Odor Taste Research Articles

Internal representation and memory formation of odor preference based on oscillatory activities in a terrestrial slug

The terrestrial slug Limax exhibits a highly developed ability to learn odors with a small nervous system. When a fluorescent dye, Lucifer Yellow (LY), is injected into the slug's body cavity after odor-taste associative conditioning, a group of neurons in the procerebral (PC) lobe, an olfactory center of the slug, is labeled by LY. We examined the relationships between conditioning strategies and LY labeling. The positions of LY-labeled neurons in the PC lobe after appetitive conditioning were more apical than those after aversive conditioning and did not depend on the conditioned odor, suggesting that the biological value of odors affected the position of LY-labeled neural clusters. A simple computational model consisting of two layers of oscillators with electrical synaptic interaction was constructed based on physiological features of the PC lobe, and showed that the oscillatory phase difference between the layers contributed to determination of the positions of LY-labeled neurons, suggesting that phase difference in oscillatory activity plays a role in the association of odors and the preference for them.

Removal of Taste and Odor Model Compounds (2-MIB and Geosmin) with the NF Membrane

The objectives of this research were to identify seasonal variations of 2-MIB and geosmin which have been one of the biggest problems in the drinking water in the Han River in Korea and to evaluate the performance of the loose and tight NF membranes with respect to 2-MIB and geosmin rejection. Two kinds of NF membranes with different NaCl rejections were compared using a batch stirred cell to determine the membrane flux and the solute rejection for feed water. The results of the analysis of the occurrence characteristics of 2-MIB and geosmin, the major taste and odor material in the Han River water system show that the occurrence of 2-MIB continued from winter to spring (January–May) and through autumn (August–September), whereas geosmin occurred for about one to two weeks from summer to autumn (July–September) and spring (March–April). Following the rejection test of the taste and odor using the loose and tight NF membranes, it appeared that the two showed high rejection rates of 98% and above, irrespective of their concentration factor. The rejection of 2-MIB and geosmin increased with increasing shear rates for all of the NF membranes tested. Hydrodynamic operating conditions greatly affect the rejection of solutes in NF treatment. The rejection of taste odor compounds should increase with increased shear rates near the membrane surface. This suggests that the rejection will be further improved using dynamic membrane filtration.

Corrigendum to “Improved smell pleasantness after odor–taste associative learning in humans” [Neurosci. Lett. 434 (2008) 108–112

Corrigendum to “Improved smell pleasantness after odor–taste associative learning in humans” [Neurosci. Lett. 434 (2008) 108–112

Taste and odour and cyanobacterial toxins: impairment, prediction, and management in the Great Lakes

This paper reviews the issues associated with algal–cyanobacterial taste–odour (T&O) compounds and toxins in the Great Lakes. As with other remediated water bodies, the Great Lakes have undergone significant shifts in nutrient and food-web regimes and are exhibiting erratic blooms and noxious algal metabolite (NAM) outbreaks, despite reduced offshore nutrient levels. We appraise the chemistry, biota, and distribution of NAM impairments and conclude that management strategies based on lakewide monitoring and remedial action plans are often unsuccessful because they attempt NAM control through an unsustainable reliance on water treatment and broad-scale nutrient–biomass models. This approach is undermined by several factors: (i) only some species produce NAMs; (ii) different taxa show disparate patterns across nutrient and mixing regimes; (iii) nuisance species may be planktonic or benthic and located outside remedial boundaries; and (iv) species differ significantly in NAM biochemistry and release. Thus, there are no robust relationships between total plankton biomass, toxins, and T&O compounds in these and other source waters. Given the potential ecological and socioeconomic threats posed by NAM outbreaks, there is a critical need to develop a multistep management framework based on more stringent restoration targets, combining broad-scale screening and nutrient management with system and taxa-specific approaches.

Taste–Odor Integration in Espresso Coffee

Espresso coffee samples were freshly prepared with 10% sucrose, 0.0143% sucralose (equivalent in sweetness to 10% sucrose), or unsweetened, each with and without nondairy creamer. A sensory panel rated the intensities of “malty,” “caramel,” “roasty,” and “coffee-like.” The concentrations of flavor chemicals associated with the latter three sensations (Furaneol, 2-ethyl-3,5-dimethyl [EDM] pyrazine, and 2-furfuryl thiol, respectively) were determined by gas chromatography, using solid-phase microextraction sampling of coffee headspace. Furaneol and furfuryl thiol were essentially unaffected by creamer addition, but the more nonpolar EDM pyrazine was greatly reduced. The malty, caramel, roasty, and coffee-like flavor intensities were not significantly affected by creamer addition. This appears to be a case of disconnect between the absence of an odorant and perception. Furaneol, furfuryl thiol, and EDM pyrazine concentrations were unaffected by adding either sweetener. The malty sensation was the same with and without added sweetener. The roasty and coffee-like ratings both decreased to similar extents in the samples with the two added sweeteners. The ratings for caramel were considerably increased, again to a similar extent, by both sweeteners. Since the added sweeteners were both nonvolatile, this is clearly a case where taste affected odor perception.

Improved smell pleasantness after odor–taste associative learning in humans

Whereas some aspects of olfactory hedonism in humans are present from birth, others form during development and throughout adulthood. Although it is generally agreed that such hedonic representations emerge by associative learning, it is not yet clear which learning parameters are prominent. The present study investigated the influence of number of trials on odor preference acquisition in human adults. Forty-eight subjects randomly assigned to three groups were tested in three sessions. In the first session, subjects ranked eight food odors from most pleasant to most unpleasant. The second session consisted in an associative learning, the two most neutral odors were randomly associated with a drink: one odor with water (CS-) and the other odor with a pleasant sweet solution (CS+). In the third session subjects ranked the eight food odors again. In group A, CS+ was paired three times with the US, and in group B only once; in group C, CS+ was paired only once with the US but with a total duration identical to that in group A. Results showed that CS+ was ranked as significantly more pleasant after learning in group A (p<.05), but not in groups B and C (p>.05). In conclusion, the study showed that a neutral smell can acquire positive emotional features after being paired with a pleasant taste, and that this learning depends on the number of associations between smell and taste.

Microbial Characteristics of Water Distribution: Compiled Investigations in a German Drinking Water Distribution System

In the last few years microbial activities within the drinking water distribution network have gained more and more attention. Hygienic problems, harassment with odor and bad taste, and even material deterioration are the consequences of microbial life in the pipes. The growth of adhesive bacteria, so-called biofilms, seems to be the main reason for the problems mentioned above. Bacteria settling down as biofilm develop specific characteristics concerning persistence, increased metabolic activities, and sheltering opportunistic microbes. Moreover, biofilms are difficult to detect and to identify by conventional microbiological methods. In the distribution network of a German city biofilms were sampled and characterized by sensitive molecular biological and biochemical techniques. The correlation between different pipe materials and biofilm growth could be followed up over the time. The source and quality of the raw water influenced the population diversity as well as the metabolic activity of the biofilms...

The Capacity of Humans to Identify Components in Complex Odor–taste Mixtures

Despite the fact that humans experience mixtures of odors and tastes each time they eat, little is known of their capacity to detect the individual components of foods. To investigate this capacity, 43 subjects were trained to identify three odors and three tastes and were required to indicate which of these could be identified in stimuli consisting of one to six components. Although the odor and taste components of most binary mixtures were identified, subjects encountered substantial difficulties with more complex mixtures with only two components being identified in the four- to six-component mixtures. In general, tastes were more easily identified than smells and were the only stimuli identified in the five- to six-component mixtures. Several mechanisms are proposed to account for the poor identification of components.

CROSS‐MODAL ADDITIVITY OF TASTE AND SMELL

ABSTRACT Subjects were simultaneously given subthreshold levels of taste and odor stimuli, delivered orally, for both a commonly paired and an uncommonly paired taste–odor combination. Results indicate cross‐modal summation of subthreshold concentrations of both taste–odor pairs when the olfactory stimulus is delivered orally. Results of control studies suggest that the summation was indeed across modalities, and not due to the taste of the odor compound or the smell of the taste compounds. Furthermore, results indicate that regardless of taste–odor pair commonness, taste and smell can combine in a completely additive fashion (i.e., at threshold detectability when both stimuli are presented simultaneously at 50% threshold level) if the taste–odor pair is presented orally. In several instances, but not all, measured probabilities exceeded those predicted by probability summation, indicating that hyperadditive mixing often occurs, but there do seem to be individual differences. Cross‐modal summation, regardless of taste–odor pair commonness, has broader implications for the development of foods, beverages and pharmaceuticals, especially in masking undesirable tastes and smells.

Relationships between proteolytic and lipolytic activity and sensory properties (taste–odour) of traditional Turkish white cheese

Protein and lipid changes and their effects on the sensory properties (taste–odour) of Turkish white cheese were studied. Mean values for the chemical properties of white cheese were: total solids (TS) 44.39 g/100 g; titratable acidity 2.15% (as lactic acid); pH value 4.50; fat‐in‐dry matter 47.80 g/100 g; salt‐in‐dry matter 8.65 g/100 g; total nitrogen (TN) 2.50 g/100 g; water‐soluble nitrogen (WSN) 0.48 g/100 g; ripening index (RI) 18.98%; tyrosine 65.00 mg/100 g; acid degree value (ADV) 385.96 mg KOH/100 g fat; volatile fatty acids (VFA) 15.54 mL 0.1 N NaOH/100 g and total free fatty acids (TFFA) 1325.96 mg/100 g cheese. Sensory scores for taste and odour were 23.67 (out of 35) and 8.28 (out of 10), respectively. The chemical qualities of the cheeses, including acidity, dry matter, fat‐in‐dry matter and VFA had an effect on flavour (P &lt; 0.05).

Perception of temporal order and the identification of components in taste mixtures

The capacity of humans to identify the components of taste mixtures is limited to 3 for most people [D.G. Laing, C. Link, A. Jinks, I. Hutchinson, The limited capacity of humans to identify the components of taste mixtures and taste–odor mixtures. Perception 31 (2002) 617–635]. Here, the hypothesis that temporal processing differences have a major role in limiting capacity is investigated. Thirty two subjects were trained to identify sucrose, sodium chloride and citric acid at FIVE concentration levels and were then required to indicate (1) which tastant was perceived first and (2) the identity of each component, in binary and ternary mixtures. Within each mixture set, e.g. sucrose–citric acid, the concentrations of components were adjusted to provide some conditions where intensities and time differences in processing the individual components were minimized. With binary mixtures, changes in intensity resulted in identification of only one component when the differences were largest, and both being identified when intensities were similar. In contrast, subjects found it difficult to indicate which component was perceived first when the intensities were similar and easy when they were substantially different. The most profound effects occurred with ternary mixtures . With each of the three sets, there were several where subjects could not indicate which component was perceived first, and in 13/18 mixtures not all components were identified above chance. Indeed, the most common number of components identified was 2. However, although perception of order was lost in a number of mixtures, this did not preclude identification of one or all three components. This result contrasts with the finding with odors where total loss of order resulted in loss of identity of all components in ternary mixtures [A. Jinks, D.G. Laing, Temporal processing reveals a mechanism for limiting the capacity of humans to analyze mixtures. Cognitive Brain Res. 8 (1999) 311–325]. Thus, loss of identity with taste mixtures seems to occur to a lesser degree. Indeed suppression rather than temporal effects may be the main cause of the loss of identity of components with ternary taste mixtures.

Validation of a stimulation protocol suited to the investigation of odor–taste interactions with fMRI

A protocol suited to the investigations of odor–taste interactions in a functional magnetic resonance imaging (fMRI) scanner is described and results that confirm the validity of that protocol are presented. Stimuli were dissolved in water and presented to the mouth of the participant through plastic syringes and plastic tubes as 50 μl every 3 s for 18 s. Participants were lying on the back to simulate the conditions in a fMRI scanner and gave pleasantness and intensity ratings in response to each stimulus using a Labeled Magnitude Scale (LMS). Stimuli were three concentrations of two tastants (i.e., sucrose and NaCl) and two odorants [i.e., ethyl butyrate (fruity) and citral (citrus)] and all possible odor–taste mixtures. Results showed that additivity of intensity in odor–taste mixtures was linear and did not depend on the pleasantness of the mixture. This study showed the feasibility of acquiring reliable psychophysical data with a stimulation device compatible with the fMRI environment and provided the foundation for the interpretation of future fMRI investigations of odor–taste interactions in flavor.

Delayed-onset amnesia caused by protein synthesis inhibition in odor-taste associative memory of the terrestrial slug Limax valentianus

The terrestrial slug Limax avoids the odor of innately preferred food after it is presented with the aversive taste of quinidine. This type of associative memory persists for several weeks. We investigated effects of protein synthesis inhibitors on the retention of this odor–taste associative memory. Anisomycin or cycloheximide applied to the slug 30 min prior to conditioning impaired the memory retention as late as two or more days after the conditioning, while the retention of a short-term memory was normal for up to 24 h. In contrast, the inhibition of protein synthesis by these inhibitors decays within several hours. In Limax, the onset of amnesia is unusually delayed when protein synthesis is suppressed at the time of conditioning.

味と匂いセンサの研究&amp;middot;開発動向

味と匂いセンサの研究&amp;middot;開発動向

THE EFFECT OF AMARANTH GRAIN FLOUR ON THE QUALITY OF BREAD

Different levels of amaranth grain flour −0 to 50% (w/w) were mixed with the wheat flour and other ingredients (1% salt, 2.5% fat, 1.5% yeast, 10% sugar and 52–74% water), fermented, molded, pan-proved and baked. The baked products were evaluated for loaf volume, moisture content and sensory qualities (color, odor, taste and texture) and compared with bread made from 100% wheat flour. The water absorption of the composite flour increase with increased in level of amaranth grain flour. The loaf volume index decreased from 3.29 to 1.9 and the moisture content increased from 22 to 42% with increase in amaranth grain flour. The sensory means scores of the odor taste, colour and texture decreased from 6.9 to 4.0, 7.1 to 4.8, 7.1 to 6.8 and 6.9 to 4.7 respectively. Generally, above 15% (w/w) amaranth grain flour, there were significant different (p ≤ 0.05) in the evaluated sensory qualities and the product unacceptable.

Counter-conditioning Following Human Odor–Taste and Color–Taste Learning

Tasting an odor in citric acid can result in that odor becoming less liked and sourer smelling. Both these changes appear to be resistant to extinction. As acquired hedonic responses to faces are also resistant to extinction, but amenable to counter-conditioning, the current experiment tested whether conditioned changes in odors could also be counter-conditioned. Presenting an odor in citric acid and then in sucrose did not change the perceptual and hedonic consequences of the initial pairing in citric acid. However, pairing a color with citric acid and then with sucrose produced a color–sweetness association. These findings are suggestive of a difference in counter-conditioning sensitivity between odors and other types of stimuli, which may result from encoding odor–taste mixtures in a relatively unanalyzed configural form.

The acquisition of taste properties by odors

Certain odors are routinely described as smelling sweet. This phenomenon may result from the co-occurrence of such odors and tastes outside the laboratory. Experiment 1 tested this possibility by pairing a selected odor with sucrose and another with citric acid in a masked design, using 24-h spaced sessions, preceded and followed by ratings of the odors' taste attributes when sniffed and when rated with tastes in solution. Following conditioning, the odor paired with sucrose smelled sweeter and with citric acid, sourer. In Experiment 2, contingency awareness was examined using a recognition measure, in an otherwise similar design. Again, odors smelled sweeter and sourer postconditioning. Contingency aware and unaware subjects did not differ in performance. Experiment 3 examined an exposure account of these changes, using a similar paradigm to Experiment 1, but with no exposures to sucrose or citric acid. No changes in odor taste attributes were observed, Overall, these findings demonstrate that associative learning, irrespective of awareness, has an important role in the acquisition of odor-taste qualities.

玉ねぎ香味成分生成におよぼすγ線照射の影響

玉ねぎの香味成分生成に対するγ線照射の影響について, 生成に関与する酵素の活性低下およびその基質の水溶液中における分解について調べた。低線量率で照射した場合, 1×105rad程度の線量では玉ねぎを個体のゝ照射した場合にも, また酵素液を調製して照射した場合にも酵素活性の著るしい低下はみられなかった。またその基質水溶液について照射した場合には2×104rad程度ですでに分解が認められた。

British Food Journal Volume 43 Issue 10 1941

British Food Journal Volume 43 Issue 10 1941

The Trend of Modern Taste and Odor Control

Tastes and odors are the subject of much conversation. Whenever a water supply develops an off taste or peculiar odor, immediate steps should be taken to improve the palatability of the water. This is not only important from a sense of duty to the consumer, but of unquestionable importance in keeping public relations satisfactory. With the methods of control now at hand there is little excuse for characteristic tastes and odors, which in the past many cities have experienced. The steps of most importance in eliminating these characteristic tastes are discussed below.