A fluorescence-based multivariate method for biodiesel quantification in undiluted diesel-biodiesel blends without sample preparation.

In this work, excitation-emission matrices (EEMs) were used in association with parallel factor analysis (PARAFAC) to assess biodiesel content in undiluted diesel-biodiesel blends (DBBs) without pre-sample preparation. EEMs were decomposed using the PARAFAC (EEMs-PARAFAC), and the loading values of the PARAFAC component as a function of biodiesel content in the blends were used to build an analytical model to quantify the biodiesel content in DBBs. The proposed model presenting a limit of detection (LOD) and a limit of quantification (LOQ) of 2.5% and 11% w/w, respectively, successfully predicted the biodiesel content in the validation samples. The robustness of the model was confirmed by a close analysis of the root mean square error of prediction, standard error of prediction, relative standard deviation of prediction, and Bias. Therefore, an accurate and robust analytical model based on EEMs-PARAFAC was developed to quantify the biodiesel content in undiluted DBBs without sample preparation.

Miniaturized 3D-Printed Cell Enables Water/Ethanol Quantification Using Electrochemical Impedance Spectroscopy.

A miniaturized and low-cost electrochemical 3D-printed system for rapid and accurate quantification of ethanol content in ethanol fuel using electrochemical impedance spectroscopy (EIS) was developed. The monolithic design of the system incorporates insulating thermoplastic electrode separators, with only the cover being mobile, allowing for easy assembly and handling. The portable device, measuring approximately 26 × 24 mm, has a maximum capacity of 1 mL, making it suitable for lab-on-a-chip and portable analysis. By utilizing the dielectric constant of ethanol and ethanol fuel mixtures with water, the miniaturized EIS cell quantifies ethanol content effectively. To validate its performance, we compared measurements from four gas stations with a digital densimeter, and the values obtained from the proposed system matched perfectly. Our miniaturized and low-cost electrochemical 3D-printed device can be printed and assembled in two hours, offering a cost-effective solution for fast and precise ethanol quantification. Its versatility, affordability, and compatibility with lab-on-a-chip platforms make it easily applicable, including for fuel quality control and on-site analysis in remote locations.

Oxidative stability and elemental analysis of sunflower (Helianthus annuus) edible oil produced in Brazil using a domestic extraction machine.

The consumption of regular vegetable oils has been linked to energy acquisition, nutritional benefits, health improvement, and the regulation of metabolic diseases. This study evaluated fatty acids composition, physicochemical, thermal, oxidative, and optical properties, and quantified trace elements in the sunflower oil extracted by a domestic cold-press machine. The oil presented linoleic (54.00%) and oleic (37.29%) primary unsaturated fatty acids (91.67%), in which atherogenic (0.05), thrombogenic (0.16), hypocholesterolemic/hypercholesterolemic (21.97), peroxide (16.16), saponification (141.80), and relative density indices (0.92) demonstrated to be suitable for human consumption and possible health promotion. In addition, the concentrations of trace elements by ICP OES were ordered Zn > Fe > Al > Cu > Mn > Cr. Concentrations of Zn, Fe, Al, Cu, and Mn were lower than FAO/WHO and DRI/AI limits, while Cr concentrations exceeded the FAO/WHO limits, which can be used as an indicator of the polluted ambiance. Sunflower oil quantities daily consumption were calculated by taking into account non-carcinogenic risk (CR < 10-4), and total non-carcinogenic hazard index (HI < 1). Based on trace elements determined in this study, the suitable quantity of sunflower oil consumption varies according to individuals aged 8, 18, and 30 years and will be deemed 0.61, 1.46, and 1.65 g/kg, respectively, attending HI = 0.99 and CR < 10-4.

Characterization of Buriti (Mauritia flexuosa) Pulp Oil and the Effect of Its Supplementation in an In Vivo Experimental Model.

Mauritia flexuosa (Buriti) pulp oil contains bioactive substances and lipids that are protective against cardiovascular and inflammatory diseases. We performed physical and chemical analyses to verify its quality and stability. Buriti oil was stable according to the Rancimat test, presenting an induction period of 6.6 h. We evaluated the effect of supplementation with crude buriti oil and olive oil on metabolic parameters in 108 Swiss mice for 90 days. We investigated six groups: extra virgin olive oil (EVOO) 1 and 2 (1000 and 2000 mg/kg), buriti oil (BO) 1 and 2 (1000 and 2000 mg/kg), synergic (S) (BO1 + EVOO1), and control (water dose 1000 mg/kg). The animals were euthanized to examine their blood, livers, and fats. The supplementation did not interfere with food consumption, weight gain, and histological alterations in the liver. Group S showed the strongest relationship with the fractions HDL-c and non-HDL-c, indicating a possible cardioprotective effect. Moreover, we observed significantly higher IL-6 levels in the control, EVOO2, and BO1 groups than in the EVOO1 group. Resistin was also significantly higher for the synergic treatment than for the control. We conclude that BO combined with EVOO could be an excellent food supplement for human consumption.

Eco-Friendly Production of AuNPs and Their Impact on the Oil Oxidative Stability.

Vegetable oils have been used for different applications and, more recently, as an active host medium to obtain nanoparticles for employment in bionanotechnological applications. Nevertheless, oils are very susceptible to oxidation during production, storage, and transportation because of their chemical composition. Consequently, any modification in their production must be accompanied by an analysis of the oxidative stability. In this study, naked and biocompatible gold nanoparticles (AuNPs) were grown on sunflower oil during sputtering deposition using different deposition times. Size and morphology were determined by transmission electron microscopy (TEM) and their concentrations were found by inductively coupled plasma-optical emission spectroscopy (ICP-OES). Rancimat® method was employed to evaluate the AuNPs influence on the oxidative stability of the vegetable oil. Well-dispersed quasi-spherical NPs were produced with a mean diameter in the 2.9-3.7 nm range and they were concentration-dependent on the deposition time. A concentration of about 11 mg/L, 38 mg/L, and 225 mg/L of AuNPs was obtained for a deposition time of 5 min, 15 min, and 30 min, respectively. The results also revealed that AuNPs negatively affected the oxidative stability of the sunflower oil and exponentially reduced the induction period (IP) with the increase in AuNPs content. IP reductions of 63%, 77%, and 81% were determined for the AuNPs containing samples at 11 mg/L, 38 mg/L, and 225 mg/L. For the first time, it is reported that naked AuNPs promote the rapid degradation of vegetable oil and this points out the need for attention relative to the quality of vegetable oils used to host metal nanoparticles.

Characterization and oxidative stability of oils and bioactive compounds of the fruits of Byrsonima cydoniifolia A. Juss. at different ripening stages.

BACKGROUND: Fruits present high concentrations of bioactive compounds that are beneficial to health due to their antioxidant properties. New alternatives to vegetable oils with such properties have been studied. We determined the chemical compounds of Byrsonima cydoniifolia A. Juss. fruits in three ripening stages as well as the optical behavior and quality level of the oils. RESULTS: The ripening stage affected the chemical composition of the fruits and oils. The fruits presented high values of bioactive compounds, as ascorbic acid (1.46-1.82 g kg-1 ) and total phenols (3.54-15.91 g gallic acid equivalents kg-1 ), as well as showed excellent antioxidant activity. The ripe fruits showed high content of carotenoids (45.90 mg kg-1 ) were lutein is the major carotenoid, representing 55.56%. The oil of the ripe fruits showed high lipid content (252.6 g kg-1 ) and contained oleic (521.83 g kg-1 ), palmitic (209.13 g kg-1 ) and linoleic (195.4 g kg-1 ) fatty acids. The oil of ripe fruits showed the best oxidative stability, with longer induction period (22.29 h) than the other oils. CONCLUSION: Fruits of B. cydoniifolia A. Juss. demonstrate to possess a promising potential for the use as functional ingredients. The oil of the ripe fruits was more stable and presents a greater potential to be used for edible purposes. © 2018 Society of Chemical Industry.