Evolution of phenols and pigments in extra virgin olive oil from irrigated super‐intensive orchard

Phenolic compounds have a high importance in olive oil because of their effect on shelf life and sensory properties. This study reports on the HPLC profiles of the phenolic compounds of virgin olive oils obtained from Arbequina olives from the harvesting in a super‐intensive orchard under a linear irrigation system. In addition, phenolic content, carotenoid and chlorophyllic pigments, and oxidative stability were analyzed. Total phenol content and 3,4‐DHPEA‐EDA increased up to a maximum throughout the ripening process. The simple phenols tyrosol and hydroxytyrosol acetate increased throughout the ripening process, however, there was not found a clear trend in hydroxytyrosol content. Minor constituents such as vanillic acid and p‐coumaric acid increased up to a maximum and then decreased, since vanillin decreased progressively throughout the time of harvest. 3,4‐DHPEA‐EDA and lignans were present in considerable amounts in the studied samples, while oleuropein aglycone was present in a low amount. Total phenol content and oil stability followed the same trend throughout the study, so a very good correlation was established between them. Total secoiridoids and, specifically, 3,4‐DHPEA‐EDA seemed to be responsible for oil stability. The pigment content decreased during ripening, and not a positive correlation was found between pigments and oil stability. Practical applications : The results can be used to determine the best time for harvesting in order to obtain olive oils with different phenols and pigment contents. This is important for sensory characteristics of the olive oils and also for olive oil stability.     

Rejection of As(III) and As(V) from arsenic contaminated water via electro-cross-flow negatively charged nanofiltration membrane system

A specially designed electro-cross-flow nanofiltration (NF) membrane system was used for this investigation. To enhance the rejection of arsenic ionic species like H₂AsO₄⁻, a NF membrane having a negative surface charge was fabricated via the interfacial polymerization process. The membrane was characterized by SEM, AFM, surface charge density, molecular weight cut-off (MWCO), total and skin thickness and pure water flux. The parameters that affected the rejections of As(III) and As(V) were studied; they included the initial arsenic concentration, the applied potential, pH of the feed, the cross-flow filtration pressure and the presence of different salts in the feed. Among those parameters, the pH of the feed greatly affected As(V) rejection; As(V) ([As(V)]_o = 1000 ppb) rejection was increased from 72.3 to 98.5% when pH of the feed was changed from 3.0 to 10.0. This might be due to the fact that higher pH enhanced the formation of negative divalent anion like HAsO₄²⁻ which should be rejected more effectively by the negative surface charge of the NF membrane. Beside the effect of the negative surface charge of the membrane, applied potential increased the As(V) rejection by 48.2% when the applied potential was increased from 0 to 2.0 V for a feed containing 1000 ppb initially. For the same change of applied potential rejection of As(III) was increased from 52.3 to 70.4%; this might be the result of the formation of anionic species like H₂AsO₃⁻ from the neutral molecule of H₃AsO₃ by the applied potential.     

Effect of loading‐unloading cycles on impact‐damaged jute/glass hybrid laminates

The production of glass/plant fiber hybrid laminates is a possibility for obtaining semistructural materials with sufficient impact properties, and a better life cycle analysis (LCA) profile than fiberglass. The simplest and possibly the most effective configuration for the production of these hybrids would involve the use of a plant fiber reinforced laminate as the core between two glass fiber reinforced laminates. A main limitation to the use of composites including plant fibers is that their properties may be significantly affected by the presence of damage, so that even the application of a low stress level can result in laminate failure. In particular, it is suggested that when loading is repeatedly applied and removed, residual properties may vary in an unpredictable way. In this work, E‐glass/jute hybrid reinforced laminates, impacted in a range of energies (10, 12.5, and 15 J), have been subjected to post‐impact cyclic flexural tests with a step loading procedure. This would allow evaluating the effect of damage dissipation offered by the plant fiber reinforced core. The tests have also been monitored by acoustic emission (AE), which has confirmed the existence of severe limitations to the use of this hybrid material when impacted at energies close to penetration. POLYM. COMPOS., 2009. © 2009 Society of Plastics Engineers     

Catalysts for the Ethoxylation of Esters

The intermediates for the production of nonionic surfactants can be derived from petrochemicals and/or from renewable raw materials. In both, the role of catalysis is fundamental. In this paper the main results reported in the literature related with the catalysis for ethoxylation of fatty esters will be reviewed. The main open challenges for these technologies will be outlined.     

Middle distillates from hydrocracking of FT waxes: Composition,characteristics and emission properties

A light cobalt catalyzed Fischer–Tropsch (FT) wax was subjected to hydrocracking in the range of temperature 319–351 °C and hydrogen pressure between 3.5 and 6.0 MPa. The catalyst used was platinum on amorphous silica–alumina. Hydrocracking reaction led to an increase of middle distillate yield up to 85% with a contemporary increase of iso-paraffins concentration which resulted in a remarkable improvement of cold flow properties of the products. The freezing point of C₁₀–C₁₄ fraction passed from ?23 to ?45 °C while the pour point of C₁₅–C₂₂ fraction decreased from 13 to ?23 °C. The latter fraction displayed high cetane numbers ranging between 75 and 80. Changes in carbon distribution and molecular structure of products during hydrocracking have been rationalized in the light of the accepted hydrocracking mechanism where n-paraffins undergo to consecutive isomerization reactions leading to isomers with progressively higher branching degree and concomitant cracking reaction. Experimental evidences support the view that apparent reactivity of n-paraffins is chain length dependent, increasing with the molecular weight. Detailed characterization by NMR and GC showed that branching groups abundance in the middle distillate products was the following: methyl ? ethyl > propyl.Emission tests carried out with FT diesel and commercial ultra low sulfur diesel showed that FT diesel has excellent combustion properties and leads to a reduction of emissions.     

Rheological behavior and morphological and interfacial properties of PLA/TPE blends

Rheological and interfacial tension data were employed to predict the morphology and thermal and mechanical properties of noncompatibilized and compatibilized poly(lactic acid) (PLA)/thermoplastic elastomer (TPE) blends. PLA was melt blended with thermoplastic polyurethane (TPU) and ethylene elastomer (EE) and compatibilized by ethylene–butyl acrylate–glycidyl methacrylate (EBG) in an internal mixer chamber. Both TPU and EE TPEs have higher viscosities than PLA, and the interfacial properties evaluated have revealed better adhesion between domains of PLA–TPU. The efficiency of the compatibilizer agent EBG depended on the TPE type inferred by modifications in the scanning electron microscopy images of PLA/TPE blends and by the Izod impact strength (improved by 23%). The EBG was more effective in the PLA/TPU blend. The TPEs and EBG did not affect the PLA thermal stability, and no thermal event was observed in the usual PLA extrusion and injection temperature range. © 2019 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2019 , 136, 47962.     

Thiol precursors in Catarratto Bianco Comune and Grillo grapes and effect of clarification conditions on the release of varietal thiols in wine

Background and Aims

Varietal thiols characterise the typical aroma of several white wines, such as Sauvignon Blanc. Their presence and sensory perception were suggested in two Sicilian grape cultivars, Catarratto Bianco Comune (CBC) and Grillo, though it has not been analytically proven.

Methods and Results

Varietal thiol precursors and free varietal thiols were assessed in CBC and Grillo grapes, musts and wines by ultra‐performance liquid chromatography/electrospray ionisation high‐resolution MS. The isobaric compounds including S‐3‐(hexanal)‐glutathione and S‐3‐(4‐mercapto‐4‐methylpentan‐2‐one)‐glutathione (GSH‐4MMP) were distinguished by comparing their accurate masses and high‐resolution‐MS/MS spectra with those of their synthetic standards. S‐3‐(Hexanal)‐glutathione, S‐3‐(hexan‐1‐ol)‐glutathione and S‐3‐(hexan‐1‐ol)‐cysteine were found in grape, must and wine, whereas GSH‐4MMP and its hydrolysed forms were not found. Their concentration decreased during winemaking, mostly after grape pressing. We compared the effect of clarification conditions based on the exposure of must to either air or CO₂ on the concentration of thiol precursors and free thiols in wine; however, negligible differences were observed. The concentration of free thiols in the wines was found to be in the range 400–1100 ng/L and they were unaffected by the two clarification conditions tested.

Conclusions

The isobaric S‐3‐(hexanal)‐glutathione and GSH‐4MMP were clearly distinguished for the first time by ultra‐performance liquid chromatography/high‐resolution MS through their retention times and MS spectra. These varietal thiols were revealed in CBC and Grillo wines for the first time. The air‐free and air‐exposed clarification treatments had little effect on the concentration of the varietal thiols.

Significance of the Study

This study highlights the major impact of the varietal thiols (mainly 3‐mercapto‐hexan‐1‐ol and its acetate form) on the sensory properties of CBC and Grillo wines.     

Efficacy of new commercial formulations to control downy mildew and dissipation of their active fungicides in wine after good agricultural practices

BACKGROUND: The efficacy of common fungicides to control downy mildew (Plasmopara viticola) in vines decreases when the same commercial formulations are applied over several years. For this reason, new commercial formulations (containing new fungicides) have to offer to grape‐growers to increase the efficacy of antifungal treatments. The efficacy of five new commercial formulations (Cabrio Top, Equation Pro, Fantic M, Mikal Premium and Fobeci) to control downy mildew in an experimental vineyard producing white grapes (Vitis vinifera cv. Godello) was studied. All these products have in common a new fungicide (pyraclostrobin, famoxadone, benalaxyl‐M, iprovalicarb and benalaxyl, respectively) in their chemical formulation. RESULTS: Two commercial formulations, Cabrio Top and Fobeci, gave the highest efficacy to control this fungal disease. Once treated white grapes were harvested, the fate of these fungicides from vine to wine was studied. The white winemaking process allowed the dissipation of fungicide residues in high percentages (～95%), except for iprovalicarb (45%). Concentrations in final filtered white wines were close to or lower than 0.01 mg L^?1 for all detected fungicides except iprovalicarb and fludioxonil. The following dissipation rate was found: famoxadone > cyprodinil > pyraclostrobin > benalaxyl > folpet > fludioxonil > benalaxyl‐M > penconazole > iprovalicarb. CONCLUSION: From the data obtained in the vinification process, estimated maximum residue levels for white wines were proposed for future EU legislation to control the presence of pesticides in white wines. Thereby one helps to assure also the wine quality and protection of consumer health. Copyright © 2009 Society of Chemical Industry     

Lc/Esi/Ms/Ms determination of postharvest fungicide residues in citrus juices

An LC-ESI-MS/MS method was developed for the quantitative detection of postharvest fungicide residues in citrus juices and reported in this paper. The analyses of thiabendazole (TBZ), carbendazim (MBC), thiophanate methyl (TPM), imazalil (IMZ) and prochloraz (PCZ) residues were performed by using a gradient elution in conjunction with positive ionization mode electrospray ionization tandem mass spectrometry. Fungicides were extracted from citrus juices with recoveries ranging from 79.8 to 101.2% and relative standard deviation better than 15%. The quantification limits ranged from 0.01 μg/kg IMZ to 0.06 μg/kg for MBC. The LC-MS-MS method was applied to commercial citrus juices, detecting MBC, TBZ and IMZ residues in the 90% of the samples. Prochloraz residues were detected only in one of the multifruit juice (orange, lemon and carrot) samples.     

Effect of maillard reaction volatile products on lipid oxidation

Maillard reaction volatile compounds (MRV), prepared by heating a glucose-glycine solution, were tested as antioxidants in soybean oil (SBO) thermoxidation. The volatiles were transferred into the oil by stripping with a stream of Nitrogen and substituting the atmosphere above the oil with air containing MRV. Standard accelerated oxidation was performed by heating the SBO. Peroxide value measurement and headspace gas Chromatographic analysis were carried out on all the samples. The MRV antioxidant activity was evaluated by determining the effect of the induction period and the kinetic rate constant of peroxide and oxidation volatiles formation. The MRV showed a significant antioxidant activity. The effectiveness was variable depending on MRV transfer method to the oil, and the Maillard reaction extent was related to the browning level of glucose/glycine solution. It was found that the maximum effect of MRV prolonged about three times the induction period and reduced the kinetic rate constant by half in relation to the control sample. MRV affects oxidative stability of soybean oil by lengthening the induction period as well as by decreasing the rate of oxidation at the propagation state and reducing the formation of hexanal.