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Absolute threshold and just noticeable difference (JND) were determined for the perception of pungency using chili pepper in aqueous solutions. Absolute threshold and JND were determined using 2 alternative forced-choice sensory tests tests. High-performance liquid chromatography technique was used to determine capsaicinoids concentration in samples used for sensory analysis. Sensory absolute threshold was 0.050 mg capsaicinoids/kg sample. Five JND values were determined using 5 reference solutions with different capsaicinoids concentration. JND values changed proportionally as capsaicinoids concentration of the reference sample solutions changed. Weber fraction remained stable for the first 4 reference capsaicinoid solutions (0.05, 0.11, 0.13, and 0.17 mg/kg) but changed when the most concentrated reference capsaicinoids solution was used (0.23 mg/kg). Quantification limit for instrumental analysis was 1.512 mg/kg capsaicinoids. Sensory methods employed in this study proved to be more sensitive than instrumental methods. Practical Application: A better understanding of the process involved in the sensory perception of pungency is currently required because "hot" foods are becoming more popular in western cuisine. Absolute thresholds and differential thresholds are useful tools in the formulation and development of new food products. These parameters may help in defining how much chili pepper is required in a formulated product to ensure a perceptible level of pungency, as well as in deciding how much more chili pepper is required in a product to produce a perceptible increase in its pungency.
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S: Sensory & Food
Quality
Determination of Absolute Threshold and
Just Noticeable Difference in the Sensory
Perception of Pungency
L. Orellana-Escobedo, J.J. Ornelas-Paz, G.I. Olivas, J.A. Guerrero-Beltran, J. Jimenez-Castro, and D.R. Sepulveda
Abstract: Absolute threshold and just noticeable difference (JND) were determined for the perception of pungency
using chili pepper in aqueous solutions. Absolute threshold and JND were determined using 2 alternative forced-
choice sensory tests tests. High-performance liquid chromatography technique was used to determine capsaicinoids
concentration in samples used for sensory analysis. Sensory absolute threshold was 0.050 mg capsaicinoids/kg sample. Five
JND values were determined using 5 reference solutions with different capsaicinoids concentration. JND values changed
proportionally as capsaicinoids concentration of the reference sample solutions changed. Weber fraction remained stable
for the first 4 reference capsaicinoid solutions (0.05, 0.11, 0.13, and 0.17 mg/kg) but changed when the most concentrated
reference capsaicinoids solution was used (0.23 mg/kg). Quantification limit for instrumental analysis was 1.512 mg/kg
capsaicinoids. Sensory methods employed in this study proved to be more sensitive than instrumental methods.
Keywords: chili pepper, just noticeable difference, pungency, sensory threshold
Practical Application: A better understanding of the process involved in the sensory perception of pungency is currently
required because “hot” foods are becoming more popular in western cuisine. Absolute thresholds and differential thresholds
are useful tools in the formulation and development of new food products. These parameters may help in defining how
much chili pepper is required in a formulated product to ensure a perceptible level of pungency, as well as in deciding
how much more chili pepper is required in a product to produce a perceptible increase in its pungency.
Introduction
Chili pepper fruits are one of the most consumed spices
throughout the world. Chili peppers provide pungency, color,
and aroma to different types of foods and are appreciated not
only as food ingredients, but also because of their pharmaceu-
tical and physiological actions (Garces-Claver and others 2006;
Cisneros-Pineda and others 2007). In the United States there has
been a great increase in the demand of this fruit in recent years
because of the increased multiculturalism, popularity of ethnic
restaurants, and increased use of “flavored” vegetables in the diet
to avoid fats and cholesterol (Lawless 1989). The food industry is
the largest consumer of chili peppers, where the spice is used as
a flavoring agent in sauces, soups, processed meats, snacks, can-
dies, soft drinks, and alcoholic beverages (Mathew and others
1971).
The sensory quantification of chili pepper’s pungency is used
by the food industry for a variety of purposes including the study
of ingredient variation limits in products containing chili pepper
MS 20110882 Submitted 7/21/2011, Accepted 12/1/2011. Authors Escobedo,
Ornelas-Paz, Olivas, and Sep ´
ulveda are with Centro de Investigacion en Alimentacion
y Desarrollo, A.C. Unidad Cuauhtemoc, Av. Rio Conchos S/N, Parque Industrial,
C.P. 31570. Cd. Cuauhtemoc, Chihuahua, Mexico. Author Guerrero-Beltran is with
Universidad de las Americas Puebla. Santa Catarina Martir, Cholula Puebla. C.P.
82720, Mexico. Author Jim´
enez-Castro is with Univ. Autonoma de Chihuahua.
Av. Escorza No. 900, Zona Centro. C.P. 31000 Chihuahua, Chihuahua, Mexico.
Direct inquires to author Sepulveda (E-mail: dsepulveda@ciad.mx).
such as salsas and cheese sauces (Meilgaard and others 1991). One
metric of interest that is essential for the determination of these
variation limits is the absolute threshold (Shepherd and others
2008). The first method developed for the quantification of pun-
gency, known as the Scoville method, is a sensory test based on
the determination of the perception threshold in serially diluted
samples. Pungency thresholds are useful in the determination of
“heat”, which contributes to the sensory properties of a product.
Such values have immediate practical implications for acceptable
compared with unacceptable levels of flavor components (Lawless
and Heyman 1999). There is also another metric that is rele-
vant for food product developers: the just noticeable difference
(JND). JND is the minimal difference that can be detected between
2 stimuli (Lawless and Heymann 1999). JNDs are important, for
example, when a negative change, such as the reduction in an
expensive ingredient in a formula is not readily discernible to
consumers (below JND), or when a positive change, such as an
increment in the amount of a consumers’ favorable ingredient, is
very apparent to consumers (above JND; Chang and Chiou 2006).
Research on pungent food products have been conducted to study
the interaction of chili peppers with other food ingredients such as
cheese sauces, chicken patties, pork patties, sucrose, sodium chlo-
ride, and citric acid, among others (Sizer and Har ris 1985; Carden
and others 1999; Emrick and others 2005; Reinbach and others
2009).
There is little investigation on pungency thresholds. JND for
pungency has never been reported and a few studies have re-
ported absolute threshold values. The reported values for absolute
C
2012 Institute of Food Technologists R
doi: 10.1111/j.1750-3841.2011.02589.x Vol. 77, Nr. 3, 2012 rJournal of Food Science S135
Further reproduction without permission is prohibited
S: Sensory & Food
Quality
Pungency sensory perception . . .
threshold have been obtained using different sensory methods such
as magnitude estimation and the method of limits (Krajewska and
Powers 1988; Lawless and others 2000). These are good methods
but may present some limitations. Magnitude estimation meth-
ods produce results having ratio problems such as judges having
a strong favored-number effect (O’Mahony 1982). It is also said
that magnitude methods are incapable of providing stable and re-
producible values for flavor intensity (Meilgaard and others 1991).
Similarly, the method of limits is slightly biased and can be very
biased if subjects falling on the upper or lower limits of the range
under test are not reexamined (Meilgaard and others 1991). On
the other hand, 2 alternative forced-choice sensory tests (2AFC)
may be used to estimate both absolute thresholds and difference
thresholds (JND) in an unbiased manner (Ulrich and Miller 2004).
Prior research shows that this test appears to be an especially sen-
sitive psychophysical tool (Macmillan and Creelman 1991), dis-
courages response biases, produces an especially high level of per-
formance and produces results that are stable and valid (Fausti and
others 1979; James and others 1997; Mojet and others 2001; Braun
and others 2004; Shepherd and others 2008; Ulrich and Vorberg
2009).
The objective of this study was to determine the absolute thresh-
old and JND in the sensory perception of chili pepper pungency
using 2AFC tests.
Materials and Methods
HPLC analysis of capsaicinoids
Dry Piquin chili pepper (Capsicum annuum L. var. aviculare)
found at local market was used in this study. High-performance
liquid chromatography (HPLC) was employed to determine its
capsaicin and dihydrocapsaicin content. These 2 capsaicinoids
were quantified as they are good predictors of the pungency
of chili peppers, constituting about 90% of the total capsaici-
noid content (Reilly and others 2001). Total capsaicinoid content
in this study was defined as the sum of capsaicin and dihydro-
capsaicin found in the studied sample. The capsaicinoids extrac-
tion method used in this study was an adaptation of the method
reported by Cisneros-Pineda and others (2007). Methanol was
used instead of acetone (Kurian and Starks 2002; Ornelas-Paz and
others 2010). Solid chili pepper samples were blended to a fine
powder and 0.6 g of powdered chili were mixed with 10 mL
of methanol HPLC grade and kept for 2 h at 4 C. Samples
were then centrifuged for 5 min at 11000 ×gand the super-
natant was filtered through a polyethylene membrane of 0.45 μg
of pore size previous to analysis by HPLC. Three replicates were
conducted.
The following HPLC operating conditions, used by
Ornelas-Paz and others (2010), were employed. The HPLC set-
up consisted of a Varian (Model 9012) solvent delivery system and
a Varian (Model 9050) UV-VIS detector (set at a λ=236 nm).
A Supelcosil LC-C18 column (25 cm ×4.6 mm, 5 μm) was
used. The mobile phase consisted of acetonitrile/water/acetic acid
50:50:1 at a flow rate of 1 mL/min. Injection volume was 20 μL,
run time 30 min, and temperature 25 C.
Standards of capsaicin and dihydrocapsaicin (Sigma-Aldrich, St.
Louis, Mo., U.S.A.) were used to identify and quantify these cap-
saicinoids. HPLC grade methanol was used to prepare standard
curve solutions for capsaicin and dihydrocapsaicin. Standard curves
were prepared using concentrations of 5 to 1000 μg/mL. Two
replicates were conducted. A correlation coefficient of 0.9960 was
achieved on the construction of the curves.
Determination of instrumental quantification limit (LOQ)
Forty-five solutions containing different capsaicinoid concen-
trations were analyzed to obtain an instrumental quantification
limit for this study. Determination of the signal-to-noise ratio
was performed by comparing measured signals from samples with
known low concentrations of the analyte and by establishing the
minimum concentration at which the analyte can be reliably quan-
tified, considering a limit signal-to-noise ratio of 20 to 1.
Sensory determination of pungency
Absolute threshold. Sensory tests were performed at a local
market in Cuauhtemoc City, Chihuahua, Mexico. Two hundred
and fifty subjects (18–60 y old; female) volunteered to participate
in the study (50 tests per comparison level). There was no training
session and none of the subjects knew about the objective of the
study. Each subject participated only once in the study.
2AFC were used to determine the absolute threshold of pun-
gency’s sensory perception, which was defined as the concentra-
tion corresponding to 76% correct responses. Paired samples con-
sisted of one pungent sample and a purified water sample. Pungent
samples were prepared as described in the ASTM method E1083-
00 (Standard Test Method for Sensory Evaluation of Red Pepper
Heat 2000) employing polysorbate-80 for capsaicinoids emulsifi-
cation. Test samples were produced by serial dilutions, obtaining
concentrations of 0.039, 0.043, 0.050, 0.053, and 0.061 mg/kg
total capsaicinoids.
Two 10 mL samples (one containing plain water and one con-
taining the stimulus) were presented to each subject randomly in
plastic cups. Subjects swallowed the entire sample, waited 30 sec
and rinsed the palate using spring water. Subjects were asked to
choose the one item they thought was more pungent.
Just noticeable difference
JND tests were also performed at a local market in Cuauhtemoc
City, Chihuahua, Mexico. One thousand two hundred and fifty
subjects (18–60 y old; female) volunteered to participate (50 tests
per comparison level, 5 reference solutions, 5 comparison solutions
per reference solution). There was no training session and none of
the subjects knew about the objective of the study. Each subject
participated only once in the study.
Reference solutions (0.05, 0.11, 0.13, 0.17, and 0.23 mg/kg
total capsaicinoids) were used to obtain different values of JND.
2AFC tests were used to determine JND. In every case, the JND
was defined as the concentration difference where 76% correct
responses were found. Two samples (one containing the reference
solution and another containing a solution of a higher capsai-
cinoids concentration) of 10 mL each were presented to each
judge (5 comparison solutions of higher pungency were used for
comparison against each reference solution). Subjects waited 30
sec between samples and rinsed palate using spring water. Sub-
jects were asked to choose the one item they thought was more
pungent.
Weber fraction determination
Weber’s law states that the just noticeable difference between
2 stimuli is a fixed proportion of the value of the stimuli being
judged (reference; Goldstein 1980). JND values obtained in this
study were employed to calculate the Weber fraction for pungency
perception. Weber fraction (k) was calculated using
k=I
I
S136 Journal of Food Science rVol. 77, Nr. 3, 2012
S: Sensory & Food
Quality
Pungency sensory perception . . .
where Iis the increase in the physical stimulus needed to be
judged different (JND) and Iis the starting level of the stimulus
(reference solution concentration) (Lawless and Heymann 1999).
Statistical analysis
Data were analyzed by a χ2goodness-of-fit test. Sensory thresh-
old data were analyzed by calculating the correlation between the
proportion of correct responses and total capsaicinoids content
(mg/kg) using Microsoft Excel 2007.
Results and Discussion
The total capsaicinoids content in Piquin chili pepper was
3.6 mg/g (dry matter). Results for the sensory determination of
the absolute threshold are shown in Figure 1. A linear correlation
between the proportion of correct responses and the concentra-
tion of the pungent sample was found. The R2value indicated that
more than 99% of the variation in the proportion of correct re-
sponses can be explained by the variation in capsaicinoids concen-
tration. The proportion of correct responses (n=50) was obtained
for each 1 of 5 studied concentrations. No evidence of carryover
effects was observed as no statistically significant preference for
the first or second tasted sample was found. Correct responses
increased as capsaicinoid concentration content increased.
The absolute threshold and JND are usually defined as the
stimulus intensity at which the proportion of correct responses
is 76% (Klein 2001). Concentration of stimuli for absolute thresh-
old at 76% correct responses was 0.05 mg/kg total capsaicinoids,
which indicates that pungency is perceptible by human subjects
at that concentration and above. Krajewska and Powers (1988)
found similar results using the method of magnitude estimation.
They reported absolute threshold within a range of 0.039 to
0.078 mg/kg total capsaicinoids using ethanol for capsaicinoids
extraction/emulsification. It is interesting to find coincidence be-
tween the absolute threshold value found by Krajewska and Powers
Figure 1–Linear response observed between the proportion of correct
responses and the concentration of capsaicinoids in aqueous solutions
compared against pure water in 2AFC paired tests.
(1988) and the one found in this study, because it would be reason-
able to believe that Mexican judges participating in this study, who
consume hot peppers on a regular basis (around 8 kg per year per
capita on average), would present a higher threshold for pungency
perception than American judges due to desensitization caused by
continuous periodic exposure to the stimulus (Lawless and others
1985). Furthermore, more recent studies conducted with Ameri-
can judges (Lawless and others 2000) have found higher threshold
values (0.31 ±0.03 mg/L) when using the method of limits,
both when using ethanol and polysorbate-80 for capsaicinoids ex-
traction/emulsification. Lawless and others (2000) compared the
efficiency of using ethanol and polysorbate-80 for capsaicinoids
extraction/emulsification, but documented that the comparison
did not show clear effects, and no differences were observed.
In comparison with other types of stimuli commonly present
in foodstuffs, it may be said that the human senses are especially
sensitive to capsaicinoids, as absolute threshold values reported in
literature for aqueous solutions of other products are much higher
(that is, sweet: 2% sucrose, sour: 0.07% citric acid, salty: 0.2%
sodium chloride, and bitter: 0.07% caffeine; ASTM 1981).
Defining absolute threshold as the stimulus concentration where
the outcome of 76% of the conducted 2AFC tests is correct is
not the only way to define absolute threshold values. Exper-
imental data derived from 2AFC tests may also be evaluated
by a χ2goodness-of-fit analysis. Threshold values may be es-
timated by testing against the null hypothesis stating that the
observed proportion of correct responses in the sample corre-
sponds to a sample taken from a population with a 50/50 pro-
portion of correct responses (chance performance in the case
of 2AFC tests). Following this strategy, threshold values may be
estimated with various degrees of confidence, as illustrated in
Table 1. Absolute threshold values derived from this study
(Table 1) may be located in the range 0.043 to 0.50 mg/kg to-
tal capsaicinoids with varying degrees of confidence from 93% to
99.96%, the latter being the confidence level corresponding to the
76% criterion, which may be considered by statistical standards as
overconservative.
Results for JND and Weber fraction are shown in Table 2.
JND values indicate the amount of additional stimulus required to
Table 2– Reference solution values, Weber fraction, and just
noticeable difference concentration values.
Total capsaicinoid
concentration for Just noticeable
reference solutions Weber difference (I)
(I) (mg/kg) fraction(k)(mg/Kg)
0.05 0.60 0.030
0.11 0.62 0.068
0.13 0.59 0.077
0.17 0.64 0.108
0.23 0.76 0.174
Table 1–χ2goodness-of-fit test for absolute threshold values corresponding to different significance levels.
Number of trials Correct responses Proportion C/I χ2Significance level (α) Threshold (mg/kg)
50 32 64/36 3.38 0.0700 0.043
50 33 66/34 4.50.0300 0.044
50 34 68/32 5.78 0.0200 0.045
50 35 70/30 7.22 0.0070 0.046
50 36 72/28 8.82 0.0029 0.048
50 37 74/26 10.58 0.0011 0.049
50 38 76/24 12.50 0.0004a0.050a
C/I, proportion of correct/incorrect responses.
aStatistical significance and absolute threshold value corresponding to the absolute threshold value criterion of 76% correct responses.
Vol. 77, Nr. 3, 2012 rJournal of Food Science S137
S: Sensory & Food
Quality
Pungency sensory perception . . .
Figure 2–Linear response observed between the
proportion of correct responses and the
differential concentration of capsaicinoids in
aqueous solutions compared against reference
aqueous solutions of 5 different concentrations.
Just noticeable difference values (JND).
perceive a difference between 2 samples, both containing the
stimulus. JND results were congruent with Weber’s law. Calcu-
lated Weber fraction values for suprathreshold scaling functions
(0.59–0.64) were similar among tests conducted with reference
solution ranging from 0.05 to 0.17 mg/kg total capsaicinoids.
However, the reference solution with the highest capsaicinoids
concentration (0.23 mg/kg) showed a different Weber fraction
(0.76). This abnormality may be attributed to the nature of the
stimulus produced by capsaicinoids, which easily implies fatigue
when the aftertaste of the first tasted sample interferes as “noise”
with the tasting of a subsequent sample, together with the de-
sensitization produced after capsaicin intake (Stevens and Lawless
1987). Another possible documented explanation for the exis-
tence of deviations from Weber’s law is derived from experimental
evidence that has proven that Weber’s law holds true for most
senses as long as the stimulus intensity is not too far to the thresh-
old (Goldstein 1980). This information suggests that an aqueous
capsaicinoids solution with a concentration of 0.23 mg/kg capsai-
cinoids is probably far enough from the threshold concentration as
to cause deviations from Weber’s law. Finally, in Figure 2 absolute
threshold and JND graphics are shown. Linear responses for every
test conducted with different reference solutions, show a similar
tendency.
The quantification limit of the conducted instrumental analysis
was 0.352 mg/kg for capsaicin and 1.160 mg/kg for dihydrocap-
saicin. Total capsaicinoids quantification limit was 1.512 mg/kg.
Quantification limits previously reported in literature establish val-
ues of 13 mg/kg with UV detection and 4 mg/kg (Sein and
others 1998) and 5 mg/kg (Chiang 1986) employing a fluores-
cence method. These results are similar in order of magnitude,
to the instrumental values obtained in this study. On the other
hand, Chiang (1986) developed an HPLC-ECD and UV method,
which results in a detection limit as low as 0.06 mg/kg which is
closer to the sensory threshold values found in this study. The re-
sults of this study demonstrate that sensory quantification methods
are more sensitive than instrumental methods in the quantification
of capsaicinoids. Prior studies conducted on the comparison of
sensory methods compared with instrumental methods, including
taste, odor and texture, have already reported that sensory meth-
ods are more sensitive than instrumental methods (Min 1983; Lu-
cisano and others 1989; Rousset and others 1995; McIlveen and
Armstrong 1996; Bae and others 2002; Prakash and others 2005).
In view of this, an increasing amount of attention is being paid
to correlating instrumental and sensory methods. In fact there is
a desire to interpret the instrumental measurements in terms of
sensory principles (Todd and others 1977; Hoffman and others
1983; Parrish 1996). Although improvements on instrumentation
contribute to the production of better measurements and to low-
ering quantification limits, the most important point in the use
of sensory analysis is that only human beings can perceive, ana-
lyze, integrate, and interpret the entire spectrum of characteristics
in one evaluation (Kramer and Szczesniak 1973). Flavor research
has shown that instrumental analysis does not totally reflect the
sensory profile of a food product and sensory evaluation gives a
realistic opinion about the likes and dislikes of a particular flavor,
so it is recommended to obtain a blend of both instrumental and
sensory techniques (Hariom and others 2006). Sensory methods
determine the perception of foods through the human senses and
this can only be achieved with one instrument: the human being.
Conclusions
The absolute threshold for the sensory perception of pungency
was 0.050 mg/kg capsaicinoids and instrumental quantification
limit for instrumental analysis was 1.512 mg/kg capsaicionids,
which makes sensory methods more sensitive. JND changed pro-
portionally while intensity of the reference sample increased. We-
ber fraction results were similar (0.59–0.64) for the first 4 reference
concentrations studied, and slightly higher for the highest studied
reference concentration (0.76). The use of an aqueous vehicle in
this study may represent a limitation when extrapolating its find-
ings to a different food system, as it is well known that presence of
lipidic substances modifies the perception of pungency affecting
perception threshold values.
Acknowledgments
The authors thank Liliana Nunez, Nabil Carmona, Veronica
Gonzalez, and Angel Esparza for their technical assistance and
Consejo Nacional de Ciencia y Tecnologia (CONACYT) for
providing the funding for the graduate studies of author Orellana-
Escobedo.
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Vol. 77, Nr. 3, 2012 rJournal of Food Science S139
... Spicy foods are part of diverse food cultures around the globe, and their popularity in western cuisine is increasing (Orellana-Escobedo et al., 2012). The most common pungent substance is capsaicin, which is known from hot pepper (Spence, 2018(Spence, , 2019. ...
... Many studies on pungency thresholds have been conducted in recent decades. Most of these studies have examined the pungency of capsaicinoids (Lawless, Hartono, & Hernandez, 2000;Orellana-Escobedo et al., 2012;Schneider, Seuss-Baum, & Schlich, 2014 Fenwick et al. (1983) reported sinigrin in aqueous solution to be bitter with a detection threshold of 10.6 mg/100 ml. ...
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In 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 applications Threshold 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.
... Frequency of correct responses was plotted against salt concentration (%) using Microsoft Excel 2017®. Straight lines were fitted to a linear correlation (Mcburney & Collings, 1977;Orellana-Escobedo et al., 2012;Pfaffmann, Bartoshuk, & McBurney, 1971) for cooked sausages. For cooked chorizo, a logarithmic correlation was plotted (Bobowski & Vickers, 2012;Rohm & Raaber, 1992). ...
... Few studies have carried out salt reduction taking into account threshold methodology and none, to our knowledge, evaluated meat products (Antúnez, Giménez, & Ares, 2016;Orellana-Escobedo et al., 2012). Besides, some studies have evaluated salt reduction in foods using consumers to measure sensory attributes and acceptability; however, lack of experience, vocabulary and consumers' concept alignment prevents generation of quality descriptive data (Ishii et al., 2007). ...
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Several sodium reduction strategies have been studied on meat products because of its association with non-communicable diseases; however, overall flavor is usually affected. This study’s aim was to reduce salt in three meat products (chorizo and two sausages: regular and low fat) without consumers awareness using the JND methodology. The threshold constant stimuli method used 1.95% salt in chorizo, and 2.24% in both sausages as the constant stimulus. Salt concentrations around these numbers were compared against the constant stimulus using a 2-AFC difference test to calculate the JND. A second study was performed to confirm consumers did not perceive a difference on salt perception of reduced salt products. Total salt reduction obtained was between 18.5% and 22% for the three products. Consumers did not find difference in saltiness between regular and reduced-salt versions. Using JND methodology, gradual salt reduction programs could achieve accurate and major salt reductions without consumers’ awareness.
... Meanwhile, Weber's Law can be written as an equation by introducing a unitless constant, : Bouguer 5 , whose stimulus was candle-light. The quantity ∆ ⁄ itself is called the Weber Fraction and continues to be employed into the 21 st Century to quantify human discriminability in vision 6-10 , in hearing [11][12][13][14][15][16][17] , and in flavor [18][19][20] (formerly called "taste"). There has been special interest in the pressure senses (touch, vibration, weight) 10, 21-40 . ...
... This capsaicin concentration was comparable to the previously reported range for capsaicin threshold (0.29 to 1.14 µM in a 10-ml volume) (Sizer and Harris 1985), or the group mean capsaicin threshold of 1 µM (0.31 mg/l in a 10-ml volume) (Lawless et al. 2000). Although this concentration is higher compared to the capsaicin threshold level (e.g. a threshold between 0.16 and 0.49 µM) reported in other studies (Okamoto et al. 2018;Orellana-Escobedo et al. 2012), it is distinct from (far below) the concentration that could induce perception of irritation, for example, a concentration of around 0.36 µM (0.11 ppm) was barely detectable, and 0.9 µM of capsaicin (0.275 ppm) was barely detectable to weak sensation (Nolden and Hayes 2017). The variability between thresholds obtained in different studies may also be explained by different modes of stimulation and especially by differences in the volume of the administered stimuli. ...
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Introduction Taste perception is affected by trigeminal stimuli, i.e., capsaicin. This has been studied at suprathreshold concentrations. However, little is known about taste perception at threshold level in the presence of low concentration of capsaicin. The aim of the study was to explore whether taste sensitivity for sweet, sour, salt, bitter, and umami is modulated by the presence of capsaicin in the peri-threshold range. Methods Fifty-seven adults (age range 19–85 years; 32 women) with functional gustation participated in the study. Based on their perception of phenylthiocarbamide (PTC), the group was stratified into non-tasters ( n = 20) and tasters ( n = 37). Threshold for sweet (sucrose), sour (citric acid), salty (sodium chloride), bitter (quinine-hydrochloride), and umami (sodium-glutamate) tastes was estimated using a single-staircase paradigm (3-alternative forced choice; volume per trial 0.1 ml) with or without 0.9-µM capsaicin added. This capsaicin concentration had been determined in pilot studies to be in the range of oral perception thresholds. Results The addition of capsaicin produced lower taste thresholds for sweet, sour, salty, and bitter but not for umami. In contrast, neither PTC taster status nor sex affected these results. Conclusion The current results indicate that a low concentration of capsaicin increases gustatory sensitivity. Implications The current findings provide evidence supporting different effects of capsaicin on taste perception at threshold level. It has implications for boosting taste sensitivity or flavor enjoyment with low concentration of capsaicin.
... Four main methods are currently used to measure individual sensitivity to basic taste (Bartoshuk et al., 1995;Tepper et al., 2001;Mojet et al., 2005;Keast & Roper, 2007;Garneau et al., 2014;Webb et al., 2015;ISO standard 13,301:2018). The first involves individual detection and recognition thresholds based on logistic and best-estimate threshold models (ISO standard 13,301:2018;Orellana-Escobedo et al., 2012). However, these thresholds may not correlate or may be inversely related to the perceptions of suprathreshold intensities due to the complex nature of the oral peripheral and central cognitive system (Keast & Roper, 2007;Mojet et al., 2005). ...
Article
Sensory tests involving taste-sensitive individuals provide the food industry with valuable information. However, the traditional evaluation of 6-n-propylthiouracil (PROP) tasters, which is assumed to reflect general taste sensitivity, is controversial. Therefore, the present study aimed to develop a rapid method for the classification of an individual’s sensitivity to chemesthetic sensation, and to investigate the relationship between taste and chemesthetic sensation sensitivity at the suprathreshold level. In all, 72 young adults were screened and participated in the tests. The intensity of the pungency, heat, bitterness and saltiness that were presented via five concentrations of Sichuan pepper oleoresin (Spo), capsaicin, PROP and NaCl, respectively, were rated using generalized Labeled Magnitude Scales (gLMS). The method, namely 20% relative standard deviation (RSD), was developed for the classification of an individual’s sensitivity. The results of ordinal multinomial logistic regression showed that the sensitivity to bitterness could be partly predicted by the sensitivity to saltiness, as well as the heat and pungency sensations. Furthermore, it was found that threshold should be used in conjunction with suprathreshold intensity ratings for classifying individuals. These findings regarding panelist sensitivity will be most useful in sensory evaluations of pungent food and in large-scale consumer studies.
... Rutinariamente, las investigaciones para reducir el contenido de sodio en diferentes productos emplean metodos hedónicos o descriptivos (23). Sin embargo, los resultados aquí expuestos e investigaciones realizadas bajo esta metodológico (23,35,36) confirman que las pruebas de discriminación y la determinación de umbrales representa un alternativa promisoria para lograr reducir el contenido de sodio en alimentos sin que el consumidor perciba diferencias. La OMS ha recomendado reducciones progresivas en el contenido de sodio de los alimentos para lograr niveles más bajos de ingesta en la dieta (1). ...
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El consumo excesivo de sodio es causa importante de enfermedades no transmisibles incluyendo hipertensión. En esta investigación se evaluó una metodología sensorial para reducir el contenido de sodio en salsas de tomate y mayonesas, productos altamente consumidos en Costa Rica. Se caracterizaron, por triplicado, 16 salsas y 7 mayonesas comerciales para determinar los ingredientes más comunes y sus características físicoquímicas. Se comparó el contenido de sodio reportado en la etiqueta contra el valor determinado experimentalmente. Se formularon prototipos de ambos productos y se determinó el umbral de diferencia apenas perceptible (DAP) para el gusto salado utilizando el método de estímulo constante con 40 panelistas no entrenados (d'= 1, significancia de 0,05 y potencia de prueba de 0,95). Se contruyeron las curvas psicofísicas con concentraciones de sal entre 0,67% y 2,5% para salsa de tomate y 0,13% y 4,16% para mayonesa; obteniéndose DAPs de 0,51% y 0,26% respectivamente; equivalentes a 28,3% y 14,4% menos de sal en cada producto. Para la validación del umbral, se aplicó una prueba de discriminación 2-AFC con 40 panelistas comparando la formulación regular con la reducida en sodio. Los panelistas no detectaron diferencias significativas entre mayonesas (P>0,05) pero sí entre salsas (P<0,05), por lo que se aplicó una prueba de agrado con 112 consumidores y se determinó que la salsa reducida en sodio resultó de mayor o igual agrado que la contraparte. Estos resultados guiarían a la industria alimentaria regional hacia el mejoramiento del perfil nutricional de estos productos. The excessive consumption of sodium is an important cause of noncommunicable diseases including hypertension. This research aimed, using a sensorial methodology, to reduce sodium content in tomato sauces and mayonnaise, highly consumed products in Costa Rica. A total of 16 commercial sauces and 7 mayonnaises were characterized to determine their most common ingredients and physicochemical properties. The sodium content reported in the labed was compared against values obtained experimentally. Prototypes for both products were developed and the threshold for the just noticiable difference (JND) for salty flavor was determined using the constant stimulus method with 40 panelists (d'= 1, 0.05 significance and a test power of 0,95). Psychophysical curves were built with salt concentrations between 0.67% and 2.5% for tomato sauce and 0.13% and 4.16% for mayonnaise; obtaining JNDs of 0.51% and 0.26% respectively; equivalent to 28.3% and 14.4% less salt in tomato and mayonnaise. To validate the threshold, a discriminatory 2-AFC test with 40 panelists was performed to compare the regular formulations against those reduced in sodium. Panelists did not detect significant differences among mayonnaises (P>0.05) but they did found differences between sauces (P<0.05). Thus, for tomato sauce a consumer liking test with 112 consumers was performed and it was found that sodium reduced tomato sauce was equally or more liked than its counterpart. These results guide the regional food industry towards the improval of the nutritional profile of both products.
... Two alternative forced-choice sensory tests were used to determine the absolute threshold of the aroma's sensory perception, which was dened as the concentration corresponding to 80% correct response. 21 Paired samples consisted of one test sample and a puried water sample. The test samples were prepared by serial dilutions of aroma compound standard in distilled water, thereby obtaining a series of concentrations of more than 3 mg L À1 . ...
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Biofilm formation in the production of fermented vegetable might impact its quality and safety. In this study, physicochemical and microbial properties, volatile and aroma-active compounds between PRPs without biofilm (NPRP) and with biofilm (FPRP) were investigated by gas chromatography-mass spectrometry, gas chromatography-olfactometry, aroma extract dilution analysis, and spiking tests. The pH and titratable acidity were 3.66 ± 0.00 and 0.47 ± 0.08 g/100 g lactic acid in NPRP and 3.48 ± 0.01 and 0.87 ± 0.10 g/100 g lactic acid in FPRP, respectively. The nitrite level of the two PRPs was 1.87–1.92 mg kg⁻¹, which was below the limited value (20 mg kg⁻¹) of fermented vegetables regulated by the GB2760-2017. FPRP had relatively higher microbial and yeast numbers than NPRP, three common pathogens, namely, Salmonella spp., Staphylococcus aureus, and Shigella spp. were not detected. A total of 70 and 151 aroma compounds were detected in NPRP and FPRP, respectively, including 13 classes of compounds. The dominant aroma attributes of FPRP were sour, floral, mushroom-like, green, and smoky, while NPRP exhibits a mushroom-like flavor. Acetic acid, ethanol, α-terpineol, (E)-2-nonenal, 2-heptanol, phenylethyl alcohol, and linalool were potent key aroma-active compounds in NPRP and FPRP. Results of spiking tests showed that the addition of each substance not only increased its own odour, but also had significant effects on other smells. FPRP displayed richer varieties and contents of aroma profile than NPRP. However, some compounds, such as 4-ethylguaiacol and 4-vinylguaiacol, which were only detected in FPRP, had negative roles on the aroma attributes.
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Most studies on the operation and planning of integrated systems have been based on the needs of public transport users without disabilities. However, people with disabilities face different challenges when riding public transport. This study adopts Weber’s Law "Just Noticeable Difference" to investigate the travel time savings and transfer time desired by public transport users with disabilities when selecting a route with transfer(s). An online survey was undertaken in major cities around New Zealand. A total of 108 public transport users with disabilities who have traveled independently in the last five years participated. Results show a variation among the travel time savings required by different groups of users with disabilities when choosing transfers. Participants with multiple impairments were less willing to choose a transfer route (k=0.458), followed by participants with cognitive impairments (k=0.315). There is a negligible difference in willingness between participants with physical (k=0.255) and visual impairments (k=0.253). Findings from this study are expected to assist transport planners and public transport operators in reconsidering how they design integrated systems to ensure ease of transfers for people with disabilities.
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Capsaicinoids, volatile compounds, and fatty acids were analyzed in red pepper seeds to determine any changes at different roasting temperatures. The contents of capsaicin and dihydrocapsaicin decreased as roasting temperatures increased. 3-Ethyl-2,5-dimethylpyrazine, 2,3,5,6-tetramethylpyrazine, 2-methoxy-3-(2-methylpropyl)pyrazine, 1-methylpyrrole, hexanedial, benzeneacetaldehyde, 2-acetylfuran, and butane-2,3-diol were newly detected in red pepper seeds roasted at 100 °C. Concentrations of pyrazines, pyrroles, oxygen-containing heterocyclic compounds, carbonyls, and alcohols increased rapidly in red pepper seeds as the roasting temperature increased. Such compounds could contribute roasted, grilled, and sweet odor notes to roasted red pepper seeds. Linoleic acid was the predominant fatty acid in all red pepper seeds. There were no significant differences in polyunsaturated fatty acids in red pepper seeds as roasting temperature increased. In conclusion, roasting red pepper seeds could be used in thermally processed foods because during roasting their pungency is reduced, desirable savory odors are enhanced, and the levels of polyunsaturated fatty acids remain unchanged.
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Excessive salt in the diet can pose significant health risks and, therefore, the reduction of salt derived from food is an important issue relating to human nutrition and health. Furthermore, the perception of saltiness will be different among people when considering their innate sensitivity, gender, age, psychological traits and dietary habits. In this study, 31 younger participants and 29 older participants were used as research subjects. A web-based questionnaire survey was used to collect information regarding of socio-demographics, consumption frequency and liking for salty and pungent food, as well as personality traits throughout the younger and the older participants. In addition, the 6-n-propylthiouracil (PROP) ratings were tested by generalized Labeled Magnitude Scale (gLMS) in the laboratory conditions. Two-alternative forced choice (2-AFC) method was used to test the sensitivity differences in the saltiness of NaCl and the pungent sensation elicited by Sichuan pepper oleoresin between the younger and older groups. The results showed significant differences in the liking for pungent food, consumption frequency of salty food, life satisfaction, negative affect, sensation seeking and PROP ratings between the younger and older groups (p<0.05). Moreover, except for the detection threshold of saltiness, thresholds were significantly lower in the younger group than in the older group. The saltiness recognition threshold and salty intensity in the presence of pungent carriers were further analyzed by using the 2-AFC and 15 cm linear scale methods. Interestingly, the results showed that the saltiness recognition threshold decreased in the presence of the sub-threshold pungency solution, while, the salty intensity was promoted in both the younger and older groups when exposed to the slightly pungent solution (0.106 g Sichuan pepper oleoresin /L water solutions) compared to the control (spring water). For the younger group, the percentage enhancement of the salty intensity was between 9.3% and 12.5 % (p<0.05), while, at the concentration of 4.05 g/L, the salty-increasing percentage increased by 6.4% in the older group (p<0.05). In addition, the percentage reduction of NaCl reached a level of up to 34.4% in the younger group and was 4.4% in the older group (p<0.05). The Partial Least Squares Regression (PLSR) method was used to further analyze the relationship between the individual physical and psychological factors, and the percentage change in salty intensity. The results indicated that the percentage change in salty intensity increased when the detection threshold of saltiness, the sensation seeking ratings and PROP ratings increased. On the contrary, the change decreased when the age, life satisfaction ratings, detection threshold of pungency and consumption frequency of salty food increased. These findings not only provide new information for the flavor design of salt-reduced food and dishes, but also be valuable to public health as well as economic benefits.
Article
Sixteen laboratories participated in an AOAC–American Spice Trade Association (ASTA) collaborative study of a liquid chromatographic (LC) method for determining capsaicinoids in capsicums and their extractives. Capsicums are extracted with ethanol by refluxing and then filtered. Capsaicinoids in the filtrate are separated by re- versed-phase LC and detected spectrophotometri� cally with external standard quantitation. Participants analyzed 6 ground capsicum and 3 oleoresin products as 12 samples from a mixed scheme of blind duplicates and Youden matched pairs. Average repeatability and reproducibility standard deviations (sr and sR, respectively) and average relative standard deviations (RSDr and RSDR, respectively) for ground red pepper were as follows: sr, 610 Scoville heat units (SHU); sR, 1730 SHU; RSDr, 1.7%; RSDR, 4.9%. For ground chili peppers, the values were sr, 60 SHU; sR, 160 SHU; RSDr, 4.0%; RSDR, 10.6%. For oleoresin red pepper, the averages were sr, 46820 SHU; sR, 54990 SHU; RSDr, 8.5%; RSDR, 11.2%. The LC method has been adopted first action by AOAC INTERNATIONAL.
Article
Quantitation of capsaicinoids in Capsicum oleoresin has been performed by relative techniques as UV spectrophotometry and HPLC. The determinations were done on the oleoresin obtained from a local species, Capsicum chacoense A.T. Hunziker, as well as on oleoresins included in pharmaceutical dosage forms. The techniques employed are accesible to convencional laboratories of pharmaceutical analysis and can be used to the study of oleoresins coming from different species.
Article
Sixteen laboratories participated in an AOAC- American Spice Trade Association (ASTA) collaborative study of a liquid Chromatographic (LC) method for determining capsaicinoids in capsicums and their extractives. Capsicums are extracted with ethanol by refluxing and then filtered. Capsaicinoids in the filtrate are separated by reversed-phase LC and detected spectrophotometrically with external standard quantitation. Participants analyzed 6 ground capsicum and 3 oleoresin products as 12 samples from a mixed scheme of blind duplicates and Youden matched pairs. Average repeatability and reproducibility standard deviations (sr and SR, respectively) and average relative standard deviations (RSDr and RSDR, respectively) for ground red pepper were as follows: sr, 610 Scoville heat units (SHU); SR, 1730 SHU; RSDr, 1.7%; RSDR, 4.9%. For ground chili peppers, the values were sr, 60 SHU; SR, 160 SHU; RSDr, 4.0%; RSDR, 10.6%. For oleoresin red pepper, the averages were sr, 46820 SHU; SR, 54990 SHU; RSDr, 8.5%; RSDR, 11.2%. The LC method has been adopted first action by AOAC INTERNATIONAL.
In order to demonstrate the practicality of two newly developed taste-and-odor methods, raw and filtered water samples from the Songchon water treatment plant, and tap water samples from houses were analyzed from July to October 2000 using three sensory methods (TON, 2-out-of-5 odor test and attribute difference test for the presence or absence of geosmin) and one instrumental method (closed-loop stripping analysis, CLSA, followed by gas chromatography, GC). Comparison of TON values with CLSA indicated a discernible relationship only when the odorant level was relatively high. The two newly developed methods, however, were more sensitive than TON when the odor intensity of samples was low. The attribute rating test for geosmin is more sensitive than the 2-out-of-5 odor test when the TON value is less than 10. These new methods seem better than current methods for identifying the occurrence of odor compounds in raw and filtered waters. They also have practical use in tracking the efficiency of treatment methods, such as adsorption and oxidation, used for controlling taste-and-odor episodes.
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Detection thresholds for NaCl, KCl, sucrose, aspartame, acetic acid, citric acid, caffeine, quinine HCl, monosodium glutamate (MSG) and inosine 5′-monophosphate (IMP) were assessed in 21 young (19–33 years) and 21 elderly (60–75 years) persons by taking the average of six ascending two-alternative forced choice tests. A significant overall effect was found for age, but not for gender. However, an interaction effect of age and gender was found. The older men were less sensitive than the young men and women for acetic acid, sucrose, citric acid, sodium and potassium chloride and IMP. To detect the compound dissolved in water they needed a 1.32 (aspartame) to 5.70 times (IMP) higher concentration than the younger subjects. A significant decline in thresholds with replication was shown. The age effect found could be attributed predominantly to a generic taste loss.