Susan S. Schiffman

The how and why of electronic noses

Witnessing the swift advances in the electronic means of seeing and hearing, scientists and engineers scent a market for systems mimicking the human nose. Already commercial systems from several companies are targeting applications, present and potential, that range from quality assurance of food and drugs to medical diagnosis, environmental monitoring, safety and security and military use. Here, the authors outline the major transducer technologies-in one sense, the key component of an electronic nose.

Effect of flavor enhancement of foods for the elderly on nutritional status: Food intake, biochemical indices, and anthropometric measures

The irreversible declines in taste and smell acuity that occur in many elderly persons can contribute to inadequate food intake and nutrition that are prevalent among the aged. Although chemosensory deficits cannot be reversed, previous studies have shown that the addition of intense flavors to foods can compensate for perceptual losses and improve food palatability and acceptance. In this study, the effect of sustained (3 week) flavor enhancement of typical institutional foods on the diet, health, and well being of 39 elderly (average age 84.6 SE 0.81 years) retirement-home residents was evaluated. For 3 weeks subjects ate an institutional diet (unenhanced). During another 3-week period, the same subjects ate identical foods to which intense flavors were added (enhanced). The 39 subjects were tested in two groups. For group 1 the unenhanced food period preceded the enhanced food period. For group 2, the order was reversed. Food intake was measured every weekday throughout the study, and the nutritional composition of the diet was analyzed. Biochemical measures of health status were obtained at the beginning of the study (baseline) and following both the unenhanced and enhanced periods. These measures included somatomedin-C/insulin-like growth factor I, transferrin, total T- and B-lymphocytes, and routine blood chemistries. Weight, height, midarm circumference, and triceps skinfold thickness were also measured. Handgrip strength and pinch strength were measured in group 1.(ABSTRACT TRUNCATED AT 250 WORDS)

A psychophysical model for gustatory quality

Abstract Nineteen gustatory stimuli were ordered in a multidimensional space using two types of psychophysical data: judgments of similarities among the stimuli, and semantic differential ratings of the stimuli. The relationships between the stimuli in the two resultant spaces were quite similar. Since the structure of the space based on similarity judgments was more stable over subjects and seemed to represent more completely the tastes of the stimuli, it was considered more appropriate as a gustatory model. Using the semantic differential descriptions as well as physical continua to designate useful dimensions, it was found that the similarity space based on equi-intensive gustatory stimuli could be accurately represented by three criteria: relative goodness or badness of the taste of the stimuli, molecular weight, and departure of the stimuli from the neutral pH of 7. This model, specific to the concentrations used, shows similarities to previous psychophysical models, especially Hennings, as well as models of stimulus relationships based on neural gustatory data.

Splenda Alters Gut Microflora and Increases Intestinal P-Glycoprotein and Cytochrome P-450 in Male Rats

Splenda is comprised of the high-potency artificial sweetener sucralose (1.1%) and the fillers maltodextrin and glucose. Splenda was administered by oral gavage at 100, 300, 500, or 1000 mg/kg to male Sprague-Dawley rats for 12-wk, during which fecal samples were collected weekly for bacterial analysis and measurement of fecal pH. After 12-wk, half of the animals from each treatment group were sacrificed to determine the intestinal expression of the membrane efflux transporter P-glycoprotein (P-gp) and the cytochrome P-450 (CYP) metabolism system by Western blot. The remaining animals were allowed to recover for an additional 12-wk, and further assessments of fecal microflora, fecal pH, and expression of P-gp and CYP were determined. At the end of the 12-wk treatment period, the numbers of total anaerobes, bifidobacteria, lactobacilli, Bacteroides, clostridia, and total aerobic bacteria were significantly decreased; however, there was no significant treatment effect on enterobacteria. Splenda also increased fecal pH and enhanced the expression of P-gp by 2.43-fold, CYP3A4 by 2.51-fold, and CYP2D1 by 3.49-fold. Following the 12-wk recovery period, only the total anaerobes and bifidobacteria remained significantly depressed, whereas pH values, P-gp, and CYP3A4 and CYP2D1 remained elevated. These changes occurred at Splenda dosages that contained sucralose at 1.1–11 mg/kg (the US FDA Acceptable Daily Intake for sucralose is 5 mg/kg). Evidence indicates that a 12-wk administration of Splenda exerted numerous adverse effects, including (1) reduction in beneficial fecal microflora, (2) increased fecal pH, and (3) enhanced expression levels of P-gp, CYP3A4, and CYP2D1, which are known to limit the bioavailability of orally administered drugs.

Bitterness of sweeteners as a function of concentration

Sixteen trained tasters provided sweetness and bitterness intensity ratings for 19 compounds including: acesulfame-K, alitame, aspartame, fructose, glucose, glycine, lactitol, maltitol, monoammonium glycyrrhizinate, neohesperidin dihydrochalcone, neosugar (fructo-oligosaccharide), palatinit (isomalt), rebaudioside-A, sodium cyclamate, sodium saccharin, stevioside, sucralose, sucrose, and thaumatin. With increasing concentration, high-potency sweeteners including acesulfame-K, neohesperidin dihydrochalcone, sodium saccharin, rebaudioside-A, and stevioside tended to become more bitter. Low-potency sweeteners including fructose, sucrose, and lactitol tended to become less bitter with increasing concentration.

Investigation of synergism in binary mixtures of sweeteners

The purpose of the present study was to determine the presence and degree of synergism among all binary mixtures of 14 sweeteners varying in chemical structure. A trained panel evaluated binary combinations of the following sweeteners: three sugars (fructose, glucose, sucrose), two polyhydric alcohols (mannitol, sorbitol), two diterpenoid glycosides (rebaudioside-A, stevioside), two dipeptide derivatives (alitame, aspartame), one sulfamate (sodium cyclamate), one protein (thaumatin), two N-sulfonyl amides (acesulfame-K, sodium saccharin), and one dihydrochalcone (neohesperidin dihydrochalcone). Each sweetener was tested at three concentrations that were isosweet with 3%, 5%, and 7% sucrose. Two methods of analysis were performed to determine synergistic effects. In Method I, an ANOVA was performed for each intensity level to determine if the mean sweetness intensity ratings of each binary mixture were equal to nominal sweetness (i.e., additivity) or not equal to nominal sweetness (i.e., synergism or suppression). In Method II, an additional ANOVA was performed to determine if the sweetness intensity ratings of any given mixture were equal to or greater than the average of the sweetness ratings of the two pure components in that blend.

Comparison of taste qualities and thresholds of D- and L-amino acids.

Abstract The traditional generalization concerning the influence of chirality on the taste of amino acids, i.e. that L-forms are bitter or tasteless and D-forms are sweet, must be amended on the basis of the data presented here. For example, some enantiomer pairs such as L- and D-serine and L- and D-alanine exhibit similar sweet qualities. Other enantiomer pairs taste quite different from one another, such as L-proline which has a sweet component and D-proline which is bitter. The rank order of the threshold values for the D-forms tends to parallel those for the L-forms; the rank order correlation (Spearmans rho) is 0.87. However, several statistically significant threshold changes were found. Two amino acids with aromatic side chains, tryptophan and phenylalanine, have greatly reduced thresholds in the D-form while asparagine and aspartic acid, along with proline, have considerably higher thresholds in the D-form. In general, it was found that whenever a marked taste difference exists, there is a trend toward a relatively large difference in threshold values between the enantiomers. It was not found, however, that a large difference in threshold was always accompanied by a significant quality difference, or that the particular taste quality of either of the pair was a predictor of the magnitude of the threshold ratio or of which of the two forms had the highest threshold.

Qualitative differences among sweeteners

Seventeen sweeteners varying widely in chemical structure were arranged in a three-dimensional space by two multidimensional scaling procedures, INDSCAL and ALSCAL. Fructose, glucose, sorbose, xylitol and xylose tended to fall near one another. Two sweeteners with a syrupy component, maltose and sorbitol, fell further away. Ca cyclamate and the dipeptide aspartame were the two artificial sweeteners which fell closest to and thus tasted most like the sugars. The proteins monellin and thaumatin, as well as the chalcone glycoside, neohesperidin dihydrochalcone, all have long aftertastes and thus tended to fall proximate to one another. Stimuli with the highest metallic and bitter ratings (acetosulfan, sodium saccharin, rebaudioside and stevioside) tended to fall near one another with the amino acid d-tryptophan located a little farther away. Adjective scales were related to the spatial arrangement. Wide variability in the patterns of intensity ratings over subjects suggests that the sweet taste may be mediated by several peripheral receptor mechanisms.

Air Pollution and Odor in Communities Near Industrial Swine Operations

Background Odors can affect health and quality of life. Industrialized animal agriculture creates odorant compounds that are components of a mixture of agents that could trigger symptoms reported by neighbors of livestock operations. Objective We quantified swine odor episodes reported by neighbors and the relationships of these episodes with environmental measurements. Methods Between September 2003 and September 2005, 101 nonsmoking volunteers living within 1.5 mi of industrial swine operations in 16 neighborhoods in eastern North Carolina completed twice-daily odor diaries for approximately 2 weeks. Meteorological conditions, hydrogen sulfide, and particulate matter ≤ 10 μm in aerodynamic diameter (PM10) were monitored in each neighborhood. We used mixed models to partition odor variance within and between people and between neighborhoods, and to quantify relationships between environmental factors and odor. Results Participants reported 1,655 episodes of swine odor. In nine neighborhoods, odor was reported on more than half of study-days. Odor ratings were related to temperature, PM10, and semivolatile PM10 in standard but not mixed models. In mixed models, odor increased 0.15 ± 0.05 units (mean ± SE) for a 1-ppb increase in H2S, and 0.45 ± 0.14 units for a 10-μg/m3 increase in PM10 at wind speeds > 6.75 miles per hour. The odds of reporting a change in daily activities due to odor increased 62% for each unit increase in average odor during the prior 12 hr (t-value = 7.17). Conclusions This study indicates that malodor from swine operations is commonly present in these communities and that the odors reported by neighbors are related to objective environmental measurements and interruption of activities of daily life.

Taste of nutrients: Amino acids, vitamins, and fatty acids

Multidimensional scaling techniques were used to determine the range in taste of nutrients for human subjects. The nutrients tested (amino acids, vitamins, and fatty acids) span the traditional sweet, sour, salty, and bitter gustatory quality range. The results also suggest that alkaline, sulfurous, and fatty qualities exist as well; the possibility that these three quality groupings are due to olfactory or tactile rather than gustatory input is discussed.