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1.
Retention of aldehydes by whey proteins in solutions buffered at a range of pH values was studied under static and dynamic headspace conditions and in vivo in exhaled air. Static headspace measurements showed a clear increase in retention in the presence of whey proteins for aldehydes with longer carbon chains and for buffer solutions with higher pH values. For in vivo aldehyde release measurements, these effects were much less pronounced. The presence of saliva or the binding of aldehydes to the surface of the oral cavity was not responsible for this effect. This difference can be explained by the highly dynamic conditions of in vivo aroma release of liquid products, due to the relatively large flow of air during exhalation. After swallowing, a thin film of aldehyde solution remains in the pharynx; subsequent exhalation will release both the free aldehydes present in this film and those reversibly bound to the whey protein.  相似文献   

2.
Mastication, swallowing, breath flow, and aroma release were measured simultaneously in vivo using electromyography, electroglottography, a turbine air flow meter, and the MS-Nose, respectively. Signals were synchronized either electronically or by aligning the nasal airflow data with the breath by breath release of acetone. Chewing affected nasal airflow, with the flow fluctuations following the mastication pattern. Data analysis suggested that air was pumped out of the mouth into the throat with each chew, and the mean volume was 26 mL. Aroma release was associated with the pulses of air pumped from the mouth with each chew. During swallowing, there was no nasal airflow, but after swallowing, aroma release was evident. The volume of the retronasal route was estimated at 48 mL when swallowing and 72 mL when samples were chewed. The combination of techniques shows the effects of physiological processes on aroma release.  相似文献   

3.
The effects of oil content and droplet size distributions of dilute oil-in-water emulsions on release of four esters with different hydrophobicities were studied under in vivo, static headspace, and artificial throat conditions. The effect of oil content on orthonasal and retronasal perceived intensity of ethyl hexanoate was studied using a seven-person panel. With increasing oil content and with a higher hydrophobicity of the aroma compound, a stronger decrease in aroma release was found. This effect was stronger under static headspace conditions than under in vivo and artificial throat conditions, and the sensory intensity of ethyl hexanoate was perceived stronger orthonasally than retronasally. The lowest effective oil content was determined for all systems. Of the compounds tested, droplet size distribution only influenced the in vivo release of geranyl acetate. The artificial throat results correlated well with in vivo release, giving support to the assumption that a thin layer of liquid remaining in the throat after swallowing determines aroma release.  相似文献   

4.
To assess the influence of orthonasal and retronasal stimulation on cross-modal interactions between texture and flavor perception of food, a series of experiments have been conducted. Healthy human subjects were exposed to strawberry aroma pulses delivered by a computer-controlled stimulator based on air dilution olfactometry. Just prior to exposure to the aroma, the human subjects consumed water, custard, or protein gels with different textures without any added aroma. The aroma was delivered as a sequence of aroma pulses, in either an orthonasal or a retronasal fashion. The retronasal presentation of aroma with concomitant presentation of texture is thought to more closely mimick the in vivo flavor release of semisolid food products as compared to orthonasal stimulation. The time between oral consumption of the food, including swallowing, and the exposure to the aroma varied between 0.5 and 6.5 s. The subjects rated the intensity of the strawberry aroma. It was observed that the intensity of aroma decreased with increasing firmness of the food that was consumed. Aroma pulses delivered 6.5 s after swallowing were perceived as being more intense as compared to aroma pulses delivered immediately after swallowing. In conjunction with late delivery, the effect cross-modal interactions apparently decreased. Significantly higher odor intensities were reported for the aroma stimuli supplied orthonasally in comparison to retronasal administration. The observed cross-modal effect of texture on aroma intensity was not significantly altered by the mode of aroma delivery, i.e., orthonasal or retronasal stimulus administration.  相似文献   

5.
Using atmospheric pressure chemical ionization-mass spectrometry, aroma release was investigated in vivo and in vitro from three cheese-like gels with different hardnesses. In vivo, nosespace experiments were performed with 14 subjects. Results showed that the harder gel induced a greater and a faster release of all aroma compounds. In vitro, aroma release was followed in a mouth simulator where breakdown was mechanically produced. The same rate of stirring was applied to the three gels. In these conditions, we found that the amount of aroma released from the three gels was not discriminant. Thus, modification of gel structure had a strong impact on in vivo aroma release, but structural variations alone were not sufficient to induce a greater release. Natural breakdown provided by panelists during food consumption and adapted to the texture of the food was proposed to be the key parameter affecting in vivo aroma release.  相似文献   

6.
Processes controlling aroma release and delivery during and after the consumption of a beverage were studied using real-time physiological and aroma release measurements. The key processes were as follows. During swallowing, a portion of the buccal gas phase was transferred first to the throat and then to the nasal passages via the tidal breath flow. This mechanism accounted for the sharp pulse of aroma seen at the beginning of the swallow breath and on subsequent swallows. The persistence effect was due to liquid-air partition from beverage coated on the throat and was dependent on the concentration of volatile compounds in the beverage. Lipid in the beverage caused a decrease in the intensity of volatile compounds on the breath, but the presence of a thickening agent had no effect on persistence.  相似文献   

7.
The influence of flavored yogurt texture on aroma perception and in-nose aroma release measured by atmospheric pressure chemical ionization mass spectrometry analysis was investigated. The study was carried out on six yogurts varied by protein composition and mechanical treatment. For the same matrix composition, the complex viscosity of yogurts influenced in-nose release and perception. After swallowing, aroma release and intensity of olfactory perception were stronger in low-viscosity yogurts than in high-viscosity yogurts. Moreover, the protein composition influenced aroma release only when yogurts exhibited wide variations of complex viscosity and consequently texture. In mouth, aroma release and perception were influenced more by yogurt mechanical treatment than by protein composition. On the basis of mass transfer analysis, the main physical mechanism which could explain the difference in aroma release would be the surface exchange area developed in the mouth and in the throat.  相似文献   

8.
Decreasing the fat content of a food, while maintaining the same aroma content, changes both aroma release (due to partition effects) and the viscosity of the food. To understand the relative contribution of these two factors on flavor perception, a series of flavored emulsions were prepared to control aroma release and viscosity using different aroma, oil, and hydroxypropyl methyl cellulose (HPMC) contents. Samples were formulated to deliver the same aroma-release in vitro and in vivo, and their viscosity was measured using the Kokini oral shear stress parameter. Despite the in vivo aroma release being constant, there were perceptual differences between the samples, and the flavor intensity decreased as in-mouth viscosity increased. For these iso release samples, the Kokini oral shear stress parameter correlated well with the decrease in perception, suggesting that there may be a viscosity stimulus or that the viscosity affects release of tastant and hinders aroma-taste interactions.  相似文献   

9.
Six model dairy desserts, with three different textures and two sucrose levels, were equally flavored with a blend of four aroma compounds [ethyl pentanoate, amyl acetate, hexanal, and (E)-2-hexenal] and evaluated by a seven person panel in order to study whether the sensory perception of the flavor and the aroma release during eating varied with the textural characteristics or the sweetness intensity of the desserts. The sensory perception was recorded by the time intensity (TI) method, while the in vivo aroma release was simultaneously measured by the MS-nose. Considering the panel as a whole, averaged flavor intensity increased with sucrose level and varied with the texture of the desserts. Depending on the aroma compound, the averaged profile of in vivo aroma release varied, but for each aroma compound, averaged aroma release showed no difference with the sucrose level and little difference with the texture of the desserts. Perceptual sweetness-aroma interactions were the main factors influencing perception whatever the texture of the desserts.  相似文献   

10.
The effect of textural modifications of solid milk gels on in vivo aroma release and aroma perception was investigated with a panel of 14 subjects. Great inter-individual differences were observed on aroma-release data, and the consequences of these differences on aroma perception were studied. From a hierarchical cluster analysis performed with several parameters extracted from release curves, the subjects were gathered into two groups, and a specific aroma-release profile was identified for each one. Then, by using a sensory profile, we showed that the intensity of the aroma perception was dependent on the release profile presented by the panelist. Second, we observed that, during the chewing phase, the aroma was perceived as more intense for the firmer gel and for panelists for whom the aroma release begins during the chewing of the product.  相似文献   

11.
The increasing popularity of low-fat products increases the need for a better understanding of how flavor release is affected by partial substitution of fat with hydrocolloids. Partitioning and release of aroma compounds from four pectin gels with different compositions were studied with static headspace and with a model mouth. Air/product partition coefficients determine the potential extent of aroma release, and mass transfer determines the rate at which aroma compounds are released to the vapor phase. This study showed that the gel network had large effects on the partition of aroma compounds between the gel and vapor phase. The specific properties of the aroma compounds were also of importance for the air/gel partition. Storage of the four gels showed that one of the weaker gels was influencing the concentration of aroma compounds in the headspace, probably caused by formation of a denser network over time.  相似文献   

12.
The influence of gel texture on parameters such as positioning of food material in the oral cavity during mastication, and salivation, and their influence on aroma release in vivo was studied. Retronasal perception was followed by means of time-resolved sensory evaluation, while volatile release patterns were observed by means of PTR-MS. A clear correlation was found between individual-specific consumption patterns and the respective sensory perception. Also, gel texture could be clearly correlated with respective physicochemical release patterns in vivo and to the corresponding retronasal aroma perception.  相似文献   

13.
This study aims to follow the kinetics of aroma compound release during model cheese consumption in order to clarify the relationships between flavor release and some oral parameters. Eight subjects participated in the study. Breathing, salivation, chewing, and swallowing were monitored during the eating process. Temporal nosespace analyses were performed using on-line atmospheric pressure ionization-mass spectrometry (API-MS) and off-line solid-phase Micro extraction-gas chromatography-mass spectrometry (SPME-GC-MS). Flavor release profiles were obtained only for ethyl hexanoate, heptan-2-one, and heptan-2-ol. Among them, only the concentrations of ethyl hexanoate and heptan-2-one could be determined by API-MS. Absence of competition between the aroma compounds was checked for both techniques. In-nose maximum concentration (C(max)) varied with aroma compounds. However, C(max) was reached at the same time (T(max)) for the three compounds. Interindividual differences were observed for most of the parameters studied and for all of the aroma compounds. They were related to the interindividual differences among the oral parameters. The aroma release parameters C(max) and AUC (area under the curve) could be related to respiratory and masticatory parameters. In most cases, the same relationships were observed whatever the nature of the aroma compound.  相似文献   

14.
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15.
微热管阵列式太阳能空气集热-蓄热系统性能试验   总被引：3，自引：3，他引：0  
该文采用了以微热管阵列(micro heat pipe arrays,MHPA)为核心元件的真空管型空气集热器与新型相变空气蓄热器,设计搭建了以空气为传热介质的太阳能集热-蓄热系统.集热器采用微热管阵列与真空管结合的新形式,蓄热器以相变温度42℃的月桂酸为蓄热相变材料,测试了系统在不同空气流量下集热过程的集热效率,蓄放热过程中蓄热放热的时间、功率,并在不同空气流量下对蓄热器的蓄热、放热特性进行了研究.研究表明:空气流量240m3/h工况下,集热效率最高;蓄热器的蓄热时间和放热时间最短,蓄热功率和放热功率最大,分别是633和486W;而空气流量60 m3/h能提供更加稳定的出口温度与放热功率,在供暖与干燥领域更加适用.集热-蓄热过程和放热过程阻力分别小于327和40 Pa,说明放热过程系统阻力损失较小,选用功率较小的风机就可提供空气流动的动力.  相似文献   

16.
日光温室主动蓄放热系统应用效果研究   总被引：11，自引：0，他引：11  
针对日光温室冬季夜晚温度低、作物易发生冷害等问题,设计了以水为蓄热介质的主动蓄放热系统.系统由集/放热装置、储热装置和控制装置等组成.白天进行太阳辐射热的吸收与储存,夜晚释放热量用于温室增温.试验结果表明,晴天条件下,主动蓄放热系统的集热功率为0.3kW/m2,蓄热量为6.9MJ/m2;夜间放热功率为0.2kW/m2,放热量为5.7MJ/m2,热利用效率为0.83,试验温室与对照温室的平均气温相差6.3℃;阴天及多云天气条件下,试验温室与对照温室的夜间平均气温相差4.6℃,表明主动蓄放热系统能有效改善日光温室夜间低温状况,进而保障蔬菜安全越冬生产.  相似文献   

17.
The relationship between the physical structure of espresso coffee foam, called crema, and the above-the-cup aroma release was studied. Espresso coffee samples were produced using the Nespresso extraction system. The samples were extracted with water with different levels of mineral content, which resulted in liquid phases with similar volatile profiles but foams with different structure properties. The structure parameters foam volume, foam drainage, and lamella film thickness at the foam surface were quantified using computer-assisted microscopic image analysis and a digital caliper. The above-the-cup volatile concentration was measured online by using PTR-MS and headspace sampling. A correlation study was done between crema structure parameters and above-the-cup volatile concentration. In the first 2.5 min after the start of the coffee extraction, the presence of foam induced an increase of concentration of selected volatile markers, independently if the crema was of high or low stability. At times longer than 2.5 min, the aroma marker concentration depends on both the stability of the crema and the volatility of the specific aroma compounds. Mechanisms of above-the-cup volatile release involved gas bubble stability, evaporation, and diffusion. It was concluded that after the initial aroma burst (during the first 2-3 min after the beginning of extraction), for the present sample space a crema of high stability provides a stronger aroma barrier over several minutes.  相似文献   

18.
The presence of fat in food plays an important role in the way aroma is released during consumption and in the creation of the overall sensory impression. Fat acts as a reservoir for lipophilic volatile compounds and modulates the timing and delivery of aroma compounds in a unique manner. Despite considerable research, reproducible in vitro methods for measuring the effect of fat on volatile release are lacking. An open in vitro cell was used to simulate the open human naso-oropharygeal system and was interfaced with a proton transfer reaction mass spectrometer (PTR-MS) to examine some of the fundamental effects of fat on dynamic volatile release in liquid fat emulsions. Lipid emulsions with various fat contents (0-20%) and droplet sizes (0.25, 0.5, and 5.0 μM) were spiked with flavor volatiles representing a range of lipophilicity (K(o/w) = 1-1380). Preloaded syringes of spiked emulsion were injected into the cell, and temporal changes in release were measured under dynamic conditions. Significant differences in release curves were measured according to the lipid content of emulsions, the vapor pressure, and K(o/w) values of the volatile compounds. With increasing addition of fat, the critical volatile release parameters, maximum concentration (I(max)), time to maximum concentration (T(max)), and the integrated area under the concentration curve (AUC), were affected. The in vitro curves were reproducible and in agreement with theory and correlated with the preswallow phase of in vivo release data. An exponential model was used to calculate changes in mass transfer rates with increased fat addition.  相似文献   

19.
The temporal change in the headspace composition of an aroma model mimicking Longjing green tea aroma was studied in the presence of nonvolatile Longjing green tea constituents. Upon storage at 50 degrees C, the formation of 2-butyl-2-octenal was found, which increased with time. This enal was generated by crotonization of hexanal as demonstrated in model experiments. The formation of 2-butyl-2-octenal was also detected in Longjing tea infusions and Longjing tea leaves upon storage at 50 degrees C. The presence of nonvolatiles induced a strong decrease in aroma release. These effects were mainly due to catechins, major constituents of green tea infusion. Free amino acids, that is, glycine, contributed only to significantly decrease alpha,beta-unsaturated carbonyl aroma compounds, that is, 1-octen-3-one and geranial. Model reaction containing a mixture of 1-octen-3-one and glycine indicated on the basis of NMR and MS data the formation of the tentatively identified N-1-(3-oxo-octyl)glycine resulting from a 1,4-addition. The perceived aroma of green tea infusion is very likely to be affected by the formation of new aroma compounds and the changes in aroma release affected by interactions with tea nonvolatile components. This deserves further investigations on the sensory level.  相似文献   

20.
The use of solvent-assisted flavor evaporation extraction (SAFE) and purge and trap in Tenax allowed the identification of more than 100 volatile compounds in a sponge cake (SC-e). Gas chromatography-olfactometry (GC-O) of the SAFE extracts of crumb and crust were achieved in order to determine the most potent odorants of SC-e. The change in the traditional dough formulation of SC-e in which eggs were substituted by baking powder (SC-b) as the leavening agent produced important changes in some key aroma compounds. The release curves of some aroma compounds-some of them generated during baking and others added in the dough-were followed by cumulative headspace analysis. In the flavored SC-b, the aroma release curves showed a plateau after 15 min of purge, while the release increased proportionally with the purge time in the flavored SC-e. In general, except for some of the aroma compounds with the highest log P values, the rate of release of most of the added and generated aroma compounds was significantly influenced by the changes in the cake formulation. The higher rates of release found for the aroma compounds in SC-b could contribute to explain its rapid exhaustion of aroma compounds in the purge and trap experiments and might lead to poorer sensorial characteristics of this cake during storage.  相似文献   

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