Lucélia Hoehne

Antimicrobial activities of six essential oils commonly used as condiments in Brazil against Clostridium perfringens.

Despite recent advances in food production technology, food-borne diseases (FBD) remain a challenging public health concern. In several countries, including Brazil, Clostridium perfringens is among the five main causative agents of food-borne diseases. The present study determines antimicrobial activities of essential oils of six condiments commonly used in Brazil, viz., Ocimum basilicum L. (basil), Rosmarinus officinalis L. (rosemary), Origanum majorana L. (marjoram), Mentha × piperita L. var. Piperita (peppermint), Thymus vulgaris L. (thyme) and Pimpinella anisum L. (anise) against C. perfringens strain A. Chemical compositions of the oils were determined by GC–MS (gas chromatography–mass spectrometry). The identities of the isolated compounds were established from the respective Kováts indices, and a comparison of mass spectral data was made with those reported earlier. The antibacterial activity was assessed from minimum inhibitory concentration (MIC) and minimum bactericidal concentration (MBC) using the microdilution method. Minimum inhibitory concentration values were 1.25 mg mL−1 for thyme, 5.0 mg mL−1 for basil and marjoram, and 10 mg mL−1 for rosemary, peppermint and anise. All oils showed bactericidal activity at their minimum inhibitory concentration, except anise oil, which was only bacteriostatic. The use of essential oils from these common spices might serve as an alternative to the use of chemical preservatives in the control and inactivation of pathogens in commercially produced food systems.

Validation of an analytical method for the quantitative determination of selenium in bacterial biomass by ultraviolet–visible spectrophotometry

The present paper describes the validation of a spectrophotometry method involving molecular absorption in the visible ultraviolet-visible (UV-Vis) region for selenium (Se) determination in the bacterial biomass produced by lactic acid bacteria (LAB). The method was found to be suitable for the target application and presented a linearity range from 0.025 to 0.250 mg/L Se. The angular and linear coefficients of the linear equation were 1.0678 and 0.0197 mg/L Se, respectively, and the linear correlation coefficient (R2) was 0.9991. Analyte recovery exceeded 96% with a relative standard deviation (RSD) below 3%. The Se contents in LAB ranged from 0.01 to 20 mg/g. The Se contents in the bacterial biomass determined by UV-Vis were not significantly different (p > 0.05) those determined by graphite furnace atomic absorption spectrometry. Thus, Se can be quantified in LAB biomass using this relatively simpler technique.

Poly(methylene blue)-modified electrode for indirect electrochemical sensing of OH radicals and radical scavengers

A new modified electrode for indirect sensing of OH· and radical scavengers was described. The electrochemical polymerization of methylene blue in aqueous solutions and the properties of the resulting films on a glassy carbon electrode were carried out using cyclic voltammetry. A surface coverage of 1.11 × 109mol cm2 was obtained, revealing a complete surface coverage of the polymeric film on the electrode surface. OH· was able to destroy the poly(methylene blue) film by exposure to a Fenton solution. The loss of the electrochemical signal of the residual polymeric film attached to the electrode surface was related to the extent of its dissolution. The applicability of the sensor was demonstrated by evaluating the OH radical scavenging effect on different concentrations of ascorbic acid. The obtained radical scavenging capacity were 31.4%, 55.7%, 98.9% and 65.7% for the ascorbic acid concentrations of 5, 10, 30 and 50 mM, respectively.

Cantilever nanobiosensor using tyrosinase to detect atrazine in liquid medium

ABSTRACT The aim of this study was to develop a cantilever nanobiosensor for atrazine detection in liquid medium by immobilising the biological recognition element (tyrosinase vegetal extract) on its surface with self-assembled monolayers using gold, 16-mercaptohexadecanoic acid, 1-ethyl-3-[3-dimethylaminopropyl] carbodiimide hydrochloride/n-hydroxysuccinimide. Cantilever nanobiosensors presented a surface compression tension increase when atrazine concentrations were increased, with a limit of detection and limit of quantification of 7.754 ppb (parts per billion) and 22.792 ppb, respectively. From the voltage results obtained, the evaluation of atrazine contamination in river and drinking water were very close to those of the reference sample and ultrapure water, demonstrating the ability of the cantilever nanobiosensor to distinguish different water samples and different concentrations of atrazine. Cantilever nanosensor surface functionalization was characterised by combining polarisation modulation infrared reflection-absorption spectroscopy and atomic force microscopy and indicating film thickness in nanometric scale (80.2 ± 0.4 nm). Thus, the cantilever nanobiosensor developed for this study using low cost tyrosinase vegetal extract was adequate for atrazine detection, a potential tool in the environmental field.

Identification of Tobacco Types and Cigarette Brands Using an Electronic Nose Based on Conductive Polymer/Porphyrin Composite Sensors

Three tobacco types (Burley, Flue Cured, and Oriental) and eight cigarette brands were unequivocally identified using an electronic nose formed by only three sensors based on a single novel conducting polymer (PF-BTB) doped with different porphyrins (H2TPP, H2TPFP, and H2BTBOP). The synthesis and characterization of the polymer are also discussed. Small changes in the porphyrin structure caused significant changes in the electrical conductance response patterns of the sensors upon exposure to complex chemical matrixes, representing a novel approach for tuning the selectivity of chemiresistive sensors for e-nose application. This e-nose is fast, cheap, reliable, can be easily operated, and could be a valuable tool for border agents fighting cigarette smuggling around the world, helping them prevent losses of millions in tax revenues and sales.

Chemical Composition and Evaluation Preliminary of Antileishmanial Activity in vitro of Essential Oil from Leaves of Eugenia pitanga, A Native Species of Southern of Brazil

Abstract Eugenia pitanga (O.Berg) Nied., Myrtaceae, popularly known as pitanga-do-campo, is a species native from Pampa biome, in southern of Brazil and is popularly used as antidiarrheal, anti-rheumatic, stimulant and febrifuge. The aim of this work was to determine the chemical composition of essential oil from fresh leaves of Eugenia pitanga (O.Berg) Nied. Preliminaries data about antileishmanial activity in vitro of essential oil against promastigotes forms of Leishmania amazonensis are presented. The method to determine the chemical composition of the essential oil from fresh leaves of E. pitanga (EoEp) was gas chromatography-mass spectrometry. EoEp was assayed in vitro for antileishmanial activity against promastigotes of Leishmania amazonensis. The EoEp comprised 57 components and was rich in oxygenated sesquiterpenes (72.97 %) with spathulenol (15.34 %), globulol (10.93 %) and (2E,6E) methyl farnesoate (7.40 %) as the major constituents. EoEp was effective against L. amazonensis promastigotes with IC50 value of 6.10 ± 1.80 μg/mL. This work reports for the first time the composition of essential oil from leaves of E. pitanga from Pampa Biome, and it suggests the importance of continuing the studies in order to explain the antileishmanial activity.

Assessment of selenium bioaccumulation in lactic acid bacteria

Selenium is an essential micronutrient for living beings, as it helps to maintain the normal physiological functions of the organism. The numerous discoveries involving the importance of this element to the health of human beings have fostered interest in research to develop enriched and functional foods. The present study evaluated the potential for bacterial strains of Enterococcus faecalis (CH121 and CH124), Lactobacillus parabuchneri (ML4), Lactobacillus paracasei (ML13, ML33, CH135, and CH139), and Lactobacillus plantarum (CH131) to bioaccumulate Se in their biomass by adding different concentrations of sodium selenite (30 to 200 mg/L) to the culture medium. Quantification of Se with UV and visible molecular absorption spectroscopy showed that the investigated bacteria were able to bioaccumulate this micromineral into their biomass. Two of the L. paracasei strains (ML13 and CH135) bioaccumulated the highest Se concentrations (38.1 ± 1.7 mg/g and 40.7 ± 1.1 mg/g, respectively) after culture in the presence of 150 mg/L of Se. This bioaccumulation potential has applications in the development of dairy products and may be an alternative Se source in the diets of humans and other animals.

Rubus sellowii Cham. & Schlitdl. (Rosaceae) fruit nutritional potential characterization

The aim of this study was to know the physical, chemical and nutritional characteristics of Rubus sellowii (Rosaceae) fruits, known as blackberry, native plant mainly to Rio Grande do Sul State (RS), Brazil. For this, three different populations of this plant were selected and the fruits were analyzed through moisture, ash, titratable acidity, pH, lipids, fibers, carbohydrates, proteins, carotenoids, lycopene, ascorbic acid, aminogram and in vitro digestibility. Fruits showed high acidity (3.28 percent), ash and protein (1.02 and 0.93 percent) and higher ascorbic acid (38.43 mg per 100 g) if compared to Rubus cultivars. Due to Rubus sellowii nutritional properties, they provide benefits to human health.

Enzymatic hydrolysis of the Eisenia andrei earthworm: Characterization and evaluation of its properties

Abstract Some studies have carried out in order to retrieve proteins from the by-product of animal-processing industries. Earthworms are rich in protein and usually are used in animal feed. Thus, this study aimed to optimize the hydrolysis process of Eisenia andrei earthworms by employing Alcalase enzyme. Using the response surface methodology, we evaluated the following conditions: temperature, hydrolysis time, stirring speed, and enzyme/substrate ratio. The optimal conditions for the experimental design were determined through the analysis of the foaming and emulsifying properties, in vitro starch digestibility, and antioxidant activity. The results demonstrate that the highest degree of hydrolysis (i.e., 92%) was obtained under the following conditions: pH, 9.5; temperature, 25 °C; hydrolysis time, 2.25 h; stirring speed, 200 rpm; and enzyme/substrate ratio, 1.77%, using Alcalase enzyme. Evaluation of the amino acid composition under these conditions revealed higher concentrations of aspartic acid, glutamic acid, and leucine. The in vitro protein digestibility of the hydrolysate was approximately 73%. There were no significant improvements in either foam stability or emulsification after enzymatic hydrolysis. Additional studies on the antioxidant activity are required. This bioproduct could potentially serve as a promising supplementary food product.

Addition of Vermicompost to Heavy Metal-Contaminated Soil Increases the Ability of Black Oat (Avena strigosa Schreb) Plants to Remove Cd, Cr, and Pb

The contamination of soil with heavy metals is a serious agricultural issue. The presence of foods contaminated with heavy metals in the human diet can cause health damages. Metal phytoextraction processes remove soil contaminants through plant absorption; however, plants display different responses to the metal contamination of the soil. Thus, the purposes of this paper were to determine cadmium (Cd), chromium (Cr), and lead (Pb) immobilization in soil mixed with different amounts of stabilized vermicompost (obtained by earthworm composting) and verify if this vermicompost helps in the removal of heavy metal through the phytoextraction technique with black oat (Avena strigosa Schreb cv IAPAR 61) plants. The addition of a high quantity of vermicompost (50, 75, and 100%) to the soil presents similar results to the immobilization of Cd, Cr, and Pb, and a similar trend was observed in lower quantities (0 and 25%) of vermicompost. The addition of vermicompost improves the growth of black oat plants, but only the treatment with 25% of vermicompost showed promising results in the absorption of Cr and Pb, and the treatment with 50% in the absorption of Cd. Finally, we suggest that “IAPAR 61” black oat cultivar is efficient Cd, Cr, and Pb accumulators. However, heavy metal remained mostly in the root, indicating that root-to-shoot translocation was not efficient, hindering its application for phytoremediation strategies.