenated compounds (from 5 to 8 times) compared with hydrodistillation. Extraction yields of flavour volatiles have been calculated giving a range 0.04-0.13% by ultrasound and 0.01-0.02% by hydrodistillation.

Analysis of the Volatile Compounds of Flowers and Essential Oils from Lavandula angustifolia Cultivated in Northeastern Italy by Headspace Solid-Phase Microextraction Coupled to Gas Chromatography-Mass Spectrometry

Headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography and mass spectrometry using the divinyl/carboxen/polydimethylsiloxane (DVB-CAR-PDMS) fibre was applied for the analysis of aroma profiles of Lavandula angustifolia L. flowers and the corresponding essential oils. The optimal sampling time was determined by studying the equilibrium time profile of the major volatile compounds for the lavender flowers (50 min) and the essential oil (20 min). Comparative analysis of L. Angustifolia L. cultivated in Friuli Venezia Giulia (northeastern Italy) highlighted that the contents of linalool and linalyl acetate were the major differences between the composition of flowers and the hydro-distilled products. Lavender essential oil from Middle-Friuli Venezia Giulia was evaluated as the highest quality for its high level of linalyl acetate (31.7 %) and linalool (45.0 %) and low percentage of camphor (0.5 %). The use of headspace SPME was shown to be a convenient and effective analytical tool for the sampling of volatile compounds and it could be used to test the quality of flowers and essential oils from Lavandula species.

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.

Analysis of the Volatile Compounds of Aerial Parts and Essential Oil from Thymus serpyllum L. Cultivated in North East Italy by HS-SPME/GC-MS and Evaluation of its Flavouring Effect on Ricotta Cheese

Abstract Headspace solid-phase microextraction (HS-SPME) coupled to gas chromatography and mass-spectrometry using the divinylbenzene/carboxen/polydimethylsiloxane fiber was applied for the analysis of flavor profiles of Thymus serpyllum L. aerial parts and the corresponding essential oil. At 30°C, the optimal sampling time determined by the equilibrium time of the major volatile compounds both for the thyme aerial parts and the essential oil was 30 min. Twenty-six volatile compounds were identified. Carvacrol and carvacrol methyl ether were the main compounds (44.9 %). The flavoring effect of different amounts (0.26, 0.33 and 0.40 g ) of essential oil for 100 g of ricotta cheese was studied by HS-SPME/GC-MS. Significant differences (p≥0.05) were found for monoterpene hydrocarbons and oxygenated monoterpenes for 0.40 g essential oil/ 100 g ricotta cheese. Interactions between thyme essential oil and ricotta cheese highlighted that hydrocarbons monoterpene and sesquiterpene were retained by ricotta, whilst oxygenated monoterpenes were released.

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).