Araceli Peña-Alvarez

Analysis of capsaicin and dihydrocapsaicin in peppers and pepper sauces by solid phase microextraction–gas chromatography–mass spectrometry

A simple method for the analysis of capsaicin and dihydrocapsaicin in peppers and pepper sauces by solid phase microextraction-gas chromatography-mass spectrometry has been developed. A novel device was designed for direct extraction solid phase microextraction in order to avoid damage to the fiber. The analysis was performed without derivatization for the gas chromatography-mass spectrometry analysis. Selection fiber, extraction temperature, extraction time and pH, were optimized. The method was linear in the range 0.109-1.323 microg/mL for capsaicin and 0.107-1.713 microg/mL for dihydrocapsaicin with correlation coefficient up to r=0.9970 for both capsaicinoids. The precision of the method was less than 10%. The method was applied to the analysis of 11 varieties of peppers and four pepper sauces. A broad range of capsaicin (55.0-25 459 microg/g) and dihydrocapsaicin (93-1 130 microg/g) was found in the pepper and pepper sauces samples (4.3-717.3 and 1.0-134.8 microg/g), respectively.

Capabilities and limitations of dispersive liquid–liquid microextraction with solidification of floating organic drop for the extraction of organic pollutants from water samples

Dispersive liquid-liquid microextraction with solidification of floating organic drop (DLLME-SFO) is one of the most interesting sample preparation techniques developed in recent years. Although several applications have been reported, the potentiality and limitations of this simple and rapid extraction technique have not been made sufficiently explicit. In this work, the extraction efficiency of DLLME-SFO for pollutants from different chemical families was determined. Studied compounds include: 10 polycyclic aromatic hydrocarbons, 5 pesticides (chlorophenoxy herbicides and DDT), 8 phenols and 6 sulfonamides, thus, covering a large range of polarity and hydrophobicity (LogKow 0-7, overall). After optimization of extraction conditions using 1-dodecanol as extractant, the procedure was applied for extraction of each family from 10-mL spiked water samples, only adjusting sample pH as required. Absolute recoveries for pollutants with LogKow 3-7 were >70% and recovery values within this group (18 compounds) were independent of structure or hydrophobicity; the precision of recovery was very acceptable (RSD<12%) and linear behavior was observed in the studied concentration range (r(2)>0.995). Extraction recoveries for pollutants with LogKow 1.46-2.8 were in the range 13-62%, directly depending on individual LogKow values; however, good linearity (r(2)>0.993) and precision (RSD<6.5%) were also demonstrated for these polar solutes, despite recovery level. DLLME-SFO with 1-dodecanol completely failed for extraction of compounds with LogKow≤1 (sulfa drugs), other more polar extraction solvents (ionic liquids) should be explored for highly hydrophilic pollutants.

Enzymatic hydrolysis of fructans in the tequila production process.

In contrast to the hydrolysis of reserve carbohydrates in most plant-derived alcoholic beverage processes carried out with enzymes, agave fructans in tequila production have traditionally been transformed to fermentable sugars through acid thermal hydrolysis. Experiments at the bench scale demonstrated that the extraction and hydrolysis of agave fructans can be carried out continuously using commercial inulinases in a countercurrent extraction process with shredded agave fibers. Difficulties in the temperature control of large extraction diffusers did not allow the scaling up of this procedure. Nevertheless, batch enzymatic hydrolysis of agave extracts obtained in diffusers operating at 60 and 90 degrees C was studied at the laboratory and industrial levels. The effects of the enzymatic process on some tequila congeners were studied, demonstrating that although a short thermal treatment is essential for the development of tequilas organoleptic characteristics, the fructan hydrolysis can be performed with enzymes without major modifications in the flavor or aroma, as determined by a plant sensory panel and corroborated by the analysis of tequila congeners.

Characterization of Five Typical Agave Plants Used To Produce Mezcal through Their Simple Lipid Composition Analysis by Gas Chromatography

Five agave plants typically used in Mexico for making mezcal in places included in the Denomination of Origin (Mexican federal law that establishes the territory within which mezcal can be produced) of this spirit were analyzed: Agave salmiana ssp. crassispina, A. salmiana var. salmiana, Agave angustifolia, Agave cupreata, and Agave karwinskii. Fatty acid and total simple lipid profiles of the mature heads of each plant were determined by means of a modified Bligh-Dyer extraction and gas chromatography. Sixteen fatty acids were identified, from capric to lignoceric, ranging from 0.40 to 459 microg/g of agave. Identified lipids include free fatty acids, beta-sitosterol, and groups of mono-, di-, and triacylglycerols, their total concentration ranging from 459 to 992 microg/g of agave. Multivariate analyses performed on the fatty acid profiles showed a close similarity between A. cupreata and A. angustifolia. This fact can be ascribed to the taxa themselves or differences in growing conditions, an issue that is still to be explored. These results help to characterize the agaves chemically and can serve to relate the composition of mezcals from various states of Mexico with the corresponding raw material.

ANALYSIS OF CAPSAICIN AND DIHYDROCAPSAICIN IN HOT PEPPERS BY ULTRASOUND ASSISTED EXTRACTION FOLLOWED BY GAS CHROMATOGRAPHY–MASS SPECTROMETRY

A simple method for the analysis of capsaicin and dihydrocapsaicin in peppers by ultrasound assisted extraction (USAE) followed by gas chromatography–mass spectrometry (GC-MS) has been developed. USAE conditions were optimized by experimental design in order to maximize analyte extraction. A full factorial design involving extraction variables such as solvent (ethanol and water), extraction time (5–25 min), extraction temperature (25–50 °C), sample amount (0.25–0.5 g), and ultrasound amplitude (40–80%) was applied. The most significant conditions for capsaicinoid extraction by USAE were solvent type, extraction time, and sample amount. The obtained results were compared with other extraction methods: the official Soxhlet method and a previously reported solid phase microextraction method. Results showed that the extraction efficiency with the application of USAE (98%) was as good as that obtained with Soxhlet and the precision of recovery was less than 5%; in addition, the extraction time was decreased from 5 h to 25 min. The GC-MS analytical method was linear in the range 10–100 μg/mL for capsaicin and dihydrocpsaicin with correlation coefficient r = 0.998 and peak area variability of ∼1% for both capsaicinoids. The method was applied to the analysis of 11 varieties of hot peppers cultivated in México. A large concentration range for capsaicin (101–6800 μg/g) and dihydrocapsaicin (110–2736 μg/g) was found in these pepper samples.