Flavor release measurement from gum model system

Flavor release from a mint-flavored chewing gum model system was measured by atmospheric pressure chemical ionization mass spectroscopy (APCI-MS) and sensory time-intensity (TI). A data analysis method for handling the individual curves from both methods is presented. The APCI-MS data are ratio-scaled using the signal from acetone in the breath of subjects. Next, APCI-MS and sensory TI curves are smoothed by low-pass filtering. Principal component analysis of the individual curves is used to display graphically the product differentiation by APCI-MS or TI signals. It is shown that differences in gum composition can be measured by both instrumental and sensory techniques, providing comparable information. The peppermint oil level (0.5-2% w/w) in the gum influenced both the retronasal concentration and the perceived peppermint flavor. The sweeteners' (sorbitol or xylitol) effect is less apparent. Sensory adaptation and sensitivity differences of human perception versus APCI-MS detection might explain the divergence between the two dynamic measurement methods.     

Flavor perception and aroma release from model dairy desserts

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.     

Flavor release from salad dressings: sensory and physicochemical approaches in relation with the structure

The effect of process and formulation on sensory perception and flavor release was investigated on salad dressing models. Oil/vinegar emulsions (phi = 0.5, droplet size > 10 microm) with thickeners and a whey protein concentrate were prepared with different fat droplet sizes and different distributions of fat droplet size. The effect of the amount of emulsifier was also tested. Sensory profile analysis was performed by a trained panel and flavor release quantified by dynamic headspace analysis. When the droplet size is increased, the lemon smell and citrus aroma significantly increase, whereas the egg note, mustard, and butter aroma significantly decrease. The concentrations of alcohols and acids significantly increase when droplet size increases, whereas those of other compounds such as limonene or benzaldehyde significantly decrease. The dispersion of the droplet size has a small effect on flavor perception, and the effect of the increase of the amount of emulsifier is noticed only by instrumental analysis.     

Computerized apparatus for measuring dynamic flavor release from liquid food matrices

A fully computer-controlled apparatus was designed. It combines a glass reactor with a temperature-controlled hood, in which headspace volatiles are captured. Flavored liquids can be introduced into the reactor and exposed to conditions of temperature, air flow, shear rate, and saliva flow as they occur in the mouth. As the reactor is completely filled before measurements are started, creation of headspace just before sampling start prevents untimely flavor release resulting in real time data. In the first 30 s of flavor release the concentrations of the volatiles can be measured up to four times by on-line sampling of the dynamic headspace, followed by off-line trapping of the samples on corresponding Tenax traps and analysis using GC-TDS-FID. Flavor compounds from different chemical classes were dissolved in water to achieve concentrations typically present in food (micrograms to milligrams per liter). Most of the compounds showed constant release rates, and the summed quantities of each volatile of three 10 s time intervals correlated linearly with time. The entire method of measurement including sample preparation, release, sampling, trapping, thermodesorption, and GC analysis showed good sensitivity [nanograms (10 s)(-1)] and reproducibility (mean coefficient of variation = 7.2%).     

Flavor encapsulation in yeasts: limonene used as a model system for characterization of the release mechanism

Empty yeast cells are used as a new delivery system for flavor encapsulation. The flavor release mechanism from yeast cells is characterized using a series of analytical techniques, and limonene is used as a model representing a hydrophobic flavor. Furthermore, the thermal stability of the capsules was assessed. The characterization of the cell wall structure gives rise to the development of an empirical model explaining water adsorption as well as the desorption singularities observed on drying. The study of the rate of flavor release as a function of temperature and water uptake in the cell wall clearly demonstrated a particular behavior of the yeast cell wall permeability. Below a water activity around 0.7, no flavor release is permitted whereas release occurs above it. Surface analysis on dry or wet cells using atomic force microscopy is discussed.     

Flavor release and perception in hard candy: influence of flavor compound-compound interactions

The influence of flavor compound-compound interactions on flavor release properties and flavor perception in hard candy was investigated. Hard candies made with two different modes of binary flavor delivery, (1) L-menthol and 1,8-cineole added as a mixture and (2) L-menthol and 1,8-cineole added separate from one another, were analyzed via breath analysis and sensory time-intensity testing. Single-flavor candy containing only L-menthol or 1,8-cineole was also investigated via breath analysis for comparison. The release rates of both L-menthol and 1,8-cineole in the breath were more rapid and at a higher concentration when the compounds were added to hard candy separate from one another in comparison to their addition as a mixture (conventional protocol). Additionally, the time-intensity study indicated a significantly increased flavor intensity (measured as overall cooling) for hard candy made with separate addition of these flavor compounds. In conclusion, the flavor properties of hard candy can be controlled, at least in part, by flavor compound-compound interactions and may be altered by the method of flavor delivery.     

Flavor release and perception of flavored whey protein gels: perception is determined by texture rather than by release

Five whey protein gels, with different gel hardnesses and waterholding capacities, were flavored with ethylbutyrate or diacetyl and evaluated by a 10-person panel to study the relation between the gel structure and the sensory perception, as well as the nosespace flavor concentration during eating. The sensory perception of the flavor compounds was measured by the time-intensity method, while simultaneously the nosespace flavor concentration was monitored by the MS-Nose. The nosespace flavor concentration was found to be independent of the gel hardness or waterholding capacity. However, significant changes in flavor intensity between the gels were perceived by the majority of the panelists, despite the fact that the panelists were instructed to focus only on flavor perception and to not take texture into account. From these observations it is concluded that the texture of gels determines perception of flavor intensity rather than the in-nose flavor concentration.     

Flavor release in the presence of melanoidins prepared from L-(+)-ascorbic acid and amino acids

High-molecular-weight (HMW) water-soluble melanoidins were prepared from model systems of L-(+)-ascorbic acid-glycine, L-(+)-ascorbic acid-lysine, L-(+)-ascorbic acid-glutamic acid, and glucose-glycine using a very recently approved standard protocol. The amount of HMW water-soluble melanoidins prepared from L-(+)-ascorbic acid was over 5-15 times higher than the amount obtained from glucose. The study of the release of a model flavor compound, namely isoamyl acetate, from melanoidins by solid-phase microextraction (SPME) showed that SPME is a suitable technique for the analysis of flavor release from melanoidin-containing solutions. From the studies on the retention capacity of the melanoidins toward isoamyl acetate, an increased release of the flavor compound was observed from the melanoidins prepared from the L-(+)-ascorbic acid-glycine model system, whereas the opposite effect was observed from the melanoidins prepared from the L-(+)-ascorbic acid-lysine/glutamic acid model systems. The melanoidins prepared from the glucose-glycine model system had the same effect as the melanoidins prepared from the L-(+)-ascorbic acid-glycine model system.     

Flavor release and perception in hard candy: influence of flavor compound-flavor solvent interactions

The release kinetics of l-menthol dissolved in propylene glycol (PG), Miglyol, or 1,8-cineole (two common odorless flavor solvents differing in polarity and a hydrophobic flavor compound) were monitored from a model aqueous system via atmospheric pressure chemical ionization mass spectrometry (APCI-MS). Breath analysis was also conducted via APCI-MS to monitor release of l-menthol from hard candy that used PG and Miglyol for l-menthol incorporation. The quantities of l-menthol released when dissolved in PG or Miglyol from the model aqueous system were found to be similar and overall significantly greater in comparison to when dissolved in 1,8-cineole. Analogous results were reported by the breath analysis of hard candy. The release kinetics of l-menthol from PG or Miglyol versus from 1,8-cineole were notably more rapid and higher in quantity. Results from the sensory time-intensity study also indicated that there was no perceived difference in the overall cooling intensity between the two flavor solvent delivery systems (PG and Miglyol).     

七种钾释放动力学方程的比较和动力学参数的应用

Batch equilibrium experiments were conducted to investigate cadmium （Cd） sorption by two permanent-charge soils, a yellow-cinnamon soil and a yellow-brown soil, and two variable-charge soils, a red soil and a latosol, with addition of selected organic acids （acetate, tartrate, and citrate）. Results showed that with an increase in acetate concentrations from 0 to 3.0 mmol L^-1, Cd sorption percentage by the yellow-cinnamon soil, the yellow-brown soil, and the latosol decreased. The sorption percentage of Cd by the yellow-clnnamon soil and generally the yellow-brown soil （permanent-charge soils） decreased with an increase in tartrate concentration, but increased at low tartrate concentrations for the red soil and the latosol. Curves of percentage of Cd sorption for citrate were similar to those for tartrate. For the variable-charge soils with tartrate and citrate, there were obvious peaks in Cd sorption percentage. These peaks, where organic acids had maximum influence, changed with soil type, and were at a higher organic acid concentration for the variable-charge soils than for the permanent charge soils. Addition of cadmium after tartrate adsorption resulted in higher sorption increase for the varlable-charge soils than permanent-charge soils. When tartrate and Cd solution were added together, sorption of Cd decreased with tartrate concentration for the yellow-brown soil, but increased at low tartrate concentrations and then decreased with tartrate concentration for the red soil and the latosol.     

Formulation of a first-order kinetic model and release of added phosphorus in a savanna soil

Adsorption–desorption of added phosphorus (P) was studied in a batch experiment using anion-exchange resin. Total P sorbed by adding 400 mg P kg^?1 by Nigerian soil ranged from 10.8 mg kg^?1 in the Idofian Basement complex to 35.5 mg kg^?1 in Alkaleri Sandstone, representing 3 and 9% of applied P. Phosphorus release kinetics was apparently described by the first-order, second-order, Elovich, parabolic diffusion and fractional power equations, but not in soils derived from sandstone. The mechanism underlying the release pattern was concluded to be dissolution followed by diffusion of sorbed P from the good fit to the Elovich and parabolic diffusion equations. The inability to clearly relate the P sorbed by the soil to OH^- and SO₄ ^2- released into the soil solution during the adsorption process further corroborated the above conclusion, thereby overruling the possibility of ligand exchange as a dominant mechanism in the sorption/desorption of P in these soils.     

Flavor release and rheology behavior of strawberry fatfree stirred yogurt during storage

The influence of storage on the aroma release in headspace and rheological properties in strawberry-flavored fatfree stirred yogurts was determined. Three periods of storage at 10 degrees C were chosen for analysis: 7, 14, and 28 days. The headspace composition was assessed in a flask in static mode. The SPME fiber was carefully chosen, and results are presented in detail (choice and degradation). The flow properties of the final product were measured in order to follow n (flow behavior index) and K (consistency index), and the apparent viscosity was determined (eta in Pa.s). The quantity of flavors in the headspace of products at the 28 days of aging was significantly weaker for methyl 2-methyl butanoate, ethyl hexanoate, and hexyl acetate. The decrease was half of that in comparison with the seventh day. It was supposed that modification in rheological parameters can partly explain these results. Indeed, the apparent viscosity of the products significantly increased during the three times of storage. The composition of the flavored yogurt, proteins, exopolysaccharides, and fruit preparation, seemed to have a great impact on the release of aroma compounds. The aroma compound amount in the headspace decreased when the matrix changed from water to yogurt. With the fruit preparation, the headspace amounts for esters were significantly lower than in water alone, respectively, 23, 27, 29, and 17% less for methyl 2-methylbutanoate, ethyl hexanoate, hexyl acetate, and benzyl acetate. In flavored yogurt, the amount of aroma compounds in the headspace decreased again in comparison with the result obtained with the fruit preparation. Ethyl hexanoate and hexyl acetate presented the higher decreases of 48 and 53%, respectively.     

Development and validation of a dynamic vapor sorption-fast gas chromatography-flame ionization detection method for rapid analysis of volatile release from glassy matrices

Historically, saturated salt solutions in desiccators have been used to investigate the effects of increasing relative humidity and temperature on the volatile retention efficiency of amorphous glasses. Obtaining data using desiccators is a static process that gives the researcher discrete data points with which to draw conclusions. Dynamic vapor sorption (DVS; SMS, London, U.K.) is a humidification system that creates specific relative humidity and temperature environments within a chamber that contains the material being investigated. This study had two specific aims: (1) to develop a DVS-fast GC-FID method that dynamically evaluates the effects of humidification and temperature increases on volatile release from amorphous carbohydrate glasses and (2) to evaluate the validity of the DVS-fast GC-FID method. Artificial cherry Durarome (Firmenich, Plainsboro, NJ) was used as the model system. The DVS-fast GC-FID method proved to be an innovative, accurate, and precise technique that can be used to conduct humidification/temperature-volatile release studies.     

Uncertainty analysis of a dynamic vapor sorption-fast gas chromatography-flame ionization detection method for the rapid analysis of volatile release from glassy matrices

Uncertainty analysis was conducted with a dynamic vapor sorption-fast gas chromatography-flame ionization detection (DVS-fast GC-FID) method, developed to rapidly analyze the extent of volatile release that occurs from carbohydrate glasses due to humidification and temperature increases. Triplicate samples progressed through a two-step special automatic operation method in the DVS. Samples were exposed to relative humidities ranging from 40 to 90% (in 10% increments) at 15, 25, and 35 degrees C. Uncertainty analysis shows that the DVS-fast GC-FID method uncertainty is smaller than the natural sample uncertainty, indicating that the variability in a sample's physical properties has a dominant impact on the overall uncertainty of the volatile retention results obtained using the DVS-fast GC-FID method. Uncertainty analysis also indicates that the variance associated with the mass of benzaldehyde measured by the DVS-fast GC-FID is the largest contributor to the overall benzaldehyde retention variance when the cumulative mass of benzaldehyde measured is small.     

Controlled release of tebuconazole from a polymer matrix microparticle: release kinetics and length of efficacy

Preparation and characterization of microencapsulated tebuconazole, its release kinetics in water, and the bioefficacy of these formulations in controlling wheat rust in spring wheat is described herein. Controlled-release (CR) formulations based on matrix microparticles were prepared by the oil-in-water emulsion process. Polymer-based matrix was prepared from poly(methyl methacrylate) (PMMA) and poly(styrene-co-maleic anhydride) (PSMA). Modification of the matrix was achieved by the use of different low molecular weight or polymeric additives. These additives were found to lower the glass transition temperature of the matrix and enhance the release rate of tebuconazole in water, under infinite sink conditions. Release of tebuconazole from matrix microparticles was found to be diffusion controlled. CR formulations were found to be very efficacious in controlling wheat rust. Soil-applied CR formulations prepared from a PMMA or PSMA matrix, modified with poly(vinyl acetate), were as effective in controlling wheat rust (Puccinia recondita) as foliar-applied tebuconazole, Raxil, from Bayer AG. Results suggest that CR formulations with a systemic fungicide, such as tebuconazole, applied as either a soil or seed treatment, may provide control of foliar diseases, possibly eliminating or reducing the need for traditional foliar applications.     

Flavor enhancement of chicken broth from boiled celery constituents

The flavor-enhancing effects of the volatile constituents in celery were investigated. The test samples were prepared by adding celery fractions to chicken broth at a concentration that distinct odors of them were not detected, and the samples were sensorially evaluated for the perceived intensities of 8 terms such as "thick," "impactful," "mild," "lasting," "satisfied," "complex," "refined," and "clarified," which are considered to be the elements of the complex flavor and for 3 terms such as "sweet," "salty," and "umami" taste. A comparison of effects between the volatile and nonvolatile fractions of celery revealed that the volatile compounds in celery enhanced the complex flavor of chicken broth more than the nonvolatile compounds. Among the characteristic odorants of celery, three phthalides, namely, sedanenolide, 3- n-butylphthalide, and sedanolide, were shown to contribute to the complex flavor of chicken broth, and sedanenolide was most effective. The three phthalides enhanced perceived intensities of "umami" and "sweet" despite their no taste properties in addition to the complex flavor.     

Photodegradation of the acaricide abamectin: a kinetic study

The acaricide abamectin is a mixture of two colorless homologues in a molar ratio of at least 4:1 with the same structure of macrocyclic lactone. The kinetics of its degradation under direct (254 nm) and dye-sensitized (>400 nm) photoirradiation in methanol solution has been studied by UV-vis spectrophotometry, potentiometric detection of dissolved oxygen, stationary fluorescence, laser flash photolysis, and time-resolved detection of singlet molecular oxygen (O2((1)Delta(g))) phosphorescence. The results indicate that the degradation is very efficient under direct irradiation with UV light (254 nm), with a quantum yield of 0.23. On the contrary, under visible-light irradiation, using the natural pigment riboflavin or the synthetic dye rose bengal as sensitizers, the degradation is very inefficient and proceeds through a O2((1)Delta(g))-mediated mechanism, with a bimolecular rate constant for the overall O2((1)Delta(g)) quenching (the sum of physical and chemical quenching) of 5.5 x 10(5) M(-1) s(-1). This value is similar to those reported for the rate constants of the reactions of O2((1)Delta(g)) with isolated double bonds or conjugated dienes and points to similar processes in the case of abamectin.     

The elusiveness of coffee aroma: new insights from a non-empirical approach

Aroma is central to a pleasurable eating/drinking experience but is one of the most labile components of food. Coffee is an outstanding example. Attempts to avoid or control aroma degradation are often frustrated by ignorance of the microscopic mechanisms that are responsible for it. One of the processes most frequently invoked is radical formation, yet the identity of the radicals and their involvement in aroma degradation are poorly understood at the molecular level. Here a step forward in the fundamental understanding of this complex problem is taken by identifying the most relevant radicals and their products using first-principles calculations. Over 100 radicals originating from key aroma compounds found in coffee and other foods have been studied and classified according to an unambiguous criterion: their thermodynamic stability relative to common radical sources. This classification scheme predicts that most aroma molecules are resistant to both peroxidation and attack from phenolic antioxidants but are unstable with respect to radicals such as .OH. Dimers--generated from radical reactions--were also considered, and the most volatile species, which may further contribute to coffee aroma degradation, were focused on. Those--which are very few indeed--that have this potential have been identified.     

Controlled release of carbofuran from an alginate-bentonite formulation: water release kinetics and soil mobility

The insecticide-nematicide carbofuran was incorporated in alginate-based granules to obtain controlled-release (CR) properties. The basic formulation [sodium alginate (1.61%)-carbofuran (0. 59%)-water] was modified by addition of sorbents. The effect on carbofuran release rate, caused by the incorporation of natural and acid-treated bentonite (0.5 and 1.0 M H(2)SO(4)) in alginate formulation, was studied by immersion of the granules in water under shaking. The time taken for 50% of the active ingredient to be released into water, t(50), was longer for those formulations containing natural bentonite (6.1 h) or acid-treated bentonite (9.0 and 11.7 h for 0.5 and 1.0 M H(2)SO(4) treatments, respectively) than for the preparation without bentonite (4.7 h). It appears from the results that the release of carbofuran from the various formulations is controlled by a diffusion mechanism according to the n values obtained, which were close to 0.5 in all cases. The mobility of carbofuran from alginate-based CR formulations was investigated by using soil columns packed with a clay soil (53% clay and 0.08% organic matter). Two alginate-based CR formulations containing natural bentonite or acid-treated bentonite (0.5 M H(2)SO(4)) were compared to technical grade carbofuran. The use of alginate-based CR formulations resulted in a reduction of the leached amount of carbofuran compared with the total amount of pesticide leached using the technical product (50 and 75% for CR granules containing natural and acid-treated bentonite, respectively). Alginate-bentonite CR formulations might be efficient systems for reducing carbofuran leaching in clay soils, which would reduce the risk of groundwater pollution.