Chemical and sensory characterization of Brazilian virgin olive oils.

Brazil is an emerging virgin olive oil producer country whose oils have been scarcely studied till now and, in particular, no data are present in literature about their volatile profiles and organoleptic characteristics as well as the Pearson's correlations between chemical and sensory parameters. Hence, giving insights about these aspects was the aim of the current investigation. The volatile profiles showed the presence of the aldehydes responsible for the positive attribute of VOOs (i.e. trans-2-Hexenal and hexanal) although, in some cases, volatiles from anaerobic and aerobic fermentation were also detected. The panel test showed low values of fruity and pungent notes (mean values of 1.1 and 0.6, respectively) whereas the bitter taste was detected only in one sample, probably due to the low amount of total phenolic compounds (ranging from 40 to 280 mg kg-1). Accordingly to the volatiles analysis, slight defects of the oils were evidenced by the panelists. Tocopherols ranged from 123 to 222 mg kg-1; carotenoids from 10.69 to 26.18 mg kg-1, chlorophylls from 14.06 to 54.90 mg kg-1, antioxidant activity from 976 to 1790 µmol TE g-1, and fatty acid ethyl esters from 2.56 to 19.22 mg kg-1. Positive Pearson's correlations were highlighted between hydroxytyrosol derivatives and antioxidant activity (r = 0.9601, p < .0001), trans-2-hexenal and fruity median (r = 0.6526, p < .05), acetic acid and vinegary defect (r = 0.7854, p < .0001), and fatty acid ethyl esters and vinegary defect (r = 0.8418, p < .0001). Our findings give first insights about sensory characteristics of Brazilian virgin olive oils and their association with chemical quality parameters. Finally, based on the obtained data, an improvement of preliminary operations (harvesting, storage) of the extraction process is recommended.

Decomposition of the organic matter of natural and concentrated vinasse in sandy and clayey soils.

Vinasse has been used as fertilizer by sugarcane growers, due to its potential to completely replace mineral fertilizers. However, if the application is not adequate, this practice may cause environmental contamination. This study used a respirometry test to evaluate the organic matter (OM) decomposition present in natural vinasse and concentrated vinasse (CV), with or without urea addition. The experiment involved two soil types and two types of vinasse at different application rates. The vinasse chemical characterization showed high levels of pseudo-total potassium (K) in both vinasses, which are not considered in the application rates. Decomposition rates above 90% and between 70 and 80% were obtained for sandy and clayey soils, respectively, over a brief 41-day period, indicating rapid OM decomposition. Positive priming effect was observed for CV and CV + urea treatments in sandy soil. An important implication of these findings revealed that K not available in vinasse was released in the soil solution by the OM mineralization, indicating the possibility of overestimation in the vinasse application rates. Therefore, K pseudo-total values should be considered in the calculation of the vinasse application rates. However, studies involving K mobility into soil are needed to validate this hypothesis.

Concentration of Cu, Zn, Cr, Ni, Cd, and Pb in soil, sugarcane leaf and juice: residual effect of sewage sludge and organic compost application.

Many researchers have evaluated the effects of successive applications of sewage sludge (SS) on soil plant-systems, but most have not taken into account the residual effect of organic matter remaining from prior applications. Furthermore, few studies have been carried out to compare the effects of the agricultural use of SS and sewage sludge compost (SSC). Therefore, we evaluated the residual effect of SS and SSC on the heavy metal concentrations in soil and in sugarcane (Saccharum spp.) leaves and juice. The field experiment was established after the second harvesting of unburned sugarcane, when the organic materials were applied. The SS and SSC rates were (t ha(-1), dry base): 0, 12.5, 25, and 50; and 0, 21, 42, and 84, respectively. All element concentrations in the soil were below the standards established by São Paulo State environmental legislation. SS promoted small increases in Zn concentrations in soil and Cu concentrations in leaves. However, all heavy metals concentrations in the leaves were lower than the limits established for toxic elements and were in accordance with the limits established for micronutrients. There were reductions in the concentrations of Ni and Cu in soil and the concentration of Pb in juice, with increasing rates of SSC. The heavy metal concentrations were very low in the juice. Under humid tropical conditions and with short-term use, SS and SSC containing low heavy metal concentrations did not have negative effects on plants and soil.

Concentrations of Cu, Fe, Mn, and Zn in tropical soils amended with sewage sludge and composted sewage sludge.

Sewage sludge may be used as an agricultural fertilizer, but the practice has been criticized because sludge may contain trace elements and pathogens. The aim of this study was to compare the effectiveness of total and pseudototal extractants of Cu, Fe, Mn, and Zn, and to compare the results with the bioavailable concentrations of these elements to maize and sugarcane in a soil that was amended with sewage sludge for 13 consecutive years and in a separate soil that was amended a single time with sewage sludge and composted sewage sludge. The 13-year amendment experiment involved 3 rates of sludge (5, 10, and 20 t ha(-1)). The one-time amendment experiment involved treatments reflecting 50, 100, and 200 % of values stipulated by current legislation. The metal concentrations extracted by aqua regia (AR) were more similar to those obtained by Environmental Protection Agency (EPA) 3052 than to those obtained by EPA3051, and the strongest correlation was observed between pseudo(total) concentrations extracted by AR and EPA3052 and bioavailable concentrations obtained by Mehlich III. An effect of sewage sludge amendment on the concentrations of heavy metals was only observed in samples from the 13-year experiment.