The Experts below are selected from a list of 4170 Experts worldwide ranked by ideXlab platform
José S. Câmara - One of the best experts on this subject based on the ideXlab platform.
-
Profiling of Passion fruit volatiles: An effective tool to discriminate between species and varieties
Food Research International, 2015Co-Authors: Priscilla Porto-figueira, Ana Freitas, Catarina J. Cruz, José A. Figueira, José S. CâmaraAbstract:Abstract The aim of this work was to gain insights on the volatile composition of nine Passion Fruits grown at Madeira Island (Portugal) – Yellow, Purple, Lemon, Orange, Pineapple, Peach, Melon, Banana and Tomato – and discriminate between them. The volatile composition of these Fruits has been investigated using the same analytical technique, HS–SPME/GC–MS and multivariate analysis (MVA). The selected SPME methodology (DVB/CAR/PDMS fiber at 40 ± 1 °C for 30 min and 10% (w/w) of NaCl under stirring mode (47 × g)) was applied in the profiling of nine different Passion fruit samples by GC–MS, allowing the identification of up to 169 volatile compounds belonging to different chemical groups, namely linear and branched esters, terpenes, alcohols and others. Esters were found to be the dominant metabolites regardless of Passion fruit sample, with hexyl hexanoate (ranging from 6 to 31%), methyl hexanoate (14–75%) ethyl hexanoate (12–53%) and hexyl butanoate (11–26%) being the principal volatile compounds found, followed by cis-β-ocimene (from 8 to 55%), (E)-2-hexenal (4 to 10% for Banana and Tomato Passion fruit samples) and eucalyptol (18% for Tomato Passion fruit). The results revealed that the differences in the volatile profile among the studied Passion Fruits were essentially qualitative, with only 7 common volatiles found in all samples, in different abundance. Advanced statistical techniques (PCA and PLS-DA) were used to explore data. Characteristic markers were successively identified using the NIST library, thus showing that the volatile profile was able to differentiate all nine species and varieties. Profiling of Passion fruit volatile metabolites can provide an effective tool to characterize the product and to extract useful information concerning its quality or geographic origin.
-
Effect of time and temperature on vitamin C stability in horticultural extracts. UHPLC-PDA vs iodometric titration as analytical methods
LWT - Food Science and Technology, 2013Co-Authors: Vítor Spínola, José S. Câmara, Berta Rodrigues Mendes, Paula C. CastilhoAbstract:Abstract Several Fruits and vegetables from Madeira Island (Portugal) were evaluated by two analytical methods for their total vitamin C content ( l -ascorbic acid, l -AA and dehydroascorbic acid, DHAA). DHAA was determined indirectly with DL-1,4-dithiotreitol (DTT) applied as a pre-column reductant. Ultra high performance liquid chromatography coupled to photodiode array (UHPLC-PDA) determinations were compared with l -AA content obtained by a classic iodometric titration method. The stability of vitamin C in horticultural extracts stored at different temperatures was also investigated. Red peppers represented the better source of vitamin C followed by green peppers and papayas. Passion Fruits and cherimoyas were the analyzed foodstuffs with lowest vitamin C content. Both analytical methods were suitable for l -AA analysis in various food commodities, the UHPLC-PDA technique being preferred due to its advantages of selectivity, speed and accuracy. The degradation study showed that horticultural extracts were stable at least 24 h at 4 °C and during 4 weeks when stored at −80 °C.
Gabrieli Alves De Oliveira - One of the best experts on this subject based on the ideXlab platform.
-
comparison of nir and mir spectroscopic methods for determination of individual sugars organic acids and carotenoids in Passion fruit
Food Research International, 2014Co-Authors: Catherine M.g.c. Renard, Gabrieli Alves De Oliveira, Fernanda De Castilhos, Sarah BureauAbstract:Abstract In this work, NIR and MIR spectroscopy was investigated and compared for predicting Passion fruit ripening parameters as sugars, organic acids and carotenoids. Spectra of 56 samples of the lyophilized Passion fruit were collected using an integrating sphere in NIR range and attenuated total reflectance accessory in MIR range. Individual sugars (sucrose, glucose and fructose), organic acids (malic and citric acids) and carotenoids (β-carotene) contents were determined by reference methods. Spectral and reference data were analyzed by principal component analysis. Partial least square regression (PLSR) was used to establish calibration models. MIR technique was better than the NIR technique for glucose (R 2 v = 0.942), fructose (R 2 v = 0.855), sucrose (R 2 v = 0.818), total sugar (R 2 v = 0.914) and citric acid (R 2 v = 0.913) content determination. On the other hand, NIR was superior for total acids (R 2 v = 0.903) content determination. For malic acid and β-carotene contents both methods were unsatisfactory due to low concentrations of these constituents in the Passion Fruits.
Armin Mosandl - One of the best experts on this subject based on the ideXlab platform.
-
Stereoisomeric Flavor Compounds. 72. Stereoisomeric Distribution of Some Chiral Sulfur-Containing Trace Components of Yellow Passion Fruits
Journal of Agricultural and Food Chemistry, 1995Co-Authors: Bernhard Weber, Birgit Maas, Armin MosandlAbstract:The enantiomeric distributions of cis- and trans-2-methyl-4-propyl-1,3-oxathiane and 3-mercaptohexyl acetate and butanoate in Passion fruit extracts were determined by means of multidimensional gas chromatography (MDGC) using sulfur-selective detection. 4S-configured oxathianes and S-configured 3-mercaptohexyl alkanoates of high enantiomeric purity were detected. 2,2-Dimethyl-4-propyl-1,3-oxathiane and 3-mercaptohexyl propanoate were used as internal standard components, allowing a quantification of the volatiles investigated. The trace components were found in a range from less than 0.5 to 18 ppb. The results are discussed with regard to the biosynthesis of these volatiles. Due to the high enantiomeric purities detected, the differentiation between naturally occurring flavor compounds and synthetic racemates added to Passion fruit products is realized conclusively.
-
stereoisomeric flavour compounds stereoisomere aromastoffe lxvi enantiomerenverteilung der chiralen schwefelhaltigen alkohole in gelben und roten Passionsfrchten lxvi enantiomeric distribution of the chiral sulphur containing alcohols in yellow and p
European Food Research and Technology, 1994Co-Authors: Bernhard Weber, Armin Dietrich, Birgit Maas, Anja Marx, Jana Olk, Armin MosandlAbstract:The enantiomeric distribution of 3-mercaptohexanol (1) and 3-methylthiohexanol (2) in yellow and purple Passion Fruits was determined by capillary gas chromatography (GC) using two different chiral stationary phases and a flame photometric detector. The results were confirmed by enantioselective capillary GC combined with mass spectrometric detection. 1 shows an enrichment of the (S)-enantiomer, but the enantiomeric purity varies in a wide range. Irrespective from the enantiomeric distribution of 1, 2 was detected with high enantiomeric purity in favour of the (S)-enantiomer. Using the method presented the addition of synthetic, racemic 2 is easily detected
-
Stereoisomeric flavour compounds@@@Stereoisomere Aromastoffe. LXVI. Enantiomerenverteilung der chiralen schwefelhaltigen Alkohole in gelben und roten Passionsfrchten: LXVI. Enantiomeric distribution of the chiral sulphur-containing alcohols in yellow
Zeitschrift f�r Lebensmittel-Untersuchung und -Forschung, 1994Co-Authors: Bernhard Weber, Armin Dietrich, Birgit Maas, Anja Marx, Jana Olk, Armin MosandlAbstract:The enantiomeric distribution of 3-mercaptohexanol (1) and 3-methylthiohexanol (2) in yellow and purple Passion Fruits was determined by capillary gas chromatography (GC) using two different chiral stationary phases and a flame photometric detector. The results were confirmed by enantioselective capillary GC combined with mass spectrometric detection. 1 shows an enrichment of the (S)-enantiomer, but the enantiomeric purity varies in a wide range. Irrespective from the enantiomeric distribution of 1, 2 was detected with high enantiomeric purity in favour of the (S)-enantiomer. Using the method presented the addition of synthetic, racemic 2 is easily detected
Sarah Bureau - One of the best experts on this subject based on the ideXlab platform.
-
comparison of nir and mir spectroscopic methods for determination of individual sugars organic acids and carotenoids in Passion fruit
Food Research International, 2014Co-Authors: Catherine M.g.c. Renard, Gabrieli Alves De Oliveira, Fernanda De Castilhos, Sarah BureauAbstract:Abstract In this work, NIR and MIR spectroscopy was investigated and compared for predicting Passion fruit ripening parameters as sugars, organic acids and carotenoids. Spectra of 56 samples of the lyophilized Passion fruit were collected using an integrating sphere in NIR range and attenuated total reflectance accessory in MIR range. Individual sugars (sucrose, glucose and fructose), organic acids (malic and citric acids) and carotenoids (β-carotene) contents were determined by reference methods. Spectral and reference data were analyzed by principal component analysis. Partial least square regression (PLSR) was used to establish calibration models. MIR technique was better than the NIR technique for glucose (R 2 v = 0.942), fructose (R 2 v = 0.855), sucrose (R 2 v = 0.818), total sugar (R 2 v = 0.914) and citric acid (R 2 v = 0.913) content determination. On the other hand, NIR was superior for total acids (R 2 v = 0.903) content determination. For malic acid and β-carotene contents both methods were unsatisfactory due to low concentrations of these constituents in the Passion Fruits.
Sylvie Bureau - One of the best experts on this subject based on the ideXlab platform.
-
Comparison of NIR and MIR spectroscopic methods for determination of individual sugars, organic acids and carotenoids in Passion fruit
Food Research International, 2014Co-Authors: Gabrieli Alvès De Oliveira, Fernanda De Castilhos, Catherine Renard, Sylvie BureauAbstract:In this work, NIR and MIR spectroscopy was investigated and compared for predicting Passion fruit ripening parameters as sugars, organic acids and carotenoids. Spectra of 56 samples of the lyophilized Passion fruit were collected using an integrating sphere in NIR range and attenuated total reflectance accessory in MIR range. Individual sugars (sucrose, glucose and fructose), organic acids (malic and citric acids) and carotenoids (beta-carotene) contents were determined by reference methods. Spectral and reference data were analyzed by principal component analysis. Partial least square regression (PLSR) was used to establish calibration models. MIR technique was better than the NIR technique for glucose (R-v(2) = 0.942), fructose (R-v(2) = 0.855), sucrose (R-v(2) = 0.818), total sugar (R-v(2), = 0.914) and citric acid (R-v(2) = 0.913) content determination. On the other hand, NIR was superior for total acids (R-v(2) = 0.903) content determination. For malic acid and beta-carotene contents both methods were unsatisfactory due to low concentrations of these constituents in the Passion Fruits. (C) 2013 Published by Elsevier Ltd.