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Aroma Compounds (aroma + compound)
Selected AbstractsODOR PERCEPTION OVER LIQUID EMULSIONS CONTAINING SINGLE AROMA COMPOUNDS: EFFECTS OF AROMA CONCENTRATION AND OIL VOLUME FRACTIONJOURNAL OF SENSORY STUDIES, Issue 6 2002CHANTAL BROSSARD ABSTRACT This study aimed to check the hypothesis that aroma concentration in the aqueous phase of an oil-in-water emulsion controlled the odor intensity of single aroma compounds. A set of flavored oil-in-water emulsions, prepared according to a 22 experimental design (aroma concentration, oil volume fraction) with two central points, was assessed for odor intensity by a 24-member panel during four sessions. In each session, three of the four-studied aroma molecules (benzaldehyde, ethyl butyrate, linalool and acetophenone) were investigated. Whatever the aroma, the experimental data showed that the oil volume fraction of the emulsion (from 0.12 to 0.48) did not influence the odor intensity. For each emulsion composition, aroma concentrations at equilibrium in both phases were calculated using the oil-water partition coefficient of the compound. Odor intensities, estimated from aroma concentration in the aqueous phase using previously reported modeling of odor intensity above water solutions, were then compared to experimental data. It is confirmed that the perceived odor intensity is governed by the aroma concentration in the aqueous phase at the time of the trial and not by the averaged apparent concentration in the emulsion. [source] INFLUENCE OF AROMA COMPOUNDS ON LARGE DEFORMATION PROPERTIES OF STARCH-BASED SYSTEMS DURING AGINGJOURNAL OF TEXTURE STUDIES, Issue 3 2001G. ARVISENET The effect of aroma compounds on the texture of gelled aqueous corn starch systems was studied by uniaxial compression during aging for 18 days. Three different types of behavior were observed, depending on the nature of the added aroma compound. Isoamyl acetate did not modify the measured parameters, compared with nonflavored products. Linalool, known for its ability to form inclusion complexes with amylose, modified the parameters which are usually considered to be governed by the rearrangement of amylose chains. Ethyl hexanoate modified the parameters depending mostly on amylopectin. These results suggest that the nature of the aroma compound may play a major role in interactions with starch. These interactions can be different from inclusion complexes involving amylose chains only, the latter being widely described by different authors. [source] Recovery of Aroma Compounds from Dilute Model Blueberry Solution by PervaporationJOURNAL OF FOOD SCIENCE, Issue 9 2003M. PENG ABSTRACT Pervaporation (PV) is a membrane-separation process showing unique capability of separating target compound(s) from dilute systems. Experiments were performed on a bench-scale flat sheet PV unit with a model solution to evaluate separation factor of 6 constituent aroma compounds (1-hexanol, 1-heptanol, trans-2-hexenal, ethyl acetate, linalool, and d-limonene), representing some of typical flavoring ingredients from blueberry juice. The results showed that separation factor was in the range of 70 to 430, depending on molecule size and polarity property of the compounds. Except for 1-heptanol, all compounds showed no significant coupling effect in the mixture system. The effect of temperature was also examined for a given feed-flow rate. Keywords: pervaporation, membrane, aroma compounds, blueberry, multicomponent diffusion [source] Decomposition and Transformation of Aroma Compounds and Anthocyanins during Black Currant (Ribes nigrum L.) Juice ProcessinJOURNAL OF FOOD SCIENCE, Issue 9 2002B.B. Mikkelsen ABSTRACT: Processing of black currant juice includes crushing, heating, enzyme treatment, pressing, pasteurization, clarification, and filtration. Changes in concentration of impact aroma compounds and anthocyanins during black currant juice processing in pilot plant scale were examined. Impact compounds were identified by gas chromatography-olfactometry and quantified by dynamic headspace and gas chromatography-mass spectrometer. Anthocyanins were analyzed by the pH-differential method. Identified aroma compounds comprised volatiles like esters, terpenes, terpenoids, and ketones. The reduction of aroma compounds and anthocyanins during the process was approximately 50 to 100% and 25%, respectively. The pressing step definitely had a negative effect on the concentration of aroma compounds and anthocyanins, and the heating treatments were mainly negative as well. [source] Transcriptional analysis of the gdhA gene in Streptococcus thermophilusJOURNAL OF APPLIED MICROBIOLOGY, Issue 4 2009C. Lazzi Abstract Aims:, To study the transcriptional analysis of glutamate dehydrogenase gene, involved in the amino acid conversion to aroma compound in Streptococcus thermophilus. Methods and Results:, Analysis of the gdhA gene nucleotide sequence of S. thermophilus CNRZ1066 revealed that the coding region is 1353 nucleotides long. The deduced amino acids sequence exhibits the putative GDH active site and some conserved domains characteristic of family I of hexameric GDHs. Phylogenetic analysis revealed that the gdh gene of S. thermophilus clustered with the orthologues of other streptococci such as Streptococcus mutans, Streptococcus agalactiae and Streptococcus infantarius. Studying the structural organization of the gdhA locus the amino acid similarity of GDHs was higher than 87%, but the locus organization was not conserved. A dominant transcript of approximately 1·4 kbp was revealed by Northern blot hybridization, suggesting that gdhA mRNA is monocystronic. Primer extension showed that transcription start point of gdhA was localized 43 bp upstream of the potential start codon (ATG). Conclusions:, The gdhA represents a monocistronic operon highly conserved in phylogenetic-related bacteria. Significance and Impact of the Study:, A deeper knowledge of gdh transcriptional mechanisms could lead to develop S. thermophilus industrial starter cultures with optimized aromatic properties. [source] INFLUENCE OF AROMA COMPOUNDS ON LARGE DEFORMATION PROPERTIES OF STARCH-BASED SYSTEMS DURING AGINGJOURNAL OF TEXTURE STUDIES, Issue 3 2001G. ARVISENET The effect of aroma compounds on the texture of gelled aqueous corn starch systems was studied by uniaxial compression during aging for 18 days. Three different types of behavior were observed, depending on the nature of the added aroma compound. Isoamyl acetate did not modify the measured parameters, compared with nonflavored products. Linalool, known for its ability to form inclusion complexes with amylose, modified the parameters which are usually considered to be governed by the rearrangement of amylose chains. Ethyl hexanoate modified the parameters depending mostly on amylopectin. These results suggest that the nature of the aroma compound may play a major role in interactions with starch. These interactions can be different from inclusion complexes involving amylose chains only, the latter being widely described by different authors. [source] Interactions between aroma compounds and latex films: partition coefficients and influence on latex film formationPACKAGING TECHNOLOGY AND SCIENCE, Issue 2 2006A. Nestorson Abstract The potential of various latex grades to take up, retain and release different types of aroma compound has been explored. The latex grades used included two styrene,acrylate latices and two styrene,butadiene latices, of which one contained talc. The aroma compounds used were ethyl butyrate, 1-hexanol, heptanal, 3-octanone, ,-pinene and limonene dissolved in propylene glycol. It was shown that talc improves both the uptake of aroma compounds in the dispersion phase and the retention during the film formation process. However, the styrene,acrylate latex had a greater ability than the styrene,butadiene latex to hold the aroma compounds once the films were formed. These results have been compared to calculated solubility parameters. The uptake of 1-hexanol and propylene glycol in the latex dispersions were higher than expected from the theoretical calculations, probably because of the amphiphilic nature of these molecules. In addition, the influence of aroma compounds on the film formation was evaluated. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effect of polyphenols on the perception of key aroma compounds from Sauvignon Blanc wineAUSTRALIAN JOURNAL OF GRAPE AND WINE RESEARCH, Issue 1 2009C.M. LUND Abstract Background and Aims:, Sensory wine research has mainly focused on the role of volatile compounds and their contribution to the aroma profile. Wines also contain polyphenolic compounds, which are not volatile. This research begins to investigate the interactions of volatile and non-volatile wine compounds and the consequential effects on sensory perception of aroma. Methods and Results:, Trained panellists of this study measured the perception of four aroma compounds (isobutyl methoxypyrazine, 3-mercaptohexanol, 3-mercaptohexanol acetate and ethyl decanoate) in wine. Panellists assessed the four compounds in combinations with three polyphenols (catechin, caffeic acid and quercetin) commonly found in white wine. The perception of isobutyl methoxypyrazine, 3-mercaptohexanol and ethyl decanoate was largely suppressed by the added polyphenols, while the perception of 3-mercaptohexanol was accentuated with the addition of caffeic acid. Of the three polyphenols, only catechin had a slight effect of accentuating the mercaptohexanol acetate perception. Conclusions:, Results showed each polyphenol had a unique effect when blended with a specific aroma compound, either suppressing, accentuating or showing little effect on the perception of the aroma compounds. Significance of the Study:, Understanding these interactions can assist winemakers in managing polyphenol levels to optimize selected volatile compounds to achieve desirable aroma profiles. [source] Downstream Processing of Enzymatically Produced Geranyl GlucosideBIOTECHNOLOGY PROGRESS, Issue 5 2001B. Mattheus de Roode Geraniol plays an important role in the fragrance and flavor industry. The corresponding glucoside has interesting properties as a "slow release" aroma compound. Therefore, the enzymatic production and downstream processing of geranyl glucoside were investigated. Geranyl glucoside was produced in a spray column reactor with an initial production rate of 0.58 mg U,1 h,1. A pretreated hydrophobic microfiltration membrane was used to prevent migration of the aqueous, enzyme-containing phase to the downstream process. No retention of the glucoside, which accumulated in the geraniol phase, was found. On the basis of examples from the literature, four downstream processes were tested on their viability for this system. Extraction with water and foaming were not suitable to recover geranyl glucoside from geraniol. In the first case, the glucoside selectivity for the geraniol phase was found to be high, which made extraction with water unsuccessful. In the second case it was possible to obtain a stable foam, but significant enrichment of the foam with glucoside did not occur. Adsorption on alumina and distillation under reduced pressure were applied successfully and tested in-line with the bioreactor. A maximum glucoside adsorption of 7.86 mg g,1 was achieved on alumina. After desorption and evaporation of the extractant the pure glucoside was obtained quantitatively. A pure product could not be obtained after distillation because a small amount of glucose was present in the permeate as well, which accumulated in the bottom fraction. It was shown that with this reactor system a production of 1 kg of geranyl glucoside in 2 days is possible using an initial amount of 50,000 units of enzyme. [source] Flavour formation by lactic acid bacteria and biochemical flavour profiling of cheese productsFEMS MICROBIOLOGY REVIEWS, Issue 3 2005Gerrit Smit Abstract Flavour development in dairy fermentations, most notably cheeses, results from a series of (bio)chemical processes in which the starter cultures provide the enzymes. Particularly the enzymatic degradation of proteins (caseins) leads to the formation of key-flavour components, which contribute to the sensory perception of dairy products. More specifically, caseins are degraded into peptides and amino acids and the latter are major precursors for volatile aroma compounds. In particular, the conversion of methionine, the aromatic and the branched-chain amino acids are crucial. A lot of research has focused on the degradation of caseins into peptides and free amino acids, and more recently, enzymes involved in the conversion of amino acids were identified. Most data are generated on Lactococcus lactis, which is the predominant organism in starter cultures used for cheese-making, but also Lactobacillus, Streptococcus, Propionibacterium and species used for surface ripening of cheeses are characterised in their flavour-forming capacity. In this paper, various enzymes and pathways involved in flavour formation will be highlighted and the impact of these findings for the development of industrial starter cultures will be discussed. [source] Production of fermentation aroma compounds by Saccharomyces cerevisiae wine yeasts: effects of yeast assimilable nitrogen on two model strainsFEMS YEAST RESEARCH, Issue 7 2008Francisco M. Carrau Abstract The contribution of yeast fermentation metabolites to the aromatic profile of wine is well documented; however, the biotechnological application of this knowledge, apart from strain selection, is still rather limited and often contradictory. Understanding and modeling the relationship between nutrient availability and the production of desirable aroma compounds by different strains must be one of the main objectives in the selection of industrial yeasts for the beverage and food industry. In order to overcome the variability in the composition of grape juices, we have used a chemically defined model medium for studying yeast physiological behavior and metabolite production in response to nitrogen supplementation so as to identify an appropriate yeast assimilable nitrogen level for strain differentiation. At low initial nitrogen concentrations, strain KU1 produced higher quantities of esters and fatty acids whereas M522 produced higher concentrations of isoacids, ,-butyrolactone, higher alcohols and 3-methylthio-1-propanol. We propose that although strains KU1 and M522 have a similar nitrogen consumption profile, they represent useful models for the chemical characterization of wine strains in relation to wine quality. The differential production of aroma compounds by the two strains is discussed in relation to their capacity for nitrogen usage and their impact on winemaking. The results obtained here will help to develop targeted metabolic footprinting methods for the discrimination of industrial yeasts. [source] Metabolic profiling as a tool for revealing Saccharomyces interactions during wine fermentationFEMS YEAST RESEARCH, Issue 1 2006Kate S. Howell Abstract The multi-yeast strain composition of wine fermentations has been well established. However, the effect of multiple strains of Saccharomyces spp. on wine flavour is unknown. Here, we demonstrate that multiple strains of Saccharomyces grown together in grape juice can affect the profile of aroma compounds that accumulate during fermentation. A metabolic footprint of each yeast in monoculture, mixed cultures or blended wines was derived by gas chromatography , mass spectrometry measurement of volatiles accumulated during fermentation. The resultant ion spectrograms were transformed and compared by principal-component analysis. The principal-component analysis showed that the profiles of compounds present in wines made by mixed-culture fermentation were different from those where yeasts were grown in monoculture fermentation, and these differences could not be produced by blending wines. Blending of monoculture wines to mimic the population composition of mixed-culture wines showed that yeast metabolic interactions could account for these differences. Additionally, the yeast strain contribution of volatiles to a mixed fermentation cannot be predicted by the population of that yeast. This study provides a novel way to measure the population status of wine fermentations by metabolic footprinting. [source] Characterization of the aroma-active compounds in five sweet cherry cultivars grown in Yantai (China)FLAVOUR AND FRAGRANCE JOURNAL, Issue 4 2010Shu Yang Sun Abstract This study was conducted to determine the aroma-active compounds of five sweet cherry cultivars grown in Yantai region, China, viz. ,Lapins', ,Rainier', ,Stella', ,Hongdeng' and ,Zhifuhong'. The samples were extracted by headspace solid phase microextraction (HS,SPME) and analysed by gas chromatography,mass spectrometry (GC,MS) on DB-wax and DB-5 columns. A total of 52 volatiles were identified. Among these, hexanal, (E)-2-hexenal, 1-hexanol, (E)-2-hexen-1-ol, benzaldehyde and benzyl alcohol were the main volatile compounds in the five cherries. Furthermore, the aroma compounds of five cherry samples were evaluated using a combination of HS,SPME and GC,olfactometry (GC,O) dilution analysis, and a total of 40 aroma-active compounds were identified. The results suggested that hexanal, (E)-2-hexenal, (Z)-3-hexenal, nonanal, benzaldehyde and geranylacetone (FD , 16), responsible for the green, orange, almond and floral characters of the cherries, were the potentially important common odorants in these cherry cultivars. Benzyl alcohol and linalool were significant aroma compounds in most cherries, with the exception of ,Stella' and ,Rainier'. In addition, (E,Z)-2,6-nonadienal (cucumber-like odour) could be important to ,Hongdeng' and ,Zhifuhong', and (E,E)-2,4-nonadienal (fatty odour) probably made great contributions to the aromas in ,Lapins' and ,Stella'. From the present result, it was concluded that the aroma profiles were similar in the five cherry cultivars, but significant variation was found in the contributions of these compounds to each cherry. Copyright © 2010 John Wiley & Sons, Ltd. [source] Influence of carbonation on aroma release from liquid systems using an artificial throat and a proton transfer reaction,mass spectrometric technique (PTR,MS)FLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2009Maria Ángeles Pozo-Bayón Abstract To determine whether carbonation affects aroma release from liquid systems, carbonated and non-carbonated flavoured model systems were prepared and volatile release was determined under static (equilibrium) and dynamic conditions. A model flavour system was added as a single compound or as a mixture of the six aroma compounds used in this study. Volatile release under dynamic conditions involved using a home-made device simulating an artificial throat, coupled to a proton transfer mass spectrometer (PTR,MS). The results showed that carbonation increased the release of most of the aroma compounds in both static and in dynamic testing conditions. The extent of this effect depended, however, on the physicochemical characteristics of the aroma compounds (the most volatile and most hydrophobic compounds were affected more). Release was also increased if the aroma compounds were added as a mixture rather than as individual compounds. CO2 appears to be a key factor responsible for the enhanced release of flavourings from carbonated liquid systems. Copyright © 2009 John Wiley & Sons, Ltd. [source] Determination of linear response in the detection of mixtures of aroma compounds by atmospheric pressure ionization,mass spectrometry (API,MS)FLAVOUR AND FRAGRANCE JOURNAL, Issue 1 2008Roberto A. Buffo Abstract The linearity of atmospheric pressure ionization,mass spectrometry (API,MS) response in mixtures of aroma compounds was determined for a ,homogeneous' system (four esters) and a ,heterogeneous' system (five compounds of different chemical functionality). All combinations analysed within each system followed a saturation pattern as concentration increased. Total linear responses were determined by the linear behaviour of individual compounds. Ionization patterns within each mixture were explained by proton affinity data (i.e. the species' ability to accept protons), molecular reaction rates (defined by molecular weight), and product ion distribution (according to fragmentation of the corresponding parent ion). Copyright © 2007 John Wiley & Sons, Ltd. [source] Antimicrobial effect of vapours of geraniol, (R)-(,)-linalool, terpineol, , -terpinene and 1,8-cineole on airborne microbes using an airwasherFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2007Kei Sato Abstract Five selected compounds, geraniol, (R)-(,)-linalool, terpineol, , -terpinene and 1,8-cineole, were tested for their influence on airborne microbes when vaporized with an air washer. Terpineol and 1,8-cineole showed the highest antimicrobial activities. The average reduction of germ count was 68% and 64%, respectively. Although , -terpinene gave the lowest result among the compounds investigated, the average reduction of germ count was still 40%. When water without volatile compounds was sprayed, the colony forming units increased. These results show the positive effect of selected aroma compounds on the reduction of microbes in the room. Copyright © 2007 John Wiley & Sons, Ltd. [source] Volatile composition of the laksa plant (Polygonum hydropiper L.), a potential source of green note aroma compoundsFLAVOUR AND FRAGRANCE JOURNAL, Issue 5 2005J. Jiang Abstract Volatile compounds were extracted from laksa plant (Polygonum hydropiper L.) by three isolation techniques,dynamic headspace sampling, simultaneous distillation and extraction (SDE) and liquid,liquid extraction with dichloromethane (DCM). In the GC,MS analysis of the volatile extracts, a total of 46 compounds were identi,ed, including 14 carbonyls, 14 alcohols, 10 hydrocarbons, four esters, two furans, one acid and one base. Carbonyls (aldehydes/ketones) and alcohols are the predominant classes of volatile compounds, accounting for almost 90% (or above) of the total volatiles extracted from the plant. The major compounds include dodecanal (3,40%), (E)-2-hexenal (20,35%), decanal (4,22%), (Z)-3-hexen-1-ol (4,31%), hexanal (1.7,5.1%) and , -caryophyllene (1.7,2.3%). Signi,cantly high levels of both (E)-2-hexenal (leaf aldehyde) and (Z)-3-hexen-1-ol (leaf alcohol) may make the weed plant become a potential source of green note aroma componds. More (Z)-3-hexen-1-ol was found in the stem while more (E)-2-hexenal was detected in the leaf. The laksa stem appeared to contain more decanal and dodecanal but less esters than the leaf. Different isolation techniques produced volatile extracts with different proportions of the major volatile components. Copyright © 2005 John Wiley & Sons, Ltd. [source] Effects of the nature and concentration of substrates in aqueous solutions on the solubility of aroma compoundsFLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2005Marco Covarrubias-Cervantes Abstract The solubility of nine aroma compounds (acetone, 2-butanone, 2-hexanone, 2-octanone, ethyl acetate, ethyl butanoate, ethyl hexanoate, n -hexanal, and n -hexanol) in both water and various aqueous solutions was measured at 25 °C using the mutual solubility method. The aqueous solutions consisted of sucrose, glucose, sorbitol, glycerol, polyethylene glycol 200, or maltodextrins at different concentrations. Aroma solubility in water decreased with increased hydrophobicity. For aroma molecules which have the same number of carbon atoms in their structure, aqueous solubility decreased as follows: aldehyde > methyl ketone > alcohol > ethyl ester. When using a group contribution method, the estimated solubility of ethyl esters and methyl ketones in water was, respectively, underestimated and overestimated. Compared to water, the solubility of the volatile molecules in aqueous solutions was higher in the aqueous polyols solutions than in the carbohydrate solutions, although solubility decreased as substrate concentration increased. Aqueous solutions properties, such as water activity, also in,uenced aroma compound solubility. Copyright © 2004 John Wiley & Sons, Ltd. [source] Perceptual interactions between fruity and woody notes of wineFLAVOUR AND FRAGRANCE JOURNAL, Issue 6 2004Boriana Atanasova Abstract The quantitative olfactory interactions in three binary mixtures of wine aroma compounds were studied. For the ,rst two mixtures, whisky lactone (woody note) was mixed separately with two esters (fruity note), ethyl butyrate and isoamyl acetate. For the third mixture, guaiacol (woody note) was mixed with ethyl butyrate (fruity note). Perceived odour intensity of 24 stimuli (four supra-threshold concentration levels of two compounds and the respective 16 mixtures) were evaluated in ,ve replications, by a trained panel of 13 subjects. The results showed that for the three binary mixtures studied, quantitative perceptual interactions were non-level independent, non-symmetrical, and reached the compromise level of hypo-addition. The experimental data highlighted that generally mixtures with high whisky lactone levels led to the compromise level of mixture intensity perception, whereas mixtures with high fruity note intensity proportions did not. A tendency to hyper-addition was observed in iso-intense mixtures only at the lowest intensity level. Copyright © 2004 John Wiley & Sons, Ltd. [source] Analysis of the enantiomeric ratios of chiral components in absolute jasmineFLAVOUR AND FRAGRANCE JOURNAL, Issue 3 2001S. Tamogami Abstract Determination of the enantiomeric ratios of chiral components in absolute jasmine, an important raw fragrance material, was studied. Jasmine oils from Egypt, India and France were employed. It was remarkable that the enantiomeric excess of most of these chiral components was not 100% ee. There was a significant difference in the ratios of enantiomers of several characteristic aroma compounds among these products. In particular methyl jasmonate in Indian jasmine oil contains less of the major (1R, 2R)-isomer compared with those of France and Egypt. Copyright © 2001 John Wiley & Sons, Ltd. [source] Volatile composition and proteolysis in traditionally produced mature Kashar cheeseINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 7 2009Ali Adnan Hayaloglu Summary Twelve samples of raw milk mature Kashar cheese at different stages of ripening were collected from retail outlets. The average pH, moisture, fat-in-dry matter, protein, salt-in-dry matter and titratable acidity contents of the samples were 5.33, 39.39%, 45.20%, 27.33%, 6.62% and 0.65% (as lactic acid), respectively. Indices of proteolysis varied from 10.72% to 23.75% and 7.09% to 12.26% for pH 4.6-soluble and 12% trichloroacetic acid-soluble nitrogen fractions, respectively, and total free amino acid concentrations ranged from 6.36 to 36.03 mg Leu g,1 of cheese. The cheeses were analysed for volatile compounds by Solid Phase Microextraction and Gas Chromatography-Mass Spectrometry (GC-MS). A total of 113 compounds were detected and identified belonging to the following chemical groups: acids (eleven), esters (sixteen), ketones (sixteen), aldehydes (six), alcohols (twenty-seven), sulphur compounds (seven), terpenes (seven) and miscellaneous compounds (twenty-three). The potential effect of each compound on the flavour profile of Kashar cheese is discussed. Acids, esters, ketones and alcohols were found at considerable levels in the samples. Kashar cheeses obtained from different retail outlets displayed some differences in terms of chemical composition, proteolysis and patterns of aroma compounds; and may be attributed to their production technologies and age-related variations. [source] The quality of orange juice processed by coupling crossflow microfiltration and osmotic evaporationINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 1 2005Mady Cisse Summary Crossflow microfiltration (CFM) and osmotic evaporation (OE) were implemented on a semi-industrial pilot scale to obtain clarified orange juice concentrates at 450 and 620 g kg,1 of total soluble solids. The characteristics of the juice were then assessed and compared with fresh juice and commercial concentrates. With CFM, most aroma compounds and vitamin C remained in the permeate while the more apolar compounds such as terpenic hydrocarbons and carotenoids were strongly retained by the membrane. With OE, significant losses of vitamin C and aroma compounds occurred at first, with losses progressively decreasing during treatment. Pre-conditioning the membrane and cold regeneration of the brine reduced losses drastically, with the aroma composition tending towards that of the initial juice. The quality of pulp, a blend of the CFM retentate and OE concentrate, was high and much closer to that of the initial fresh juice than to the commercial thermal concentrate. [source] Persistence effects in flavour release from liquids in the mouthINTERNATIONAL JOURNAL OF FOOD SCIENCE & TECHNOLOGY, Issue 3 2003Kevin M. Wright Summary The flavour of drinks, creams and liquid-like food consumed without chewing is an important quality factor for consumers and manufacturers alike, so reliable predictive models of flavour release from liquids in the mouth are highly desirable. In this paper we show how the breath-by-breath concentration of aroma in the headspace after swallowing an aliquot of liquid can be modelled using basic principles of interfacial mass transfer. This mechanistic model is used to fit the experimental data for dilute aqueous solutions of five aroma compounds consumed by trained panellists. It is shown that many aroma compounds give detectable concentrations in the exhaled breath several minutes after swallowing and after ten or more exhalations. The influence of liquid composition on this aroma persistence effect is discussed. [source] HTPB-based polyurethaneurea membranes for recovery of aroma compounds from aqueous solution by pervaporationJOURNAL OF APPLIED POLYMER SCIENCE, Issue 1 2007Yunxiang Bai Abstract Hydroxyterminated polybutadiene (HTPB)-based polyurethaneurea (PU), HTPB-PU, was synthesized by two-step polymerization and was firstly used as membrane materials to recover aroma, ethyl acetate (EA), from aqueous solution by pervaporation (PV). The effects of the number,average molecular weight (Mn) of HTPB, EA in feed, operating temperature, and membrane thickness on the PV performance of HTPB-PU membranes were investigated. The membranes demonstrated high EA permselectivity as well as high EA flux. The DSC result showed two transition temperatures in the HTPB-PU membrane and contact angle measurements revealed the difference of hydrophobicity of the membrane at both sides, which were induced by glass plate and air, respectively, due to movement of the soft hydrophobic polybutadiene (PB) segments in HTPB-PU chains. Furthermore, the PV performance of the HTPB-PU membrane with the hydrophobic surface facing the feed was much better than that with the hydrophilic surface. © 2007 Wiley Periodicals, Inc. J Appl Polym Sci 104: 552,559, 2007 [source] Liquid membrane technology: fundamentals and review of its applicationsJOURNAL OF CHEMICAL TECHNOLOGY & BIOTECHNOLOGY, Issue 1 2010M. F. San Román Abstract OVERVIEW: During the past two decades, liquid membrane technology has grown into an accepted unit operation for a wide variety of separations. The increase in the use of this technology owing to strict environmental regulations and legislation together with the wider acceptance of this technology in preference to conventional separation processes has led to a spectacular advance in membrane development, module configurations, applications, etc. IMPACT: Liquid membrane technology makes it possible to attain high selectivity as well as efficient use of energy and material relative to many other separation systems. However, in spite of the known advantages of liquid membranes, there are very few examples of industrial applications because of the problems associated with the stability of the liquid membrane. APPLICATIONS: Liquid membrane technology has found applications in the fields of chemical and pharmaceutical technology, biotechnology, food processing and environmental engineering. On the other hand, its use in other fields, such as in the case of hydrogen separation, the recovery of aroma compounds from fruits, the application of ionic liquids in the membrane formulation, etc., is increasing rapidly. Copyright © 2009 Society of Chemical Industry [source] STUDY ON IMPROVEMENT OF THE QUALITY IN CHINESE NEW-TYPE LIQUOR BY PERVAPORATION WITH POLYDIMETHYLSILOXANE MEMBRANEJOURNAL OF FOOD PROCESS ENGINEERING, Issue 1 2007ER SHI ABSTRACT A composite polydimethylsiloxane (PDMS) membrane was used to separate aroma compounds from Chinese new-type liquor by pervaporation at 30, 35 and 40C and 10-mmHg downstream pressure. The gas chromatography analysis of aroma compounds in the retentate and permeate showed that PDMS membrane had excellent separation performance. Separation efficiencies for five kinds of esters (except ethyl lactate) and acetal in the original liquor are 100%, over 70% for alcohols (except methanol) and above 87% for aldehyde. The average flux for ethanol reached 3,539 g/m2 · h at 40C. Sensory analysis of the separated ingredients indicates that the sensory quality of the new liquor was significantly superior to that of the original liquor. Experiments suggest that pervaporation is a promising technique for the improvement of Chinese new-type liquor in terms of its flavor. [source] MICROBIOLOGICAL AND PHYSICOCHEMICAL CHARACTERIZATION OF NATURAL FERMENTED CAMEL MEAT SAUSAGEJOURNAL OF FOOD PROCESSING AND PRESERVATION, Issue 2 2008JAZILA EL MALTI ABSTRACT In this study, fermentations of camel meat were followed by analyzing the microbiological and physicochemical aspects of this product. The sausages were characterized by an important microbial activity of lactic acid bacteria that resulted in a product with a final pH of about 5.06. No Listeria monocytogenes, Salmonella spp. and sulfite-reducing clostridia were ever isolated from the raw materials or the fermented sausages during the maturation, underlining the safety of this product. The final water activity of the product was 0.91. Identification showed that the majority of lactobacilli isolated from de Man,Rogosa,Sharpe agar strains were assigned to the species of Lactobacillus plantarum. PRACTICAL APPLICATIONS The production of fermented foods is based on the use of starter cultures, for instance lactic acid bacteria that initiate rapid acidification of the raw material. They contribute to the microbial safety or offer one or more organoleptic, technological, nutritional, or health advantages. Also, their production of acetic acid, ethanol, aroma compounds, bacteriocins, exopolysaccharides, and several enzymes is of importance. In this way they enhance shelf life and microbial safety, improve texture, and contribute to the pleasant sensory profile of the end product. [source] PROTECTIVE CULTURES USED FOR THE BIOPRESERVATION OF HORSE MEAT FERMENTED SAUSAGE: MICROBIAL AND PHYSICOCHEMICAL CHARACTERIZATIONJOURNAL OF FOOD SAFETY, Issue 3 2008JAZILA EL MALTI ABSTRACT In this paper, 150 isolates, originating from horse meat, were subjected to step-by-step screening and characterization to search for potential protective cultures to be used in the meat industry. Isolates were first tested on their homofermentative and salt tolerance. Second, the antibacterial capacities toward Listeria monocytogenes were determined in an agar spot test. In total, 50% of the tested isolates were inhibitory toward Listeria monocytogenes. However, only 12 isolates produced a bacteriocin. Finally, three isolates with the strong bacteriocin activity were evaluated on their competitive nature by comparing their growth rate, acidifying character and lactic acid production at 15C under anaerobic conditions in a liquid broth. All three isolates combined a fast growth rate with a deep and rapid acidification caused by the production of high levels of lactic acid. Lactobacillus sakei was used as starter culture for producing sausage horse meat. In this study, fermentations were followed analyzing the microbiological and physicochemical aspects of this product. The sausages were characterized by an important microbial activity of lactic acid bacteria that resulted in a product with a final pH of about 4.56. No Listeria monocytogenes, Salmonella spp. or sulfite reducing clostridia were ever isolated from the raw materials or the fermented sausages during the maturation, underlining the microbial safety of this product. The final water activity of the product was 0.85. Starter cultures showed that Lactobacillus sakei was really efficient in reducing the amine production since this strain caused a quick pH drop during sausage fermentation. PRACTICAL APPLICATIONS A starter culture can be defined as a microbial preparation of large numbers of cells of at least one microorganism to be added to a raw material to produce a fermented food by accelerating and steering its fermentation process. The group of lactic acid bacteria (LAB) occupies a central role in these processes, and has a long and safe history of application and consumption in the production of fermented foods and beverages. They cause rapid acidification of the raw material through the production of organic acids, mainly lactic acid. Also, their production of acetic acid, ethanol, aroma compounds, bacteriocins, exopolysaccharides and several enzymes is of importance. The main reason for suitability of LAB is their natural origin, and they can contribute to food safety and/or offer one or more organoleptic, technological, nutritional or health advantages. [source] Electronic Nose Technology in Quality Assessment: Predicting Volatile Composition of Danish Blue Cheese During RipeningJOURNAL OF FOOD SCIENCE, Issue 6 2005Jeorgos Trihaas ABSTRACT This work describes for the 1st time the use of an electronic nose (e-nose) for the determination of changes of blue cheeses flavor during maturation. Headspace analysis of Danish blue cheeses was made for 2 dairy units of the same producer. An e-nose registered changes in cheeses flavor 5, 8, 12, and 20 wk after brining. Volatiles were collected from the headspace and analyzed by gas chromatography-mass spectrometry (GC-MS). Features from the chemical sensors of the e-nose were used to model the volatile changes by multivariate methods. Differences registered during ripening of the cheeses as well as between producing units are described and discussed for both methods. Cheeses from different units showed significant differences in their e-nose flavor profiles at early ripening stages but with ripening became more and more alike. Prediction of the concentration of 25 identified aroma compounds by e-nose features was possible by partial least square regression (PLS-R). It was not possible to create a reliable predictive model for both units because cheeses from 1 unit were contaminated by Geotrichum candidum, leading to unstable ripening patterns. Correction of the e-nose features by multiple scatter correction (MSC) and mean normalization (MN) of the integrated GC areas made correlation of the volatile concentration to the e-nose signal features possible. Prediction models were created, evaluated, and used to reconstruct the headspace of unknown cheese samples by e-nose measurements. Classification of predicted volatile compositions of unknown samples by their ripening stage was successful at a 78% and 54% overall correct classification for dairy units 1 and 2, respectively. Compared with GC-MS, the application of the rapid and less demanding e-nose seems an attractive alternative for this type of investigation. [source] Recovery of Aroma Compounds from Dilute Model Blueberry Solution by PervaporationJOURNAL OF FOOD SCIENCE, Issue 9 2003M. PENG ABSTRACT Pervaporation (PV) is a membrane-separation process showing unique capability of separating target compound(s) from dilute systems. Experiments were performed on a bench-scale flat sheet PV unit with a model solution to evaluate separation factor of 6 constituent aroma compounds (1-hexanol, 1-heptanol, trans-2-hexenal, ethyl acetate, linalool, and d-limonene), representing some of typical flavoring ingredients from blueberry juice. The results showed that separation factor was in the range of 70 to 430, depending on molecule size and polarity property of the compounds. Except for 1-heptanol, all compounds showed no significant coupling effect in the mixture system. The effect of temperature was also examined for a given feed-flow rate. Keywords: pervaporation, membrane, aroma compounds, blueberry, multicomponent diffusion [source] | |||||||||||||||||||||||||||||||