Sensory profiling of canned lager beers using consumers in their own homes

FOOD QUALITYAND PREFERENCE2, (1990) 3947

SENSORY PROFILING OF CANNED LAGER BEERS USING CONSUMERS IN THEIR OWN HOMES

Neil Gains* & David M. H. Thomson-t Department of Food Science and Technology, University of Reading, Whiteknights,

PO Box 226, Reading RG6 2AP, UK

(Received 28 March 1990; accepted 14J4ne 1990)

ABSTRACT

An advantage offree-choice profiling for the sensory characterisation offoods and beverages is that it can, in principle, be carried out with inexperienced consumers. The technique will work best if consumers are regular users of the product range to

be investigated, are allowed to familiarise them-

selves with the products, and are allowed to develop and score these products using their own vocabulary

0 Elsevier Science Publishers Ltd

*To whom correspondence should be addressed:

Reading Scientific Services Ltd, The Lord Zuckerman

Research Centre, The University, Whiteknights, PO

Box 234, Reading RG6 2LA, UK.

t Present address: Mathematical Market Research Ltd,

PO Box 58, Wallingford, Oxfordshire OX10 OYD, UK.

of terms in the situations in which they would normally use the products. This implies free-choice profiling in consumers’ own homes. In the study

reported here, 19 consumers profiled a range of 17 canned lager beers in just such a way. The results of this profiling agree well with previous ‘expert’

profiling of similar products and, in addition, yield a vocabulary of consumer relevant descriptors.

Keywords: Beer; consumer; familiarisation; free- choice profiling; generalised Procrustes analysis; individual; sensory characteristics.

INTRODUCTION

Sensory profiling is a modern technique which is used to establish a detailed qualitat-

39

40 NEIL GAINS, DAVID M. H. THOMSON

ive and quantitative specification of the sen-

sory characteristics ofa food or beverage. How-

ever, the general principle of sensory pro-

filing dates back as far as the long established

practices of the expert tasters in the wine,

whisky, tea and coffee industries. Although

these traditional methods are still used very

effectively in their original contexts, they de-

pend entirely on the expertise and aptitude of

a few highly trained individuals and as such

are fundamentally incompatible with the re-

quirements of the modern food and beverage

industries.

The Flavor Profile Method (FPM), devel-

oped at the laboratories of Arthur D. Little

Inc., and first described by Cairncross and Sjo-

Strom (1950), transformed this type of sensory

analysis by offering one of the first practical

alternatives to the use of expert tasters. This

procedure normally involves four to six se-

lected and trained sensory assessors working

in a ‘laboratory ’ environment. Typically, the

assessors derive a consensus vocabulary of

terms to describe some of the more obvious

flavour characteristics and then agree a score

for the magnitude of each character (Powers,

1984).

The next development in profiling tech-

niques came with Quantitative Descriptive

Analysis (QDA), which is broadly similar to

FPM in that a consensus vocabulary is also

derived by a group of selected and trained

sensory assessors (Stone et al., 1974; Stone &

Sidel, 1985). However, QDA differs signifi-

cantly from FPM in that the vocabulary is

usually more extensive and normally em-

braces visual and textural attributes as well as

flavour, and that assessors independently rate

the amount of each attribute in each product.

This process is repeated several times for each

product and, hence, yields data that are

highly amenable to statistical analysis (analysis

of variance and principal component analy-

sis). Since replicate data are obtained it is

also possible to check the reliability of the

assessors. The next milestone in the evolution of pro-

filing methods was the introduction of free-

choice profiling (FCP) by Williams and Lan-

gron (1984). This differs from the previous methods in that untrained assessors may be

used and in that each assessor creates his/her

own vocabulary of terms to describe the sen-

sory characteristics of the products under in-

vestigation. The assessor then rates the

amount of each sensory characteristic in each

product. As typically implemented, FCP is

laboratory-based and involves some degree of

direct supervision and instruction. In some

applications, assessors are even supplied with

a basic lexicon from which they can select

appropriate descriptive terms.

One of the main attractions of FCP is that

it can, at least in principle, be used with in-

experienced consumers. This means that em-

phasis is placed on the attributes which are

most readily apparent to consumers and that

these are described in everyday language. Al-

though the procedures used to interpret these

individual profiles are complex, there is now

abundant evidence to prove the fundamental

efficacy of FCP.

There are several obvious extensions of

FCP which might further improve its re-

levance to the typical product consumption

situation. First of all, the assessors should be

selected from amongst heavy users of that par-

ticular type of product. Secondly, they should

be given the opportunity to familiarise them-

selves with all of the products involved in the

study, in normal situations of use. Thirdly,

they should generate their own vocabulary of

sensory terms, and score these, whilst using

the products in the normal manner. For many

types of product, this would effectively mean

conducting the entire study in the consumer’s

own home.

Guy et al. (1989) successfully carried out

FCP of Scotch whisky using home-based con-

sumers; however the experimenters retained

a large degree of supervision over their asses-

sors. This paper describes the further exten-

sion of this principle to largely unsupervised,

home-based FCP. This would be a very effi-

cient way of collecting profile data, in terms

of both time and cost.

SENSORY PROFILING OF CANNED LAGER BEERS USING CONSUMERS IN THEIR OWN HOMES 41

EXPERIMENTAL PROCEDURE Materials

Samples of 17 brands of canned lager were

chosen from the range available on the UK

market. These are listed in Table 1 according

to the four categories used in the UK retail

market: standard, premium, pils and super-

strength lagers.

Products were presented to consumers as

normally packaged and priced, with clear

brand and other label information.

Sensory assessors

The 15 males and four females involved in

this study, were drawn from amongst the tech-

nical, managerial and student population of

Reading University campus. None of these

had any previous experience of free-choice

TABLE 1. Canned Lagers with Stated Original

Gravities

Type of lager Stated original gravity

Standard lagers

Carling Black Label

Carlsberg

Castlemaine XXXX

Harp Heineken

Ind Coope Long Life Kestrel

Miller Lite

Norseman

Skol

Premium lagers

Grolsch

Kronenbourg 1664 Stella Artois

Pils lagers

Holsten Pils

Super-strength lagers

Carlsberg Special Brew Tennents Super

1034-38

1030-34

1033-37

103&34

1031-35

103-2

1030-34

103&34

1030-34

1031-35

1044-50

104-9

1044-50

1044-50

1078-82

1082-86

profiling, but all were regular consumers of

canned lagers.

Initial vocabulary development

Each assessor was given a can of each of the

17 lagers and asked to taste the products in

his/her own time, in his/her own way, and

in his/her own home (e.g. some assessors

drank straight from the can). The only instruc-

tions given to the consumers were that they

should consider appearance, odour, flavour,

mouthfeel and aftertaste characteristics, and

that they should make written notes of the

sensory characteristics perceived in each lager.

Definition of scales

When each assessor had evaluated all I7

lagers, a list was compiled, by interaction be-

tween individual consumer and experimenter,

of all the terms used by that individual to de-

scribe the range of products. The assessor was

then advised that the amount of each sensory

attribute was to be evaluated in each lager,

and so they were asked to define the mini-

mum and maximum extent of each attribute.

These descriptions were subsequently used as

verbal anchors on the scales of that individual.

Refined vocabulary development

Assessors were given a second set of products,

and asked to sample them again and to refine

their list of terms, where appropriate. In par-

ticular they were requested to eliminate any

redundant and synonymous descriptors, and

also to include any terms omitted in their in-

itial evaluation of the lagers.

Scoring of terms

Each of the terms on each individual’s list was

associated with a 100 mm visual analogue


scale, labelled with verbal anchors as pre-

viously described. Using a third set of canned

lagers, each assessor rated all the products on

each of the scales he/she had refined.

Duration of study

This FCP exercise, integrated within an ex-

tensive consumer study of canned lagers, was

conducted over a period of three months.

DATA ANALYSIS

The data matrices (lagers x attributes) derived

from each of the assessors were input to gener-

alised Procrustes analysis (GPA). GPA was

used to produce a separate product (lager) con-

figuration for each assessor, a consensus con-

figuration of the lagers across all 19 assessors

and to correlate each individual’s set of sen-

sory descriptors with each dimension of this

consensus configuration. This was sub-

sequently interpreted by identifying the con-

structs for each assessor which were most

highly correlated (+ or -) with the di-

mensions of the consensus. Arnold and

Williams (1986) and Gains et al. (1988) have

previously described the principles of GPA.

Principal co-ordinate analysis (Chatfield &

Collins, 1980) on the distances (residual Pro-

crustes distances) between the individual asses-

sors’ product configurations, was used to ob-

tain a two-dimensional assessor plot (Arnold

& Williams, 1986). This was used to identify

possible sub-groups and outliers within the as-

sessor population. The GPA program used in this study is avail-

able as part of the GENSTAT statistical pack-

age (Numerical Algorithms Group Ltd, Ox-

ford, UK).

RESULTS

The number of terms used by the consumers

to describe the sensory characteristics of the

lagers ranged from 14 to 40, although most

assessors used between 20 and 25 descriptors.

Table 2 lists the percentage variance ex-

plained by each of the first 10 principal com-

ponents (dimensions) of the consensus con-

figuration, for each individual and for the

whole data set. A four-dimensional solution,

which accounts for more than 60 % of the

total variation in the data, is presented here.

Although more than four principal com-

ponents (PCs) were examined, interpretation

of subsequent PCs added nothing to the sen-

sory characterisation of the canned lagers as

described below, but merely highlighted

specific differences which were already appa-

rent in higher dimensions.

Figures 1 and 2 show PC1 against PC2, and

PC3 against PC4, of the consensus con-

figuration respectively, along with interpret-

ations of these dimensions. Tables 3-6 show

the sensory descriptors from each assessor

which are most highly correlated with the

four dimensions of the consensus product con-

figuration. Th e interpretations of the di-

mensions shown in Figs 1 and 2 are based on

the experimenters’ interpretation of Tables 3

to 6.

PCl, which accounts for almost 43 % of

the variation in the entire data set, apparently

separates the lagers largely by mouthfeel and

strength of taste. Carlsberg Special Brew and

Tennents Super (both super-strength lagers),

in particular, were perceived as having very

full and rich mouthfeels and strongly alco-

holic tastes. Conversely, the lagers on the

right-hand side of the plot were found to

have a much thinner mouthfeel.

Along PC2, Grolsch, Holsten Pils and

Stella Artois, and to a lesser extent Kronen-

bourg 1664 and Carlsberg (mainly premium lager brands) were perceived as having a


TABLE 2. Percentage Variance Accounted for by Projecting on to First Ten Principal Components of Consensus

Configuration for each Assessor

Principal component

Assessor 1 2 3 4 5 6 7 8 9 10

1 33.2 143 5.4 42 6.1 3.6 3.4 43 3.7 3.4 2 428 12.1 5.9 7.7 2.7 2.1 2.8 27 1.6 46 3 38.9 8.9 4.7 7.4 2.6 5.4 6.2 2.1 45 2.9 4 322 48 8.4 5.1 9.0 6.9 48 1.9 6.3 3.4 5 26.6 14.0 10.9 64 42 65 2.2 3.1 6.7 3.6 6 28.9 17.7 8.2 7.7 9.5 2.3 2.4 2.7 2.7 2.6 7 702 38 3.1 2.4 3.4 2.1 1.1 42 1.8 2.5 8 20.5 4.4 6.1 7.3 7.0 125 62 48 6.0 49 9 51.2 9.6 45 47 26 3.2 4.6 1.7 3.5 2.6

10 32.0 5.7 78 64 10.2 40 63 6.0 6.9 2.3 11 45.6 5.6 8.1 7.2 5.6 6.9 3.3 6.3 1.8 29 12 61.0 2.5 8.0 3.2 1.4 3.0 46 20 1.5 1.7 13 35.1 11.3 3.3 3.2 6.8 3.9 46 6.2 6.0 48 14 22.0 9.9 7.1 5.7 99 5.4 5.2 4.7 4.3 44 15 37.3 4.9 41 65 60 6.0 5.6 40 3.8 3.1 16 27.4 12.4 5.9 8.8 4.1 11.6 5.4 44 45 3.0 17 55.4 3.0 68 28 28 5.0 3.4 3.6 2.2 2.4 18 65.1 46 5.9 47 3.1 2.2 1.5 4.0 1.3 1.1 19 36.6 8.4 11.6 5.1 24 32 6.6 45 3.1 3.5

Consensus 425 7.8 63 5.3 48 45 42 3.9 3.6 3.2

Crolscb. 0 Holsten Fils

Stella Artois ??

??Kronenbourg 16~54OCarlsberg

Rich / full / viscous Heineke Castlemaine XXX: Syr~@y / thick muthfeel Carling Black _abei@ 0 ??_ swet / syrupy flavour PC1 (43%) -Kestrel Strong / alcoholjc flavour Skol.

Ind Coope Long Life0 0 Miller Lite

??Carlsberg Special Brew Hofme~.ZtZ~~orsX,

0 Tennents Super F s

Long aftertaste

Mtallic / SD”P taste

Syrugy muthfeel

FIG. 1. Plot of the canned lagers in the plane defined by the first and second principal components of the derived

consensus configuration.

more bitter and malty flavour (generally posi- long aftertaste. These terms also apply to the

tive qualities) than the other lagers. The asses- lagers at the bottom of the large group on the

sors also reported that these lagers had much right (Hofmeister, Norseman, Harp, etc.), al-

longer head retention than the others. Ten- beit to a lesser extent.

nents Super Lager, in particular, was de- PCs 3 and 4 are best interpreted together. scribed as having a metallic/sour taste and a In the bottom right of Fig. 2, Hofmeister and


TABLE 3. Constructs Most Highly Correlated with the First Principal Component for each Assessor

Assessor Constructs Respective correlations

1 2

3

4 5

6

7

8

9

10

11 12

13

14

15

16

17

18 19

Rich ; fullness

Aromatic smell; viscous Perceived strength ; syrup mouthfeel

Alcohol smell ; perceived strength Bitterness ; astringency

Alcoholic ; malty Aftertaste ; bite

Flavour strength ; strength

Strong Aavour; good body

Strength; coating mouthfeel

Estery flavour ; warming

Raw alcoholic taste; initial impact (taste)

Sweet/syrupy flavour; body

Strong flavour ; thick

Syrupy ; body Aroma (bland-intense) ; body/strength

Sweet/alcoholic odour ; alcoholic flavour

Body; bland taste

Creamy mouthfeel; thin (watery) mouthfeel

-@92 -@95

- 0.90 - 0.90

-0.93 -0993

- 0.93 -0.96

-0.92 -088

-088 -0888 - 0.95 -096

- 0.84 -@91 -0997 -096

-@87 -0.88

- 0.96 - 0.96

-@96 - 0.95

- 0.96 -0.89

-@90 - 0.88

-0.96 -0.96

-082 -088

-0.97 -0994

- 099 098

-089 094

TABLE 4. Constructs Most Highly Correlated with the Second Principal Component for each Assessor


1 Head retention ; persistent aftertaste 0.74 -073

2 Head (little-lots) ; refreshing taste 079 0.79

3 Continental taste; effervescence 090 076

4 Maltiness ; sourness 0.64 @68 5 Astringency; duration of aftertaste 081 0.81

6 Yeasty; duration -070 -0.81

7 Head retention; taste (tinny-smooth) 085 0.61

8 Head ; salty -054 - 0.46

9 Dull flavour ; refreshing - 084 088

10 Yeasty odour; yeasty flavour 059 0.80 11 Sulphury odour; hoppy Aavour @90 -0662

12 Colour (light-dark) ; bitter taste 059 0.49

13 Metallic flavour ; metallic aftertaste - 072 -070

14 Brown ; metallic flavour -0.75 068

15 Cereal ; burnt -@75 0.69

16 Caramel ; hops 083 0.71

17 Bitter flavour ; overall flavour 061 0.59

18 Bitter taste; metallic taste 069 0.82

19 Syrupy mouthfeel ; astringent mouthfeel -0.61 0.60

Stella Artois particularly, but also Ind Coope

Long Life, Kronenbourg 1664, Tennents Super and Norsernan were found to have

bitter aromas and flavours, as opposed to Cas-

tlemaine XXXX, in the top left of Fig. 2, and

also Skol and Carlsberg Special Brew which

were perceived as being sweet. Additionally,

Castlemaine XXXX and Ind Coope Long

Life had longer head retention, and the lagers

at the bottom of Fig. 2 were considered to

have a slightly sour and flat taste.

Figure 3 is a two-dimensional represen-

tation of the differences between the assessors,

these two dimensions accounting for approxi-

mately one-third of the assessor variation.

With the possible exception of assessors 7 and

SENSORY PROFlLINC OF CANNED LAGER BEERS USING CONSUMERS IN THEIR OWN HOMES 45

TABLE 5. Constructs Most Highly Correlated with the Third Principal Component for each Assessor


1

2 3 4 5 6 7 8 9

10 11

12

13 14

15

16

17

18 19

Medicinal aroma ; metallic flavour

Astringent taste; acidic taste

Sweet smell; hop taste

Green smell; green taste

Strength of odour; strength of taste

Head (stable) ; clarity

Colour (pale yellow-golden) ; head retention

Sweetness; salty

Heady ; unsweet

Head; soapy flavour Nutty flavour; bitter beer Aavour

Metallic odour ; metallic flavour

Stale dishcloth odour; estery flavour

Yeast odour; bland flavour

Pungent odour ; bitter

Caramel ; smooth taste

Gassy ; tongue furring Hoppy aroma; bitter taste

Straw colour ; golden colour

0.83 072

077 0.70

-057 078

-061 -0666

- 0.73 -0.74

075 0.69

054 - 0.84

-0553 -0.52

-0667 0.53

075 -0662

0.74 062

- 074 -0.82

-0558 -062 -0.61 0.57 -0.68 059 -0.68 -@61 -060 -0.83

0.63 084

- 0.73 0.72

16, most of the assessors seem to be tightly

clustered. Apart from these two individuals,

there are no consistent and obvious differ- DISCUSSION

ences in the data derived from assessors situ-

ated at opposite extremities of the plot. A poss-

ible explanation for the isolation of assessors

7 and 16 is that they used far fewer terms than

the others.

These findings concur with previous reports

(Brown & Clapperton, 1978 ; Clapperton,

1978; Clapperton & Piggott, 19790; Meil-

Darker colour

Ftzzy / frothy / good head

??Ind Coope Long Life

??Castlemaine XXXX

Carlsberg Special Brew0

??Kronenbourg 1664

??Norseman

PC3 (6%)

Gro,ecm~ ‘:arlsberg + @k eineken

Harp

81 t te?r / happy Golden colour

FIG. 2. Plot of the canned lagers in the plane defined by the third and fourth principal components of the derived consensus contiguratjon.


TABLE 6. Constructs Most Highly Correlated with the Fourth Principal Component for each Assessor


1

2

3 4

5

6

7

8 9

10

11

12

13

14

15

16

17

18 19

Hoppy smell ; liquorice flavour

Sour smell; malty taste

Colour (light-dark) ; several aftertastes

Lager smell; lager Aavour

Sour odour ; head (small-large)

Colour (yellow-brown) ; sharp

Flavour (watery-bitter) ; bite

Time head stays; bitterness

Fizzy ; flat

Astringency ; yeasty aftertaste

Bitter flavour; bitter aftertaste

Flavour strength; bitter taste

Bitter aftertaste; metallic aftertaste

Pale; hop odour

Hops odour; head/frothy

Fizzy ; gassy taste

Metallic odour ; retention of head

Sweet taste; hoppy taste

Floral odour; nutty taste

-065 -0.68

-0.79 O-84

0.74 0.75

- 0.66 -0.69

@70 0.75

067 -0.71

- 0.56 -0.61

0.63 084

085 -0.74

@50 0.54

- 0.74 - 0.75

-061 - 0.60

-0.63 - @54

-@o-58 @54

0.66 0.61

0.77 0.69

-0.45 0.51

062 0.87

0.89 0.54

gaard, 1982), which indicate that the most im-

portant discriminator of different beers and

lagers are mouthfeel terms. Meilgaard (1982)

states that terms associated with the bitter and

fizzy characteristics of lagers are the other pri-

mary discriminators. The results of Clap-

perton and Piggott (1979a) indicate that the

differences between high and low alcohol

lagers are at least as great as those between

ales and lagers. Indeed, in this study, these dif-

ferences account for a substantial proportion

of the variation in this data set.

Clapperton and Piggott (1979b) report

flavour characterisation of four beers by both

trained and untrained assessors. They con-

clude that untrained assessors are just as cap-

able of producing a flavour characterisation of

beers and lagers as trained assessors, and that

the level of training merely improves repro-

ducibility of results and leads to the use of

more and better (i.e. more specific) flavour

terms by assessors. The object of the study reported in this

paper is not to examine the utility of FCP, as

this has already been established by others.

Our specific objective was to test the hypoth-

esis that FCP could be executed by consumers

in their own homes, with minimal super-

vision. The very fact that the study was suc-

FIG. 3. Assessor plot derived by principal co-ordinate

analysis.

cessfully completed by all of the assessors, com-

bined with the fact that most reported no par-

ticular difficulty in conducting the profile, pro-

vides initial support for this hypothesis. How-

ever, this is greatly reinforced by the obser-

vation that the information derived from this

investigation accords well with the findings

from other, more conventional, beer and

lager profiling studies. This study was ex-

ecuted with minimal cost and minimal use of

the experimenters’ time.

It could, of course, be argued that the con-

sumers used in the canned lager study might

have been more intelligent, or more aware

than the ‘average ’ customer. Furthermore, it


is also acknowledged that the selection of lagers used in the study embraced fairly large sensory differences. Clearly, it would have been much more difficult for the consumers to profile the tight group of standard strength lagers included in this study, but this would also prove a considerable challenge to highly trained assessors.

Nevertheless, it is justifiable to conclude that consumers can profile products in their own homes with minimal supervision, yield- ing information that is both meaningful and useful. The key lies in the fact that regular consumers of a product, or product type, have a certain awareness of the sensory characteristics of these products. Provided that these individuals are capable of expressing themselves verbally, even if only by using loose and idiosyncratic terminology, there is no reason why these people should not be used in FCP. Moreover, the sensory attributes to which they specifically attend are more likely to be consumer relevant than those which emerge from a panel of highly trained assessors.

ACKNOWLEDGEMENTS

The authors gratefully acknowledge financial support from the Agricultural and Food Re- search Council, UK, and the Brewers’ Soci- ety, London.

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Documents

Sensory profiling of canned lager beers using consumers in their own homes