No abstract

Context: Currently, there is a great tendency in cosmetic area to use natural extracts. Coffee silverskin (CS) is the most abundant solid by-product generated during roasting of coffee processing. Objectives: To evaluate different CS extracts as promising cosmetic ingredients, regarding antioxidant, antimicrobial, and cytotoxic properties. Materials and methods: Aqueous, hydroalcoholic and ethanolic CS extracts were obtained by an environmentally friendly procedure considering costs and pollution. Extracts were characterized for total phenolic and flavonoid contents (TPC and TFC, respectively), antioxidant activity by 1,1-diphenyl-2-picrylhydrazyl (DPPH), ferric reducing antioxidant power (FRAP), antimicrobial activity expressed as minimal inhibitory concentration (MIC) and cytotoxicity using the 3-(4,5-dimethylthiazol-2-yl)-5-(3-carboxymethoxyphenyl)-2-(4-sulfophenyl)-2H-tetrazolium (MTS) and lactate dehydrogenase (LDH) assays in two skin cell lines (fibroblasts and keratinocytes). Results: The TPC of extracts was 18.33-35.25 mg of gallic acid equivalents per g of material on a dry basis (mg GAE/g db). The TFC of extracts was 1.08-2.47 mg cathechin equivalents per g dry material (mg CE/g db). The antioxidant activity was high, with values ranging between 95.95 and 216.40 mmol Fe 2+ /g for aqueous and alcoholic samples, respectively. Preliminary assays for antimicrobial potential showed that extracts display antibacterial activity. The MIC varied from 31.3 to 250 mg/mL for Gram-positive, and from 31.3 to 1000 mg/mL for Gram-negative. Extracts did not affect in vitro cell viability, with values near 100% in all concentrations tested. Conclusion: Results seem show that CS is a safe source of natural antioxidants with antifungal and antibacterial activity and no cytotoxicity, with potential usefulness for cosmetic applications.

This study focused on the development of a sensitive enzymatic biosensor for the determination of pirimicarb pesticide based on the immobilization of laccase on composite carbon paste electrodes. Multi-walled carbon nanotubes (MWCNTs) paste electrode modified by dispersion of laccase (3%, w/w) within the optimum composite matrix (60:40%, w/w, MWCNTs and paraffin binder) showed the best performance, with excellent electron transfer kinetic and catalytic effects related to the redox process of the substrate 4-aminophenol. No metal or anti-interference membrane was added. Based on the inhibition of laccase activity, pirimicarb can be determined in the range 9.90 × 10(-7) to 1.15 × 10(-5) mol L(-1) using 4-aminophenol as substrate at the optimum pH of 5.0, with acceptable repeatability and reproducibility (relative standard deviations lower than 5%). The limit of detection obtained was 1.8 × 10(-7) mol L(-1) (0.04 mg kg(-1) on a fresh weight vegetable basis). The high activity and catalytic properties of the laccase-based biosensor are retained during ca. one month. The optimized electroanalytical protocol coupled to the QuEChERS methodology were applied to tomato and lettuce samples spiked at three levels; recoveries ranging from 91.0 ± 0.1% to 101.0 ± 0.3% were attained. No significant effects in the pirimicarb electroanalysis were observed by the presence of pro-vitamin A, vitamins B1 and C, and glucose in the vegetable extracts. The proposed biosensor-based pesticide residue methodology fulfills all requisites to be used in implementation of food safety programs.

Twenty-four coffee samples of different botanical and geographical origins were analyzed for their FA composition, including trans isomers. The analysis used high-resolution GC/FID/CP Sil 88 capillary column to separate FAME obtained by esterification with BF 3 /methanol. The purpose of this work was to verify whether this parameter could be applied in the discrimination of arabica and robusta coffees, either in green or in roasted stage. Statistical approaches were applied to check the efficiencies of some univariate and multivariate procedures, and the results permitted the conclusion that the FA profile can be used as a coffee variety marker and may inform on the historical background, mainly in terms of heat-processing conditions. Paper no. J9895 in JAOCS 80, 511-517 (June 2003).Of all the species of Coffea available, two have acquired high commercial value, namely, C. arabica Linn. and C. canephora Pierre ex Froehner var. robusta, and are used to prepare coffee drinks. The beans of the preferred species are easily identified by their macroscopic characteristics when in the green stage. After roasting, this distinction is still possible with whole beans, but after milling, when the anatomic characteristics are lost, identification becomes extremely difficult. Since C. arabica and C. robusta display different appeals and have different commercial values, the discrimination of these species is essential to be able to avoid adulteration and to prevent unfair commercial practices (1).To guarantee the authenticity of coffees, several chemical and physical parameters have been tried, namely, hydroxycinnamic acid derivatives (2), unsaponifiable lipid fractions (3,4), furanic aldehydes (5), trace element profiles (6), stable isotope ratios (7), aroma profiles (8), and spectroscopic techniques (9-11).With regard to the FA composition of the two coffee varieties, an unambiguous position among authors is not yet available, especially when roasted beans are considered (12-16).Therefore, the approach presented in this paper is (i) a new attempt to verify the utility of FA profiles in the discrimination between arabica and robusta coffee varieties, both in the green and roasted stage, (ii) a study of the possible role played by trans isomers of unsaturated FA in the discrimination of the roasted coffees, and (iii) an attempt to develop a statistical model for green and roasted arabica and robusta coffee varieties for use as a starting point for the development of a database. EXPERIMENTAL PROCEDURES Samples.A total of 16 samples of coffee beans from C. canephora Pierre ex Froehner var. robusta and 8 samples of C. arabica Linn., before and after roasting, were studied. The 16 C. robusta samples in the green stage were identified as RG01-RG16, and the same 16 samples after roasting were identified as RR01-RR16. These samples had several geographical origins (India, Vietnam, Uganda, Amboim/Angola, Angola, Cameroon, and the Ivory Coast). Like the C. robusta samples, the 8 C. arabica samples were prepared in green and roasted st...