Sucrose Octaacetate Research Articles

The effect of two weeks ingestion of a bitter tastant mixture on energy intake in overweight females

Triggering of gastro-intestinal bitter taste receptors might have implications for appetite and food intake, but the evidence in humans is mixed and limited to acute studies. We previously reported that 15-days consumption of drinks with purified Hoodia gordonii extract and its taste-matched control both produced similar, significant energy intake (EI) reductions in females in an in-patient setting, with no significant differences between treatments. In that study the control was matched to Hoodia flavour and bitterness using Raisin Flavour (RF), Sucrose Octa Acetate (SOA) and Quassia Extract (QE). As triggering of gastrointestinal bitter receptors might have produced shared effects on EI, our objective here was to assess the effects of sustained exposure to capsules containing the same bitter RF + SOA + QE mix itself on EI, compared to a non-bitter placebo.In this randomized, double-blind study, sixty slightly overweight women in parallel groups consumed twice-daily capsules without (placebo) or with the tastant mixture (0.88 mg SOA, 0.088 mg QE, 0.22 mg RF) on days 1–14. On day 0 all subjects received placebo capsules at 0800 and 1600, ad libitum meals at 0900, 1300, 1700, and snacks after 1900. On day 14 these test procedures were repeated. Changes in EI on days 14 versus 0 between treatment groups were assessed using ANCOVA.Total EI differences on days 14 versus 0 were not significant (mean active-placebo treatment difference −109 kcal, SE 71, P = 0.13), nor was this significant when analyzed separately for each meal within the test day. Body weight changes were negligible.In conclusion, sustained exposure to these encapsulated bitter tastants did not significantly affect EI in overweight females.

Is the Association Between Sweet and Bitter Perception due to Genetic Variation?

Perceived intensities of sweetness and bitterness are correlated with one another and each is influenced by genetics. The extent to which these correlations share common genetic variation, however, remains unclear. In a mainly adolescent sample ( n = 1901, mean age 16.2 years), including 243 monozygotic (MZ) and 452 dizygotic (DZ) twin pairs, we estimated the covariance among the perceived intensities of 4 bitter compounds (6- n -propylthiouracil [PROP], sucrose octa-acetate, quinine, caffeine) and 4 sweeteners (the weighted mean ratings of glucose, fructose, neohesperidine dihydrochalcone, aspartame) with multivariate genetic modeling. The sweetness factor was moderately correlated with sucrose octa-acetate, quinine, and caffeine ( rp = 0.35-0.40). This was mainly due to a shared genetic factor ( rg = 0.46-0.51) that accounted for 17-37% of the variance in the 3 bitter compounds' ratings and 8% of the variance in general sweetness ratings. In contrast, an association between sweetness and PROP only became evident after adjusting for the TAS2R38 diplotype ( rp increased from 0.18 to 0.32) with the PROP genetic factor accounting for 6% of variance in sweetness. These genetic associations were not inflated by scale use bias, as the cross-trait correlations for both MZ and DZ twins were weak. There was also little evidence for mediation by cognition or behavioral factors. This suggests an overlap of genetic variance between perceptions of sweetness and bitterness from a variety of stimuli, which includes PROP when considering the TAS2R38 diplotype. The most likely sources of shared variation are within genes encoding post-receptor transduction mechanisms common to the various taste G protein-coupled receptors.

The Effects of Odor Quality and Temporal Asynchrony on Modulation of Taste Intensity by Retronasal Odor.

The experiments had 2 main goals: 1) to add to the sparse literature on how retronasal aromas interact with bitter tastes, and 2) to determine whether modulation of taste intensity by aroma depends on temporal contiguity, as one might expect if flavor interactions depend on cross-modal binding (similar to object perception in other modalities). An olfactometer-gustometer allowed independent oral presentation of odorized air and liquid samples. First, using simultaneous presentation of odors and tastes (Experiments 1a-d) we found that a "sweet-smelling" aroma enhanced the rated sweetness of sucrose and decreased the rated bitterness of sucrose octaacetate (SOA), and that a "bitter-smelling" aroma enhanced the bitterness of SOA and decreased the sweetness of sucrose. Thus, with respect to effects on taste intensity, sweet and bitter aromas mimicked mixture-interactions between sweet and bitter tastes under current conditions. Next (Experiment 2), both odors were again paired with both tastes, with a parametric manipulation of odor onset. Odor presentation ranged from before taste delivery to after taste delivery. Enhancement of taste intensity was greatest with simultaneous onset, and greatly attenuated with offsets of 1s. These results are consistent with the idea that enhancement of taste by retronasal aroma depends on a temporal binding window like many other cross-modal interactions. The effects of temporal offsets on suppression of taste were inconclusive. These findings are discussed within the context of past work on odor-taste interactions.

Multi-scale modelling of OSN batch concentration with spiral-wound membrane modules using OSN Designer

Three commercial spiral-wound membrane modules of different sizes, from 1.8″×12″ to 4.0″×40″, are used to concentrate a solution of sucrose octaacetate in ethyl acetate under different operating conditions. A mathematical model to describe the batch concentration process is developed, based on a combination of the classical solution diffusion membrane transport model and the film theory, to account for the mass transfer effects. The model was implemented using the “OSN Designer” software tool. The membrane transport model parameters as well as all parameters in the pressure drop and mass transfer correlations for the spiral-wound modules were obtained from regression on a limited number of experimental data at steady state conditions. Excellent agreement was found between the experimental and multi-scale modelling performance data under various operating conditions. The results illustrate that the performance of a large scale batch concentration process with spiral-wound membrane modules can be predicted based on laboratory crossflow flat sheet test data when the fluid dynamics and mass transfer characteristics in the module, and the necessary channel geometry are known. In addition, the effects of concentration polarisation, pressure drop through feed and permeate channels, and thermodynamic non-ideality of the solution at large scale batch concentration are also investigated.

Performance of spiral-wound membrane modules in organic solvent nanofiltration – Fluid dynamics and mass transfer characteristics

During the past few decades organic solvent nanofiltration has received a great deal of attention and a growing number of studies has been reported on development and optimisation of solvent resistant membranes and their transport mechanism. However, most of these studies have used flat sheet membranes. On the other hand, many researchers studied fluid dynamics and mass transfer in spiral-wound membrane modules, almost exclusively in aqueous solutions. This paper reports the performance of four spiral-wound membrane modules tested in 0–20wt% solutions of sucrose octaacetate in ethyl acetate under various pressures and retentate flowrates. These modules were made of two different types of membranes (a commercial membrane, PuraMem® S600, and a development product, Lab-1, from Evonik Membrane Extraction Technology Limited) and covered three module sizes (1.8″×12″, 2.5″×40″ and 4.0″×40″). All modules had the same feed and permeate spacers. The classical solution diffusion model was applied to describe the transport of solute and solvent through the membrane and regress the unknown model parameters from flat sheet data. Correlations for characterising the fluid dynamics and mass transfer in the spiral-wound membrane modules, as well as the parameters describing the feed and permeate channels, were determined by performing the regression of experimental data of a 1.8″×12″ PuraMem® S600 membrane module. The classical solution–diffusion model, combined with the film theory, was then successfully applied to predict the performance of other modules of larger size (such as the 2.5″×40″ and 4.0″×40″ module sizes) and/or made of a different membrane material (such as Lab-1). The procedure proposed in this paper predicts the performance of a specific module by obtaining a limited number of experimental data for flat sheets and a 1.8″×12″ spiral-wound membrane module only (necessary to obtain the fitting parameters characteristic of the membrane and the module). Furthermore, with this procedure, it is not necessary to know a priori the spacer geometry, because the necessary information about the spacer geometry will be also obtained by regression of few experimental data.

Field-stepped direct detection electron paramagnetic resonance

The widest scan that had been demonstrated previously for rapid scan EPR was a 155G sinusoidal scan. As the scan width increases, the voltage requirement across the resonating capacitor and scan coils increases dramatically and the background signal induced by the rapidly changing field increases. An alternate approach is needed to achieve wider scans. A field-stepped direct detection EPR method that is based on rapid-scan technology is now reported, and scan widths up to 6200G have been demonstrated. A linear scan frequency of 5.12kHz was generated with the scan driver described previously. The field was stepped at intervals of 0.01 to 1G, depending on the linewidths in the spectra. At each field data for triangular scans with widths up to 11.5G were acquired. Data from the triangular scans were combined by matching DC offsets for overlapping regions of successive scans. This approach has the following advantages relative to CW, several of which are similar to the advantages of rapid scan. (i) In CW if the modulation amplitude is too large, the signal is broadened. In direct detection field modulation is not used. (ii) In CW the small modulation amplitude detects only a small fraction of the signal amplitude. In direct detection each scan detects a larger fraction of the signal, which improves the signal-to-noise ratio. (iii) If the scan rate is fast enough to cause rapid scan oscillations, the slow scan spectrum can be recovered by deconvolution after the combination of segments. (iv) The data are acquired with quadrature detection, which permits phase correction in the post processing. (v) In the direct detection method the signal typically is oversampled in the field direction. The number of points to be averaged, thereby improving the signal-to-noise ratio, is determined in post processing based on the desired field resolution. A degased lithium phthalocyanine sample was used to demonstrate that the linear deconvolution procedure can be employed with field-stepped direct detection EPR signals. Field-stepped direct detection EPR spectra were obtained for Cu2+ doped in Ni(diethyldithiocarbamate)2, Cu2+ doped in Zn tetratolylporphyrin, perdeuterated tempone in sucrose octaacetate, vanadyl ion doped in a parasubstituted Zn tetratolylporphyrin, Mn2+ impurity in CaO, and an oriented crystal of Mn2+ doped in Mg(acetylacetonate)2(H2O)2.

Multiharmonic electron paramagnetic resonance for extended samples with both narrow and broad lines

Multiharmonic electron paramagnetic resonance spectroscopy was demonstrated for two samples with both narrow and broad lines: (i) α,γ-Bisdiphenylene-β-phenylallyl (BDPA) with ΔBpp of 0.85G plus ultramarine blue with ΔBpp of 17G, and (ii) a nitroxide radical immobilized in sucrose octaacetate. Modulation amplitudes up to 17G at 41kHz were generated with a rapid scan coil driver and Litz wire coils that provide uniform magnetic field sweeps over samples with heights of 5mm. Data were acquired with a 2-D experiment in the Xepr software through the transient signal path of a Bruker E500T and digitized in quadrature with a Bruker SpecJet II. Signals at the modulation frequency and its harmonics were calculated by digital phase-sensitive detection. The number of harmonics with signal intensity greater than noise increases as the ratio of the modulation amplitude to the narrowest peak increases. Spectra reconstructed by the multiharmonic method from data obtained with modulation amplitudes up to five times the peak-to-peak linewidths of the narrowest features have linewidths that are broadened by up to only about 10% relative to linewidths in spectra obtained at low modulation amplitudes. The signal-to-noise improves with increasing modulation amplitude up to the point where the modulation amplitude is slightly larger than the linewidth of the narrowest features. If this high a modulation amplitude had been used in conventional methodology the linewidth of the narrowest features would have been severely broadened. The multiharmonic reconstruction methodology means that the selection of the modulation amplitude that can be used without spectral distortion is no longer tightly tied to the linewidth of the narrowest line.

Migration resistant glucose esters as bioplasticizers for polylactide

ABSTRACTEnvironmental and sustainability issues have catalyzed efforts to replace traditional polymer additives with biobased alternatives. Glucose pentaacetate (GPA) and sucrose octaacetate (SOA) as model commercial saccharide esters and three synthesized glucose hexanoate esters (GHs) were evaluated as bioplasticizers for polylactide (PLA). For the GHs different reaction times were utilized to reach plasticizers with different number of hexanoate groups to establish how the degree of substitution influences miscibility and migration resistance of the plasticizers. The synthesized GHs, GPA, and SOA all showed good miscibility with PLA. Largest improvements in strain at break were observed for the PLA films containing GH plasticizers. These films also exhibited simultaneous increase in stress at break as compared to plain PLA. The GH plasticizers had low tendency to migrate during aging in water and this migration resistance increased with increasing degree of substitution. The GHs are, thus, promising plasticizer alternatives for bioplastics as they also retain the biodegradable nature of these biobased materials. © 2015 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2015, 132, 41928.

Glucose esters as biobased PVC plasticizers

Utilization of glucose, produced by liquefaction of cellulose or other abundant biomass sources, as raw material for production of green plasticizers would offer an attractive alternative to traditional phthalate plasticizers. Three glucose hexanoate esters (GHs) were synthesized by one-step reaction and evaluated as green plasticizers for poly(vinyl chloride) (PVC). The esterification was carried out for three different time periods to obtain plasticizers with different number of hexanoate groups, as the degree of substitution could influence the miscibility between PVC and GHs. A fast and powerful laser desorption ionization-mass spectrometry (LDI-MS) method was developed to obtain molecular level structural information of the plasticizer structures. All the GHs showed good miscibility with PVC and the GH blends exhibited better mechanical properties, in the form of higher strain at break and lower modulus, as compared to glucose pentaacetate (GPA) and sucrose octaacetate (SOA) blends that were studied in comparison. Altogether the results indicate that the synthesized glucose esters have large potential as green PVC plasticizers and they could be a promising option to overcome the environmental problems caused by phthalate plasticizers.

Drinking of flavored solutions by high preferring (WHP) and low preferring (WLP) alcohol-drinking rats

BackgroundSelective breeding alcohol-preferring (P) and alcohol-nonpreferring (NP) rats showed a strong preference for the sucrose solutions, whereas P rats intake greater amounts than NP rats.The aim of this study was the estimation of selectively bred ethanol-preferring (WHP – Warsaw High Preferring) and ethanol-nonpreferring (WLP – Warsaw Low Preferring) rats for their preference for various tastes. MethodsThe oral drinking of the following substances was studied at a range of concentrations: sucrose (0.5–64.0g/100ml), NaCl (0.025–3.2g/100ml), citric acid (0.008–2.048g/l), and sucrose octaacetate (0.002–0.512g/l) solutions. Separate groups of 7–8 rats from each line were investigated of each of the four tastes. The investigated solutions were presented continuously keeping water and food always available. Concentrations of the various flavors were doubled every 48h. ResultsRats from WHP and WLP lines clearly revealed the preference for the sucrose solution and the highest preference was at the 4.0 and 8.0g/100ml sucrose concentration. Similar to sucrose, both lines exposed strong preference for the NaCl solution and this preference enhanced together with the increase of the NaCl concentration. Nevertheless their preference for the NaCl solutions decreased when the concentration of NaCl reached 1.600g/100ml. Both lines of rats did not differ in citric acid or sucrose octaacetate intake at any of the concentrations studied. ConclusionSelective breeding of rats (WHP) for high and rats (WLP) for low ethanol drinking is favorably correlated with the drinking of sweet and salty solutions and negatively correlated with the consumption of sour and bitter tastes.

Comparative Antimicrobial Activities of some Monosaccharide and Disaccharide Acetates

A number of furanose (2,4) and pyranose (5,7,9,11,13) acetates were prepared by direct acetylation method. For comparative antimicrobial studies sucrose octaacetate (14) was also prepared. All the compounds (1-14) were screened for in vitro antibacterial activity against ten human pathogenic bacteria viz. Bacillus subtilis, Bacillus cereus, Bacillus megaterium, Staphylococcus aureus, Escherichia coli, INABA ET (Vibrio), Pseudomonas species, Salmonella paratyphi, Salmonella typhi and Shigella dysenteriae. These compounds were also screened for in vitro antifungal activity against four pathogenic fungi viz. Aspergillus niger, Alternaria alternata, Curvularia lunata and Fusarium equiseti. The study revealed that the pyranose acetate derivatives (5,7,9,11,13) are more prone towards antimicrobial functionality than those of the furanose acetates (2,4) and sucrose octaacetate (14). Keywords: Glucofuranose; Glucopyranose; Acetylation; Antimicrobial activity; Structure activity relationship (SAR). © 2013 JSR Publications. ISSN: 2070-0237 (Print); 2070-0245 (Online). All rights reserved. doi: http://dx.doi.org/10.3329/jsr.v5i3.15695 J. Sci. Res. 5 (3), 515-525 (2013)

Topochemical activation of pulp fibres

A new concept for topochemical activation of mechanical pulp fibres was investigated. The activation concept was based on attachment of precursors of peracids onto the surface of the fibres prior to hydrogen peroxide bleaching. The activators used in this work were: tetraacetylethylenediamine (water soluble), lactose octaacetate (LOA, colloidal particles, and low water solubility) and sucrose octaacetate (partially soluble in water). LOA showed promising results for application in the surface activation concept due to attachment of colloidal particles on the outmost surface of the fibres, simultaneously contributing to a brightness increase. Surface coverage by lignin on fibres had decreased after the bleaching process with activators, which was detected by X-ray photoelectron spectroscopy and time-of-flight secondary ion mass spectrometry.

Green Plasticizers from Liquefied Wood

Green plasticizers were designed from liquefied wood flour, a non-edible biobased waste product. Wood flour was liquefied to low molecular weight polyols by acid catalyzed reaction. The resulting polyol mixture, including the remaining liquefaction solvents glycerol and diethylene glycol, was further utilized for the synthesis of low molecular weight ester plasticizers. Monomeric (MLWP) and oligomeric (OLWP) plasticizers were prepared by esterification of the polyols by hexanoic acid or a mixture of hexanoic and adipic acid, respectively. Liquefied wood polyol mixture and the synthesized plasticizers were characterized by size exclusion chromatography, electrospray ionization–mass spectrometry and fourier transform infrared spectroscopy. MLWP, OLWP and traditional dioctyl phthalate (DIOP) plasticizer were blended with poly(vinyl chloride) (PVC) and tensile testing was performed to evaluate the plasticizing efficiency of the new plasticizers. In addition PVC blends containing model disaccharide ester, sucrose octaacetate (SOA), were prepared and tested. Highest strain at break was obtained after addition of SOA ester, which clearly shows the potential of sugar esters as PVC plasticizers. Addition of MLWP also resulted in slightly higher strain at break as compared to films plasticized with same amount of phthalate plasticizer, DIOP. Differential scanning calorimetry showed one concentration dependent glass transition temperature for all the studied blends indicating good miscibility. Our novel plasticizers are attractive environmentally friendly alternatives for phthalate plasticizers and could be prepared from biomass waste from agriculture and forest industry.

Explaining tolerance for bitterness in chocolate ice cream using solid chocolate preferences

Chocolate ice cream is commonly formulated with higher sugar levels than nonchocolate flavors to compensate for the inherent bitterness of cocoa. Bitterness, however, is an integral part of the complex flavor of chocolate. In light of the global obesity epidemic, many consumers and health professionals are concerned about the levels of added sugars in foods. Once a strategy for balancing undesirable bitterness and health concerns regarding added sugars has been developed, the task becomes determining whether that product will be acceptable to the consumer. Thus, the purpose of this research was to manipulate the bitterness of chocolate ice cream to examine how this influences consumer preferences. The main goal of this study was to estimate group rejection thresholds for bitterness in chocolate ice cream, and to see if solid chocolate preferences (dark vs. milk) generalized to ice cream. A food-safe bitter ingredient, sucrose octaacetate, was added to chocolate ice cream to alter bitterness without disturbing other the sensory qualities of the ice cream samples, including texture. Untrained chocolate ice cream consumers participated in a large-scale sensory test by indicating their preferences for blinded pairs of unspiked and spiked samples, where the spiked sample had increasing levels of the added bitterant. As anticipated, the group containing individuals who prefer milk chocolate had a much lower tolerance for bitterness in their chocolate ice cream compared with the group of individuals who prefer dark chocolate; indeed, the dark chocolate group tolerated almost twice as much added bitterant in the ice cream before indicating a significant preference for the unspiked (control) ice cream. This work demonstrates the successful application of the rejection threshold method to a complex dairy food. Estimating rejection thresholds could prove to be an effective tool for determining acceptable formulations or quality limits when considering attributes that become objectionable at high intensities.

Radiosynthesis of the fluorinated sucrose analogue, 1′‐[18F]fluoro‐1′‐deoxysucrose

Fluorinated and deoxysucrose analogues have been proven useful in probing the substrate specificity and roles of sucrose processing enzymes and transporters in plants. To synthesize an 18F‐labeled fluorodeoxysucrose analogue suitable for in vivo studies, an acyl‐protected, disaccharide‐based radiofluorination precursor (sucrose 1′‐O‐trifluoromethanesulfonyl‐2,3,4,6,3′,4′,6′‐hepta‐O‐acetate; 2) was prepared by regioselective mono‐deacetylation of sucrose octaacetate using a commercial esterase enzyme followed by conversion of the resultant sucrose heptaacetate to the corresponding triflate. Reaction of this triflate precursor with [18F]fluoride followed by base hydrolysis to remove the acetate groups and HPLC purification gave 1′‐[18F]fluoro‐1′‐deoxysucrose (4) in an overall synthesis time of 80 min and with a median decay corrected yield of 26% (n = 4). This study demonstrates the use of an enzymatic approach to aid the synthesis of a regiospecific radiofluorination precursor starting from the readily available fully acetylated sugar, thus avoiding the need for a complex classical carbohydrate protection strategy to individually protect each hydroxyl group in the molecule. Copyright © 2012 John Wiley & Sons, Ltd.

Rejection Thresholds in Solid Chocolate‐Flavored Compound Coating

Classical detection thresholds do not predict liking, as they focus on the presence or absence of a sensation. Recently however, Prescott and colleagues described a new method, the rejection threshold, where a series of forced choice preference tasks are used to generate a dose-response function to determine hedonically acceptable concentrations. That is, how much is too much? To date, this approach has been used exclusively in liquid foods. Here, we determined group rejection thresholds in solid chocolate-flavored compound coating for bitterness. The influences of self-identified preferences for milk or dark chocolate, as well as eating style (chewers compared to melters) on rejection thresholds were investigated. Stimuli included milk chocolate-flavored compound coating spiked with increasing amounts of sucrose octaacetate, a bitter and generally recognized as safe additive. Paired preference tests (blank compared to spike) were used to determine the proportion of the group that preferred the blank. Across pairs, spiked samples were presented in ascending concentration. We were able to quantify and compare differences between 2 self-identified market segments. The rejection threshold for the dark chocolate preferring group was significantly higher than the milk chocolate preferring group (P= 0.01). Conversely, eating style did not affect group rejection thresholds (P= 0.14), although this may reflect the amount of chocolate given to participants. Additionally, there was no association between chocolate preference and eating style (P= 0.36). Present work supports the contention that this method can be used to examine preferences within specific market segments and potentially individual differences as they relate to ingestive behavior. This work makes use of the rejection threshold method to study market segmentation, extending its use to solid foods. We believe this method has broad applicability to the sensory specialist and product developer by providing a process to identify how much is too much when formulating products, even in the context of specific market segments. We illustrate this in solid chocolate-flavored compound coating, identifying substantial differences in the amount of acceptable bitterness in those who prefer milk chocolate compared to dark chocolate. This method provides a direct means to answer the question of how much is too much.

Bitter Taste Stimuli Induce Differential Neural Codes in Mouse Brain

A growing literature suggests taste stimuli commonly classified as “bitter” induce heterogeneous neural and perceptual responses. Here, the central processing of bitter stimuli was studied in mice with genetically controlled bitter taste profiles. Using these mice removed genetic heterogeneity as a factor influencing gustatory neural codes for bitter stimuli. Electrophysiological activity (spikes) was recorded from single neurons in the nucleus tractus solitarius during oral delivery of taste solutions (26 total), including concentration series of the bitter tastants quinine, denatonium benzoate, cycloheximide, and sucrose octaacetate (SOA), presented to the whole mouth for 5 s. Seventy-nine neurons were sampled; in many cases multiple cells (2 to 5) were recorded from a mouse. Results showed bitter stimuli induced variable gustatory activity. For example, although some neurons responded robustly to quinine and cycloheximide, others displayed concentration-dependent activity (p<0.05) to quinine but not cycloheximide. Differential activity to bitter stimuli was observed across multiple neurons recorded from one animal in several mice. Across all cells, quinine and denatonium induced correlated spatial responses that differed (p<0.05) from those to cycloheximide and SOA. Modeling spatiotemporal neural ensemble activity revealed responses to quinine/denatonium and cycloheximide/SOA diverged during only an early, at least 1 s wide period of the taste response. Our findings highlight how temporal features of sensory processing contribute differences among bitter taste codes and build on data suggesting heterogeneity among “bitter” stimuli, data that challenge a strict monoguesia model for the bitter quality.

Charge-Transfer Interactions in a Multichromophoric Hexaarylbenzene Containing Pyrene and Triarylamines

Two different hexaarylbenzenes with three pyrene and three triarylamine substituents in different positions (trigonal symmetric and asymmetric arrangement) were synthesized, and their charge-transfer states were investigated by optical spectroscopy. In these multichromophoric systems triarylamine acts as the electron donor and pyrene as the electron acceptor. A reference chromophore with only one donor-acceptor pair was also investigated. All these chromophores form charge-transfer states upon photoexcitation which relax with a moderate fluorescence quantum yield to the ground state. The compounds do not differ significantly concerning most of their fluorescence properties, which shows that the fluorescent charge-transfer state is very similar in all chromophores. This observation indicates symmetry breaking for the symmetric chromophore within fluorescence lifetime of several tens of ns. This interpretation was substantiated by fluorescence excitation anisotropy measurements in a sucrose octaacetate matrix.

Rejection thresholds in chocolate milk: Evidence for segmentation

Bitterness is generally considered a negative attribute in food, yet many individuals enjoy some bitterness in products like coffee or chocolate. In chocolate, bitterness arises from naturally occurring alkaloids and phenolics found in cacao. Fermentation and roasting help develop typical chocolate flavor and reduce the intense bitterness of raw cacao by modifying these bitter compounds. As it becomes increasingly common to fortify chocolate with ‘raw’ cacao to increase the amount of healthful phytonutrients, it is important to identify the point at which the concentration of bitter compounds becomes objectionable, even to those who enjoy some bitterness. Classical threshold methods focus on the presence or absence of a sensation rather than acceptability or hedonics. A new alternative, the rejection threshold, was recently described in the literature. Here, we sought to quantify and compare differences in rejection thresholds (RjT) and detection thresholds (DT) in chocolate milk spiked with a food safe bitterant (sucrose octaacetate). In experiment 1, a series of paired preference tests was used to estimate the RjT for bitterness in chocolate milk. In a new group of participants (experiment 2), we determined the RjT and DT using the forced choice ascending method of limits. In both studies, participants were segmented on the basis of self-declared preference for milk or dark solid chocolate. Based on sigmoid fits of the indifference–preference function, the RjT was ∼2.3 times higher for those preferring dark chocolate than the RjT for those preferring milk chocolate in both experiments. In contrast, the DT for both groups was functionally identical, suggesting that differential effects of bitterness on liking of chocolate products are not based on the ability to detect bitterness in these products.

Sweet taste and menthol increase cough reflex thresholds

Cough is a vital protective reflex that is triggered by both mechanical and chemical stimuli. The current experiments explored how chemosensory stimuli modulate this important reflex. Cough thresholds were measured using a single-inhalation capsaicin challenge. Experiment 1 examined the impact of sweet taste: Cough thresholds were measured after rinsing the mouth with a sucrose solution (sweet) or with water (control). Experiment 2 examined the impact of menthol: Cough thresholds were measured after inhaling headspace above a menthol solution (menthol vapor) or headspace above the mineral oil solvent (control). Experiment 3 examined the impact of rinsing the mouth with a (bitter) sucrose octaacetate solution. Rinsing with sucrose and inhaling menthol vapor significantly increased measured cough thresholds. Rinsing with sucrose octaacete caused a non-significant decrease in cough thresholds, an important demonstration of specificity. Decreases in cough reflex sensitivity from sucrose or menthol could help explain why cough syrups without pharmacologically active ingredients are often almost as effective as formulations with an added drug. Further, the results support the idea that adding menthol to cigarettes might make tobacco smoke more tolerable for beginning smokers, at least in part, by reducing the sensitivity of an important airway defense mechanism.