Flavor Release Research Articles

Investigation on the rheological properties of agar gels and their role on aroma release in agar/limonene solid emulsions

A lipophilic aroma widely used in the food field, R-(+)-limonene, was entrapped in a solid emulsion in absence of emulsifiers using agar gel as encapsulating medium. The perception of the flavour release was evaluated by means of an electronic nose. The relation between structural organization of the agar gels and flavour release and perception was studied. Different viscoelastic properties of the continuous phase of the solid emulsion were achieved by varying the gelling polysaccharide concentration from 0.2% up to 1% (w/v) and the consequent aroma trapping effect was correlated with the perception of the flavour release from the solid emulsion during aging up to 15 days storage. Release phenomena were finally accelerated by increasing temperature of the gel from 30 to 77 °C. Structure assessment of the gelled phase take place within 24 h from the gel setting time and during this transient period most of the aroma release happens.

Relationship between the emulsifying properties of Acacia gums and the retention and diffusion of aroma compounds

Five samples of Acacia senegal gum were selected because of their different emulsifying properties. Acacia gum samples were first characterized by various analytical methods including intrinsic viscosity and arabino-galactan protein amount as determined by gel permeation chromatography. In a second step, stability of emulsions containing orange essential oil and Acacia gums was evaluated by measurement of turbidity. In addition, flavour release of two different hydrophobic aroma compounds from Acacia gum aqueous solutions was studied. Retention was measured using the phase ratio variation method under equilibrium whereas diffusion was assessed by DOSY NMR. This study established the relationship between the emulsifying ability of Acacia gum and the behaviour of aroma compounds in the corresponding solution. Better emulsifying ability of Acacia gum sample appears strongly correlated to an increase in flavour retention and a decrease in molecular mobility as the result of mostly hydrophobic interactions.

Functional characterization of the gels prepared with pectin methylesterase (PME)-treated pectins

High- and low-methoxyl pectins were treated with pectin methylesterase (PME) and the functional properties of the resulting pectin gels were characterized. The degree of esterification of high- and low-methoxyl pectins decreased from 74.5% to 6.3% and 40.0% to 6.5%, respectively while not changing their molecular weight. Also, the addition of glucono-delta-lactone (GDL) dramatically affected the gel strength and the pH reduction by the GDL led to the increased syneresis of the pectin gels, which was also observed in the PME-treated samples. When flavor compounds were incorporated into the pectin gels, the flavor release from the gels increased with decreasing the degree of esterification due to increased hydrophilic properties.

A Quantitative Structure−Property Relationship Study of the Release of Some Esters and Alcohols from Barley and Oat β-Glucan Matrices

This study investigates the release of selected strawberry flavor compounds from aqueous solutions of two barley and oat beta-glucan products at concentrations of 5, 10, and 15% (w/w). The flavor release of 12 esters and 3 alcohols was measured by dynamic headspace GC-MS. For each compound the ratio of the flavor release from the beta-glucan solution to the release from aqueous solution, A(rel), was recorded. In general, esters were retained in the beta-glucan matrices in a mass-dependent manner where heavier molecules were retained more. A(rel) for alcohols was found to be significantly larger than for the esters. Whereas A(rel) values for esters were always below unity, this parameter was above unity for alcohols in some preparations of beta-glucan. This implies that relative to esters, alcohols were rejected from some matrices. An increase in the concentration of the beta-glucan products was associated with an increased retention of alcohols and esters. For solutions of oat and barley beta-glucan products at the same concentration, the oat product retained the flavor compounds more strongly. This difference was more pronounced at low concentrations of the beta-glucan products. To investigate the potential of a multivariate approach for the analysis of the flavor release from beta-glucan products, partial least-squares regression was employed on a large selection of calculated molecular descriptors, yielding simple QSPR models capable of explaining the variation in A(rel). The robustness of the QSPR models was verified by cross-validation and permutation tests. The results indicate that the multivariate modeling approach might provide a useful tool for the investigation of flavor release systems similar to those studied here.

Reducing salt and fat content: Impact of composition, texture and cognitive interactions on the perception of flavoured model cheeses

Abstract To better understand which composition levers are available to reduce salt content in food without altering flavour perception, this paper aimed at quantifying the impact of texture and composition (salt, fat and dry matter) of a model cheese: (i) on salt and flavour perception, and; (ii) on profile texture and flavour release. Variations of salt, fat and dry matter highly influenced texture perception and instrumental texture parameters. Differences in aroma release and olfactory perception (“blue cheese” odour perception) between different model cheeses were highlighted when salt and fat content varied. However, a major result of this study showed that salty perception was not influenced by texture characteristics of model cheeses. Furthermore, olfactory perception modified texture perception but only for model cheeses with low fat and low-dry matter contents. Variations in salt content and sensory interactions therefore seem to have a greater impact on products with low fat content than on those with high-fat content.

In-mouth flavour release from milk proteins

The in-mouth release of flavour (2-nonanone) from whey protein isolate (WPI) and sodium caseinate in aqueous solutions, and the influence of the thickener, sodium carboxymethylcellulose (CMC), on the release of 2-nonanone were investigated using proton-transfer-reaction mass spectrometry. During consumption, a significant release of 2-nonanone from WPI (2%) was observed. After swallowing the samples, a substantial amount of flavour was detected in the breath, suggesting that some sample solution remained in the mouth and throat, resulting in a further release of flavour from proteins. In the presence of CMC, a significant release of 2-nonanone from not only WPI but also sodium caseinate was observed, which may be attributable to the increase in viscosity of the solutions. It is likely that a thicker coating of the mouth and throat with the higher viscosity sample after swallowing results in additional release of protein-bound flavour.

Time-intensity Analysis of Sourness of Commercially Produced Gummy Jellies Available in Japan

The flavor release of commercial gummy jellies was studied. Time-intensity (T-I) assessments, electromyography (EMG) of the jaw-closing muscles, and mechanical tests were conducted to characterize the gummy jellies. After a preliminary sensory test and round-table discussion by expert panelists, six samples of gummy jelly were selected from 25 products to represent the various gummy jelly products produced in Japan. Six trained panelists participated in the T-I assessment coupled with EMG measurement. Sourness was perceived shortly after starting to chew; it reached a maximum intensity after sufficient mastication (18-32 chewing strokes) and lasted for a relatively long time (16.8-45.9 s) after the main chewing activity had finished. The results obtained from EMG measurements and T-I assessments showed that sourness was perceived mildly and late with very tough samples, strongly and early with tender and rubbery samples, and mildly and early with samples that were easy to chew. Thus, sourness and texture are closely related in the gummy jelly products commercially available in Japan.

The Effect of Body Position on Flavor Release and Perception: Implications for fMRI Studies

Increasingly functional magnetic resonance imaging (fMRI) of the brain is being used to assess the cortical response to flavor perception. fMRI requires the subject to adopt a supine position; hence, if the results from such experiments are to be meaningfully extrapolated to flavor perception, it is pertinent to establish whether body position has a significant impact on consumers’ sensitivity to flavor. Body position is known to impact on some aspects of sensory perception, but no studies have reported the effect of body position on retronasal flavor perception. In this study, A/Not-A tests (ISO 1987), together with sureness ratings, were performed to evaluate subjects’ (n = 10) ability to differentiate between two subtly different emulsion samples under two conditions: seated in a quiet sensory booth environment and supine in a 3 T fMRI scanner mimicking real scanning conditions. In vivo volatile release was also measured in both seated and supine positions using atmospheric pressure chemical ionization mass spectrometry. Results indicated that body position had some impact on volatile release, but no overall effect on subject’s ability to discriminate between the two samples was observed. Consequently, brain imaging data collected in this context at least would have direct relevance to sensory perception data. However, more extensive research is required to fully understand the impact of body position on flavor perception and release.

Imaging New Transient Nanostructures Using a Microfluidic Chip Integrated with a Controlled Environment Vitrification System for Cryogenic Transmission Electron Microscopy

Nanostructures (vesicles, micelles, bilayers) are important in nanomedicine and biochemical processes. They are agents for encapsulation and eventual release of drugs, flavors, and fragrances. The structural transition from micelles to vesicles through disk-like intermediate states has been demonstrated previously. Here, we disclose a new route for the micelle-vesicle transition, where micelles aggregate to first form long tubules that become unstable, and break up into vesicles. A simple theory, based on energy principles, is presented to explain the tubule-vesicle transition. Observation of this new tubular intermediate state has been facilitated by the development of an integrated microfluidic chip/cryogenic transmission electron microscopy (cryo-TEM) unit. Although this transition has been observed in a specific amphiphilic system where micellar solutions of cetyltrimethylammonium bromide (CTAB) and dodecylbenzene sulfonic acid (HDBS) are mixed to form vesicles, this new tool can be applied broadly to study transient structures in nanoscale systems under the very controlled conditions provided by microfluidics.

Encapsulation of Flavor Molecules, 4-Hydroxy-3-Methoxy Benzoic Acid, into Layered Inorganic Nanoparticles for Controlled Release of Flavor

4-hydroxy-3-methoxybenzoic acid (vanillic acid: VA), which is a widely used flavoring agent in foods, was successfully intercalated into layered double hydroxide (LDH) to produce VA-LDH nanohybrids. The structure and VA release kinetics of the nanohybrids were systematically investigated with respect to charge density of host LDHs.

Matrix effects on flavour volatiles release in dark chocolates varying in particle size distribution and fat content using GC–mass spectrometry and GC–olfactometry

Influences of matrix particle size distribution (PSD) (18, 25, 35 and 50 μm) and fat content (25%, 30% and 35%) on flavour release of dark chocolate volatiles were quantified by static headspace gas chromatography using GC–MS. Sixty-eight (68) flavour compounds were identified, comprising alcohols, aldehydes, esters, ketones, furans, pyrans, pyrazines, pyridines, pyroles, phenols, pyrones and thiozoles. From GC–olfactometry, 2-methylpropanal, 2-methylbutanal and 3-methylbutanal had chocolate notes. With cocoa/roasted/nutty notes were trimethyl-, tetramethyl-, 2,3-dimethyl-, 2,5-dimethyl-, 3(or 2),5-dimethyl-2(or 3)-ethyl- and 3,5(or 6)-diethyl-2-methylpyrazine and furfuralpyrrole. Compounds with fruity/floral notes included 3,7-dimethyl-1,6-octadien-3-ol and 5-ethenyltetrahydro- R, R,5-trimethyl- cis-2-furanmethanol. Caramel-like, sweet and honey notes were conferred by 2-phenylethanol, phenylacetaldehyde, 2-phenylethylacetate, 2,3,5-trimethyl-6-ethylpyrazine, 2-carboxaldehyde-1 H-pyrrole, furancarboxaldehyde, furfuryl alcohol and 2,5-dimethyl-4-hydroxy-3(2 H)furanone. There were direct relationships of fat content with 3-methylbutanal and branched pyrazines but inverse ones with 2-phenylethanol, furfuryl alcohol, methylpyrazine, phenylacetaldehyde, 2, 3, 5-trimethyl-6-ethylpyrazine and 2-carboxaldehyde-1- H-pyrrole. Particle size influenced higher alcohol, aldehyde, ester, ketone and pyrazine concentrations at all fat contents. A multivariate product space suggested flavour effects of the interacting factors.

ESTIMATION OF MOISTURE SORPTION ISOTHERMS IN KERMAN PISTACHIO NUTS

ABSTRACT Various postharvesting processes such as handling, drying, storing and transportation of pistachio nuts are affected by their equilibrium moisture content (EMC). The static gravimetric method, along with different saturated salt solutions, was used in a range of water activity of 0.11–0.88, and at 15, 25, 35 and 40C to obtain sorption isotherms of pistachio nuts. Each set of sorption data was fitted to six mathematical equations, including Brunauer, Emmett and Teller; Guggenheim, Anderson and De Boer; Smith; Oswin; Halsey; and Henderson. The Smith model gave the most appropriate results (fitness) over the entire range of the mentioned temperatures. The isosteric sorption heats were determined for adsorption and desorption of pistachio nuts using the relevant thermodynamic relations (i.e., Clausius–Clapeyron equation). Based on experimental sorption data, a noticeable hysteresis effect between adsorption and desorption processes was observed, and their EMC plots were significantly deviated and different from each other. PRACTICAL APPLICATIONSThe rehydration rate of pistachio kernels and powder when they are mixed with various ice creams, desserts and confectionary products depends mainly on their sizes, temperature, and water activity. These factors have considerable effects on texture properties and release of flavor of pistachio's final products. To enhance the organoleptic properties of the above‐mentioned products, it is important to choose proper sizes of pistachio kernels. Since hysteresis and binding energy of pistachio powder are less than those of pistachio kernels, especially at 15°C, its rehydration rate is faster, and therefore it releases more flavor to the product (water activity in the range of 0.2–0.7) than pistachio kernels. However, the crunchy taste in pistachio powder is less than that in pistachio kernels. Overall, more research is needed to choose proper sizes of pistachio kernels for mixing with different products (such as ice cream) to keep their high crispness and maximize their flavor‐releasing process during rehydration, and also to use minimum energy for cooling and freezing.

Influence of Flavor Solvent on Flavor Release and Perception in Sugar-Free Chewing Gum

The influence of flavor solvent [triacetin (TA), propylene glycol (PG), medium chained triglycerides (MCT), or no flavor solvent (NFS)] on the flavor release profile, the textural properties, and the sensory perception of a sugar-free chewing gum was investigated. Time course analysis of the exhaled breath and saliva during chewing gum mastication indicated that flavor solvent addition or type did not influence the aroma release profile; however, the sorbitol release rate was statistically lower for the TA formulated sample in comparison to those with PG, MCT, or NFS. Sensory time-intensity analysis also indicated that the TA formulated sample was statistically lower in perceived sweetness intensity, in comparison with the other chewing gum samples, and also had lower cinnamon-like aroma intensity, presumably due to an interaction between sweetness intensity on aroma perception. Measurement of the chewing gum macroscopic texture by compression analysis during consumption was not correlated to the unique flavor release properties of the TA-chewing gum. However, a relationship between gum base plasticity and retention of sugar alcohol during mastication was proposed to explain the different flavor properties of the TA sample.

Mechanisms of Flavor Release in Chewing Gum: Cinnamaldehyde

Recently we reported that the release profile of cinnamaldehyde from a sugar-free chewing gum was correlated to the release of the sugar alcohol phase or was not in agreement with the log P model. The objective of this study was therefore to investigate mechanisms of cinnamaldehyde release from a sugar-free chewing gum; p-cresol (similar log P value) was also analyzed for comparison. Breath analysis of the chewing gum samples over an 8 min consumption period reported that the maximum concentration of cinnamaldehyde was 2- to 3-fold higher during the initial phase of mastication in comparison to the later phase, whereas the concentration of p-cresol was relatively constant over these two time periods. By contrast the release profile of cinnamaldehyde from a flavored gum base (no sugar alcohol phase) was constant over the 8 min consumption period and similar to the release of cresol from the flavored gum base. On the basis of tandem mass spectrometry, cinnamaldehyde was reported to react with sorbitol and generate hemiacetal reaction products that were not stable under slight alkaline conditions; it was suggested to revert back to free cinnamaldehyde and sugar alcohol in the oral cavity. The increased polarity of these transient cinnamaldehyde-sorbitol hemiacetal reaction products would result in a more rapid release rate of cinnamaldehyde than would be typically predicted based on the affinity of cinnamaldehyde for the gum base.

Food matrices – determination of odorant partition coefficients and application of models for their prediction

Foods are complex multi-component systems which are composed of volatile and non-volatile substances. The flavour profile of a food is an important criterion for the selection of our foodstuffs. The main objective of this study was the clarification of the complex relationships of the flavour release as a function of the composition of the food matrix at molecular level. Therefore the influence of matrix effects onto the odorants partition coefficients in oil–water model systems and a custard sample were investigated. The studies included a series of lactones, ester and alcohols (γ- and δ-octalactone, γ- and δ-nonalactone, γ- and δ-decalactone, ethyl hexanoate, 3-methyl-1-butanol and 2-phenylethanol). The partition coefficients were determined using static headspace gas chromatography (SH-GC). The results indicated that the custard/air partition coefficients of selected odorants are located between the water/air- and miglyol/air partition coefficients. Furthermore the mass transfer rates of selected odorants were investigated in custard- and milk powder–water samples. The values of the mass transfer rate were found higher in milk powder/water systems than in custard model. Nevertheless the results indicated that the viscosity of the matrix did not significantly influence the values of mass transfer rate of selected flavour compounds.

Study of structure and flavour release relationships in low moisture bakery products by means of the acoustic–mechanical combined technique and the electronic nose

A combined acoustic–mechanical technique was employed to simultaneously characterise in uniaxial compression mode the texture properties of commercial toasted sliced breads and laboratory-made ones that were made by modifying the amount of sucrose in the recipe. Also an Image Analysis technique was used to describe the morphology of the gas cells. The analysis of the flavour release was performed by means of a commercial electronic nose system. Advanced techniques of multivariate statistical analysis were employed to get the maximum information from the proposed instrumental techniques. Some selected mechanical parameters and flavour release responses are dominant in discriminating sliced bread samples and both express similar information. The Regularised Discriminant Analysis output for the acoustic, mechanical and flavour release data was: Non Error Rate Cross Validated equal to 80.1% in the cross-validation mode. The NER CV % index is an estimation of the predictive potential of the model that was validated according to the leave one out (LOO) method. The LOO procedure removes each sample from the data set, one at a time. The classification model is rebuilt and the class of the removed sample is predicted by using the obtained model. By combining these instrumental characterisation methods, the result of the texture/aroma description of these cellular solids was improved.

Interactions between flavour release and rheological properties in model custard desserts: Effect of starch concentration and milk fat

The influence of the concentration of various reagents and of the storage time on the flavour release of custard desserts was evaluated by headspace solid-phase microextraction and supported by rheological measurements. The presence of milk fat induced a significant decrease of the headspace concentration of flavour compounds, mainly due to hydrophobic matrix–flavour interactions. An elevated starch concentration enhanced the strength of the custard gels considerably. However, the increasing starch concentration resulted in an increased flavour release at low flavour concentrations, while a tendency to flavour retention was noted at higher flavour concentrations. During storage time, a denser network was formed as shown by rheological measurements, but no significant difference in flavour release was noted upon storage (three days). These results show that the complex interactions between flavour compounds and the food matrix in a model custard are difficult to predict and have to be carefully evaluated by a combination of rheological parameters and physicochemical interactions.

Influence of pectin and CMC on physical stability, turbidity loss rate, cloudiness and flavor release of orange beverage emulsion during storage

In the present work, the effect of type and concentration of two hydrocolloids namely pectin (1.5%, 3% and 4.5%) and CMC (0.1%, 0.3% and 0.5%) on physical stability, turbidity loss rate, cloudiness and flavor release of orange beverage emulsion was investigated during six months storage. From the turbidity loss rate results, the orange beverage emulsions containing 4.5% and 1.5% (w/w) pectin showed the highest and least storage stability, respectively. In contrast to the first two months storage, the replacement of both supplementary emulsion components resulted in a significant ( p < 0.05) increase in turbidity loss rate of all orange beverage emulsions, thus indicating a decrease in capability of beverage emulsion to maintain the cloudiness during storage. The cloudiness of all samples significantly ( p < 0.05) decreased during storage. The differences between the volatile release behaviors of target volatile compounds from orange beverage emulsions having different formulations indicated that the overall volatile flavor release was strongly influenced by the emulsion composition. This finding may be explained by the interactions between emulsion matrix and volatile flavor compounds. The release contents of most of target flavor compounds were significantly ( p < 0.05) decreased during storage, especially for the aldehyde compounds studied (i.e. octanal, decanal, neral, geranial).

Rheology, flavour release and perception of low-fat dairy desserts

Little information is available regarding the effect exerted by the composition of low-fat products on physical, chemical and sensory properties. This work studies the influence of two thickening agents, starch and κ-carrageenan, on the rheological properties, flavour release, thickness and perceived flavour in low-fat, strawberry flavoured dairy desserts. The addition of κ-carrageenan and increase in starch concentration raised the consistency index values ( K), and the viscoelastic parameters G′, G″ and η* but decreased the flow index values ( n). In general, the thickeners did not affect the headspace or the in vivo release of the volatile compounds (ethyl hexanoate, ethyl iso-pentanoate, ethyl butyrate and cis-3-hexen-1-ol). The application of R-index analysis to rank sensory data indicated significant differences in thickness between samples, while differences in strawberry flavour intensity were not detected.

Effect of Arabic gum, xanthan gum and orange oil on flavor release from diluted orange beverage emulsion

The influence of main emulsion components namely Arabic gum (13–20% w/w), xanthan gum (0.3–0.20% w/w) and orange oil (10–14% w/w) on semi-quantitative headspace analysis of target volatile flavor compounds released from a model orange beverage (diluted orange beverage emulsion) was evaluated by using a three-factor circumscribed central composite design (CCCD). For optimization procedure, the peak area of 13 volatile flavor compounds (i.e. ethyl acetate, α-pinene, ethyl butyrate, β-pinene, 3-carene, myrcene, limonene, γ-terpinene, octanal, decanal, linalool, neral and geranial) were considered as response variables. The response surface analysis exhibited that the significant ( p < 0.05) second-order polynomial regression equations were successfully fitted for all response variables except for ethyl butyrate. A satisfactory coefficient of determination ( R 2) ranged from 0.831 to 0.969 (>0.8) was obtained for the response variables studied. No significant ( p > 0.05) lack of fit was indicated for the reduced models except for the models fitted for limonene and linalool. This observation confirmed an accurate fitness of the reduced response surface models to the experimental data. The multiple response optimizations indicated that an orange beverage emulsion containing 15.87% (w/w) Arabic gum, 0.5% (w/w) xanthan gum and 10% (w/w) orange oil was predicted to provide the minimum overall flavor release.