THE PSYCHOPHYSICAL RELATIONSHIP BETWEEN COLOR AND SALT CONCENTRATIONS IN CHICKEN FLAVORED BROTHS

THE PSYCHOPHYSICAL RELATIONSHIP BETWEEN

IN CHICKEN FLAVORED BROTfIs COLOR AND SALT CONCENTRATIONS

SANDRA R. GIFFORD and FERGUS M. CLYDESDALE'

Department of Food Science and Nutrition Massachusetts Agricultural Experiment Station

University of Massachusetts Amherst, Massachusetts 01003

and

RICHARD A. DAMON, JR.

Department of Veterinary and Animal Science University of Mawachusetts

Amherst, Massachusetts 01003

Accepted for Publication July 28, 1987

ABSTRACT

Taste panelists evaluated the effect of color on salt perception in chicken flavored samples using magnitude estimation. Samples were colored to simulate commercial chicken broth. Five color intensities were added to 5 NaCl concentrations ranging from 0.34 to 0.66% (wh). Color had no influence on salt perception. Panelists were able to perceive color differences among samples (P < 0.001) and these were correlated with the objective color function cot-' (a/b) calculated from the L,a,b values obtained from the Gurdner XL-23. Overall flavor preference was evaluated by a taste panel using the technique of magnitude estimation. NaCl concentrations ranged from 0.52 to 0.80% (wh). Overall flavor preference was urnfleeted by color. A reduction in NaCl concentration from 0.80% (wh) to 0.52% (a 35% reduction) did not alter flavor preference. A 50 member consumer panel using a paired comparison test found no difference in flavor preference between an uncolored sample containing 0.80% (wh) NaCl and a colored sample containing 0.72 % (w/v) NaCl.

INTRODUCTION

The acceptance or rejection of a food product is based on many factors in- cluding visual assessment and flavor. In fact, both color and flavor are used as 'Address reprint requests to F.M. Clydesdale.

Journal of Sensory Studies 2(1987) 137-147. All Rights Reserved. @Copyright 1987by Food & Nutrition Press, Inc., Westport, Connecticut. 137

138 S.R. GIFFORD, F.M. CLYDESDALE AND R.A. DAMON, JR.

cues for identification of food products. A change in the color of a food can af- fect the perception of other characteristics of the food (O’Mahony 1984; Clydesdale 1984; Christensen 1983; Pangborn 1960). Foods that have their ”natural ” or ”normal ” color masked or altered often have reduced flavor intensity (Pangborn 1960; Christensen 1983) and in some cases dramatic decreases in flavor indentification are noted (Dubose et al. 1980; Urbanyi 1982) when compared to the appropriately colored foods.

Certain colors evoke a strong response depending on the taste (sour, bitter, sweet, salty) and or flavoring being examined (Pangborn 1960; 1963; Maga 1974; Kostyla 1978; Johnson et al. 1982, 1983). Maga (1974) found that a higher concentration of sour stimulus was required to elicit a response in green and yellow solutions, than in a red solution. Previously reported data (Gifford and Clydesdale 1986) indicated that color had no significant effect on perceived saltiness in unflavored aqueous systems. Few associations appear to exist with saltiness perhaps due to the large variety of colors associated with salty foods (Maga 1974).

Flavor significantly influenced overall liking of a soft drink product whereas color had little significance (Tuorilla-Ollikainen et al. 1984). Flavor preference of the samples is an important consideration. Gillette (1985) identified five flavor enhancing effects of NaC1; mouthfeel, sweetness, metallic/chemical off notes, balance and saltiness.

Reduction of salt in the formulation of a processed food while still maintaining an acceptable product may offer protection to the segment of the population con- sidered at risk of developing hypertension. Little and Brinner (1985) found it possible to reduce the salt content of tomato juice by 50% through the substitu- tion of citric acid for NaCl without altering the palatability or apparent saltiness.

The present research was undertaken to evaluate the psychophysical interaction between color and NaCl perception in chicken flavored solutions and to ex- amine overall flavor preference of chicken flavored solutions at various NaCl concentrations. Such interactions are critical to document if a decrease in salt with minimal change in acceptability is a goal in product formulation.

MATERIALS AND METHODS

Eighteen untrained students and employees (13 females, 5 males; 22-32 years of age) in the Department of Food Science and Nutrition at the University of Massachusetts volunteered to participate in the taste panel test. All individuals were screened for normal color vision using the Ishihara test for color blindness (Ishihara 1977). Correct identification of all eleven test plates was required for acceptance on the panel. A 30 min training session was provided to familiarize the panelists with the concept of magnitude estimation using a series of lines and

COLOR FLAVOR INTERACTIONS 139

shapes (Moskowitz 1977). A ranking test was used to determine that the panelists were able to discriminate among various NaCl concentrations (Steel and Torrie 1980). For experiment one, 10 of the 18 panelists tasted twice a day, once in the morning and again in the afternoon, so that two observations per sample per panelist per day were obtained. Nine panelists participated in experiment two.

All samples were formulated using freshly made, double distilled deionized water (DDW), prepared using a Coming still (model AG-3,220 volt, 2300 watt) and Bantom Demineralizer (model BO-5 Barnstead Still and Sterilizer Cop ; Boston, MA). The designated colors were added to the DDW at the beginning of each individual experiment. Twenty-two hours prior to the taste panel session the appropriate amount of NaCl was added to each colored solution which was stored in covered glass flasks. Two hours prior to tasting 0.15 g/100 mL chicken flavored powder was added to each colored solution. One hour before tasting half of each sample was poured into stainless steel soup containers, covered and placed in a waterbath (Will Scientific Inc. No. 0266) set at 60 "C. The remaining solutions were used in the afternoon session. Odorless white china soup bowls which had been coded with a 3 digit random number were heated in a standard household oven (105 "C) for 15 min prior to serving. A 50 mL sample was placed in each bowl approximately 5 min before the start of the taste panel session and covered with a watch glass to provide a sampling temperature of 50 "C. The reference was placed on the left side of the tray and the remaining samples were randomized for each panelist. The samples were served in individual, controlled atmosphere booths illuminated by 100 W incandescent bulbs.

Triangle Tests

Preliminary triangle tests were conducted to determine if food colors con- tributed taste and or flavor to the DDW. The highest and lowest concentrations of colorants used in the magnitude estimation tests were evaluated against DDW. The colors of the solutions were masked by serving them in red-colored glasses under red lights. Results from this study concurred with those of Kostyla (1978) and Johnson and Clydesdale (1982) who found that the food colors had no significant effect on the taste of the samples.

Sample Formulation

Experiment 1 Magnitude Estimation of Perceived Saltiness and Color. Ex- periment 1 was conducted to determine if perceived saltiness was influenced by a change in color intensity of chicken flavored samples. Five samples were colored to simulate commercial chicken broth. Increasing concentrations of 0.05 % FD&C Red 40 (Warner-Jenkinson Co. No. 7700, St. Louis, MO) 0.05, 0.10,

140 S.R. GIFFORD, F.M. CLYDl3DALEANDR.A. DAMON, JR.

0.20, 0.40, and 0.60% were added to the following concentrations of 0.10% FD&C Yellow 5 (Warner-Jenkinson Co. No. 8805) 0.50, 0.50, 0.75, 0.75, 0.50%. The reference sample was anchored in the middle of the series, in terms of both color intensity and NaCl concentration, so that responses could be evaluated in both lighter and darker and more salty and less salty samples. Com- mercially available uniodized table salt was used in all experiments. The five NaCl concentrations were 0.34, 0.42, 0.50, 0.58, 0.66% (w/v). An unsalted chicken flavored powder (containing no added flavor enhancers) was obtained courtesy of Warner Jenkinson Flavors Inc. St. Louis, MO. A constant amount (O.l5g/loOmL) of chicken flavoring was added to each sample daily.

The NaCl concentrations and colors were combined at random over a six day period. Each color was combined with each NaCl concentration for a total of 25 samples. During each session a panelist would taste 6 samples: the reference, a blind duplicate of the reference, and 4 colored NaCl samples. The references was the same for each of the 6 days of the experiment.

A subjective evaluation of perceived color using magnitude estimation was conducted on the first day of experiment one prior to the taste evaluation. The panelists evaluated the color of each sample against the reference and assigned a number to the sample to reflect the ratio of color intensity. A number greater than the reference indicated a more intense color, a number less than the reference indicated a less intense color.

Tristimulus values (L, a and b) were measured directly using the transmission mode of the Gardner XL-23 colorimeter (Gardner Laboratory Inc., Bethesda, MD). The objective parameter cot-' (ah) was calculated and evaluated as a measure of perceived color intensity.

Experiment 2 Magnitude Estimation of Overall Flavor Preference. Ex- periment 2 was conducted to evaluate flavor preference rather than saltiness since the overall effects of color on flavor in salty solutions are important considerations. Five samples were prepared containing DDW along or in combination with increasing amounts of 0.05% FD&C Red 40 (0.00, 0.05, 0.20, 0.40, 0.60%) and varying amounts of 0.10% FD&C Yellow 5 (0.00, 0.50, 0.75, 0.75, 0.50%). The first sample had no colorants added. The reference was anchored in the middle of the colors and contained 0.80% (w/v) NaCl. On Day 1 all samples contained 0.80% (w/v) NaCl. On Day 2 and for the duration of the experiment the uncolored samples remained at a constant salt level of 0.80% (w/v). The NaCl concentration of the remaining colored samples was decreased by 10.0% daily in order to evaluate the effect of color on flavor perception at various concentrations of salt. NaCl concentrations for Day 2 through Day 5 were as follows: 0.72, 0.65, 0.58, 0.52% (w/v). Each sample contained 0.15g/100 mL of the chicken flavored powder.


Experiment 3 Paired Comparison Evaluation of Overall Flavor Prefer- ence. Experiment 3 was conducted to determine the overall flavor preference of 50 individuals using a paired comparison test. An uncolored sample of DDW containing 0.80% (w/v) NaCl was compared to a colored (0.20% of 0.05% FD&C Red 40 and 0.75% of 0.10% FD&C Yellow 5) sample containing 0.72% (w/v) NaCl. Each sample contained 0.15g/lOOmL of the chicken flavored powder.

Magnitude Estimation

The no-modulus approach of magnitude estimation was utilized. Panelists were instructed to taste the reference sample first, using the sip and spit method, and assign it any positive number. Each sample was tasted and assigned a number proportional to saltiness. If the sample tasted 3 times as salty as the reference, a value 3 times greater than the reference was assigned. The panelists were allowed to retaste the reference if desired but the retasting of the samples after a value was assigned was not permitted. The procedure for normalizing magnitude estimates was conducted for the 5 colors at each individual salt concentration as follows: (1) Calculation of the prenormalized geometric mean from all the magnitude estimates ascribed to the same salt level in each of the five colors. (2) Calculation of the prenormalized grand geometric mean from the prenormalized means calculated in (1). (3) Multiplication of each panelist’s magnitude estimate by the ratio grand geometric mean: sample geometric mean. (4) Calculation of the geometric mean of the values obtained in (3). ( 5 ) Conver- sion of the normalized mean score to logarithmetic values. The magnitude estimates were normalized by a computer program developed by Kostyla (1978), utilizing a modification of the method of Cardello (1977).

Statistical Analysis

The normalized grand geometric means of the magnitude estimates of saltiness for the five samples in each experiment were calculated from the geometric average of 20 normalized magnitude estimates (i.e. two observations per sample per series per panelists) for experiment 1 and 18 for experiment 2. The slope, Y intercepts and coefficients of determination were calculated. The biomedical computer programs BMDPlR, BMDPlV, BMDPSV, were used to perform linear regression analysis, covariance analysis and a two way analysis of variance respectively on the data. Analysis for the results of the paired comparison tests for the consumers study were made from tables published by Roessler et al. (1956).

142 S.R. C-IFFORD, F.M. CLYDESDALE AND R.A. DAMON, JR.

RESULTS AND DISCUSSION

Experiment 1 Magnitude Estimation of Perceived Saltiness and Color. Prior to tasting the broth samples, the panelists were asked to evaluate the color intensity of the samples to see if color differences could be perceived. A highly significant color difference (P < 0.001) was noted among the 5 colors used in the experiment.

Panelists were able to perceive a significant difference (P < 0.01) among the various NaCl concentrations used. The psychophysical relationship between saltiness and NaCl concentration as influenced by broth color are shown in Table 1 and Fig. 1 and support Stevens Power law. The intercepts were similar for all treatments and ranged from 1.72-1.85. No significant differences were found in the slopes (n) by analysis of covariance although the absolute value of n ranged from 1.12-1.59. These values approximate the documented literature values (Meiselman 1971; Moskowitz 1977, 1983; O’Mahony 1984). The exponential values were lower in this study than the colored salted unflavored samples found in a previous investigation (Gifford and Clydesdale 1986). It may be that the added flavoring affected saltiness perception. The coefficients of determination from the regression analysis of perceived saltiness versus NaCl concentration varied among the treatments and ranged from 0.91 to 0.99.

TABLE 1. REGRESSION ANALYSIS OF PERCEIVED SALTINESS VERSUS

NaCl CONCENTRATION IN EXPERIMENT la

P h y s i c a l Y I n t e r c e p t Slope C o e f f i c i e n t of Parameterb ( l o g ) n de t e rmina t ion

( l o g ) r 2

Color 1 1.79 1.42 0.91 Color 2 1.72 1.24 0.98 Color 3 1.73 1.18 0.99 Color 4 1.72 1.12 0.92 Color 5 1.85 1.59 0.97

aNaCl Concentrations: 0.34%. 0.42%. 0.50%, 0.58%, 0.66%. bColor 1 = 0.05% Red 40, 0.50% Yellow 5; Color 2 = 0.10% Red 40, 0.50% Yellow 5 ;

Color 3 = 0.20% Red40,0.75% Yellow 5; Color 4 = 0.40% Red 40,0.75% Yellow 5 ; Color 5 = 0.60% Red 40, 0.50% Yellow 5.

Although a statistically significant influence of color on salt perception was not found, it is apparent from the different slopes in Table 1 and Fig. 1 and from the mean values in Table 2 that color seemed to have some effect on salt perception.


c1 - c 2 x ..............

1.70 1 v) v) W Z

I- d

v)

(3 0

- a

c 3 ....... c4 *----- c 5 0 ................

c 3 ....... c4 *----- c 5 0 ................ -

1.70-

1.50-

1.30-

0.90-

1 I I I I I 1 I

-0.50 -0.40 -0 .30 -0.20

LOG % N a C l

FIG. 1. PERCEIVED SALTINESS (LOG SALTINESS) OF FIVE SAMPLES COLORED TO SIMULATE COMMERCIAL CHICKEN BROTH

VERSUS NaCl CONCENTRATION (LOG % NaCl) OF 0.34-0.6696 NaCl Each point is based on the log geometric mean of 20 normalized magnitude estimates (10 panelists, 2 replicates) per sample. Color levels contained increasing amounts of 0.05% FD&C Red 40 and

varying amounts of 0.10% FD&C Yellow 5 : C1 = 0.05%, 0.50%; C2 = 0.1076, 0.50%; C3 = 0.20%, 0.75%; C4 = 0.4096, 0.75%; C5 = 0.60%, 0.50%.

Experiment 2 Magnitude Estimation of Overall Flavor Preference. The normalized grand geometric means of the magnitude estimates of overall flavor preference were subjected to an analysis of variance as shown in Table 3. A 35.0% reduction in NaCl from the reference (seen on Day 5 ) produced no difference in flavor preference, indicating that the amount of NaCl used can be dramatically reduced reduced without altering the flavor preference.


TABLE 2. MEANSa AND STANDARD ERRORS FOR PERCEIVED SALTINESS IN COLORED,

FLAVORED SAMPLES CONTAINING 0.34-0.6696 NaCl ~~~ ~

NaCl Concentration Colorsb SEMC

% 1 2 3 4 5

0.34 11.51 13.15 14.46 16.22 11.75 0.041 0.42 19.46 19.08 19.20 17.67 18.20 0.045 0.50 27.14 22.85 24.27 24.45 25.56 0.017 0.58 28.00 26.85 29.67 32.49 32.00 0.020 0.66 31.48 31.93 31.91 31.27 33.65 0.029

aValues are the geometric means of 20 observations, 2 replicates for each of 10 panelists. bColor 1 = 0.05% Red 40, 0.50% Yellow 5 Color 2 = 0.10% Red 40, 0.50% Yellow 5 Color 3 = 0.20% Red 40, 0.75% Yellow 5 Color 4 = 0.40% Red 40, 0.75% Yellow 5 Color 5 = 0.60% Red 40, 0.50% Yellow 5

‘Standard errors of the mean expressed as log 10 value.

TABLE 3. MEANSa AND STANDARD ERRORS FOR OVERALL FLAVOR

PREFERENCE IN COLORED, FLAVORED SAMPLES CONTAINING 0.54480% NaCl

Y Colorsb SEMC

1 2 3 4 5

ld 16.60 13.75 17.48 17.02 16.16 0.032 2e 20.14 19.65 17.12 18.32 16.17 0.041

4g 16.76 13.26 12.78 12.15 11.46 0.047 5h 20.48 13.12 12.56 11.78 11.19 0.053

3f 15.04 13.30 12.07 12.92 10.97 0.022

aValues are the geometric means of 18 observations, 2 replicates for each of 9 panelists. bColor 1 = 0.00% Red 40, 0.00% Yellow 5; Color 2 = 0.05% Red 40, 0.50% Yellow 5; Color 3 = 0.20% Red 40, 0.75% Yellow 5; Color 4 = 0.40% Red 40, 0.75% Yellow 5; Color 5 = 0.60% Red 40, 0.50% Yellow 5 .

‘Standard error of the means expressed as log 10 value. dNaCl conc Color 1 = 0.80% Colors 2,3,4,5 = 0.80%. eNaCl conc Color 1 = 0.80% Colors 2,3,4,5 = 0.72%. ‘NaCl conc Color 1 = 0.80% Colors 2,3,4,5 = 0.65%. BNaCl conc Color 1 = 0.80% Colors 2,3,4,5 = 0.58%. hNaCl conc Color 1 = 0.80% Colors 2,3,4,5 = 0.52%.


Experiment 3 Paired Comparison Evaluation of Overall Flavor Preference. Results of the paired comparison test for overall flavor preference indicated that 24 individuals preferred the uncolored sample whereas 25 individuals preferred the colored sample. One person indicated no flavor preference. It may be that color was not a factor in overall flavor preference within the design of this study. Further preference studies employing samples with and without color added to the same salt concentrations would allow for more definitive results.

CONCLUSION

Panelists were able to perceive color differences and differences in NaCl concentrations among the samples (P < 0.001). The objective color function cot-' a h was found to correlate with the color evaluation by the panelists.

A linear relationship was found with the power function describing the effect of NaCl concentration on saltiness.

Because no statistical differences were found between perceived saltiness and color at different NaCl levels in the chicken flavored samples, an evaluation of overall flavor preference was undertaken to determine which combination of color and NaCl concentration might be most preferred in the chicken flavored samples in this investigation.

A reduction in NaCl of 35.0% from a reference concentration of 0.80% (w/v) to 0.52% (w/v) produced no significant differences in overall flavor preference of the chicken flavored samples. This finding has some implications in formulation considerations of lowered salt bouillons.

Color had no influence on flavor preference in chicken broth samples as indicated by statistical analysis. However, trends seen in this study imply that some interelationship between color, saltiness and flavor may exist.

ACKNOWLEDGMENT

Paper No. 2848 Massachusetts Agricultural Experiment Station, University of Massachusetts at Amherst. This research was supported (in part) from Ex- perimental Station Project NE116. The technical assistance of Trina Hosmer is appreciated. The cooperation of the taste panel is gratefully acknowledged.


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THE PSYCHOPHYSICAL RELATIONSHIP BETWEEN COLOR AND SALT CONCENTRATIONS IN CHICKEN FLAVORED BROTHS