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Sillick M.,Firmenich Inc. | Gregson C.M.,Firmenich Inc.
Carbohydrate Polymers | Year: 2010

Critical water activity (aw*) is employed in this study as a practical metric of the hygroscopic stability of multi-component carbohydrate glasses. Glass transition temperature (Tg) and water activity (aw) data are modeled to determine the aw at which sufficient moisture is present to yield a Tg value of 25 °C (i.e., the aw*). The results confirm the well-known effect of decreasing sensitivity to moisture with increasing molecular weight. The results also demonstrate the additional influence of molecular type. The hygroscopic stability of binary maltodextrin/disaccharide systems increased in the same order as the glass transition temperature of the disaccharide: sucrose < maltose < trehalose. General equations are proposed for predicting the aw* of mixtures, which could be used towards the formulation of stable glassy products. © 2009 Elsevier Ltd. All rights reserved.

Van Sleeuwen R.M.T.,Firmenich Inc. | Zhang S.,Firmenich Inc. | Normand V.,Firmenich Inc.
Biomacromolecules | Year: 2012

A model was developed to predict spatial glass transition temperature (T g) distributions in glassy maltodextrin particles during transient moisture sorption. The simulation employed a numerical mass transfer model with a concentration dependent apparent diffusion coefficient (D app) measured using Dynamic Vapor Sorption. The mass average moisture content increase and the associated decrease in T g were successfully modeled over time. Large spatial T g variations were predicted in the particle, resulting in a temporary broadening of the T g region. Temperature modulated differential scanning calorimetry confirmed that the variation in T g in nonequilibrated samples was larger than in equilibrated samples. This experimental broadening was characterized by an almost doubling of the T g breadth compared to the start of the experiment. Upon reaching equilibrium, both the experimental and predicted T g breadth contracted back to their initial value. © 2012 American Chemical Society.

Asadollahi M.A.,Technical University of Denmark | Asadollahi M.A.,University of Isfahan | Maury J.,Technical University of Denmark | Schalk M.,Firmenich | And 3 more authors.
Biotechnology and Bioengineering | Year: 2010

The mevalonate pathway in the yeast Saccharomyces cerevisiae was deregulated in order to enhance the intracellular pool of farnesyl diphosphate (FPP), the direct precursor for the biosynthesis of sesquiterpenes. Overexpression of the catalytic domain of HMG1, both from the genome and plasmid, resulted in higher production of cubebol, a plant originating sesquiterpene, and increased squalene accumulation. Down-regulation of ERG9 by replacing its native promoter with the regulatable MET3 promoter, enhanced cubebol titers but simultaneous over-expression of tHMG1 and repression of ERG9 did not further improve cubebol production. Furtheremore, the concentrations of squalene and ergosterol were measured in the engineered strains. Unexpectedly, significant accumulation of squalene and restoring the ergosterol biosynthesis were observed in the ERG9 repressed strains transformed with the plasmids harboring cubebol synthase gene. This could be explained by a toxicity effect of cubebol, possibly resulting in higher transcription levels for the genes under control of MET3 promoter, which could lead to accumulation of squalene and ergosterol. © 2010 Wiley Periodicals, Inc.

Fieber W.,Firmenich | Hafner V.,Firmenich | Normand V.,Firmenich Inc.
Journal of Colloid and Interface Science | Year: 2011

Droplet size distribution of flavor oils in two different solid flavor delivery systems were determined with pulsed field gradient NMR spectroscopy: yeast encapsulation system, a spray dried flavor encapsulation system based on empty yeast cells, and glassy encapsulation system, an extruded solid water soluble carbohydrate delivery system. The oil droplet sizes are limited by the yeast cell walls in the yeast encapsulation system and the size distribution is unimodal according to images from transmission electron microscopy. The droplet size determination with diffusion NMR is based on the Murday and Cotts theory of restricted diffusion of liquids in geometrical confinements. Good fits of the diffusion data could be obtained by applying a unimodal, log-normal size distribution model and average droplet sizes of about 2 μm were found that correspond approximately to the inner diameter of the yeast cells. Scanning electron microscopy images showed a multimodal droplet size distribution in the glassy extruded delivery systems. To fit the NMR data a bimodal log-normal distribution function with five independent fitting parameters was implemented that yielded consistent and robust results. The two size populations were found in the micron and sub-micron range, respectively. The method was sufficiently accurate to depict variation of droplet size distributions in glassy encapsulation systems of different formulation. © 2011 Elsevier Inc.

Zeng Q.C.,Firmenich Inc. | Wu A.Z.,Firmenich Inc. | Pika J.,Firmenich Inc.
Journal of Breath Research | Year: 2010

Increasing pH solution from 7.5 to 8.0 was found to significantly improve the effectiveness of green tea extract for methanethiol removal in vitro. Green tea extract was also found to remove hydrogen sulfide and its effectiveness was greatly improved under alkaline conditions. It was found that with green tea extract, maximum H2S removal was achieved when the pH was between 8.1 and 8.4 at 37°C for 5 min. Further increases in pH resulted in decrease of the extract effectiveness. Vegetable acetone powders which contain polyphenol oxidases or peroxidases were found to further enhance the effectiveness for the removal of thiols when used in combination with green tea extracts at body temperature under alkaline conditions. Adding 5% baking soda to green tea extract-containing chewing gum was found to buffer saliva pHs to 8.0 during 10 min of chewing. However, severe discoloration was observed and undesirable bitterness was perceived, most likely due to the polymerization of unencapsulated green tea polyphenols. Therefore, encapsulation of green tea extract is recommended for applications at elevated pHs. © 2010 IOP Publishing Ltd.

Rong Y.,Firmenich Inc. | Gregson C.M.,Firmenich Inc. | Parker A.,Firmenich
Journal of Chemical Thermodynamics | Year: 2012

A method was developed using thermo-gravimetric analysis (TGA) to determine the vapor pressure of volatile liquids. This is achieved by measuring the rate of evaporation (mass loss) of a pure liquid contained within a cylindrical pan. The influence of factors like sample geometry and vapor diffusion on evaporation rate are discussed. The measurement can be performed across a wide range of temperature yielding reasonable results up to 10 kPa. This approach may be useful as a rapid and automatable method for measuring the volatility of flavor and fragrance raw materials. © 2012 Elsevier Ltd. All rights reserved.

Although volatile aroma compounds of melon have been extensively studied, knowledge of cantaloupe aroma-impact compounds is still ambiguous, inconsistent and incomplete. In this study an authentic aroma extract of fresh cantaloupe, or muskmelon, was obtained using a room temperature sample preparation method combining solid phase extraction and gel permeation chromatography. Thirty-three compounds were determined as aroma-impact compounds of the cantaloupe sample by gas chromatography-olfactometry analysis of the aroma extract. The six most important cantaloupe aroma-impact compounds determined in this study were ethyl 2-(methylthio)acetate (fruity), (Z)-3-hexenyl acetate (fruity), (Z)-3-hexen-1-ol (green), (E)-6-nonen-1-ol (creamy, sweet), γ-octalactone (sweet, lactonic), and (Z,Z)-(3,6)-nonadien-1-ol (melon). (E,E)-2,6-Nonadienal, (E)-6-nonen-1-ol, ethyl acrylate, (Z)-1,5-octadien-3-ol, (Z)-2-nonenal and trans-4,5-epoxy-(E)-2-decenal were identified in muskmelon for the first time. Using a sensitive and selective gas chromatography-tandem mass spectrometry (GC-MS/MS) method with a synthesized reference compound, (Z,Z)-3,6-nonadienyl acetate was unambiguously identified in cantaloupe for the first time. However, the presence of (Z,Z)-3,6-nonadienal in cantaloupe was not confirmed by the GC-MS/MS analysis. Better understanding of a natural product aroma requires strategic selection of samples, a combination of complementary sample preparation methods, as well as advanced analytical techniques. © 2013 John Wiley & Sons, Ltd.

Dardelle G.,Firmenich | Subramaniam A.,Firmenich Inc. | Normand V.,Firmenich Inc.
Soft Matter | Year: 2011

This study assesses the efficiency of the chemical cross-linking in gelatin, when utilising two different cross-linking reagents. A new method using micro-calorimetry was developed to use the energy involved in renaturation of the protein for probing the efficiency of the cross-linking reaction. The enthalpy of renaturation upon cooling was measured for two different types of cross-linkers, viz. glutaraldehyde and transglutaminase. Gelatin is a polymer with the ability to form a physical thermoreversible network. When cross-linking reactions occur within the gelatin gel, covalent bonds are generated. This in turn creates a second network locked in place by chemical bonds. Therefore two different types of networks coexist. Heat flow measurement at different levels of cross-linking reagent thus permits the measurement of the reduction in enthalpy of gelation as the cross-linking reaction progresses. By introducing the concept of effective concentration, the enthalpy data can be directly related to the degree of cross-linking through an empirical model. This concept emphasizes two different mechanisms taking into consideration the cross-linkers transglutaminase and glutaraldehyde. A mechanism for the polymerisation of glutaraldehyde is proposed. © The Royal Society of Chemistry 2011.

Um E.,Princeton University | Rogers M.E.,Firmenich Inc. | Stone H.A.,Princeton University
Lab on a Chip - Miniaturisation for Chemistry and Biology | Year: 2013

We describe a microfluidic system for generating a sequence of liquid droplets of multiple concentrations in a single experimental condition. The series of final droplets has the combination of the compositions varying periodically, with polydispersity of the size less than 8%. By utilizing the design of the microchannel geometry and the passive control of three immiscible fluids (oil, water, and air) including generation, breakup, separation and coalescence of droplets, we can change the system to generate diverse sets of combination of materials. The device can be used for testing different concentration of materials in picoliter volumes and developing a new way to deliver dynamic signals of chemicals with microfluidics. © 2013 The Royal Society of Chemistry.

Duncan B.,University of Massachusetts Amherst | Landis R.F.,University of Massachusetts Amherst | Jerri H.A.,Firmenich Inc. | Normand V.,Firmenich Inc. | And 3 more authors.
Small | Year: 2015

An effective method for the generation of hybrid organic-inorganic nanocomposite microparticles featuring controlled size and high structural stability is presented. In this process, an oil-in-water Pickering emulsion is formed using hydrophilic amine-functionalized silica nanoparticles. Covalent modification using a hydrophobic maleic anhydride copolymer then alters nanoparticle wettability during crosslinking, causing a core-shell to nanocomposite structural reorganization of the assemblies. The resulting porous nanocomposites maintain discrete microparticle structures and retain payloads in their oil phase even when incubated in competitive solvents such as ethanol. Covalent crosslinking using a hydrophobic maleic anhydride copolymer induces a morphology change in oil-in-water Pickering emulsions formed using hydrophilic amine-functionalized silica nanoparticles. The resulting porous nanocomposites maintain discrete microparticle structures and retain payloads in their oil phase even when incubated in competitive solvents such as ethanol. © 2014 Wiley-VCH Verlag GmbH & Co. KGaA.

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