The Management of Irrigation and Potassium Fertilization to Mitigate the Effect of Light Frosts on the Phenolic and Volatile Compounds in Virgin Olive Oils.

The frequency of early frosts has increased in recent years, which are injurious to olive growing, causing losses in the yield and quality of virgin olive oil. In this research, it was studied how the management of agronomic factors mitigates frost damage in Arbequina olives, minimizing the loss of phenols and volatiles in virgin olive oil, at different fruit ripening stages. A Box-Behnken design and multivariate analysis were performed, with three levels of irrigation, potassium fertilization, and foliar copper application (15 treatments). Virgin olive oil was extracted from fresh and frozen olives. Light frost caused a significant decrease in the total phenols and secoiridoid compounds in and the antioxidant capacity of the frost-affected oils, which were perceived as more pungent and had the slight defect of "frostbitten olives". According to the Box-Behnken design, an 86% reference evapotranspiration (ET0) or higher with 100 potassium oxide units (UK2O) and a 100% ET0 or higher with 250 UK2O would be required to minimize the effect of light frost on phenols and volatiles. Partial Least Squares Regression-Discriminant Analysis (PLS-DA) differentiated the virgin olive oils according to their ripening stage and fresh and frost conditions. Moreover, PLS-DA positively correlated a 75-100% ET0 and 0 Uk2O with the dialdehydic form of the decarboxymethyl ligstroside aglycone (p-HPEA-EDA), the dialdehydic form of the decarboxymethyl oleuropein aglycone (3,4-DHPEA-EDA), the dialdehydic form of the ligstroside aglycone (p-HPEA-EDA-DLA), and with fruity, pungent, and bitter attributes. Precision agronomic management based on the needs of the crop itself would avoid unnecessary stress on olive trees and oil damage.

The Impact of Mild Frost Occurring at Different Harvesting Times on the Volatile and Phenolic Composition of Virgin Olive Oil.

The organoleptic characteristics of virgin olive oil (VOO), together with its nutritional and health properties, have led the olive tree to be cultivated beyond the Mediterranean basin, reaching latitudes with colder climates, with minimum temperatures below 0 °C and with a higher probability of early frosts. The freezing of olives generates destruction within the tissues and promotes degradation reactions. In this study, the impact of mild frost occurring at different harvesting times on the composition of volatiles and phenolic compounds in VOO were investigated. Arbequina variety olives were harvested at different stages of ripening. Half of the olives were subjected to oil extraction and the other half were frozen at -3 ± 1 °C for 12 h prior to oil extraction. A significant decrease of phenolic compounds with harvesting time was observed in both types of oils (fresh and frozen olives). Oils from frozen olives presented a slightly higher content of total phenols, except in the advanced ripening stage (September), and a slightly lower content of volatile compounds at all harvesting times. In addition, a higher content of 3,4-DHPEA-EDA was observed in oils from frozen olives, which is attributed to an early action of the endogenous ß-glucosidase enzyme on oleuropein in freeze-damaged olive fruits. Principal component analysis and Discriminant Partial Least Square Regression allowed the oils to be classified according to the type of fruit (fresh and frozen) and the month of harvest. This study would indicate that mild frost would have a low impact on the chemical composition of virgin olive oil, although, this depends on the ripening stage.

Effect of Storage Conditions on the Quality of Arbequina Extra Virgin Olive Oil and the Impact on the Composition of Flavor-Related Compounds (Phenols and Volatiles).

Commercialization of extra virgin olive oil (EVOO) requires a best before date recommended at up to 24 months after bottling, stored under specific conditions. Thus, it is expected that the product retains its chemical properties and preserves its 'extra virgin' category. However, inadequate storage conditions could alter the properties of EVOO. In this study, Arbequina EVOO was exposed to five storage conditions for up to one year to study the effects on the quality of the oil and the compounds responsible for flavor. Every 15 or 30 days, samples from each storage condition were analyzed, determining physicochemical parameters, the profiles of phenols, volatile compounds, α-tocopherol, and antioxidant capacity. Principal component analysis was utilized to better elucidate the relationships between the composition of EVOOs and the storage conditions. EVOOs stored at -23 and 23 °C in darkness and 23 °C with light, differed from the oils stored at 30 and 40 °C in darkness. The former was associated with a higher quantity of non-oxidized phenolic compounds and the latter with higher elenolic acid, oxidized oleuropein, and ligstroside derivatives, which also increased with storage time. (E)-2-nonenal (detected at trace levels in fresh oil) was selected as a marker of the degradation of Arbequina EVOO quality over time, with significant linear regressions identified for the storage conditions at 30 and 40 °C. Therefore, early oxidation in EVOO could be monitored by measuring (E)-2-nonenal levels.

The Chemical Compositions of Essential Oils Derived from Cryptocarya alba and Laurelia sempervirens Possess Antioxidant, Antibacterial and Antitumoral Activity Potential.

Cryptocarya alba (Peumo; CA) and Laurelia sempervirens (Laurel; LS) are herbs native to the Chilean highlands and have historically been used for medicinal purposes by the Huilliches people. In this work, the essential oils were extracted using hydrodistillation in Clevenger apparatus and analyzed by GC-MS to determine their composition. The antioxidant capacity (AC) was evaluated in vitro. The cytotoxicity was determined using cell line cultures both non tumoral and tumoral. The toxicity was determined using the nematode Caenorhabditis elegans. The antimicrobial activity was evaluated against 52 bacteria using the agar disc diffusion method and the minimum inhibitory concentrations (MICs) were determined. The principal compounds found in C. alba essential oil (CA_EO) were α-terpineol (24.96%) and eucalyptol (21.63%) and were isazafrol (91.9%) in L. sempervirens essential oil (LS_EO). Both EOs showed antioxidant capacity in vitro. Both EO showed antibacterial activity against bacteria using. LS_EO showed more inhibitory effect on these cell lines respect to CA_EO. Both EOs showed toxicity against the nematode C.elegans at 3.12-50 mg/mL. The essential oils of CA and LS have an important bioactive potential in their antioxidant, antibacterial and cytotoxicity activity. Both essential oils could possibly be used in the field of natural medicine, natural food preservation, cosmetics, sanitation and plaguicides among others.

Influence of agroclimatic parameters on phenolic and volatile compounds of Chilean virgin olive oils and characterization based on geographical origin, cultivar and ripening stage.

BACKGROUND: This study involved two commercial orchards located in Limarí Valley and Molina from two important Chilean production zones of extra virgin olive oil (EVOO). The investigation evaluated the effects of climate, soil composition, agricultural practices (fertilization and irrigation) and variety (considering two harvests) on the compounds responsible for the flavor of EVOO (volatiles and phenols) and how these compounds can explain the differences in chemical profiles by geographical origin, cultivar and fruit ripeness stage. RESULTS: Varieties from the Limarí Valley presented the highest content of phenolic compounds. A significant relationship (P < 0.05) between volatile compounds and climate indicated that the compounds produced via the lipoxygenase cascade were affected by the maximum temperature and, to a lesser extent, by evapo-transpiration and irrigation. The selection of different individual phenolic and volatile compounds independently allowed the significant differentiation of EVOOs, principally by geographical origin, crop season, fruit ripeness stage and, in a few cases, by cultivar. CONCLUSION: Soil and climate of the Chilean regions have much more influence than cultivars on the concentration of sensory quality compounds. Difference in latitude between orchards increases the importance of the geographical origin on the virgin olive oil chemical composition while full irrigation decreases the impact of the cultivar.

Rotating disk sorptive extraction of triclosan and methyl-triclosan from water samples.

A method of sample preparation based on use of rotating disk sorptive extraction (RDSE) has been developed for determination of triclosan (TCS) and methyl-triclosan (MTCS) in water samples. The sorptive and desorptive behavior of the analytes was studied by use of a rotating disk coated with polydimethylsiloxane (PDMS) on one of its surfaces. Chemical and extraction behavior were studied to establish the best conditions for extraction. The optimum conditions for both analytes were: sample volume 25 mL, pH 4.5, NaCl concentration 6% (w/v), disk rotational velocity 1,250 rpm, and extraction time 80 min. A desorption time of 30 min was used with 5 mL methanol. The detection limits for TCS and MTCS were 46 and 34 ng L(-1), respectively. Recovery was evaluated at two concentrations, 160 and 800 ng L(-1), and the values obtained were between 80 and 100%. The method was applied to analysis of influent water at two treatment plants in Santiago, Chile.

Polychlorinated biphenyl behavior in soils amended with biosolids.

Assessment of the mobility of polychlorinated biphenyls (PCBs) in soils, amended with biosolids at a rate of 30Mgha(-1), was performed using an incubation process and leaching columns. The incubation process was carried out for 0, 30, and 60d under field capacity conditions at 25 degrees C. The mobility of PCBs was assessed using solutions of 0.5molL(-1) CaCl(2) and 25mgL(-1) linear alkylbenzenes sulfonate (LAS). Ultrasound-assisted pressurized solvent extraction (US-PSE) was utilized for compound separation from the solid matrix. Compounds were determined by gas chromatography coupled to mass spectrometry. The biosolids, containing a background PCB concentration about 300microgkg(-1), were spiked with the analytes at 300mgkg(-1) to obtain a clearer determination of their behavior when the biosolid was mixed with soil. In biosolid-amended soils, an increase was observed in the extractability of PCBs with increasing incubation time, which may be attributed to organic matter breakdown. The leaching column study showed that CaCl(2) was unable to mobilize the PCBs from the biosolid to the soil, whereas LAS mobilized these compounds within the time scale implicit in the experiment (30d). The most mobilized congeners in the columns corresponded to those with the greatest molecular weight (hexa- and heptachlorinated), probably due to the higher hydrophobicity of these compounds. Results indicate that the presence of important concentrations of LAS in biosolids could mobilize PCBs from soil to the freatic level.

Rotating-disk sorptive extraction of nonylphenol from water samples.

In this study the sorption of nonylphenol was implemented on a rotating Teflon disk coated with a PDMS film on one of its surfaces. In this way, the disk, which has a high surface area, contacts only the liquid sample, which can be stirred at higher velocity than with the stir bar used in stir-bar sorptive extraction (SBSE), without damaging the phase while at the same time facilitating analyte mass transfer to the PDMS surface. We refer to the procedure as rotating-disk sorptive extraction (RDSE). Extraction variables such as disk rotational velocity, extraction time, and surface area of PDMS film were studied to establish the best conditions for extraction. With increasing rotational velocity, the amount of extracted analyte significantly increases because the stagnant layer concomitantly decreases. On the other hand, the extracted amount concomitantly increases with extraction time, reaching equilibrium at approximately 20 min, which can be reduced to 10 min when the surface area of PDMS increases from 1.74 to 6.97 cm(2). Precision of the method was determined by using the same disk (n=6) and different disks (n=3), showing relative standard deviations for the analyte of 3.7% and 10%, respectively. The detection limit of the method was 0.09 microg/L NP, defined at a signal to noise ratio of 3. The method was applied to a real sample, achieving quantitative recovery. The PDMS phase on the disk could be used for at least 50 experiments. In any case, replacement of the PDMS film on the disk is very easy and inexpensive, as compared to the commercial alternative SBSE.

Determination of polychlorinated biphenyls in biosolids using continuous ultrasound-assisted pressurized solvent extraction and gas chromatography-mass spectrometry.

An efficient continuous pressurized solvent extraction (PSE) method assisted by ultrasound energy was developed for the extraction of polychlorinated biphenyls (PCBs) from biosolids. Analytes were determined in the extracts by gas chromatography-mass spectrometry in selected ion monitoring (SIM) mode. A screening-type experimental design pointing to dynamic extraction time as the only significant variable in the extraction process was carried out to optimize PCB extraction from the biosolids. Final selected conditions for PSE were extraction temperature, 50 degrees C; static extraction time, 0 min; and dynamic extraction time, 30 min. Recovery of the PSE method was 73%, which was significantly improved (103%) when PSE was assisted with 30-min ultrasound (US-PSE). Precision of the overall method, expressed as relative standard deviation, was 3.6% and the detection limit was 0.037 mg/kg. The method was applied to the determination of PCBs in biosolids from different water treatment plants from central Chile.

Screening and determination of pesticides in soil using continuous subcritical water extraction and gas chromatography-mass spectrometry.

In the present work the efficiency of water under subcritical conditions for the extraction of pesticides having a broad spectrum of polarities from soils was evaluated. The pesticides under study were carbofuran, hexachlorobenzene, dimethoate, simazine, atrazine, lindane, diazinon, methylparathion, alachlor, aldrin-R, metholachlor, chlorpyrifos, heptachlor epoxide, dieldrin, endrin, 4,4-DDT and metoxichlor. Optimization studies were carried out using a blank soil (Non-Polluted Soil 1, CLN-1, RTC) and a real soil which were previously spiked with the pesticide mixture and aged for 60 days. A laboratory-made aluminum oven with controlled temperature was used to carry out the leaching process with subcritical water, where it is placed a pre-heater and the extraction cell. The following variables were studied, keeping the pressure controlled about 1200 p.s.i.: the extraction temperature, the time of static and dynamic extraction and the flow-rate of water (1 p.s.i. = 6894.76 Pa). The extraction efficiency of the pesticides increases with the temperature trending to the quantitative extraction at temperatures near to 300 degrees C. After the extraction process, the analytes were transferred quantitatively to 5 ml dichloromethane, before the determination by GC-MS. The results indicate that under the optimized conditions mostly of the analytes are extracted quantitatively in 90 min with recoveries quite similar to those obtained by the standard Soxhlet extraction procedure. Alternatively, by using an extraction time of 25 min, the method can be used as screening for all the pesticides, with recoveries depending on their polarity.