Orthonasal and retronasal perception of some green leaf volatiles used in beverage flavors.

Orthonasal perception of six green leaf volatiles (GLVs) classified only hexanal, (E)-2-hexenal, and (Z)-3-hexen-1-yl formate as green. (Z)-3-Hexen-1-yl hexanoate and (Z)-3-hexen-1-yl 3-methylbutyrate were more floral, and (Z)-3-hexen-1-yl acetate fell between the two groups. For retronasal perception, classification along a bipolar green-fruity scale is proposed for describing these GLVs. Data from grouping and dissimilarity tests as well as from sensory profiling show green character for these compounds in standard beverage bases having low Brix or high acidity. As the Brix value increases (or acidity decreases) within the limits encountered in commercial beverages, the character becomes fruity. Several tastant-dependent changes in intensity scores for retronasal descriptors were shown to occur for mixtures of GLVs. The GLVs did not affect intensity scores for gustatory descriptors.

Sweetener/sweetness-induced changes in flavor perception and flavor release of fruity and green character in beverages.

Green leaf volatile (GLV) mixtures, commercial orange flavors, and commercial strawberry flavors were applied to beverage bases in which concentrations of citric acid as well as a sweetener (sucrose or aspartame/acesulfame-K) were varied. Sensory profiling showed that flavor-specific fruity character increased as perceptible sweetness increased, independent of whether the sweetness resulted from sucrose (a change from 9 to 12 Brix) or aspartame/acesulfame-K (a change from 0.2 to 0.4 Brix). Sweetness was affected only by the tastants in the base and not by the flavors, although flavor-specific interactions between sweetener type and sweetener level occurred. Flavor release from the sucrose bases was compared to flavor release from bases containing aspartame/acesulfame-K by static headspace measurements and by MS-Nose measurements using an artificial throat. These measurements showed greater flavor volatility from bases having low Brix (fewer soluble solids). This negative Brix effect was also evident in the sensory data for perception of some GLV green notes. The headspace data could not support a positive Brix effect, the typical salting out, which would correspond to the observed perceptual enhancement of fruity notes.

Correcting the QT interval for changes in HR in pre-clinical drug development.

OBJECTIVES: Estimation of possible cardiovascular side effects belongs to the safety assessment of every drug candidate. Drug-induced prolongation of the QT interval can result in life-threatening ventricular arrhythmia. In pre-clinical drug development, animal experiments are used to study this possible effect. Researchers have become aware that correction formulae derived for human beings are not applicable to animal experiments. METHODS: We investigated some of the proposed models by comparing the outcomes of the analyses on the same data. The data was derived from telemetry measurements on Labrador dogs. We propose the use of both the correlation with heart rate (or RR interval) and a measure of predictive performance. As a sufficiently large number of observations were available, the data was subdivided into a training and a test set. The training set serves to estimate the respective parameters while the test set is used to determine the performance of the model. Here, a kind of PRESS statistic was used. Next, the models were considered for treated animals, using the estimated parameters. Both positive and negative controls were used. CONCLUSIONS: Most models under consideration performed quite well. These models eliminated the correlation for the most part and were reasonably predictive. Furthermore, they reliably differentiate between positive and negative controls. The next steps in identifying the best correction will be to consider additional compounds as well as other species to validate our current results.