Determination Of Detection Thresholds Research Articles

Effects of Organic Acids on the Release of Fruity Esters in Water: An Insight at the Molecular Level

It is well known that organic acids (OAs) could affect the flavour of fruit juices and beverages. However, the molecular mechanism of aroma release is still unclear. In this study, the effects of citric acid (CA), L-(-)-malic acid (MA) and L-lactic acid (LA) on the release of six selected esters and their sensory perception were investigated by means of HS-GC-MS analyses and odour detection threshold determination, respectively. Meanwhile, the density functional theory (DFT) calculation was employed to explore the interaction modes between esters and OAs. HS-GC-MS analyses showed that the concentration and the type of OAs regulated the release of esters. The results were basically consistent with the detection threshold change of those esters. The DFT calculation suggested that the main intermolecular interaction was hydrogen bonds, and several esters could form a ternary ring structure with OAs through hydrogen bonds. The interactions can induce the different release behaviours of esters in OAs water solution. The number of carboxyl functional groups in OAs and the spatial conformation of esters appeared to influence the magnitude of the interaction. The above results demonstrated the mechanism of OAs affecting the release of esters and indicated a possible flavour control way by using different OAs and OA concentrations.

Satellite On-Orbit Anomaly Detection Method Based on a Dynamic Threshold and Causality Pruning

It is difficult for existing deep learning-based satellite on-orbit anomaly detection methods to define the residual-based detection threshold and identify false anomalies. To solve the above problems, this paper proposes both a detection threshold determination and dynamic correction method and a causality-based false anomaly identification and pruning method. We use the GRU (Gated Recurrent Unit) to model and predict the telemetry parameters to obtain the residual vector; determine and dynamically correct the threshold according to the prescribed false positive rate; propose an improved multivariate transfer entropy method to identify the causal relationships between the telemetry parameters; and, based on the causality, determine whether the detected parameter anomalies are false. Experiments show that the precision, recall, and F1-score of the method proposed in this paper are superior to the current typical method, and the false positive rate is significantly reduced, demonstrating the effectiveness of the proposed method.

Determination of detection thresholds of sinigrin in water‐based matrix and allyl isothiocyanate in water‐ and oil‐based matrices

AbstractIn the present study, sensory detection thresholds for sinigrin in a water‐based matrix and allyl isothiocyanate (AITC) in water‐ and oil‐based matrices were determined using a three‐alternative forced choice test with ascending concentrations. The study consisted of a prestudy with 10 assessors (3 mustard “users”; 7 mustard “nonusers”) and a main study with 64 assessors (10 mustard “users”; 54 mustard “nonusers”). In addition, panelists were asked to locate (throat, tongue, throat, and tongue) the predominant sensation (sinigrin: bitterness; AITC: pungency). The group threshold for sinigrin in the water‐based matrix in the prestudy was 10.928 mg/100 ml. Moreover, the group thresholds for AITC in the water‐based matrix in the prestudy and main study were 0.135 and 0.121 mg/100 ml, respectively. The group thresholds for AITC in the oil‐based matrix in the prestudy and main studies were 0.497 and 0.582 mg/100 ml, respectively. However, mustard “users” and mustard “nonusers” showed no significant differences in thresholds. Sinigrin and AITC were both prevalently perceived on the tongue.Practical applicationsThreshold determination for the primary pungent substance allyl isothiocynanate (AITC) and the corresponding precursor sinigrin in cruciferous plants such as mustard, horseradish, and wasabi are important for product development and quality assurance, especially for new products. These parameters will help to estimate whether pungency is a relevant characteristic of the product. In particular, differentiation of the matrix (water‐ or oil‐based matrix) helps to evaluate whether the particular AITC concentration is noticeable in food products depending on the food composition. Further studies should be conducted to determine whether AITC is perceived at the same levels in different food systems. Sinigrin causes the unpleasant bitterness of brassica vegetables. Nevertheless, sinigrin is a desirable substance in food products owing to its potential health‐promoting effects. Therefore, knowledge about the detection threshold of sinigrin will facilitate the breeding of sinigrin‐containing products without unpleasant bitterness and may increase consumer acceptance.

Rapid Throughput Operant Taste Discrimination: Signal Detection Theory (SDT) and Concentration‐Response (CR) Analyses for Quantifying Sucrose Taste Sensitivities in Individual Human Subjects

Most human taste discrimination experiments have focused on determination of detection thresholds, which are taken as indications of the sensitivity of the taste sensory system. However, detection thresholds reported in the literature can vary substantially across and within studies, and there is little evidence to support repeatability of the values obtained. Two factors that likely contribute to the observed variability are 1) inherent low throughput, which would impact assay robustness, and 2) insufficient accounting for subject bias in the analysis. Low throughput capacity of traditional taste discrimination methods all but precludes quantification by the more broadly applicable measures of discriminability (d′) and subject bias (β) obtained by SDT, as well as the ability to conduct CR analyses. We previously have reported a novel technology for automated rapid throughput operant taste discrimination using human subjects, called the TāStation®. We applied this technology to compare sensitivities to low “threshold” concentrations of sucrose determined by SDT with EC50s obtained by CR analysis in the same subjects. Small volumes (200 μl) of sucrose solutions or water, distributed in replicate wells of a 96‐well plate, were automatically drawn by an electronic pipette from single randomly selected wells on each trial. Subjects then removed the pipette and self‐administered the stimuli to the tongue. Subjects were trained through an interactive game‐like algorithm to associate the taste of sucrose with coordinates on the right sided of a touch‐sensitive display (TSD), and water on corresponding coordinates reflected to the opposite side. Correct responses on control trials were reinforced by the appearance of a virtual poker chip carrying remunerative value (which accumulated across the 96 trials); incorrect responses were penalized by a reduction in the cumulative score. The rapid generation of large robust data sets enabled an assessment of repeatability for SDT values of d′ and β, and EC50s derived from CR functions. We found that d′ and β were relatively stable across tests for some individuals but varied for other subjects. Less variability was observed in the EC50s for all subjects. For example, in three tests each occurring on separate days, 5 mM sucrose d′ values for subject M1200 were 1.18, 1.07, 0.94; those for subject M1194 were 0.56, −0.08, and 1.29. EC50s obtained for subject M1200 were 22, 27, and 24 mM, and for subject M1194 were 16, 20, and 27 mM. The repeatability of the EC50s within subjects revealed two distinct phenotypes for sucrose potency across subjects, with one group exhibiting EC50s that ranged narrowly around 25 mM, and a second group around 60 mM. These differences in sucrose potencies across subjects suggest the possibility of alternative structural features in the sucrose binding site of the T1R2/R3 receptor. Our results further imply that EC50 values, obtained from quantitative characterization of the entire concentrations‐response function for taste, are more reliable and more informative than measures of discriminability at the lowest taste‐active concentrations (i.e., “thresholds”).Support or Funding InformationEntirely funded by Opertech Bio

Odour Detection Threshold Determination of Volatile Compounds in Topical Skin Formulations

Several studies have shown that lipid oxidation can occur in topical skin formulations, but the impact of the individual volatile compounds on off‐odour has not yet been determined. In this study, lipid oxidation is investigated in prototype skin care formulations. Firstly, lipid oxidation volatile compounds that increased in concentration during storage are identified. The results show that the concentration of six volatile compounds increased above previously reported odour detection threshold values in water. These volatile compounds are selected for odour detection threshold value determination and also odour description by a trained sensory panel. In one case, the odour detection threshold value is 50 times higher (less detectable) in skin care products than in water, whereas for other volatile compounds the odour detection threshold value is only 1.5 times higher. The odour description of the volatile compounds is, in most cases, different from that reported in literature. The observed differences are hypothesised to be due to a masking effect of the base odour of the skin care product(s), a volatile‐retaining power of the base matrix and to a cocktail effect of the combined odours from different volatile oxidation products.Practical Application: In this study, the impact of volatile compounds on off‐odour is explored in prototype skin care formulations. The odour detection threshold value and odour description are determined for butanal, pentanal, 3‐methyl‐1‐butanol, 2‐ethyl furan, 2‐pentyl furan and 1‐heptanol in prototype skin care formulations.Overview of the different odour descriptors of the same volatile (3‐methyl‐1‐butanol) when found in topical skin formulations with different lipid contents.

Determination of Target Number of Peaks for Automatic Peak Detection Threshold Determination

Determination of Target Number of Peaks for Automatic Peak Detection Threshold Determination

Normalized Knock Intensity Determination Based on the Knock Sensor Analysis to Have a Fixed Detection Threshold at Different Operating Conditions

Processing the knock sensor's signal is the most common approach for knock detection in series production vehicles. Filtration, rectification, and integration in a defined knock window (KW) are main steps to compute the standard knock intensity (SKI). The SKI strongly depends on the engine operating conditions. In this study, a novel model is proposed based on the knock sensor analysis to determine the normalized knock intensity (NKI) with much less dependency on the operating conditions, cylinder numbers (CNs), and KW. Implementing the proposed normalization model, a fixed detection threshold can be used for knock detection at all operating conditions. To verify the model, an accurate knock detection method based on cylinder pressure analysis is utilized, which comprises intensity calculation and a novel technique for detection threshold determination. Experimental results at all operating conditions show a square of correlation coefficient greater than 0.7 when the knock intensity from the presented model is compared with the reference cylinder pressure based method. In addition, the model detects all heavy knocking cycles and there is no wrongly detected knocking combustion.

Influence of phenolic compounds on the sensorial perception and volatility of red wine esters in model solution: An insight at the molecular level

Impact of (+)-catechin and gallic acid on sensory perception and volatility of isoamyl acetate, ethyl isobutyrate, ethyl butyrate and ethyl octanoate was investigated in model solutions, by means of triangle tests, detection threshold determination and HS-GC–MS analyses. Catechin significantly altered the sensory perception of most esters (ethyl isobutyrate, ethyl butyrate and ethyl octanoate) while gallic acid displayed no impact. Ethyl butyrate and ethyl octanoate odour thresholds doubled or tripled in the presence of catechin, underlining a retention impact of phenolic compounds in liquid matrix. The headspace analyses displayed a decrease only in ethyl octanoate volatility in presence of catechin, whereas no significant difference in other esters concentrations was observed. This study indicated that phenolic compounds have a variable impact on aroma compounds’ volatility and their sensory perception. The polarity of phenolic and volatile compounds as well as their spatial conformation also appeared to influence the interaction strength.

An odour detection threshold determination of all four possible stereoisomers of oak lactone in a white and a red wine

Odour detection thresholds were determined for all four stereoisomers of oak lactone in both red and white wine. The natural cis-isomer was found to have a significantly lower detection threshold than its non-natural enantiomer in both media, and lower than indicated by most other sensory studies. The odour detection threshold for the natural trans-isomer was seven times higher than for the natural cis. Compared to its enantiomer, the natural trans-isomer had a lower detection threshold in the white wine medium, but slightly higher in the red. Duo-trio difference testing between the two trans-isomers added at the same concentration showed no significant difference between the two for both media. Similarly, a duo-trio test conducted between the natural cis-isomer and a mixture of the same amount of natural cis-oak lactone plus an equivalent concentration of the trans-isomer indicated that the latter had little or no influence on the odour impact of the cis-form.

Accelerated testing of on‐board diagnostics

AbstractModern products frequently feature monitors designed to detect actual or impending malfunctions. False alarms (Type I errors) or excessive delays in detecting real malfunctions (Type II errors) can seriously reduce monitor utility. Sound engineering practice includes physical evaluation of error rates. Type II error rates are relatively easy to evaluate empirically. However, adequate evaluation of a low Type I error rate is difficult without using accelerated testing concepts, inducing false alarms using artificially low thresholds and then selecting production thresholds by appropriate extrapolation, as outlined here. This acceleration methodology allows for informed determination of detection thresholds and confidence in monitor performance with substantial reductions over current alternatives in time and cost required for monitor development. Copyright © 2006 John Wiley & Sons, Ltd.

Orbitofrontal cortex dysfunction in obsessive-compulsive disorder?: II. Olfactory quality discrimination in obsessive-compulsive disorder

Background: Olfactory quality discrimination is a putative marker of orbitofrontal cortex function in mammals. As this portion of the cerebral cortex was repeatedly implicated in the pathophysiology of obsessive-compulsive disorder (OCD) this study was designed in an attempt to quantify this behavioural function in OCD patients. Methods and Results: Olfactory quality discrimination was compared in OCD patients and healthy controls. Thirty two subjects participated in the study: 16 (13 women and 3 men) medication free OCD outpatients and 16 sex and age matched healthy controls. Olfactory tests consisted of determination of detection thresholds to isoamyl acetate, and a three way forced choice quality discrimination task, using isoamyl acetate, citral and eugenol as stimuli. No significant differences in sensitivity and performance of the quality discrimination task between the two groups were found. Within the OCD group the more severely affected patients (Y-BOCS>29) performed significantly better than the less severely affected (Y-BOCS<30) patients on the more difficult part of the quality discrimination task. Within this subgroup of patients the correlation between performance on the olfactory task and a previously reported alternation task tended to be negative as compared to a significantly positive correlation in the control group. Conclusions: It seems that olfactory quality discrimination may prove to be a useful noninvasive marker of prefrontal cortex function in OCD. Furthermore, the organization of functional modules within the orbitofrontal cortex, rather than a simple dysfunction, may prove to characterize OCD.

Hyphenated Headspace-Gas Chromatography-Sniffing Technique: Screening of Impact Odorants and Quantitative Aromagram Comparisons

A new headspace-GC-sniffing method is proposed. Using a recently developed headspace cell, the vapor phase is collected under conditions that mimic well those of an aroma above a food. Data treatment is based on detection frequency, rather than on perceived intensity or successive dilutions as used in other approaches. Repeatability appears satisfactory, and independent panels are even able to generate similar aromagrams, without training prior to the analysis. Using a minimum of six assessors, this technique seems to be more reliable than classical ones. To compare detection frequencies between two aromagrams, an estimation of the least significant difference is given. A theoretical justification of this approach is suggested, on the basis of determination of detection thresholds. Keywords: Headspace-GC-sniffing; impact odorants; detection frequency

Threshold Detection Values of Potential Fish Tainting Substances from Oil Sands Wastewaters

Chemical compounds associated with oil sands extraction and upgrading operations have been implicated in the tainting of the Athabasca River fishery, a commercial and subsistence fishery for local natives. Selected contaminants found in oil sands wastewaters, and judged to be candidate tainting compounds, were spiked in walleye flesh and subjected to screening odour and taste detection by a trained sensory panel. Twelve compounds were screened and 8 were pursued for determination of detection thresholds based upon 3 separate sessions with a minimum of 9 panelists. Taint detection threshold values ranging from 0.09 mg/kg for benzothiophene to 12.2 mg/kg for 2,6-dimethylnaphthalene were established. These values will assist in determining the significance of analytically determined concentrations of these compounds in fish flesh.

Assessment of Nerve Damage in the Feet of Long-Distance Runners

To answer the question, "Does long-distance running injure nerves of the feet and legs?" we invited the 25 members of the Rochester Track Club who had run the greatest number of miles in their lifetime to participate in a study that involved neurologic examination, determination of detection thresholds of touch-pressure, vibratory, and cooling sensations of the foot, and evaluation of nerve conduction. None of the runners had clinical symptoms or signs of peripheral neuropathy. Most of them reported having had toe and foot injuries, sometimes associated with short-lived sensory symptoms. A computer-assisted sensory evaluation of the detection threshold for vibratory sensation of the toe revealed slightly, but significantly, higher values in the runners in comparison with age- and sex-matched control subjects. Similarly, small, but statistically significant, differences were also observed for some attributes of nerve conduction in the leg and foot nerves of the runners. These results suggest that long-distance running causes multiple small injuries to the toes and feet, which lead to measurable differences in the detection threshold for vibratory sensation and in nerve conduction but not to overt neuropathy. The trivial subclinical neuropathic deficits we noted are readily offset by the assumed health and recreational benefits of running.