Volatile compound composition of sea buckthorn juice headspace was investigated before and after malolactic fermentation of the juice. Ethyl acetate, 3-methylbutanol and 3-methylbutyl acetate were formed in abundance during fermentation, whereas concentrations of ethyl 2-methypropanoate, ethyl 3-methylbutanoate, ethyl hexanoate and ethyl octanoate decreased.
The flavours of seven infant formulas were evaluated by Proton Transfer Reaction-Mass Spectrometry analysis (PTR-MS) and sensory analysis. Both types of analysis indicated significant differences between the three brands, the type of formula (infant target group), and the physical form (powder/liquid) of the formulas.
Integrated bioprocess concepts specific to the requirements of monoterpenes as precursors of microbial transformations were developed. R-Limonene and α-pinene were used as model precursors and bacteria and higher fungi served as biocatalysts. A closed-gas-loop bioreactor was set up to address the volatility of terpenoids. By this means α-terpineol was produced from R-limonene at the gram per litre scale with Penicillium digitatum. E. coli overexpressing a P450 BM-3 mutant served as biocatalyst to produce several hundreds of milligrams of pinene oxide, verbenol, and myrtenol from α-pinene. Here, an aqueous-organic two-phase bioreactor with diisononylphthalate as organic solvent was used for in situ precursor supply and product recovery.
Research on technologies to extend the shelf life of fresh salmon is complicated by the need to employ taste panels, which are time-consuming and costly to assess the sensory quality of the product. This research sought to develop an instrumental method of analysis that correlated with sensory results. A method for the analysis of volatiles in fresh salmon during storage was developed using solid phase microextraction (SPME) and gas chromatography. Salmon samples were stored under air or under modified atmosphere. The SPME technique enabled the identification of more than 100 volatile compounds, which were grouped according to whether they increased, decreased, or did not change during storage. There were clear differences in the rate of change of some volatile compounds between different conditions of storage. By comparing trends of the volatiles that changed during storage under different atmospheric conditions it was possible to identify a number of compounds that correlated with sensory changes in the salmon. It is suggested that these compounds could be used in quality control testing as markers for the evolution of salmon freshness during storage.
The aim of this study was to characterise the volatile flavour compounds in a Gruyere-type cheese manufactured from pasteurised milk using different strains of Lactobacillus casei. These strains were used as non-starter cultures to manufacture the different cheeses. A dynamic headspace extraction technique, purge and trap, coupled to gas chromatography-mass spectrometry (GC-MS), and solvent assisted flavour evaporation (SAFE) in combination with GC-MS and GC-olfactometry (GCO) were used to determine the volatile aroma compounds formed after 180 days of ripening. The purge and trap method revealed aldehydes and ketones, such as 2-methylpropanal, 2-methylbutanal, 3-methylbutanal, and 2,3-butanedione, as well as dimethyl disulfide and dimethyl trisulfide among other compounds, which have been described earlier as key aroma compounds of Gruyere and Cheddar cheeses. Free fatty acids were not detected by the purge and trap extraction method. On the other hand, the analysis of the SAFE extract revealed intense signals for propanoic, butanoic, 2- and 3-methylbutanoic acid as well as pentanoic acid and hexanoic acid. Less volatile, more polar odorants, such as the caramel-like 2,5-dimethyl-4-hydroxy-3(2H)-furanone and 2-ethyl-4-hydroxy-5-methyl-3(2H)-furanone, but also the mushroom-like smelling 1-octen-3-one were detected in the SAFE extract by GCO, however, not using purge and trap GC-MS.
Under dynamic gas flow conditions (dynamic headspace or in vivo), the measured volatile concentrations in the headspace are very different to those expected from air-water partition data. This is due to the limited amount of the sample (effectively the immediate surface) which is involved in volatile partitioning, and restricted delivery of molecules from the bulk interior over time. Compounds with high (10−2) air/water partition coefficients deliver flavour inefficiently compared those with lower ones (10−4), primarily because of the proportion of molecules that have to be transferred from the solution to the gas phase as they try to reach equilibrium.
Commercial Cheddar cheeses with and without a beefy/broth-like flavour note had a remarkable similarity in their overall GCO-AEDA and DHDA aroma compounds profiles. However, the beefy/broth-like Cheddar samples had particularly high flavour dilution factors for 3-(methylthio)propanal (methional) and 4-hydroxy-2,5-dimethyl-3(2H)-furanone (Furaneol). 2-Ethyl-4-hydroxy-5-methyl-3(2H)-furanone and 2-methyl-3-furanthiol (MFT) were identified at higher but overall low intensities in broth-like cheeses. Sensory analysis of mild flavoured Cheddar cheese spiked with a combination of methional, Furaneol and MFT showed a more intense beefy/broth-like.
Aroma release from alcoholic solutions is of great interest but the presence of excess ethanol in the APCI-MS system causes non-quantitative ionisation. A recent modification to the APCI source has allowed the study of the liquid/air partitioning of volatiles from ethanolic solutions under both static equilibrium and dynamic headspace conditions. A decrease in the static equilibrium headspace concentration of aroma compounds from ethanolic solutions was noted, depending on their hydrophobicity, while, under dynamic conditions ethanol generally enhanced volatile delivery.
The effect of gum base composition and type of bulk sweetener used in chewing gum on release of different volatile flavour compounds, all present in an artificial fruit flavour, was investigated. Release of single flavour compounds from chewing gum to the nose space during chewing was measured by APCI-MS. Both the gum base composition—one being more polar than the other—and the type of bulk sweetener (sorbitol, xylitol and mannitol, respectively) were found to affect the release of the flavour compounds investigated. Using the more polar gum base, more of the flavour compounds were released during chewing. Using mannitol as the bulk sweetener, more of the flavour compounds were released during chewing.
This work focused on the mass transfer between the gas phase above an aqueous mixture containing proteins and aroma compounds, and a polymer film. A permeation system equipped with a purge-and-trap injector coupled to GC-MS was optimised for this application. The permeability and diffusion kinetics of aroma compounds (from C4 to C8) through a low-density polyethylene film were tested simultaneously. Each permeation curve was obtained independently. The transmission rate for the penetrants is discussed with regard to the transport parameters such as permeability, diffusion, and solubility coefficients but also to the partition coefficient between gas phase (headspace) and liquid phase (protein solution).
Open pollinating cultivars and hybrids of carrots were ecologically cultivated in the spring and autum of 2002 and 2003. Sensory quality, aroma compounds as well as carotene content and texture were evaluated. The paper presents the different effects of genotypes and cultivation conditions on taste and aroma. The volatile compounds β-mycrene, α-humulene and caryophyllene are closely linked with unpleasan sensory sensations and can be proposed as marker for quality selection. In most cases expression of aroma compounds is stronger influenced by the year than by the cultivar.
The aim of the research is to study heritability of the aroma pattern in carrot. This paper presents the results of aroma analyses of 200 single plants from an F2 population using headspace solid phase microextraction GC and pattern recognition for data processing. In a parallel approach molecular markers (AFLP) are developed. Together with additional analyses (sugar and carotenoids) both chemical and molecular data will be used for genome mapping.
The Maillard reaction between [13C6]fructose and alanine was studied in glycerol/water as reaction medium using SPME-GC-MS to analyse the reaction products. Among the identified reaction products were carbonyl compounds such as 2,3-pentanedione as well as several alkylpyrazines. The isotopomer distribution of the products indicated that the ethyl group in the pyrazines stemmed largely from alanine carbons, which were also incorporated in 2,3-pentanedione. These findings are in agreement with the literature. On the other hand, a considerable amount of 2,3-pentanedione was found completely unlabelled as well as a significant percentage of carbons in the pyrazine ring. We supposed that part of the unlabelled carbons originated from glycerol used as reaction solvent. To verify this hypothesis fructose/alanine was reacted in [13C3]glycerol. A substantial percentage of 2,3-pentanedione (17%) and of the alkylated pyrazines (13–33%) was found [13C3]labelled thus confirming the integration of glycerol carbons into these molecules. Consequently glycerol not only influences the Maillard reaction by changing the physiochemical environment, but also participates as a flavour precursor.
In cheese, the breakdown of milk fat into free fatty acids (FFAs) and esters by lipases and esterases contributes to flavour development. Short-chain FFAs and short-chain ethyl esters are important for the flavour of Italian-style cheeses such as Parmesan, Grana Padano, Romano and Provolone. Esterase activity has been identified in the lactic acid bacteria (LAB) used as starter bacteria and in the adjunct microflora during cheese manufacture. A novel esterase gene, designated AA7, was identified in the genome sequence of Lactobacillus rhamnosus HN001. AA7 was shown to be the main intracellular esterase of L. rhamnosus HN001. The enzyme was characterised for both hydrolytic release of FFAs and alcoholytic synthesis of ethyl esters from synthetic substrates. AA7 was shown to be particularly active on short-chain acyl substrates and had a preference for monoacylglycerol substrates. AA7 was used in cheese manufacture and catalysed an accumulation of butyric acid and ethyl esters in cheese, two of the most important flavour compounds in Italian-style cheeses.
A Carotenoid Cleavage Dioxygenase (CCD) gene from Vitis vinifera was isolated and expressed in Escherichia coli. Recombinant VvCCD1 cleaved zeaxanthin symmetrically leading to the formation of 3-hydroxy-β-ionone, a C13-norisoprenoidic compound, and a C14-dialdehyde. Analysis of the gene expression during grape berries development revealed a significant induction of the gene before the onset of ripening, together with an increase in the level of C13-norisoprenoids throughout the maturity.
By application of the Aroma Extract Dilution Analysis on the volatiles of black tea leaves (Darjeeling Gold Selection, DG), linalool, β-ionone, 4-hydroxy-2,5-dimethyl-3(2H)-furanone (4-HDF), 3-hydroxy-4,5-dimethyl-2(5H)-furanone, phenylacetic acid and (E,E,Z)-2,4,6-nonatrienal were identified with the highest Flavour Dilution (FD) factors among the 25 odour-active compounds detected in the FD-factor range of 16 to 256. Quantitative measurements performed on the infusion prepared from DG indicated the same set of odorants as identified in the leaves, but the hot water treatment led to an increase of, in particular, most of the alcohols, i.e. geraniol, 4-HDF, 2-phenylethanol and (Z)-3-hexenol, as well as the Strecker aldehydes methylpropanal and 2-methylbutanal. Infusions prepared from four other black tea leaves of different origins also contained the same set of odorants as the infusion from DG, but the odorants identified varied significantly in their FD-factors.
Carotenoids and carotenoid-derived products were identified in green coffee beans of different origins. After extraction with acetone, the carotenoids, lutein and zeaxanthin, were identified by HPLC-Diode Array Detection. Glycosidically bound ionols were identified as carotenoid-derived products which are known to be formed by oxidative degradation of lutein and zeaxathin [1]. These glycosides were analysed by absorption on XAD-1180 resin followed by enzymatic hydrolysis of the eluted extract with β-glucosidase, and by GC-MS analysis of the released aglycones [2]. The impact of carotenoids on aroma formation was investigated by using a model roasting system. For this purpose, green coffee beans were depleted of their naturally occurring potential aroma precursors, and subsequently enriched with β-carotene, a carotenoid similar in structure to lutein and zeaxanthin. Under coffee roasting conditions, β-carotene yielded the aroma compound, β-ionone, as its major degradation product [3]. Furthermore, the importance of 3-oxo-α-ionol as an aroma precursor was investigated in the model system.
Tahitian vanilla was analysed as part of IFF's ongoing Generessence® programme. This programme involves the in-depth analysis of a natural product to ultimately produce a new truly nature identical flavour and to discover new flavour molecules. Selected Tahitian vanilla beans were imported from French Polynesia and extracted by percolation. The ethanolic extract underwent further liquid/liquid extraction, and sampling by a sorptive stir bar. The volatiles of the beans were analysed by dynamic headspace and GC-MS. A total of 276 components were identified through these 3 analyses. Amongst them were novel compounds not previously reported in Tahitian vanilla [1]. These novel compounds were either purchased or synthesised for confirmation. The major semi-volatiles were analysed by HPLC. In addition the novel compounds were evaluated by an expert panel.
The odour profiles of cooked pork samples with carbohydrates added at four times the estimated natural concentration were investigated. The heated pork samples were analysed by descriptive odour profiling and the aroma volatiles were measured by GCMS. A screening of eleven different flavour precursors, which were mainly carbohydrates, showed that six precursors altered the odour compared to the reference sample without precursor addition. Glucose, glucose 6-phosphate, ribose, ribose 5-phosphate, and fructose increased the caramel and grilled odours, while lactate increased the sour odour. The remaining five precursors did not alter the sensory profile compared to the reference. GC-MS analysis of pork with added glucose, glucose 6-phosphate, and ribose, respectively, showed an increase in the formation of Maillardderived volatiles compared to the reference. Especially samples with added ribose and glucose showed increased levels. Alkylpyrazines were the most abundant class of volatiles identified in the samples.
GCO analysis has been applied to study the aroma profiles of wines from Madeira, Pedro Ximénez, Sherry, Cava and Sauternes. Wine extracts were prepared by dynamic headspace and the most relevant odorants, according to their GCO score, were ranked. Linalool, sotolon and 4-ethylguaiacol were found to be potentially important odorants when characterising some of these wines. The study also revealed the presence of three ethyl esters, not previously reported in wines. Eight additional odorants showing high GCO scores and not detected in normal dry wines remained still unidentified.
