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E. C. CROCKER AND L. B. SJOSTROM Arthur D. Little, Inc., Cambridge, Mass.
G. B. TALLMAN Massachusetts Institute of Technology, Cambridge, Mass.
In theory, foods are eaten for the nutrition they provide, but in practice, for the sensory satisfaction. Foods are selected because they look good and taste good ; the measurement of good acceptance therefore consists mostly of t h e appraisal of appearance and flavor. Appearance is objective and is easily measurable by physical instruments. Flavor, however, is subjective, creating impressions in the mind ; its evaluation is made indirectly by human tasters, through the use of so-called organoleptic techniques. The quantitative aspects of flavor appreciation are the subject of this paper. Tasting rna’y be done by professional tasters, singly or in panels. Usually such tasting determines whether the samples a t hand conform to what consumers are known to accept, or if not, why not. Single operators may be cooks who judge foods in process
or tasters who score the finished goods, frequently by comparison with accepted s6andards. The laboratory taste panel is a research tool used for the investigation of flavor defects or for making the observations needed for the improvement of flavor, in type or stabilit!y. Nonprofessional tasting is that done by a sample of the public. Consumer polls are run to find out what people like and probably will buy. T o secure a representative sampling of the public, skilled investigators are required to ensure fair tasting tests and a correct statistical evaluation of the findings. Best results are obtained by agencies that specialize in this work. Another mechanism for determining consumer acceptance is the study of sales, especially of repeat sales in test areas where the customers are exposed t o normal advertising appeal.
T“
such a long period that today it is familiar and is acceptable generally. The taste of chlorinated water, although objectionable, is gradually seeming more and more natural. Familiarity thus breeds acceptance. Regional preferences may be due to similar conditioning, although national advertising and distribution are tending to eliminate them. The South still prefers white cornmeal whereas the North uses yellow; certain areas like coffee roasted more darkly than do others and regions under the influence of New Orleans favor chicory in their coffee. There are age-group preferences also often promoted-as milk drinking or cola drinking among the youth of today. Finally, there is personal idiosyncracy. I n spite of this variability of taste within a n y locality, i t is possible usually to determine what the choice should be for the people of large areas or even of the whole country €rom a relatively small number of representative tasters. The employment of much capital, especially of risk capital, depends on the accuracy of such appraisal of public acceptance.
i acceptability of a, food, provided it is in adequate supply at a reasocable price, depends largely on the impression
that this food makes on the senses, especially those of sight, smell, and taste. Only rarely is a poor looking or poorly flavored item chosen if a more attractive one is available. Most people do not use nutritive value as a n important consideration in arriving a t a choice. Appearance factors such as size, shape, color, transparency, or opacity may be appraised by eye rather satisfactorily. For industrial purposes, many instrumental aids, including color photography, are available for checking these points. The important flavor sensations of smell, taste, and feeling must be determined by human organs without direct physical help. Therefore, a considerable part of the measurement of food acceptance is interpretation of such subjective impressions. A great deal of effort has been expended in the quantitative interpretation of the findings of consumer polls, and many books and articles have been written on the subject. Not so, however, with the work of professicenal tasters, except where their findings may result in government specifications of identity or gradc (3, 4). Each worker tends to operate alone, although the methods he uses may be employed commonly by others. Recently some methods for appraising flavor have been published (2, 7 ) ; and groups of laboratories have pooled their efforts, on occasion, t o solve industry-wide flavor problems. I n this paper various techniques that may be used by tasters are discussed to show how nearly quantitative are their findings and to suggest which techniques may work best in a particular instance. A person’s lilcing for a given food is influenced b y many causes, some of which may never occur to him as operative. For instance, he may learn to like a food by being conditioned to it through long usage until its seems natural. Thus, the flavor of soybean oil, which a t first was thought strange and frequently was disliked, has been met by all of us in so many forms over
TASTING AND
TASTERS
The generic term for the organoleptic testing of foods is tasting, and by this is meant appraisal by mouth. The tongue observes true taste, which comprises sweetness, saltiness, sourness, and bitterness. During chewing or drinking, any aroma present ascends into the nasal chamber vr-here i t is detected by the sense of smell. Feeling also is involved, such as the astringency of a green persimmon, the pleasantly painful bite of pepper or cinnamon, the coolness of peppermint, the warmth of ginger, or partial anesthesia from oil of cloves. Other names given a taster are scorer, grader, sampler, or tester. Particular branches of the food industry often have their own special terms, such as “cupper” for coffee tasters or “sniffer” for water tasters. Many of these tasters are professional operators who become very expert; they learn how t o
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December 1948
INDUSTRIAL AND ENGINEERING CHEMISTRY
cut unproductive corners and to concentrate on critical factors. Other tasters may be untrained people called in for opinionas a sample of what the man in the street thinks-to aid in assessing the taste of the public in general. For this work the services of skilled interrogators are required to obtain useful interpretation. Individual Professional Tasters. A common type of individual taster is the brewer or the cook who is interested in maintaining closely the quality of each batch of product he makes. He usually does not work against a physical standard but depends on his absolute taste, well developed by frequent use. Often he judges the product at an early or incomplete stage and must make allowances for how it should taste by the time the user gets it. From a measurement point of view, this type of tasting is primitive and inaccurate, in spite of its practical utility. Much more exacting is the taster and grader of variable finished products such as tea, coffee, wine, tobacco, butter, or cheese. These scorers or graders who frequently are the selling or purchasing agents of an organization must do their work in such a way that it is acceptable to others in a series of commercial transactions. These tasters resort t o the use of check samples and commonly work against carefully devised standards. They obtain measurements usually for type, for quality, and for strength. Although more complex, this procedure is as definitely measurement as is weighing on a balance. Both operations involve measurement by matching. Under the best of conditions, taste and odor comparisons can be made with a precision of about 12% (1). Occasionally, in the normal comfortable range of concentration, two strengths that differ by only 10% can be observed to be different, but on other occasions a difference of 25% or more may have to exist if one is to be sure that the two strengths are not the same. Some operators have such highly trained senses of odor and taste that they can estimate strength in a single sample, without another for comparison, t o reasonably close values. Flavor strength discrimination in the 12% range compares fairly well with color-depth discrimination of 5%; this is the minimum difference that most normal eyes can detect by comparison, under good conditions, in dyeings in the medium range of intensity. Taste Panels. A taste panel composed of six to a dozen or more individuals can be a most useful laboratory research tool for qualitative investigation or for quantitative appraisal of progress. It is a democratic institution, and its use implies that a group of individuals working together in an imperfectly known field should be able to discover more than can any single individual. Taste panels are in use currently on flavor reversion problems such as that of soybean oil and of shortenings containing it. Panels may be used in several different laboratories simultaneously, on the same type of samples, usually with excellent checking of findings. I n this work, which may have to be done without physical standards for comparison, it is necessary to observe conditions conducive to best tasting such as comfortable well lighted surroundings and freedom from distractions of noise, odor, or of other work competing for attention, It is best if the various workers taste and report independently on each set of samples, but afterward discuss their findings. This tends t o favor discovery of important values and to develop better interpretation of observations among the workers. Testing Coffees by Odor Comparison. In one laboratory studies were made to show the advantage of refrigerator storage (40" F.) over room temperature storage (77' F.) for the shorttime holding of ground coffee before use. The observefs were found to be in good agreement on odor comparisons and rather definite conclusions could be drawn. Previous work had shown that odor alone allowed good differentiation as to coffee freshness ' and no tasting was done. Many series, consisting of two to eight samples a t a time, were judged by comparison for freshness of aroma, first in dry coffee
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Table I. Comparison of Aromas of Stored Coffees of Various Ages (Coffees were graded by eaoh of four observers in the order of decreasing freshness) Order of Freshness Indicated by Age after Roasting and Grinding in No. of Storage Days at Room Tern erature (R) and Refrigerated itorape (C) Freshest to Least Fresh DRYCOFFEE Observers cc 5R 11C 4R 6R 8R 7R 11C 4R 5R 6R 7R SR ws BS 11C 4R 5R 6R 7R 8R CE 11C 4R 5R 6R 8R 7R 11C 4R 5R 6R 7R SR Weighted order of freshness BREWED COFFEE Observers cc 6R 5R 7R 4R 11c SR ws 5R 11c 7R 8R 6R 4R BS 11c aR 6R SR 4R 7R 5R 7R 11c 4R 8R 6R 5R 6R llC 4R ?R 8R bR 6R 7R 4R llC 8R
and then in the brewed beverage. A 12-gram portion of each sample was placed in a porcelain coffee cup. Each of four observers, trained in odor comparison but not especially familiar with the flavor of coffee, worked alone and arranged the samples in the order of decreasing freshness of odor. The cup numbers were not visible to the testers so that each test was made under virtually blindfold conditions. The odor comparison was then repeated after the coffees had been brewed in the cups. The findings of all observers were averaged to give the sequence for the dry, for the brewed, and for the combined average of dry and brewed coffees. There was good agreement in the findings between observers and the sequences of the dry and brewed coffees usually paralleled each other (Table I). T o serve as a check on their findings, several tests were made on the coffees of the series by two professional coffee cuppers in their respective establishments using their customary techniques of smelling and slorping the brewed coffees. The two methods of testing, laboratory sniffing and regular cupping practice, produced essentially identical results. Testing Salad Oils by Odor and Taste. Panel studies made on salad oils illustrate a method for the measurement of quality. In this instance, samples were scored according t o an imagined or internal set of standards; this method has been used extensively by the Northern Regional Research Laboratory (7). Using a scale from 10 for top quality to 0 for the poorest quality, examiners were asked to score oils and, if possible, to characterize them in flavor terms according to the outstanding qualities. The work was done by panel of 14 to 18 members and the final ratings for the oils were derived by averaging the individual scores. Small samples of oil were furnished each panel member in 50ml. beakers covered with watch glasses. The samples were brought t o 45' C . and held a t this temperature during the test by use of an electric heater with shallow wells for the breakers. Each examiner, working alone under good conditions, arranged the samples (usually four) according to the quality of the odor, assigned an odor score to each oil, and listed the outstanding odor notes. Tasting was done after the smelling was completed and samples were tasted usually in the order of increasing odor intensity. The taster took 3 to 10 ml. of the oil into the mouth, allowing it t o reach the back and sides. After it had remained in the mouth long enough to affect the taste and olfactory senses to the subject's satisfaction, from 5 to 30 seconds, the oil was discarded and the mouth rinsed with lukewarm water. A typical set of observations on two oils but made a t the same session are given in Table 11.
INDUSTRIAL AND ENGINEERING CHEMISTRY
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Vol. 40, No. 12
Table 11. Odor a n d Taste Ratings on Salad Oils (Rating of 10 is perfect)
~ _ _ _ ~ Oil ._
_.____
Odor
_ _ _ _ _ ~ - . _ _ _
SA
FC CC T\
12
Rating
Description
9 9
Bland Bland Bland Bland, v. sl. Oily Bland Bland Bland Faintly grassy 81. n u t r y Bland S1. painty, beans
7
8 $4 10
8 7 8 9 4 10
8 8 9
8 8 A\ eraga
8 9
Odorleas SI. oily, flat Haylike 81. sweety, iiuttjMild, t a s t y $1. n u t t v
c-
~.
Rating 7 9
7
8 9
10 8 8
7
Y
4
Taste Description Oily, sl. nutty ' Bland S u t t y , bland Tallowy feel SI. grassy Nuttv
BGZ
Buttery Faintly butters Bland, sl. sharp Buttery, nutty S1. painty Butterv beanv Oily, watery Oily, flat SI. oily beany 61. sour'at first Toast, well done Tallowy, $1. Painty"
8
8 8 9
I
7 4
OBJECTIVE AGAINST SUBJECTIVE EVALUATION Suhstant,ially reproducible results in flavor appraisal can be secured by expert individuals and by carefully trained panels. Their findings are objective and are based on careful comparisons, usually against physical standards. The public, on the other hand, does not judge foods in this manner, but rather by t'he subjective impression t8hatthe foods create because of flavor or other factors. Certain expert individuals (tea and coffee tasters a i d chefs) are able to judge r o u h c l y Tvhat the public will accept. These persons first assure themselves objectively that the important flavor factors are right,, and that the general assemblage of factors is closely the same as for articles which the public habitually accepts. Their scope is usually limitoti, hovxvrr, to the products with which they are concerned. It is generally unsound for export 1 aster;; t o v-orli suljjrc:tivialy~t,hat is, on the basis of t,hcir o;~n over-all pref their very expertness and closi: attention to the problem makey them atypical of the general corisumiiip populatioii. In order t o assure consumer acceptability, the standards IT hich expcrt tasters \vork against, ohjectivrly, must he a fairly accuratc idleetion of what consumers find acceptable. Long experience with and close olxervation of corisumer reactions and prcferences may qualify an expcrt t o spcak accurately of consumer tastes, but, there is alwa.ys the danger that consumers' tastes may change or that the expert's experience never was broad enough or sufficiently penet,rating. Therefore, reference back to the consumer as the final authority on his own likes or dislikes is sound practice. The inadequacies of experts do not stem from lack of sensory acuity on their part but rather from their lack of sufficiently accurat,e and specific lino\vledgtl of consumer backgrounds and reactions. To determine the probable acceptance of a new or improved food article, reactions should be obtained of a representative samplc of potential customers. Consumer-testing is likely t'o be a costly and time-consuming procedure. It is, therefore, to be undertaken only when simpler bases of evaluation seem inadequate. FACTORS OTHER THAN FLAVOR IN CONSUMER ACCEPTANCE Acceptance and use of a product by the consuming public involves a number of factors of which flavor is but one. Ready availability in stores, suitable price, appropriate packaging for appearance and protection, adequate proniotion to thr trade
Odor Description Cod liver oil Like olive oil Tallowy Fishy ~
Rating 3
3
0 2 2 1 3
2 4
a
1
I
1 1 6 3 2 '
1 2.2
Oil B
-
TasteDoacrigtion
_____-.
Rating
7
~
Painty Paint,>, Oily fishy Pain'ty Quite tallow-y Str. oily, rancid Paint?, beany
Painty, fl-tiy Painty Tallowy Tallowy, fi+-, Grassy, painzy Tallowy, paint? Painty, tallou-> Oily, fishy Fishy oily Tallo&y, si. n u t t y Oily, tallowy Rancid, painty
Painty, fishy Paintg, fiiihy Beany Painty Paint> Paints
Painty Painty, t e r i i ~ i i i ' s Fishy Painty S1. aroniatik Paintv. fi-113
0 0 0
2
1.5
and t o consuniers are all important and, in general, call \>e separated completely from flavor in a market evaluation (6, 6 ) . There are other factors which relate so closely to flavor as t o be entwined with i t in any appraisal; these represent risk of confusion and error in interpretation of findings. The appearance of the product may predispose the consumer to arrive at an invalid judgment. For many foods, beverages, etc., consumer3 tend to relate flavor type or strength with the character and intensity of color. The consistency, or apparent consistency, of a product also may introduce psychological implications ~ v i t l i i r i the individual's own background and servo t o prejudice his flavor judgment. The consumer-taster's knowledge or guess as t o thc NOUI'CO or niakrr of t h e product may cause assumpt,ions to he rnade as t o flavor arid quality; these will influence his opiiiioi~. The milthod used in prwenting a product,--the physical setting, thrl questions asked, the personality and attitude of thc~in\-c+gitor-all recall past experiences arid teiid to modif], t h u iwiisumer's interpretation of his immediate flavor experiencis.
METHODS O F CONSUMER TESTING Principles to be followed in conducting a consumer test have been drveloped and the extent of inaccuracy from short-cut met,hods can be estimated. Each consumer should react, only in terms of his own taste experience and not be asked to generalizc as t o the probable reaction of other consumers. Since clach consumer can report properly only for himself, results become projectable to the tota.1market only when everyone in the market is queried or a statistically valid sample of the total marlrct is used. Therefore, the sample must be representative of t h e various types' of consumers for whom the generalization is t o he made. It should be large enough so that results may be repeated in another similarly drawn sample. If the sample is the potential market in miniature, it should provide the same results a,s a census of the total. Requirements of representativeiicss will rule out dependence on people Tho have unusually arutc. tasting senses or those who are leaders in the community. The test should be conducted so that consumers will react naturally. For many p i d u c t s this may require continued uso so that any bias resulting from the novelty of the expericrice or a desire to cooperate is largely replaced by normal consumption reactions. Thus, testers are sometimes given a generous supply of each of tnvo products and the supply is replenished wheii 'necessary. Over a period of t h e , relative preference as ;vel1 a,? rate of consumption become apparent,. Possibly t,he most difficult requirement to meet in consumer testing is that the setting for the test bc as natural as possitile. In normal consumption,
December 1948
INDUSTRIAL A N D E N G I N E E R I N G CHEMISTRY
individual foods or beverages are typically associated with other foods, under circumstances of the consumers’ own choosing. As an extreme illustration: wines are not judged normally on a bare table in broad daylight, but rather, late in the day, in an appropriate setting which might well include candlelight. For consumer tests, samples are submitted usually in pairs for comparison. Presentation of more than two samples at a time may result in confusion. I n most instances, the products for comparison should be presented in uniform containers shorn of all identifying characteristics so that the effect of previous contacts or prejudices is minimized. When possible, the conis, one resumer should be faced with a painful choice-that quiring not merely acceptance or approval but rather loss of one article in order t o gain the other, presumably the preferred one. At times, i t may be desirable to present only a single sample for appraisal, as with a new or unfamiliar product. Most consumers lack the facility of expression to describe their reactions adequately. Therefore it has been found useful to expose the product first to an especially articulate group of consumers and t o include their words in a check list for use with the general group to be interviewed later. If both test products are complex, the consumer may not identify the aspects which are liked or disliked, or the ones most influencing his choice. Then there is need of questioning the testers about each element separately. If they cannot sort out individual elements this fact should be recognized and samples having only one variant should be used. I n food acceptance the reasons for like or dislike may be of importance especially if a n effort is being made to modify the consumer’s taste. These reasons can seldom be learned by a single question but require skillful probing, going well back into the chain of complex experiences which affect the present attitude. It is desirable to have all testing of consumer reaction planned by persons who are fully cognizant of the requirements and difficulties of the work. Special competence is found most often in specialized service organizations which are least likely to be biased by pride or by familiarity with established characteristics of the product. Some concerns have continuing panels of consumers; these have the advantage of providing ready contact with cooperative individuals. I n many instances, however, this involves the dangers of a nonrepresentative, nonsubjective viewpoint. A common method of testing consumer acceptance consists
2257
of placing the article on sale in a test area, such as one or more cities which are judged to be typical. The article is sold in stores under conditions as nearly normal as is possible and occasionally is advertised locally. Acceptance is judged b y the volume of sales and especially of repeat sales and customer comments. This provides an over-all acceptance reaction by the consumer based on many considerations other than flavor. The method is not intendcd for evaluation of particular factors, but is well adapted for the discovery of any marked defects. SUMMARY Measurement of food acceptance is more indirect than direct. Some of the properties of foods, such as color, size, consistency, etc., are capable of direct objective measurement whereas other properties, often most,important in matters of choice, such as the three components of flavor-odor, taste, and feeling-must be evaluated organoleptically. Such evaluation may be made by expert tasters and it can be quantitativc. These expert tasters may be individuals, as tea tasters or chefs, or taste panels composed of scientific workers; each has specific advantages for particular kinds of evaluation. By comparison with standards of known acceptable quality, evaluation may be made to ensure that foods are maintained at high acceptability. Also, taste panels may constitute a research tool for evaluating the flavor of foods being developed or improved. There are times when the expert taster is not the right type of judge, especially when information may be desired of the manner in which the consumer will react toward a new article or t o a change of name, appearance, or flavor. Then, a test must be made of the reactions of the public as such, by way of a truly representative sample of that public. However, many precautions must be taken to secure a sample free from bias or prejudice of any kind. LITERATURE CITED (1) Crocker, E. C., Food Research, 2, 273 (1937).
(2) DOVP, W. F., Quartermaster Corps Manual, QMC 17-9, 7 (1945). (3) Hoplrins, J. W., Can. J . Research. 24,203 (1946). (4) King, F. B., Food Research, 2,207 (1937). (5) Marcuse, Sophie, Food Inds., 19, 316 (1947). (6) Marcuse, Sophie, J . Am. Xtatist. Assoc., 40,214-23 (1945). (7) Moser, H. A., Jaeger, C. M., Cowan, J. C., and Dutton, H. J., J . Am. Oil Chemists’ SOC., 24,291-96 (1947). RECEIVED April 12, 1948.
