RESUMEN
A protocol was optimized to determine the volatile profile from monovarietal virgin olive oil (VOO) by multiple headspace solid-phase microextraction (MHS-SPME) followed by gas chromatography-mass spectrometry (GC-MS) analysis. For this, a Plackett-Burman (PB) and central composite rotational designs (CCRD) were used to define the best condition of extraction. Moreover, fatty acids profile and principal component analysis (PCA) was used to identify markers among the cultivars. The amount of 0.1 g of sample was enough to express the volatile composition of the olive oils by MHS-SPME. Volatile compounds [nonanal, (Z)-3-Hexen-1-ol, (Z)-3-Hexenyl Acetate, Hexyl Acetate, 3-Methylbutyl Acetate, (E)-2-Hexen-1-ol, (E)-2-Hexenyl Acetate] and fatty acids [C17:1, C18, C18:1, C18:2] were those reported such as the markers in the varieties of olive oils. The PCA analysis allowed the classification of the most representative volatiles and fatty acids for each cultivar. Through two principal components was possible to obtain 81.9% of explanation of the variance of the compounds. The compounds were quantified using a validated method. The MHS-SPME combined with multivariate analysis showed a promising tool to identify markers and for the discrimination of olive oil varieties.
Asunto(s)
Microextracción en Fase Sólida , Compuestos Orgánicos Volátiles , Microextracción en Fase Sólida/métodos , Aceite de Oliva/química , Brasil , Quimiometría , Compuestos Orgánicos Volátiles/análisis , Ácidos Grasos/análisisRESUMEN
This study investigated the diel emission of volatile organic compounds (VOCs) from intact apple (Malus x domestica Borkh., cv. Golden Delicious) and grape (Vitis vinifera L., cv. Pinot Noir) foliage. Volatiles were monitored continuously for 48 h by proton transfer reaction - time of flight - mass spectrometry (PTR-ToF-MS). In addition, volatiles were collected by closed-loop-stripping-analysis (CLSA) and characterized by gas chromatography-mass spectrometry (GC-MS) after 1 h and again 24 and 48 h later. Fourteen and ten volatiles were characterized by GC-MS in apple and grape, respectively. The majority of these were terpenes, followed by green leaf volatiles, and aromatic compounds. The PTR-ToF-MS identified 10 additional compounds and established their diel emission rhythms. The most abundant volatiles displaying a diel rhythm included methanol and dimethyl sulfide in both plants, acetone in grape, and mono-, homo- and sesquiterpenes in apple. The majority of volatiles were released from both plants during the photophase; whereas methanol, CO2, methyl-butenol and benzeneacetaldehyde were released at significantly higher levels during the scotophase. Acetaldehyde, ethanol, and some green leaf volatiles showed distinct emission bursts in both plants following the daily light switch-off. These new results obtained with a combined analytical approach broaden our understanding of the rhythms of constitutive volatile release from two important horticultural crops. In particular, diel emission of sulfur and nitrogen-containing volatiles are reported here for the first time in these two crops.
Asunto(s)
Ritmo Circadiano , Malus/química , Vitis/química , Compuestos Orgánicos Volátiles/análisis , Cromatografía de Gases y Espectrometría de Masas , Hojas de la Planta/química , Terpenos/análisisRESUMEN
The effects of xanthan gum on the release of strawberry flavor compounds in formulated soy protein isolate (SPI) beverage were investigated by headspace gas chromatography (GC). Seven strawberry flavor compounds (limonene, ethyl hexanoate, (Z)-3-hexenyl acetate, ethyl 2-methylbutanoate, ethyl butanoate, (Z)-3-hexen-1-ol and diacetyl) could be detected by GC and hence analyzed the gas-matrix partition coefficients (K). The release of flavor compounds was restrained in SPI and/or xanthan gum solution. The retention of (Z)-3-hexen-1-ol, limonene and diacetyl significantly changed (p<0.05) with increasing xanthan gum concentrations. Presence of any other esters led to suppression of the release of ester compounds in water and SPI solution. The less-volatiles (γ-decalactone, methyl cinnamate, hexanoic acid, 2-methyl butyric acid and furaneol) accelerated the release of ester compounds to some extent in different matrices. The above results demonstrated that presence of SPI and xanthan gum could bring about an imbalance in the strawberry flavor.
Asunto(s)
Fragaria/química , Polisacáridos Bacterianos/química , Leche de Soja/química , BebidasRESUMEN
We studied the chemical composition of oven and freeze dried guava powders for future use as antioxidant-rich flavour enhancers. Among thirty-one volatiles in guava powders, terpenes were predominant, even after both drying processes. In contrast, esters and aldehydes, volatiles characteristic of fresh guava fruit, appeared to have been decreased by drying. Insoluble phenolics were predominant and among the sixteen compounds identified, quercetin-3-O-rutinoside and naringenin corresponded to 56% of total phenolics. Drying processes decreased total phenolics contents by up to 44%. Oven drying promoted the release of insoluble flavonoids, generating mainly quercetin. Antioxidant capacity also decreased due to both drying processes, but guava powders still presented similar antioxidant capacity in comparison to other tropical fruit powders. Our results suggest that oven drying is a viable option for the production of a functional ingredient that would improve the phenolic content of cereal foods while adding desirable guava flavour.