Harry Lawless

Cornell University, Food Science, Faculty Member

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Papers by Harry Lawless

Detection Thresholds of 10 Odor-active Compounds Naturally Occurring in Food Using a Replicated Forced-Choice Ascending Method of Limits

Journal of Sensory Studies

A series of threshold measurements for aroma detection of 10 compounds naturally occurring in foo... more A series of threshold measurements for aroma detection of 10 compounds naturally occurring in foods were collected on 113 individuals in quadruplicate, using a 3-alternative forced-choice ascending method of limits. Mixed-model analyses examined differences among compounds, subgroups of individuals tested as cohorts, order effects and several covariates such as age, gender, propylthiouracil sensitivity and body mass index. Differences among compounds were observed, as expected. Women had lower thresholds (higher sensitivity) than men for three of the 10 compounds, cis-3-hexenol, isovaleric acid and 4-methyl octanoic acid. A consistent warm-up effect was noted for the second compound tested on any given day. The overall panel was tested in cohorts of approximately 10 panelists each, and significant residual variation was noted for β-ionone and isobutyraldehyde, for which bimodal threshold distributions were observed. The latter result suggests that testing small groups of panelists (...

Reference Matching of Dissimilar Binary Odor Mixtures

Chemosensory Perception, 2009

Hexanal (C6) and octanal (C8) exhibit two different odor qualities at all concentrations: C6 is p... more Hexanal (C6) and octanal (C8) exhibit two different odor qualities at all concentrations: C6 is perceived as green, while C8 is perceived as citrus. This paper examines the odor perception (quality + intensity) of C6–C8 binary mixtures by varying the concentration ratios within the mixtures and using an odor reference-matching task to estimate perceived intensity. Three perceptible concentrations of C6 and C8,

EXPECTATIONS AND STABILITY OF PREFERENCE CHOICE

Journal of Sensory Studies, 2006

When identical milk samples are presented, only 30% of participants respond with a "no preference... more When identical milk samples are presented, only 30% of participants respond with a "no preference" rating. Stability of the "no preference" rating was studied under a variety of conditions, having consumer panelists rate both identical and different pairs of milk samples with varying fat content. The proportion of participants choosing the "no preference" option, when the samples in the pair were identical, was largely consistent despite manipulation of pretest conditions and changes in test questions and answer formats. However, when the milk preference test was preceded by a same/different test, and those responding "same" were assumed to have no preference, the percent of "no preference" was two to three times larger for identical test samples (60-69%). Thus by branching the question, the "false preference" choice for identical milks was lowered. Among those responding "different" to identical milks, the false-alarm rate increased to 91%, suggesting that perception of (spurious or momentary) differences is driving at least part of the preference choice.

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The Cross-Adaptation of Green and Citrus Odorants

Chemosensory Perception, 2010

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Interactions of astringent substances

Chemical Senses, 1994

Two-component mixtures of astringent materials were rated for perceived intensity of astringent a... more Two-component mixtures of astringent materials were rated for perceived intensity of astringent and taste attributes over time. Components included alum (a complex salt), gallic acid (the monomeric component of hydrolyzable tannins), catechin (the monomeric component of condensed tannins) and citric acid. Mixtures of alum and gallic acid showed mixture suppression, in that the 50/50 mixture was less intense than either component in astringency, drying, roughing and puckery/drawing sensations. Suppression was seen at concentration levels producing moderate to strong astringency but was absent or less pronounced at lower concentration levels. A similar pattern held for citric acid, although the suppressive effects were less pronounced. Catechin and gallic acid mixtures were additive. Sensory interactions between astringent materials appears to depend on the substances involved and their concentrations (or intensity levels).

Time-course of astringent sensations

Chemical Senses, 1991

Page 1. Chemical Senses Vol.16 no.3 pp. 225-238, 1991 Time-course of astringent sensations Christ... more

PERCEPTUAL MAPPING OF APPLES AND CHEESES USING PROJECTIVE MAPPING AND SORTING

Journal of Sensory Studies, 2010

... The Acey Mac was placed toward the center of the sorting configuration, and on the nappe conf... more

A COMPARISON OF THE EFFECTIVENESS OF HEDONIC SCALES AND END-ANCHOR COMPRESSION EFFECTS

Journal of Sensory Studies, 2010

Three experiments were conducted to compare the relative performance of hedonic scaling methods, ... more Three experiments were conducted to compare the relative performance of hedonic scaling methods, including the labeled affective magnitude (LAM) scale. In the first study, three versions of the LAM were used to evaluate 20 phrases that described diverse sensory experiences. One scale was anchored to "greatest imaginable like/dislike for any experience" and another used the "greatest imaginable like" phrase of the LAM but with the interior phrases repositioned relative to "any experience." The scale anchored to "any experience" showed a smaller range of scale usage and lower statistical differentiation, relative to the LAM scale, with the repositioned scale intermediate. Two further experiments compared the LAM to the nine-point hedonic scale, an 11-point category scale using the LAM phrases, and to a three-label line scale, a simplified version of the LAM with only the end phrases and the neutral center-point phrase. All scales showed similar differentiation of juices in the second study and sensory experience phrases in the third. A modest advantage for the LAM scale in the second experiment did not extend to the third study. Researchers should be careful in the choice of high end anchors for hedonic scales, as a compressed range of scale usage may result in lower product differentiation. 4 Corresponding

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PREFERENCE FOR ONE OF TWO IDENTICAL STIMULI: EXPECTATIONS, EXPLICIT INSTRUCTIONS AND PERSONAL TRAITS

Journal of Sensory Studies, 2000

Most consumers, given two identical food samples, express a preference for one, rather than choos... more Most consumers, given two identical food samples, express a preference for one, rather than choosing a no-preference option. The stability and potential causes of this seemingly irrational preference were examined across three trials under different conditions, specifically, when the first test pair was identical or different, and when participants were explicitly told that the pairs would often be identical. Choice of no preference typically increased from the first to second trial, especially for groups who saw a pair of different samples on the first trial. The explicit instruction that samples might be the same failed to reduce expressing a preference on the initial trial although it had some effect on later trials. Analysis, by individuals, of sequences of preference or no-preference responses across trials support independence of sequential responses and argue against stable personal traits as a predictor of preference choice.

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A COMPARISON OF THE LABELED AFFECTIVE MAGNITUDE SCALE AND THE 9-POINT HEDONIC SCALE AND EXAMINATION OF CATEGORICAL BEHAVIOR

by Carlos Da Silva Riehl and Harry Lawless

Journal of Sensory Studies, 2010

Two experiments compared the performance of the 9-point hedonic scale with the labeled affective ... more Two experiments compared the performance of the 9-point hedonic scale with the labeled affective magnitude (LAM) scale for food acceptability ratings of a well-liked food (potato chips). Both scales performed well in discriminating products. Both scales uncovered a strong relationship between usage patterns and acceptance ratings. Both scales found a significant product by user group interaction effect that showed a consistent pattern of the type of chip consumed versus acceptance ratings. The 9-point scale showed somewhat higher reliability as measured by the correlation of scores for a duplicate product. "Categorical" usage of the LAM scale, defined as making ratings within Ϯ1-2 mm of a word phrase (depending upon the line length, approximately 1% of scale range), was observed here as seen previously. Use of a physically longer line (200 mm versus 116 mm) decreased the frequency of such categorical ratings. These results showed no strong advantage to either scaling method. The categorical use of the LAM scale may depend in part upon the physical appearance of the scale.

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THE DISRIMINATIVE EFFICIENCY OF COMMON SCALING METHODS

Journal of Sensory Studies, 1986

Four types o f rating scales, nine-point Category scales, line mar&ing, magnitude estimation, a n... more Four types o f rating scales, nine-point Category scales, line mar&ing, magnitude estimation, a n d a hybrid o f the category andline scale, were employed to assess visual, tactile and o/factory charactenstics o fproducts by consumers. The scales were compared f o r their ability to Ascriminate dffirences among products, f o r variability, f o r reliability, and f o r ease o f use. All methods were able to generate highly sign2f;;cant A8erences among products. However, a modest advantage for categoy scales was observed in almost dl compansons.

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COMPARISON OF RATING SCALES: SENSITIVITY, REPLICATES AND RELATIVE MEASUREMENT

Journal of Sensory Studies, 1986

The relative sensitivities of four scaling methods were assessed in central location tests with u... more The relative sensitivities of four scaling methods were assessed in central location tests with untrained judges. m e scales included category scales, line scales, magnitude estimation, and a hybrid of the line and category scales. Approximate parity was observed among category scales, line scales and the hybrid scale in their ability to differentiate small physical differences. Magnitude estimation was used as eflciently as the other methods by a college population, but less e@ciently by a heterogeneous sample of consumers. Judges used the scales with greater accuracy as they became familiar with the range of products to be judged. In spite of relatively small physical direrences, subjects used wide ranges of the scales, supporting the view that rating scales are relative, not absolute, measuring instruments.

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Lipid Oxidation and Warmed-Over Aroma in Cooked Ground Pork from Swine Fed Increasing Levels of Iron

Journal of Food Science, 1994

Fifteen crossbred feeder pigs were fed to market weight on corn-soy rations containing either 62,... more Fifteen crossbred feeder pigs were fed to market weight on corn-soy rations containing either 62, 131, or 209 ppm iron. After slaughter, pork was ground, cooked, and stored at 4°C for 12 days. Heavily fortifying swine rations with iron (2200 ppm) increased nonheme iron (NHI) and thiobarbituric acid reactive substances (TBARS) in cooked, stored ground pork (GP) but did not increase warmed-over aroma (WOA) (p>O.O5). NHI, TBARS, and WOA increased during storage. TBARS strongly correlated with WOA during storage (r=0.903) and with NH1 (r=O.901).

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The Influence of Fat on the Sensory Properties, Viscosity, and Color of Lowfat Milk1

Journal of Dairy Science, 1995

A sensory panel was trained to assess appearance, aroma, flavor, and textural attributes of milk ... more A sensory panel was trained to assess appearance, aroma, flavor, and textural attributes of milk containing various per- centages,of fat. The relative viscosity and color of the milk were,also meas- ured. Milk appearance,had a profound effect on the perceived mouthfeel. There was a correlation of the L-value (white- ness), a-value (greenness), and b-value (blueness)0 to 2%. Panelists were given

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Perceptual mapping of citrus juices using projective mapping and profiling data from culinary professionals and consumers

Food Quality and Preference, 2008

Projective mapping, also known as the nappe map technique is a method proposed for gathering simi... more Projective mapping, also known as the nappe map technique is a method proposed for gathering similarity data in which panelists are directed to place products on a two dimensional surface. Two groups of participants, experienced chefs and consumers, performed this task and traditional attribute scaling. Ten fresh squeezed citrus juices and one commercial juice were judged along with two duplicates for a total of 13 products. Nappe map data were analyzed using multifactor analysis (MFA) and generalized procrustes analysis (GPA). Scaling data were analyzed using MFA, GPA, and principle components analysis (PCA). Configurations were generally similar, with juices differentiated by an axis opposing sweet, orange, floral and fruity characteristics against grapefruit, bitter and sour notes. A textural (pith vs. smooth) axis was also evident in some plots. Nappe configurations were similar, especially comparing GPA and MFA analyses within a group. Comparisons of configurations between groups were less similar, as shown by lower Rv coefficients. Configurations showed a good correspondence of scaled attribute results to nappe results for the consumers, but less so for the chefs, suggesting different criteria for the chefs in the nappe and scaling tasks. The nappe method may uncover perceptions not captured by traditional scaling and PCA especially for groups such as chefs, who may have more idiosyncratic perceptions of the critical sensory attributes.

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Metallic Taste and Retronasal Smell

by Harry Lawless and J. Lim

Chemical Senses, 2004

A series of experiments investigated the nature of metallic taste reports and whether they can be... more A series of experiments investigated the nature of metallic taste reports and whether they can be attributed to the development of a retronasal smell. Two studies showed that the metallic sensation reports following oral stimulation with solutions of FeSO 4 were reduced to baseline when the nose was occluded. No such reduction was seen for CuSO 4 or ZnSO 4 , which were more bitter and astringent, respectively, and less metallic. A discrimination test based on weak but equi-intense levels of FeSO 4 and CuSO 4 showed that FeSO 4 could be discriminated from water with the nose open but not when occluded, but that discrimination of CuSO 4 from water was not impaired by nasal occlusion. A discrimination test demonstrated that the headspace over solutions of FeSO 4 was not different from water, although some subjects could discriminate FeSO 4 solutions from water in the mouth when the nose was occluded, perhaps by tactile or astringent cues. These results confirm that metallic taste reports following oral stimulation with FeSO 4 are likely due to development of a retronasal smell, possibly following a lipid oxidation reaction in the mouth. However, metallic taste reports may arise from different mechanisms with copper and zinc salts. Metallic Taste and Retronasal Smell 33 Murphy, C. and Cain, W.S. (1980) Taste and olfaction: independence vs. interaction. Physiol. Behav., 24, 601-605. Rousseau, B., Meyer, A. and O'Mahony, M. (1998) Power and sensitivity of the same-different test: comparison with triangle and duo-trio procedures. J. Sensory Stud., 13, 149-173. Schiffman, S.S., Crofton, V.A. and Becker, T.G. (1985) Sensory evaluations of soft drinks with various sweeteners. Physiol. Behav., 34, 369-377. Zacarias, I., Yanez, C.G., Araya, M., Oraka, C., Olivares, M. and Uauy, R. (2001) Determination of the taste threshold of copper in water. Chem. Senses, 26, 85-89. Zacharias, R. and Tuorila, H. (1979) Der Reiz-und Erkennungsschwellenwert für Metallverbindungen in verscheidenen Prüfmedien [Taste thresholds for metallic salts in different media].

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Metallic Taste from Electrical and Chemical Stimulation

Chemical Senses, 2005

A series of three experiments investigated the nature of metallic taste reports after stimulation... more A series of three experiments investigated the nature of metallic taste reports after stimulation with solutions of metal salts and after stimulation with metals and electric currents. To stimulate with electricity, a device was fabricated consisting of a small battery affixed to a plastic handle with the anode side exposed for placement on the tongue or oral tissues. Intensity of taste from metals and batteries was dependent upon the voltage and was more robust in areas dense in fungiform papillae. Metallic taste was reported from stimulation with ferrous sulfate solutions, from metals and from electric stimuli. However, reports of metallic taste were more frequent when the word ÔmetallicÕ was presented embedded in a list of choices, as opposed to simple free-choice labeling. Intensity decreased for ferrous sulfate when the nose was occluded, consistent with a decrease in retronasal smell, as previously reported. Intensity of taste evoked by copper metal, bimetallic stimuli (zinc/copper) or small batteries (1.5-3 V) was not affected by nasal occlusion. This difference suggests two distinct mechanisms for evocation of metallic taste reports, one dependent upon retronasal smell and a second mediated by oral chemoreceptors.

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Astringency of Organic Acids is Related to pH

Chemical Senses, 1996

Astringency and sourness of lactic, acetic and citric acids, each adjusted to pH 3, 5 and 7, were... more Astringency and sourness of lactic, acetic and citric acids, each adjusted to pH 3, 5 and 7, were evaluated in two experiments, one starting at equal concentrations in wt/vol before neutralization and the second starting at equal molarity. Astringency and sourness decreased with increasing pH. However, acids were differentially sour at equal pH, consistent with previous findings. In contrast, the tactile attributes associated with astringency (drying, roughing of oral tissues and puckery/tightening sensations) were similar across acids; pH was the major influence on astringency.

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Astringent Subqualities in Acids

Chemical Senses, 1995

Astringency, astringent subqualities (drying, roughing and puckering) and sourness were compared ... more Astringency, astringent subqualities (drying, roughing and puckering) and sourness were compared among six acids: hydrochloric, lactic, citric, acetic, fumaric and malic acids. The attribute profiles of organic acids were similar to each other but different from hydrochloric acid, the only inorganic acid, which was the most astringent and the least sour. In a second experiment, two inorganic acids (hydrochloric and phosphoric) and two organic acids (citric and malic) were tested at three concentration levels. At approximately equal levels of overall sensory impact, the inorganic acids were alike in astringency and sourness, receiving higher ratings for roughing and drying, and lower ratings for sourness than the organic acids. Interactions with concentration (differences in psychophysical functions) for the subquality of drying were noted, in addition to the differences in the astringent subqualities of roughing and drying seen across acids in both experiments. The higher level of astringency for inorganic acids suggests that the current model for tannin binding to salivary proteins as an explanation of astringency needs to be extended to include a direct pH-dependent effect.

Lack of effect of taste and nutrition claims on sensory and hedonic responses to a fat-free yogurt

by Päivi Kähkönen, Hely Tuorila, and Harry Lawless

Food Quality and Preference, 1997

Pleasantness and four sensory attributes of a fat-free strawberry yogurt were rated in three cond... more Pleasantness and four sensory attributes of a fat-free strawberry yogurt were rated in three conditions in which different information about the sample was provided: ‘Strawberry yogurt’, ‘Fat-free strawberry yogurt’ and ‘New, tasty fat-free strawberry yogurt’. Seventy-eight subjects were tested in each information condition in a between-subjects design. The effects of information were studied in subject sub-groups based on scoring background

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