1,720,972 research outputs found
Self-aggregation of amino-acidate half-sandwich ruthenium(II) complexes in solution: From monomers to nanoaggregates
Full text linkThe aggregation tendency of [RuCl(AA)(Arene)] complexes (1, AA = amino acidate = Gly, Arene = p-cymene; 2, AA = Ala, Arene = p-cymene; 3, AA = N,N'-dimethyl-Gly, Arene = benzene; 3b, AA = N,N'-dimethyl-Gly, Arene = p-cymene; 3c, AA = N,N'-dimethyl-Gly, Arene = hexamethylbenzene; 4a, AA = t-Leu, Arene = benzene; 4b, AA = t-Leu, Arene = p-cymene; 4c, AA = t-Leu, Arene = hexamethylbenzene; 5, AA = alpha,alpha'-Me(2)-Gly, Arene = p-cymene; 6, AA = alpha,alpha'-Ph(2)-Gly, Arene = p-cymene; 7, AA = Pro, Arene = p-cymene) as a function of the concentration and solvent (CDCl(3), CD(2)Cl(2), acetone-d(6), and 2-propanol-d(8)) was investigated through diffusion NMR measurements. The equilibrium constant (K) and the standard variation of the free energy (Delta G degrees) for the aggregation process were determined by applying the Equal K self-aggregation model. The highest level of aggregation was observed for complexes 1, 2, and 4, bearing the NH(2) moiety, which was involved in intermolecular H-bonding. Complex 2 formed aggregates with a hydrodynamic radius (r(H)) equal to 20.8 A in CDCl(3) (Delta G degrees(296K) = -7.1 +/- 0.7 kcal mol(-1)) at a concentration of 124.9 mM, corresponding to an aggregation number (N) of 133. On the other hand, complex 3c did not show any tendency to aggregate (N = 1.1, 0.5 mM in CDCl(3)). The aggregation tendency decreased as the steric hindrance of arene (4a > 4b > 4c) and AA (1 approximate to 2 > 5 approximate to 4b > 6) and the polarity and proticity of the solvent increased. For complex 2, -Delta G degrees(kcal/mol) was 7.1 in CDCl(3) (epsilon(r) = 4.81) > 5.6 in CD(2)Cl(2) (epsilon(r) = 8.93) > 3.9 in acetone-d(6) (epsilon(r) = 20.56) > 3.0 in 2-propanol-d(8) (epsilon(r) = 19.92). While the two diastereoisomers of complexes 2 and 4b showed substantially the same tendency to self-aggregate, diastereoisomer (R(Ru), S(N), S(C))-7 showed a remarkably higher aggregation tendency than the other one [(S(Ru), S(N), S(C))-7] throughout the entire concentration range (1.4-178.0 mM) in CDCl(3), indicating that a diastereoselective recognition process is occurring in solution [parallel to Delta(Delta G degrees(296K))parallel to = 1.8 +/- 0.5 kcal mol(-1)]
Characterization of phenolic and volatile compounds of Sicilian virgin olive oils produced from native cultivars
No full textMigliorare le proprietà salutistiche e sensoriali dell’olio extravergine: nuovi approcci tecnologici
No full textA Rapid Application to Flavor the Olive Oil with Dried Rosmarinus officinalis L. Leaves: Microwave-Assisted Maceration.
No full textMicrowave-assisted maceration (MAM) was developed as a new and rapid application to flavor the olive oil with dried Rosmarinus officinalis L. leaves. MAM was compared to conventional method (CM) in terms of rapidity of maceration, yield and sensory characteristic of flavored olive oils. Scanning electron microscopy (SEM) sheds light on the physical action of the both maceration methods. 1,8-cineole and camphor were two major volatile compounds of rosemary essential oil identified by GC/MS, they were used as keys estimating the level of maceration. The flavored olive oil obtained by MAM for 400 W and 10min was quantitatively (yield) better than those obtained by CM for 12h. The SEM showed clearly that the cells were broken and damaged more quickly in MAM than in CM. The MAM was proposed as an efficient, simple and fast application for direct maceration of olive oil with rosemary leaves. Practical Applications: Flavoring the olive oil with aromatic plants has been an increasing topic in the food industry, because it provided a new concept by adding value to the olive oil, at the same time, satisfy the sensory requirements of the consumer. Recently, much attention has been given to the application of the microwave energy in several industrial processes. Therefore, the objective of this study was to flavor the olive oil with rosemary leaves using the microwave-assisted maceration (MAM) to enhance the speed of maceration compared to the conventional method. The appropriate comparisons in terms of maceration kinetic, yield and sensory characteristic of flavored oils were determined and the results were discussed
Innovation in extraction technology for improved virgin olive oil quality and by-product valorisation.
No full textThe mechanical oil-extraction process affects sensory and health-beneficial properties of virgin olive oil (VOO), as it is directly related to the generation of volatile compounds and the release of phenolic antioxidants in the oil, which greatly affect VOO quality. Hydrophilic phenols are the most abundant natural antioxidants in VOO. Oil quality is strictly related to the biological activities of these hydrophilic phenols, which affect not only its shelf life but also its health-beneficial and sensorial properties. The prevalent classes of VOO hydrophilic phenols are phenolic alcohols, lignans and secoiridoids. The secoiridoids, derivatives of oleuropein, demethyloleuropein and ligustroside, can be also found in high amounts in the by-products of the mechanical oil-extraction process - the vegetation water and pomace. The volatile compounds, responsible for VOO flavour, are produced by the lipoxygenase pathway which catalyses the genesis of C5 and C6 saturated and unsaturated aldehydes, alcohols and esters. These compounds are correlated to the "cut grass" and "floral" sensory notes of VOO. The concentrations of hydrophilic phenols in VOO and in its by-products and the volatile compounds in the VOO are strongly affected by the operational conditions of mechanical oil-extraction processes. In this context, new approaches to VOO extraction should have the following targets: optimizing the processing conditions to improve VOO's health-beneficial and sensorial properties; valorisation of the by-products (stoned olive pomace and vegetation water)
Temperature and oxygen concentration during olive paste malaxation process: optimization study according to the phenolic and volatile composition of virgin olive oil
No full textLa scelta dei parametri operativi in gramolatura con scambio gassoso controllato: ottimizzazione in funzione della qualità degli oli vergini di oliva
No full textOptimization of the Temperature and Oxygen Concentration Conditions in the Malaxation during the Oil Mechanical Extraction Process of Four Italian Olive Cultivars.
No full textResponse surface modeling (RSM) was used to optimize temperature and oxygen concentration during malaxation for obtaining high quality extra virgin olive oils (EVOOs). With this aim, those chemical variables closely related to EVOO quality, such as the phenolic and the volatile compounds, have been previously analyzed and selected. It is widely known that the presence of these substances in EVOOs is highly dependent on genetic, agronomic, and technological aspects. Based on these data, the two parameters were optimized during malaxation of olive pastes of four important Italian cultivars using some phenols and volatile compounds as markers; the optimal temperatures and oxygen levels, obtained by RSM, were as follows for each cultivar: 33.5 degreeC and 54 kPa of oxygen (Peranzana), 32 degreeC and 21.3 kPa (Ogliarola), 25 degreeC and 21.3 kPa (Coratina), and 33 degreeC and 21.3 kPa (Itrana). These results indicate the necessity to optimize these malaxing parameters for other olive cultivars
From the orchard to the virgin olive oil quality: a critical overview.
No full textNowadays the extra virgin olive oil (EVOO) marketable quality includes parameters describing the alteration state and assuring the oil genuineness, but it does not consider markers for the EVOO health and sensory quality. With regard to health aspects, mono-unsaturated fatty acids and hydrophilic phenols are the most important compounds characterizing the EVOO health properties, whereas volatile and phenolic substances can be considered impact components of the EVOO sensory quality. EVOO natural antioxidants include not only hydrophilic phenols but also tocopherols and carotenoids. Secoiridoids are exclusive of EVOO, furthermore they are the main phenols associated to the EVOO health proprieties. They also confer bitter and pungency EVOO taste sensory notes. The EVOO volatile compounds responsible for its typical flavour (i.e., "cut grass", "floral") are C5 and C6 saturated and unsaturated aldehydes, alcohols and esters. The concentrations of phenolic and volatile compounds and monounsaturated fatty acids in the EVOO, are strongly affected by several agronomic and technological conditions of its production. Cultivar, ripening stage of the fruit and cultural practices, such as irrigation, are the main agronomic factors affecting EVOO fatty acids, phenolic and volatile compositions with a significant impact on the sensory and the health quality. Among technological factors, crushing and malaxation are the critical points of the EVOO extraction, because of their influence on hydrophilic phenols and volatiles content. The crushers, destoner included, have shown differentiated effects on oxidoreductases activity and consequently on EVOO phenolic (polyphenoloxidases and peroxidases oxidize polyphenols) and volatile composition (lypoxigenase pathway produces C6 and C5 aldehydes, alcohols and esters) as well as, time, temperature and oxygen concentration during the malaxation. Besides new EVOO extraction technologies are also oriented to increase the value of their by-products with the use of animal feeds based on stoned pomaces for improving the sheep milk quality and the recovery of bioactive phenols from vegetation waters for producing functional foods among others
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