Sensory Masking Research Articles

Proposal for Enhancing the Taste and Nutritional Value of Braised Fish

Braised fish, a highly popular Chinese dish known for its delectable taste and rich nutritional content, is prone to being affected by factors such as its inherent fishy taste. To elevate the dish's flavor profile and impart a delightful aroma, it becomes essential to mask the fishy taste effectively. This study compared the salt solution method, sensory masking method, biological method, and acid-base method to comprehensively analyze and address the underlying causes of the fishy taste. It was observed that both the salt solution method and sensory masking method proved successful in concealing the fishy smell. While the biological method effectively mitigated the production of fishy substances, it fell short in completely eliminating the fishy smell. On the other hand, the acid-base method demonstrated promising results in significantly reducing the fishy odor. Furthermore, manipulating the Maillard reaction's efficiency by controlling water activity and temperature through the use of the control variable method was studied. The highest Maillard reaction rate was achieved when the water activity was set at 0.7, and a neutral or weak base pH was maintained. Optimizing temperature and processing time led to the successful formation of aromatic compounds while minimizing damage to human cells. In addition to enhancing the taste, incorporating vegetables such as tofu, broad beans, or celery into braised fish recipes can offer additional health benefits, such as preventing obesity and reducing the presence of carcinogens.

Palatability Evaluation of Sulfamethoxazole/Trimethoprim with Sweetener Using the Two-Bottle Choice Test.

Drug taste, which affects palatability, influences drug adherence. Sensory masking may be used to confound bitter tastes in drugs with other tastes and flavors; however, evaluation of sensory masking is difficult because of the existence of multiple tastes. In this study, a new two-bottle choice test was performed in rats to evaluate bitterness masking and determine the drug-to-sweetener ratio that significantly improves palatability. Sulfamethoxazole and trimethoprim were used as model bitter drugs, and sucralose was used as sweetener. The addition of sucralose and trimethoprim at a 0.13 : 1 ratio resulted in the greatest improvement in preference. This method is a useful new technique for evaluating the palatability of drug formulations.

Experimental suppression of transcranial magnetic stimulation-electroencephalography sensory potentials.

The sensory experience of transcranial magnetic stimulation (TMS) evokes cortical responses measured in electroencephalography (EEG) that confound interpretation of TMS-evoked potentials (TEPs). Methods for sensory masking have been proposed to minimize sensory contributions to the TEP, but the most effective combination for suprathreshold TMS to dorsolateral prefrontal cortex (dlPFC) is unknown. We applied sensory suppression techniques and quantified electrophysiology and perception from suprathreshold dlPFC TMS to identify the best combination to minimize the sensory TEP. In 21 healthy adults, we applied single pulse TMS at 120% resting motor threshold (rMT) to the left dlPFC and compared EEG vertex N100-P200 and perception. Conditions included three protocols: No masking (no auditory masking, no foam, and jittered interstimulus interval [ISI]), Standard masking (auditory noise, foam, and jittered ISI), and our ATTENUATE protocol (auditory noise, foam, over-the-ear protection, and unjittered ISI). ATTENUATE reduced vertex N100-P200 by 56%, "click" loudness perception by 50%, and scalp sensation by 36%. We show that sensory prediction, induced with predictable ISI, has a suppressive effect on vertex N100-P200, and that combining standard suppression protocols with sensory prediction provides the best N100-P200 suppression. ATTENUATE was more effective than Standard masking, which only reduced vertex N100-P200 by 22%, loudness by 27%, and scalp sensation by 24%. We introduce a sensory suppression protocol superior to Standard masking and demonstrate that using an unjittered ISI can contribute to minimizing sensory confounds. ATTENUATE provides superior sensory suppression to increase TEP signal-to-noise and contributes to a growing understanding of TMS-EEG sensory neuroscience.

Novel approach in sensory color masking: Effects of colored environments on chocolates with different cocoa content

In sensory practice, the color masking procedure is executed almost exclusively with red light, regardless of the color of the product. In this work the practical application of a novel approach for sensory masking of color differences, hence the applicability of a spectrally tunable light booth was investigated. The aim of the research was to find the most appropriate masking environment, which i) can be considered as the most effective mask and ii) provides the best conditions regarding chromatic adaptation.The main idea of the novel approach in sensory color masking is that the instrumental characterization of all parameters influencing the perception of the sensory assessor. The comparison of the potential masking illuminations based on instrumental results (considering masking effect and chromatic adaptation) and the definition of the most appropriate mask should be accomplished based on sensory tests. The sensory effects of colored environments were tested on chocolate samples containing different amount of cocoa. CIELAB dE color differences between the samples were calculated based on their spectral reflectance. Four monochromatic (red, green, blue, amber) and six combined masking illuminations were developed in a spectrally tunable light booth and were instrumentally characterized by their spectral power distribution and luminance values. The chocolates were ranked according to their darkness by the assessors. The masking environments were compared based on the analysis of sequence correctness, decision time, and their combination (ANOVA, Survival-analysis).In Experiment 1 the monochromatic Blue light was not only more effective, than the commonly used Red light, but it was the most effective mask regarding color differences: the sequence error increased to 61% compared to the standard white (D65) illumination, and the decision time increased to more than double (15.74 s → 35.7 s). In Experiment 2 green and amber lights were combined with the blue mask, increasing the degree of chromatic adaptation: decision time decreased while the effectiveness of the mask did not decrease based on the sequence errors. Following the novel approach product specific masking environment considering effectiveness and chromatic adaptation was realized verified by statistical analysis of sensory test results.

The role of heat treatment in light oxidation of fluid milk

Light-oxidized flavor (LOF) resulting from photooxidation of riboflavin following light exposure is one of the most common off-flavors in fluid milk. The sensory perception of LOF has been studied extensively in high temperature, short time pasteurized (HTST) milk, but few studies have evaluated ultrapasteurized (UP) milk. The objective of this study was to evaluate the role of heat treatment in the development of LOF in UP fluid skim milk. Skim milk was processed by HTST or by direct steam injection (DSI-UP) and subsequently exposed to 2,000-lx light-emitting diode light for various times. Sensory properties were monitored by descriptive analysis and threshold tests, and volatile compounds were evaluated by solid phase microextraction with gas chromatography-mass spectrometry. Dissolved oxygen and riboflavin were determined at each time point using an oxygen meter and ultra-performance liquid chromatography with a fluorescence detector, respectively. The entire experiment was performed in triplicate. Typical cardboard and mushroom flavors (LOF) were detected by trained panelists in HTST milk after 3.5 h of light exposure. In contrast, LOF was not detected by trained panelists in UP milk until 36 h of light exposure. Similarly, the best estimate threshold for LOF from untrained consumers (n = 101) was higher for DSI-UP milk (61.0 h) than for HTST milk (15.2 h). Milks with LOF were characterized by higher relative abundance of the lipid oxidation compounds hexanal and heptanal. Dissolved oxygen (DO) and riboflavin concentrations decreased with increased light exposure time, and the decrease was slower in UP milk compared with HTST milk. Initial DO concentration was investigated as a possible influence in LOF development because DSI-UP milks had lower initial DO concentrations than HTST milks. However, follow-up evaluations of deaerated HTST milks suggested that DO was not a significant factor in LOF development. These results demonstrate that UP milk is less sensitive to LOF than HTST milk, possibly due to sensory masking effects or antioxidant effects of volatile sulfur compounds. An enhanced understanding of light and storage effects on milks will assist with best practices when transporting and displaying fluid milk products for sale.

Perceived visual time depends on motor preparation and direction of hand movements.

Perceived time undergoes distortions when we prepare and perform movements, showing compression and/or expansion for visual, tactile and auditory stimuli. However, the actual motor system contribution to these time distortions is far from clear. In this study we investigated visual time perception during preparation of isometric contractions and real movements of the hand in two different directions (right/left). Comparable modulations of visual event-timing are found in the isometric and in the movement condition, excluding explanations based on movement-induced sensory masking or attenuation. Most importantly, and surprisingly, visual time depends on the movement direction, being expanded for hand movements pointing away from the body and compressed in the other direction. Furthermore, the effect of movement direction is not constant, but rather undergoes non-monotonic modulations in the brief moments preceding movement initiation. Our findings indicate that time distortions are strongly linked to the motor system, and they may be unavoidable consequences of the mechanisms subserving sensory-motor integration.

Wine and music (II): can you taste the music? Modulating the experience of wine through music and sound

A growing body of scientific evidence now shows that what people taste when evaluating a wine, and how much they enjoy the experience, can be influenced by the music that happens to be playing at the same time. It has long been known that what we hear can influence the hedonic aspects of tasting. However, what the latest research now shows is that by playing the “right” music one can also impact specific sensory-discriminative aspects of tasting as well. Music has been shown to influence the perceived acidity, sweetness, fruitiness, astringency, and length of wine. We argue against an account of such results in terms of synaesthesia, or “oenesthesia,” as some have chosen to call it. Instead, we suggest that attention, directed via the crossmodal correspondences that exist between sound and taste (in the popular meaning of the term, i.e., flavor), can modify (perhaps enhance, or certainly highlight when attended, or suppress when unattended) certain elements in the complex tasting experience that is drinking wine. We also highlight the likely role played by any change in the mood or emotional state of the person listening to the music on taste/aroma perception as well. Finally, we highlight how the crossmodal masking of sweetness perception may come into effect if the music happens to be too loud (a form of crossmodal sensory masking). Taken together, the evidence reviewed here supports the claim that, strange though it may seem, what we hear (specifically in terms of music) really can change our perception of the taste of wine, not to mention how much we enjoy the experience. Several plausible mechanisms that may underlie such crossmodal effects are outlined.

Physiological mechanisms of intermodal interactions in the sensory masking

Physiological mechanisms of intermodal interactions in the sensory masking

Improvement of the Bitter Taste of Drugs By Complexation With Cyclodextrins: applications, Evaluations and Mechanisms

Drugs having bitter tastes cause low patient compliance. Many taste-masking techniques such as physical barrier coatings, chemical modification and sensory masking have been developed. Among chemical modification, the inclusion complexation of drugs with cyclodextrins (CyDs) can provide the effective bitter taste-masking effects without complicated formulation and/or delayed dissolution of drugs. Herein, we describe some quantitative methods to evaluate the taste-masking effects of CyD complexes with drugs in solution and the solid state. In addition, we introduce the recent applications of CyDs to excipients for taste masking against various bitter-taste drugs, as well as discuss the possible mechanisms for the taste-masking effect of CyD complexation.

Enhancing the Sensory Quality of Vegetables by Decreasing Some Less-Desired Sensory Properties With Low-Fat Pork Gravy

In this study, gravy with different fat concentrations was poured over cauliflower, broccoli, and potatoes, and the sensory changes of the vegetables were investigated. Gravy significantly reduced the vegetable's own flavor (cauliflower, broccoli, and potato flavor) and increased the fried meat flavor. However, the bitter and acidic tastes were also increased. Only 5% fat is necessary in the gravy to achieve a reduction in vegetable flavor. The effect of gravy on cabbage-like flavor has been shown to be partly due to retention of the key cabbage volatile compounds and not only a sensory masking effect.

The effect of smoking on sensory and attentional masking

This study examined the influence of smoking on low-level sensory and higher level visual cognitive abilities. Three groups (nonsmokers, deprived smokers, and nondeprived smokers) of 22 observers were tested using a visual target discrimination task. To assess sensory and visual cognitive differences, a masking task developed by Enns and Di Lollo (1997) was used. In the task, the target was masked by either a contour mask (contour masking) or an object mask (attentional masking by object substitution). The strongest masking effects were found in the group of nondeprived smokers, for both sensory and attentional masking. This pattern of results as well as results in the deprived smokers indicated changes in transient visual processing channels due to the acute actions of nicotine, not mediated by withdrawal relief.

Neural substrates of vocalization feedback monitoring in primate auditory cortex

Vocal communication involves both speaking and hearing, often taking place concurrently. Vocal production, including human speech and animal vocalization, poses a number of unique challenges for the auditory system. It is important for the auditory system to monitor external sounds continuously from the acoustic environment during speaking despite the potential for sensory masking by self-generated sounds. It is also essential for the auditory system to monitor feedback of one's own voice. This self-monitoring may play a part in distinguishing between self-generated or externally generatedauditory inputs and in detecting errors in our vocal production. Previous work in humans and other animals has demonstrated that the auditory cortex is largely suppressed during speaking or vocalizing. Despite the importance of self-monitoring, the underlying neural mechanisms in the mammalian brain, in particular the role of vocalization-induced suppression, remain virtually unknown. Here we show that neurons in the auditory cortex of marmoset monkeys (Callithrix jacchus) are sensitive to auditory feedback during vocal production, and that changes in the feedback alter the coding properties of these neurons. Furthermore, we found that the previously described cortical suppression during vocalization actually increased the sensitivity of these neurons to vocal feedback. This heightened sensitivity to vocal feedback suggests that these neurons may have an important role in auditory self-monitoring.

The Body Surface as a Communication System: The State of the Art after 50 Years

The suggestion that the body surface might be used as an additional means of presenting information to human-machine operators has been around in the literature for nearly 50 years. Although recent technological advances have made the possibility of using the body as a receptive surface much more realistic, the fundamental limitations on the human information processing of tactile stimuli presented across the body surface are, however, still largely unknown. This literature review provides an overview of studies that have attempted to use vibrotactile interfaces to convey information to human operators. The importance of investigating any possible central cognitive limitations (i.e., rather than the peripheral limitations, such as related to sensory masking, that were typically addressed in earlier research) on tactile processing for the most effective design of body interfaces is highlighted. The applicability of the constraints emerging from studies of tactile processing under conditions of unisensory (i.e., purely tactile) stimulus presentation, to more ecologically valid conditions of multisensory stimulation, is also discussed. Finally, the results obtained from recent studies of tactile information processing under conditions of multisensory stimulation are described, and their implications for haptic/tactile interface design elucidated.

Effects of a compensatory growth strategy on sensory and physical properties of meat from young bulls

The objective of the present study was to investigate the sensory properties, with special emphasis on tenderness, of meat from strategically fed young bulls (13 months of age) slaughtered when a plateau in protein turnover was observed. Twelve Holstein Friesian young bulls were divided into two feeding strategies. One group of young bulls ( n = 6) were fed ad libitum throughout the rearing period (AD) whereas the second group ( n = 6) was subjected to a compensatory growth feeding strategy (CO). Sensory profiling of beef longissimus dorsi (LD), semimembranosus (SM) and supraspinatus (SS) was performed in addition to physical measurements (shear force) and content of intramuscular fat of LD. The data was analysed using a regression-based multivariate data analytical strategy. In relation to predictivity of the various shear force measurement constituents for sensory texture, it was determined that a number of the responses collected (e.g. max mm), in addition to the commonly used max (N) may be utilised to predict subtlety in the sensory texture differences of the samples (e.g. Crumbliness) with respect to compensatory feeding. Through profiling LD and SS were found to have enhanced texture and flavour properties when the young bulls were fed ad libitum during rearing. However, the SM samples were found to improve in characteristics regarding texture and appearance when the young bulls had been fed compensatorily. Thus, compensatory feeding as a texture improvement strategy proved to be highly dependant on muscle type. Of note, LD and SS were found to develop an off-flavour designated as ‘steer taint’ when derived from compensatory feeding. This was postulated as potentially not a problem for the consumer, in LD as the level was not significant, and in SS due to sensory masking when commonly prepared as a stew or casserole. Considering the different preparation methods used for meat from LD, SM and SS, compensatory feeding may be considered to have improved the texture and elevated the eating quality where it was most relevant, namely in SM roasts.

O9 Creation of oral care flavours to deliver breath freshening benefits – an in vitro method

Flavours conventionally help to deliver breath freshening in oral care products via sensory masking. The aim of this study was to determine whether flavours could additionally inhibit formation of malodorous compounds by bacteria. Oral malodour is in large part related to the production of volatile sulphur compounds (VSCs) by Gram‐negative organisms. We therefore developed a quantitative in vitro assay for hydrogen sulphide production by Klebsiella pneumoniae. The entire Quest dental flavour palette was screened for inhibition of H2S production. A database of flavour ingredient effects was created, and used to create VSC‐inhibitory flavours. These flavours were assessed in the in vitro assay to confirm that the compounded flavour performed as expected. The best performing flavours developed in this way were selected for testing in the Quest Breath Freshness Panel (see poster, P21). Rules based on the performance of dental flavour ingredients, singly or in combination, were also used to develop a patent position. Flavours formulated using these rules (termed Q‐fresh flavours) have been incorporated into a range of oral care products including toothpastes, mouthwashes, chewing gums and breath films. These products have been tested in the Quest Breath freshness panel, and have been shown to deliver significant breath freshening benefits. An in vitro VSC‐inhibition method has allowed reliable development of flavours with breath‐freshening benefits.

Age-related differences in localized attentional interference.

Attentional selection of an object in the visual field degrades processing of neighboring stimuli in young adults. A pair of experiments examined the effects of aging on such localized attentional interference. In Experiment 1, younger and older observers made speeded same-different judgments of target shapes that varied in spatial separation. Performance declined for both age groups as the distance between targets decreased, but an Age x Distance interaction indicated that the magnitude of this effect was larger for older adults. Experiment 2 ruled out sensory masking as an explanation for these findings. Results indicate that older observers experience losses in the ability to attend to multiple spatially proximal stimuli within the visual field.

Magnetic stimulation of motor and somatosensory cortices suppresses perception of ulnar nerve stimuli

Magnetic stimulation of sensorimotor cortex interferes with the detection of electro-cutaneous stimulation. However, it is uncertain whether this interference is due to activation of the somatosensory or the motor cortex. Here, transcranial magnetic stimuli (TMS) were delivered separately over somatosensory and motor cortex contralateral to the right ulnar nerve in 12 subjects. In separate trials, TMS were given 100 ms before and 20 ms after 60 ms trains of electro-cutaneous ulnar nerve stimuli, and their effect on the subjective perception of peripheral stimuli was assessed. TMS of both motor and somatosensory cortex interfered with the perception of afferent stimuli when given before or after stimulation of the ulnar nerve. Perception was more strongly suppressed by motor cortex stimulation than by somatosensory cortex stimulation, when given before or after the peripheral stimulus. A similar proportion of errors was induced by sensory cortex stimulation between the two stimulus timing intervals. This study suggests that the inhibition of the afferent volley is unlikely to be the result of antidromic activation of thalamocortical connections or corticospinal gating. A phenomenon akin to sensory masking is the most plausible explanation for much of the suppression of sensory perception by stimulation of the motor or somatosensory cortex. The more powerful suppressive effect of motor cortex stimulation may be due to multiple mechanisms.

Motion-induced blindness in normal observers.

Cases in which salient visual stimuli do not register consciously are known to occur in special conditions, such as the presentation of dissimilar stimuli to the two eyes or when images are stabilized on the retina. Here, we report a striking phenomenon of 'visual disappearance' observed with normal-sighted observers under natural conditions. When a global moving pattern is superimposed on high-contrast stationary or slowly moving stimuli, the latter disappear and reappear alternately for periods of several seconds. We show that this motion-induced blindness (MIB) phenomenon is unlikely to reflect retinal suppression, sensory masking or adaptation. The phenomenology observed includes perceptual grouping effects, object rivalry and visual field anisotropy. This is very similar to that found in other types of visual disappearance, as well as in clinical cases of attention deficits, in which partial invisibility might occur despite the primary visual areas being intact. Disappearance might reflect a disruption of attentional processing, which shifts the system into a winner-takes-all mode, uncovering the dynamics of competition between object representations within the human visual system.

Attentional interference at small spatial separations.

The spatial characteristics of attention were studied by measuring the accuracy with which two target letters could be identified from a circular display of 24 characters. Traditional notions of spatially-limited regions of attentional enhancement predict that performance should be best when the pair of targets fall within the boundaries of a single attentional 'window'. The results were opposite to this expectation: performance was poorest when the targets were close together and improved with increasing target separation. The effects were not due to lateral sensory masking or to sensory transients and were replicated with several different types of attentional cues. Two possible models are proposed to account for the observed effects of target separation. The first model assumes that attending to one location necessarily reduces processing in the local surround. The second model proposes that the poorer performance observed at small target separations results from imprecise targeting when attention is directed to a pair of nearby locations. Both models illustrate spatially-local limits on processing capacity that attention is unable to circumvent. Enhancement at one location is achieved primarily at the expense of the immediate surround. Such spatially-local tradeoffs in processing capacity could have the useful consequence of making the attended target stand out even more against the immediate background.

Interference, Not Enhancement, When Attending to Two Nearby Targets

In an attempt to determine the size of the spatial window of attention we required subjects to identify 2 target letters from a display of 24 letters, expecting performance to improve the closer the targets were to each other. The results were opposite to this expectation. The 2 target letters were chosen randomly from a circular display (radius 4 deg) containing 24 letters. The display (duration 100 to 300 ms) was preceded and followed by masks. Attention was directed to the target locations by means of either a colour cue or a numeral cue. Identification of target letters improved as the directional separation between targets was increased from 15° to 180°. Performance was better when targets were in different hemifields but also improved with increasing separation within a hemifield. The results demonstrate interference at an attentional level analogous to lateral sensory masking. Attending to one item does not enhance recognition of nearby items, as might be expected with an expandable attentional beam or zoom lens, but rather interferes with the perception of nearby items. This outcome is consistent with the idea that nearby locations share limited processing resources and with neurophysiological findings on attentionally-mediated changes in receptive fields.