Development of Avocado Reference Material for Pesticide Residue Analysis.

BACKGROUND: Pesticide quantitation in foods relies on the availability of matrix reference materials, which, however, are scarce because of the general instability of pesticides. In particular, no avocado reference material has been developed. OBJECTIVE: This research aimed to develop a reference material to support the determination of pesticide residues in avocado. METHOD: Avocado was spiked with 11 selected pesticides at levels of 0.01-0.35 mg/kg. The production process included the assessment of between-unit heterogeneity, stability during dispatch, and best storage conditions according to ISO 17034. Reference values were estimated through an interlaboratory comparison study involving laboratories of demonstrated competence and adhering to ISO/IEC 17025. The corresponding expanded uncertainties were calculated as 4-19% in compliance with the Guide to the Expression of Uncertainty in Measurement. RESULTS: The reference material was sufficiently homogeneous and stable at 4°C during the entire study period (365 days) for most of the pesticides, and at 40°C during 10 days, but it was unstable at 50 and 60°C during 10 days. Four pesticides showed downward trends; however, this behavior was considered in the uncertainty budget. As this material complied with all requirements of proficiency testing, it was used in an interlaboratory proficiency test designed to investigate analytical performance and assist laboratories in improving the quality of measurement results. CONCLUSIONS: The presented material can be used for the development of novel analytical methods or in-house reference materials and adds to the scarce supply of reference materials for the determination of pesticides in vegetable matrixes with high oil contents and intermediate water contents. HIGHLIGHTS: A novel reference material has been developed for the reliable and accurate quantitation of multiple pesticides in avocado, allowing researchers to avoid the preparation of in-house reference materials for this purpose.

Enhancement of fine flavour cocoa attributes under a controlled postharvest process.

Despite the importance of fermentation for cocoa quality, process parameters are not controlled under spontaneous conditions at farms. This study evaluates the influence of spontaneous fermentation and processing under laboratory-controlled conditions using the acidic reagents acetic and lactic acids on the cocoa quality of two cultivars, FEAR 5 and CCN 51, at the sensory and metabolomic levels. Under spontaneous conditions, cocoa differs in flavour quality. While FEAR 5 produces chocolate with good global quality, chocolate made with CCN 51 does not have outstanding quality attributes. Transformation under controlled conditions with acidic reagents increases the perception of fine aromatic notes such as fruity, nutty and floral attributes in chocolates made from both cultivars of cocoa. Metabolomic profiles allowed grouping of cocoa samples as a function of postharvest treatment. Twenty-five differential metabolites were identified during the postharvest processes, and these metabolites may be related to the expression of fine sensory attributes; however, more research is needed.

Detection of antipersonnel landmines containing ANFO-based explosive: A review / Detección de minas antipersonal que contienen explosivos tipo ANFO: una revisión / Detecção de minas terrestres antipessoal contendo explosivo à base de ANFO: Uma revisão

Resumen After an internal conflict that lasted over half a century, the detection and removal of antipersonnel landmines in Colombia have become cumbersome challenges. Antipersonnel landmines remain scattered in Colombia and with a considerable impact on the central-western region. Most of these devices are handmade (therefore, they can also be classified as improvised explosive devices) and composed of ammonium nitrate and fossil fuel blend, a mixture known as ANFO. Due to several unique factors, including concealment tactics and non-conventional manufacturing techniques employed by guerrilla fighters, the most efficient method for the detection of ANFO-based antipersonnel landmines is the use of trained canines. This review aims at describing the current chemical strategies used in the detection of ANFO-based antipersonnel landmines. First, a detailed description of the different techniques used in the detection of explosives is made. Then, all the strategies reported in the world for antipersonnel landmines detection are described. Finally, the importance of the use of canines for antipersonnel landmines detection is explained.

Abstract Después de un conflicto interno que duró más de medio siglo, la detección y eliminación de minas antipersonales en Colombia se han convertido en desafíos engorrosos. Las minas antipersonales siguen dispersas en la región centro-occidental de Colombia. La mayoría de estos dispositivos están hechos a mano (hecho que puede clasificarlos como artefactos explosivos improvisados, AEI) y están compuestos por una mezcla de nitrato de amonio y un combustible fósil, una mezcla conocida como ANFO. Debido a varios factores únicos, que incluyen tácticas de ocultación y técnicas de fabricación no convencionales empleadas por guerrilleros, el método más eficiente para la detección minas antipersonales basadas en ANFO es el uso de caninos entrenados. Esta revisión tiene como objetivo describir las estrategias químicas actuales utilizadas en la detección de minas antipersonales basadas en ANFO. En primer lugar, se hace una descripcion detallada de las diferentes técnicas utilizadas en la detección de explosivos; luego, se describen todas las estrategias reportadas en el mundo para la detección de minas antipersonales y, finalmente, se explica la importancia del uso de caninos para la detección de minas antipersonales.

Resumo Após um conflito interno que durou mais de meio século, a detecção e remoção de minas antipessoal na Colômbia se tornaram desafios complexos. As minas antipessoal continuam espalhadas na região centro-oeste da Colômbia. A maioria desses dispositivos é feita à mão (fato que pode classificá-los como dispositivos explosivos improvisados, DEI) e composta de uma mistura de nitrato de amônio e um combustível fóssil - uma mistura conhecida como ANFO. Devido a vários fatores únicos, incluindo táticas de ocultação e técnicas de fabricação não convencionais empregadas por guerrilheiros, o método mais eficiente para a detecção de minas antipessoal baseadas em ANFO é o uso de caninos treinados. Esta revisão visa descrever as estratégias químicas atuais usadas na detecção de minas antipessoal baseadas em ANFO. Primeiro, é feita uma descrição detalhada das diferentes técnicas utilizadas na detecção de explosivos; Em seguida, são descritas todas as estratégias relatadas no mundo para a detecção de minas antipessoal e, finalmente, é explicada a importância do uso de caninos para a detecção de minas antipessoal.

Volatile Organic Compounds, Spectral Characterization and Morphology of Ammonium Nitrate Fuel Oil (ANFO) Samples.

Ammonium nitrate fuel oil is an explosive mixture found in most antipersonnel landmines (APL) buried throughout the Colombian territory. During more than 50 years of internal conflict, the Colombian government has found that trained dogs are the most effective method to detect APL. However, the olfactive signature in ANFO is unknown and also if there are differences in detection related to the explosive manufacturing origin. Therefore, this work begins with the analytical validation of the method used to determine ammonia, in its derivatized form as carbamate, released by home-made ANFO using HS-SPME-GC-FID. Once validated, the method was used to identify ammonia and other organic volatile compounds present in ANFO, under laboratory and simulated field conditions. The validation process includes the evaluation of the optimum conditions for the derivation and extraction of butylcarbamate, the determination of the working ranges with linear response in FID, the limits of detection and quantification, the sensitivity, and the precision. The results of the validation established linearity and sensitivity in a concentration between 20 and 120 mg/L, as well as low limits of detection and quantification of 6.4 and 21.4 mg/L, respectively. Also, an intermediate precision of 11% for butylcarbamate with a repeatability of 8%. The validated method showed in real samples of home-made ANFO besides ammonia, the presence of low molecular methylamines, and also exhibited differences in volatile compositions according to the origin. The objective of this work is to offer a reliable analytical methodology for the extraction and analysis of volatile compounds from ANFO.

Validation of an HPLC Method for Determination of Bisphenol-A Migration from Baby Feeding Bottles.

A simple and economic high-performance liquid chromatography (HPLC-UV-Vis) analytical method was validated for the quantitation of specific Bisphenol-A migration from baby feeding bottles. Overall and specific migration assays were done with different food simulating matrices using the filling method. Good linearity was obtained over the concentration range of 0.01-0.6 mg/kg. The limit of detection (LOD) and limit of quantification (LOQ) were 0.004 and 0.010 mg/kg, respectively. The repeatability of the method (%RSD, n=10) was between 89.5 and 99.0%, while recovery ranged from 83.2 to 98.4%. The method was applied to specific migration assays from baby feeding bottles purchased from different plastic producers in Colombia. The results show that, in a first migration assay, Bisphenol-A was not detectable in all samples. In a second migration test, Bisphenol-A concentrations were higher than the most restricted limit (0.05 mg/kg) with ethanol 95% and isooctane as food simulants.

Ensayo de migración global en empaques para alimentos: evaluación de patrones internos alternativos / Overall migration test in food packaging: Evaluation of alternative internal standards / Ensaio de migração global em embalagens de alimentos: avaliação de padrões internos alternativos

Resumen En el ensayo de migración global para empaques plásticos destinados a alimentos grasos se emplea triheptadecanoato de glicerilo (GTM) como patrón interno para la cuantificación de los ésteres metílicos de ácidos grasos (FAMEs) por cromatografía de gases. En este trabajo se evaluaron 3-fenil propanoato de etilo (EFP) y ácido tetradecanóico (AM) como patrones internos alternativos. El uso de AM presentó comportamiento lineal (r > 0,99 y %Sb < 5%), buena precisión intermedia (HORRATr % 0,9) y exactitud (%R % 100,6%). En contraste, la evaluación del EFP, demostró que este no es un patrón interno adecuado para la cuantificación de FAMEs. De otra parte, se evaluó estadísticamente que no hay diferencias significativas en el cálculo de la migración global a partir de FAMEs cuantificados usando como patrón interno GTM o AM, mientras que el uso de EFP sí presenta diferencias significativas.

Abstract In the global migration test for plastic packaging intended for fatty foods, glyceryl triheptadecanoate (GTM) is used as the internal standard for the quantification of fatty acid methyl esters (FAMEs) by gas chromatography. In this work, ethyl 3-phenyl propanoate (EFP) and tetradecanoic acid (AM) were evaluated as alternative internal standards The use of AM presented linear behavior (r > 0.99 and %Sb < 5%), good intermediate precision (HORRATr % 0.9), and accuracy (%R % 100.6%). In contrast, the evaluation of EFP demonstrated that this is not an adequate internal standard for the quantification of FAMEs In addition, it was statistically evaluated that there are no significant differences in the calculation of the global migration from FAMEs quantified using either GTM or AM as internal standards, but the use of EFP presents significant differences.

Resumo No ensaio de migração global para embalagens plásticas destinadas aos alimentos gordurosos, é usado o triheptadecanoato de glicerina (GTM) como padrão interno para a quantificação dos ésteres metílicos de ácidos gordos (FAMEs) mediante cromatografia em fase gasosa. Neste papel foram avaliados 3-fenil propanoato de etilo (EFP) e ácido tetradecanóico (AM) como padrões internos alternativos O (AM) apresentou comportamento linear (r > 0,99 e %Sb < 5%), boa precisão intermédia (HORRATr % 0,9) e precisão (%R % 100,6%). Em contraste, a avaliação do (EFP), mostrou que este não é um padrão interno adequado para a quantificação de FAMEs Por outro lado, uma avaliação estatística indicou que não há diferenças significativas no cálculo da migração global de FAMEs quantificadas utilizando como padrão interno GTM ou AM, em contrapartida o uso do EFP apresenta diferenças significativas.

Evaluación de la actividad fungicida e identificación de compuestos orgánicos volátiles liberados por Trichoderma viride / Evaluation of fungicidal activity and identification of volatile organic compounds released by Trichoderma viride

Resumen Los metabolitos secundarios producidos por hongos son ampliamente diversos en estructura y función, lo que provee una fuente de compuestos con actividad biológica para aplicaciones en agricultura, farmacia y procesamiento de alimentos. Entre los metabolitos secundarios se encuentran compuestos orgánicos volátiles (COVs) a los cuales se atribuye un papel determinante en la comunicación entre microorganismos. En este trabajo empleamos una cámara de ensayos comunicada por el espacio de cabeza para evaluar la actividad debida únicamente a COVs. Los resultados indican que los COVs liberados por T. viride afectan el crecimiento de los hongos fitopatógenos evaluados. En el caso de Fusarium sp. se afectaron los halos de crecimiento y para Colletotrichum gloeosporioides se observaron cambios morfológicos en su color. Para identificar los COVs responsables de esta actividad, se usaron 3 técnicas de extracción: Headspace dinámico (HSD), headspace estático (HSE) y extracción líquido-líquido (ELL) y el análisis por cromatografía de gases acoplada a espectrometría de masas (GCMS). Mediante el muestreo del HSD y HSE se encontraron alcoholes y lactonas, mientras que en ELL los compuestos mayoritarios fueron alcoholes y varios ácidos orgánicos. Entre los compuestos determinados por las tres técnicas se encuentran alcohol bencílico, alcohol 2-feniletílico, 6-pentil-2H-piran-2-ona y gama-butirolactona. Esta última identificada por primera vez en T. viride. La comparación de las tres técnicas de extracción permitió establecer que HSD es el método de extracción de COVs que mejor simula la situación presentada en la cámara de evaluación de actividad biológica, permitiendo así identificar los COVs responsables de la actividad antifúngica detectada.

Abstract The secondary metabolites produced by fungi widely vary in structure and function, providing a rich source of biologically active compounds with applications in farming, pharmacology and food processing. Volatile organic compounds (VOCs) are a biologically relevant class of secondary metabolites, since they are suspected of playing a crucial role in the communication between microorganisms. In this work, we use a test headspace chamber to evaluate the VOCs mediated antifungal activity of T. viride against Fusarium sp. and Colletotricum gloeosporiodes. We observed that VOCs produced by T. viride interact with both fungi affecting the growth halos of Fusarium sp. and modifying the colour of Colletotricum gloeosporiodes. The VOCs responsible for this activity were identified using three extraction techniques: Dynamical Headspace (DHS), Static Headspace (SHS) and liquid-liquid extraction (LLE), all of them analyzed via gas chromatography coupled to mass spectrometry (GCMS). DHS and SHS identified alcohols and lactones as VOCs, while with LLE we found a large number of alcohol components and several organic acids. All three techniques identified benzyl alcohol, 2-phenylethyl alcohol, 6-pentyl-2H-pyran-2-one and, for the first time associated to T. viride, gama-butirolactone. After comparison between these extraction techniques, we established that DHS provides the most accurate simulation of biological activity in the test chamber, which reflects in a reliable identification of the VCOs with antifungal activity.

Chemical studies on curuba (Passiflora mollissima (Kunth) L. H. Bailey) fruit flavour.

The odour-active volatiles of curuba fruit (Passiflora mollissima (Kunth) L. H. Bailey) were isolated by solvent assisted flavour evaporation (SAFE). GC-O and GC-MS analyses identified linalool, hexyl acetate, 1,8-cineole, and butyl acetate as key aroma compounds of this fruit. Other odorants relevant because of their contribution to the overall aroma were: 2-methylpropyl acetate, (Z)-3-hexen-1-ol, and (Z)-3-hexenyl acetate. Sulphur compounds, 3-sulfanylhexyl acetate and methional, were reported here for first time as odour-active volatiles in curuba. By HPLC-ESI-MS analyses of glycosidic mixtures and GC-MS analyses of volatiles released enzymatically with a glucosidase, (Z)-3-hexenyl ß-D-glucopyranoside and linalyl ß-D-glucopyranoside were identified as aroma precursors in P. mollissima fruit. Thermal treatment of the glycosidic mixture at native pH of fruit gave furanoid cis- and trans-linalool oxides, as well as, α-terpineol, compounds that exhibit flowery odour notes. Biogenic relationships among odour-active volatiles and their glycosidic precursors were also proposed.

ESTUDIO COMPARATIVO DE LOS COMPUESTOS VOLÁTILES DE TRES VARIEDADES DE GUAYABA BLANCA (Psidium guajava L.) DURANTE SU MADURACIÓN / COMPARATIVE STUDY OF VOLATILE COMPOUNDS OF THREE WHITE GUAVA VARIETIES (Psidium guajava L.) DURING RIPENING / ESTUDO COMPARATIVO DE COMPOSTOS VOLÁTEIS DE TRÊS VARIEDADES DE GOIABA BRANCA (Psidium guajava L.) DURANTE A MATURAÇÃO

La formación de los compuestos volátiles durante la maduración de la guayaba (Psidium guajava L.) ha sido un aspecto ampliamente estudiado; sin embargo, se desconocen los cambios de estos compuestos en variedades blancas de los cultivos colombianos como Guavatá Victoria (GV), Regional Blanca (RB) y Ráquira (RQ). Se utilizó el método Headspace-Microextracción en Fase Sólida (HS-MEFS) para comparar los perfiles olfativos de tres variedades de guayaba blanca de la región de la hoya del río Suárez (Santander, Colombia) durante tres etapas de maduración (verde, pintón y maduro). En las tres variedades se presentó un comportamiento similar, los aldehidos C-6 (hexanal, (Z)-3-hexenal y (E)-2-hexenal) responsables de la nota verde disminuyen durante la maduración, mientras que el contenido de ésteres (acetato de hexilo y acetato de (Z)-3-hexenilo) aumenta produciéndose las notas dulce y frutal características de la fruta madura. Los compuestos ácidos, furánicos y alcoholes se observan en bajas proporciones durante las tres etapas. El análisis de los compuestos volátiles mediante HS-MEFS permitió establecer una relación entre la transformación de compuestos aldehídos C6, responsables de la nota verde, en ésteres análogos, a los cuales se les atribuye la nota frutal característica durante el proceso de maduración.

The composition of volatile compounds during guava ripening (Psidium guajava L.) has been an aspect broadly studied. However, the changes of these compounds in representative white varieties from Colombia, like Guavatá Victoria (GV), Regional Blanca (RB) and Ráquira (RQ) are still unknown. Comparison of the aroma profiles was done using heads-pace-Solid Phase Micro Extraction (HS-SPME) for three white guava varieties from the Suárez River Basin region (Santander, Colombia) during three maturation stages (green, half-ripened and ripen). The three varieties presented a similar behavior, the C6- aldehydes (hexanal, (Z)-3-hexenal and (E)-2-hexenal) characterized for a green note diminished during ripening, while ester amounts (hexyl acetate and (Z)-3-hexenyl acetate) increase, producing sweet and fruity notes characteristics in a ripen fruit. The acids, furanics and alcohol compounds are present in low proportions at the three stages. Through HS-SPME analysis, we established a relation between C6-aldehy-des compounds transformation, responsible of the green note, into analogue esters that contribute to the fruity note during the ripening process.

A formação dos compostos voláteis durante o processo de amadurecimento da goiaba (Psidium guajava L.) tem sido muito estudada. Entretanto, pouco se conhece sobre as mudanças desses compostos nas variedades brancas representadas pela Guavatá Victoria (GV), Regional Blanca (RB) e Ráquira (RQ) na região do rio Suárez (Santander-Colômbia). O emprego da técnica HS-MEFS (Heads-pace-Microextração em fase sólida) para comparar o perfil olfativo durante as etapas da maturação (verde, semimaduro e maduro) mostrou um comportamento similar nas três variedades de goiaba branca: os aldeídos C-6 (hexanal, (Z)-3-hexe-nal e (E)-2-hexenal), caracterizados por uma nota verde, diminuíram ao longo do amadurecimento, enquanto que o conteúdo de ésteres (acetato de hexilo e acetato de (Z)-3-hexenilo) aumentou, produzindo as notas doces e frutal caracteristicas da fruta madura. Os compostos ácidos, furânicos e alcoólicos foram observados em baixas concentrações nas três etapas de maturação. Por fim, a técnica HS-MEFS permitiu detectar a rápida transformação dos compostos aldeídos C6, causadores da nota verde em ésteres análogos que causam a nota frutal durante o processo da maturação.

CARACTERIZACIÓN DE LOS COMPUESTOS VOLÁTILES ACTIVOS OLFATIVAMENTE EN UCHUVA (Physalisperuviana L.) / CHARACTERIZATION OF ODOR-ACTIVE VOLATILES IN UCHUVA (Physalis peruviana L.) / CARACTERIZAÇÃO DE COMPOSTOS VOLÁTEIS ATIVOS OLFATIVAMENTE EM UCHUVA (Physalis peruviana L.)

Durante el estudio de los compuestos activos olfativamente en el aroma de la uchuva (Physalis peruviana L.) se identificaron los compuestos volátiles, obtenidos por 3 técnicas, extracción líquido-líquido con pentano-diclorometano (1:1) (LL), Solvent-Assisted Flavor Evaporation (SAFE) y í/eadspace-Microextracción en fase sólida (HS-MEFS), y se encontraron diferencias en la calidad del aroma de los extractos mediante el análisis olfato-métrico. La técnica SAFE permitió obtener un extracto con un aroma muy semejante al de la fruta fresca. Los compuestos que presentaron los valores más altos de factor de dilución de aroma (FD) fueron: hexanal, 3-hidroxi-2-butanona, 2-metil-propanol, 2-hidroxibutanoato de etilo, octanoato de etilo y 3-hidroxibutanoato de butilo. En el extracto LL se detectaron algunos compuestos sin actividad olfativa en la fruta; en contraste, mediante la técnica de HS-MEFS no fue posible detectar todos los compuestos activos olfativamente, principalmente los de mayor polaridad. Estos resultados muestran la utilidad del nuevo enfoque de análisis en química de aromas, el cual le da más relevancia al análisis olfativo en estos estudios.

During the study of odor-active active compounds in the aroma of cape gooseberry (Physalis peruviana L.), volatile compounds obtained by three techniques-liquid liquid extraction with penta-ne-dichloromethane (1:1) (LL), Solvent-Assisted Flavor Evaporation (SAFE) and Headspace-Solid Phase Microextraction (HS-SPME) were identified. Differences in the aroma quality of the extracts were found by olfactometric analyses. The SAFE technique allowed obtain in ganextract with similar aroma to the freshfruit. Thecompounds with highest Flavor Dilution factor (FD) value were hexanal, 3-hydroxy-2-butanone, 2-methylpropanol, ethyl 2-hydroxybutanoate, ethyl octanoate, and butyl 3-hydroxybutanoate. Some compounds without olfactive activity in the fruit aroma were detected in the LL extract; in contrast, it was not possible todetectalloftheodor-activevolatilesby using HS-SPME technique, especially those of the most polarity. These results showtheutilityinusingthenewapproach of flavor chemistry analysis, which gives more relevance to the odor analysis during these studies.

Durante o estudo de compostos olfativos ativos no aroma de uchuva (Physalis peruviana L.), foram identificados os compostos voláteis obtidos por três técnicas: extração líquido-líquido com pentano-diclorometano (1:1) (LL), Solvent-Assisted Flavor Evaporation (SAFE) e Heads-pace-Microextração em Fase Sólida (HS-MEFS). Também se acharam diferenças na qualidade do aroma dos extratos por meio de análise de olfatometria. A técnica SAFE permitiu a obtenção de um extrato com um aroma semelhante à fruta fresca. Os compostos que apresentaram os maiores valores de fator de diluição de aroma (FD) foram: hexanal, 3-hidroxi-2-butanona, 2 metilpropanol, octanoato de etilo e 3-hidroxibutanoato de butilo. No extracto LL foram detectados alguns compostos sem atividade olfativa no fruto; em contrapartida, pela técnica de HS-MEFS não foi possível detectar todos os compostos ativos olfativamente, principalmente os de maior polaridade. Estes resultados mostram a utilidade do uso de uma nova abordagem para a análise de química do aroma, que dá mais importância á análise olfativa em estes estudos.

Characterization of the key aroma compounds in pink guava (Psidium guajava L.) by means of aroma re-engineering experiments and omission tests.

Seventeen aroma-active volatiles, previously identified with high flavor dilution factors in fresh, pink Colombian guavas (Psidium guajava L.), were quantified by stable isotope dilution assays. On the basis of the quantitative data and odor thresholds in water, odor activity values (OAV; ratio of concentration to odor threshold) were calculated. High OAVs were determined for the green, grassy smelling (Z)-3-hexenal and the grapefruit-like smelling 3-sulfanyl-1-hexanol followed by 3-sulfanylhexyl acetate (black currant-like), hexanal (green, grassy), ethyl butanoate (fruity), acetaldehyde (fresh, pungent), trans-4,5-epoxy-(E)-2-decenal (metallic), 4-hydroxy-2,5-dimethyl-3(2H)-furanone (caramel, sweet), cinnamyl alcohol (floral), methyl (2S,3S)-2-hydroxy-3-methylpentanoate (fruity), cinnamyl acetate (floral), methional (cooked potato-like), and 3-hydroxy-4,5-dimethyl-2(5H)-furanone (seasoning-like). Studies on the time course of odorant formation in guava puree or cubes, respectively, showed that (Z)-3-hexenal was hardly present in the intact fruits, but was formed very quickly during crushing. The aroma of fresh guava fruit cubes, which showed a very balanced aroma profile, was successfully mimicked in a reconstitute consisting of 13 odorants in their naturally occurring concentrations. Omission tests, in which single odorants were omitted from the entire aroma reconstitute, revealed (Z)-3-hexenal, 3-sulfanyl-1-hexanol, 4-hydroxy-2,5-dimethyl-3(2H)-furanone, 3-sulfanylhexyl acetate, hexanal, ethyl butanoate, cinnamyl acetate, and methional as the key aroma compounds of pink guavas.

Characterization of the aroma-active compounds in pink guava (Psidium guajava, L.) by application of the aroma extract dilution analysis.

The volatiles present in fresh, pink-fleshed Colombian guavas ( Psidium guajava, L.), variety regional rojo, were carefully isolated by solvent extraction followed by solvent-assisted flavor evaporation, and the aroma-active areas in the gas chromatogram were screened by application of the aroma extract dilution analysis. The results of the identification experiments in combination with the FD factors revealed 4-methoxy-2,5-dimethyl-3(2 H)-furanone, 4-hydroxy-2,5-dimethyl-3(2 H)-furanone, 3-sulfanylhexyl acetate, and 3-sulfanyl-1-hexanol followed by 3-hydroxy-4,5-dimethyl-2(5 H)-furanone, ( Z)-3-hexenal, trans-4,5-epoxy-( E)-2-decenal, cinnamyl alcohol, ethyl butanoate, hexanal, methional, and cinnamyl acetate as important aroma contributors. Enantioselective gas chromatography revealed an enantiomeric distribution close to the racemate in 3-sulfanylhexyl acetate as well as in 3-sulfanyl-1-hexanol. In addition, two fruity smelling diastereomeric methyl 2-hydroxy-3-methylpentanoates were identified as the ( R,S)- and the ( S,S)-isomers, whereas the ( S,R)- and ( R,R)-isomers were absent. Seven odorants were identified for the first time in guavas, among them 3-sulfanylhexyl acetate, 3-sulfanyl-1-hexanol, 3-hydroxy-4,5-dimethyl-2(5 H)-furanone, trans-4,5-epoxy-( E)-2-decenal, and methional were the most odor-active.