A Descriptive Method for Sensory Evaluation of Mussels

A Descriptive Method for Sensory Evaluation of Mussels

Lebensm.-Wiss. u.-Technol., 35, 563–567 (2002) A Descriptive Method for Sensory Evaluation of Mussels Nalan Go¨kog˘lu* Akdeniz University, Agricultu...

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Lebensm.-Wiss. u.-Technol., 35, 563–567 (2002)

A Descriptive Method for Sensory Evaluation of Mussels Nalan Go¨kog˘lu*

Akdeniz University, Agricultural Faculty, Food Engineering Department, Antalya (Turkey) (Received July 11, 2001; accepted December 20, 2001)

A sensory analysis panel was trained to evaluate the sensory properties of mussels using descriptive analysis method. For this purpose, freshly harvested mussels were evaluated by experienced panellists. Odour, colour, texture and appearance were assessed. Expressions of the panellists were used to generate sensory terms. Terminology characterising sensory attributes were developed from the panellists’ opinions. A final list of attributes with definitions was chosen by consensus of the panellists and a verbal scale was created. A numerical scale was pointed out on the verbal scale.

r 2002 Elsevier Science Ltd. All rights reserved. Keywords: mussel; sensory analyses; quality

performed using various hedonic scaling, but there is no freshness scoring system specifically for shucked mussels.

Introduction The word quality is widely used and with many meanings. Most often, quality is synonymous with aesthetic appearance and freshness and refers to the degree of spoilage (Huss, 1988). Quality includes characteristics that are external (appearance, feel), internal (taste, aroma, texture) and technical (nutrition, safety) (Bett, 1997). Several quality control methods have been developed. The most appropriate analytical tool for evaluating freshness is sensory analysis. Descriptive analysis is the most demanding of any sensory method. To produce a careful, thorough and complete product description a trained panel is required. Panellists determine the qualitative characteristics of odour, flavour, texture after taste. They establish a carefully defined set of descriptors acceptable and usable by the panellists (Sawyer, 1986). Quality control is important for fishery products because of their sensitivity against deterioration. There is no single set of desired qualities for all the fishery products since quality depends on regional preferences, consumer attitudes and methods of preservation and consumption (Haard, 1992). Sensory analyses of fish and fish products have always been a part of the production process (Hanna, 1992; York and Sereda, 1994). Although mussels are most frequently marketed raw in shell or as cooked, shucked meats, in several studies on the quality of mussels, sensory analyses have been

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E-mail: [email protected]

0023-6438/02/$35.00 r 2002 Elsevier Science Ltd. All rights reserved.

Materials and Methods Samples and preparation The mussels (Mytilus galloprovincialis) used in this study were obtained from the harvest area. The samples were immediately packed in ice, transferred to the laboratory and presented to panellists at arrival. Descriptive analyses Sensory analyses were conducted using ten panellists who had experience on seafood. In sensory evaluations, odour, colour, texture and appearance were assessed. Before presentation to the panel, the mussels were manually shucked and the bysus was pulled out and the samples were presented to the panellist in a glass dish. The samples were stored at 4 1C and evaluated for sensory changes every 12 h until they became unacceptable. Sensory evaluations were repeated every 12 h and the same panellists evaluated the samples in each session. The experiment was divided into two parts. Firstly, the panellists were asked to list the sensory characteristics that they considered to be important in describing the samples. Terminology characterising sensory attributes were developed from panellists’ opinion. In the second part of the experiment, a final list of attributes with definitions was chosen by consensus of the panellists and a verbal scale was created.

doi:10.1006/fstl.2001.0868 All articles available online at http://www.idealibrary.com on

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Table 1

Terms generated by the panellists

Characteristics

Terms

Characteristics

Terms

Odour

Intrinsic fresh odour Loss of intrinsic fresh odour Slight different from fresh Fairly different from fresh Normal Odourless Fruity smell Not good Slight stale Slight bad Off-odour Ammoniac Putrid Unpleasant Strong smell Fairly bad Detestable Very bad Terrible Spoiled smell

Texture

Slight firm Firm Elastic Tight Slight soft Soft Fairly soft Very soft Tender Increase of softness

Colour

Glossy Bright colour Orange Off orange Pale orange Grey discolour Brownish discolour Fairly pale colour Light colour Slight opaque Opaque Fairly opaque Grey Grey–brown Fairly pale colour

Appearance

Bright Glossy Less glossy Moist Less moist Smooth surface Opaque Slight opaque Dull Slight dull Wrinkled

Table 2

Sensory analysis scale for mussel

Sensory characteristics

Slight 1

2

Odour Intrinsic fresh odour Off-odour Putrid Offensive Colour Bright colour Orange Opaque Grey discolour Texture Firm Elastic Tight Soft Appearance Glossy Moist Smooth surface Dull

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3

Moderate 4

5

6

Strong 7

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Intensities of responses were evaluated on the verbal scale using a seven-point category scale labelled ‘slight’ (1), ‘moderate’ (4), and ‘extreme’ (7) (Cardello et al., 1982; Sawyer, 1986). Usage of sensory scale: In order to assess the usefulness of sensory scale, the mussels were sampled, prepared and stored at 4 1C as previously described. Sensory evaluations were performed every 24 h by the panellists consisting of 10 using sensory scale generated in initial sensory test.

Statistical analysis Significant differences between the means of experimental periods of storage time were determined by least significant difference. A significance level of 0.05 was chosen (Sokal and Rohlf, 1987).

Table 3 Description of sensory terms in sensory analysis scale Terms Odour Intrinsic fresh odour Off-odour Putrid Offensive Colour Bright Orange Opaque Grey discolour Texture Firm Elastic Tight Soft

Results and Discussion Totally 56 terms were used by the panellists. The number of descriptive terms varied from 10 to 20 for each of the characteristics and more descriptors were used for odour and colour than texture and appearance. Opposite terms were included in this list to define all the quality characteristics from fresh to spoiled. While some of the panellists used the same terms to define sensory characteristics, some of them used different terms. A final list of 16 scoring criteria was formed selecting the same or similar terms used by the panellists (Table 1). Opposite terms were also included in the final list to determine the freshness of mussel. The seven-point category scale was pointed out on the final list (Table 2). At the beginning of the study, fresh mussel had a typical mussel odour, glossy orange colour, slightly firm, elastic, tight texture and bright, moist appearance. When they became stale they had a detestable odour,

Appearance Glossy Moist Smooth surface Dull

Description Aromatic peculiar to fresh mussel Aromatic associated with revolting odour characteristics Aromatic associated with smelling rotten Aromatic associated with unacceptable odour characteristics Reflection of light by a certain angle Colour associated with orange colour Reflection of light by all angles Colour defect associated with formation of grey colour Expression of hardness measured physically by compression of fingers Relaxation perceived with touching Stretched structure Softness measured physically by compression of fingers Shining of surface Perception of sample as watery Free of uneven place on the surface Loss of brightness

opaque, grey colour, very soft texture and wrinkled, viscous appearance. The mussels held at 4 1C were acceptable up to 96 h. The samples were not safe to consume after 120 h. Sensory scores significantly (Po0.05) changed with time. Moderate intensity was observed between 48 and 72 h for all sensory characteristics. Although the intensities of acceptable characteristics significantly (Po0.05) decreased, unacceptable characteristics significantly (Po0.05) increased during the storage (Figs. 1–4).

Fig. 1 Sensory scores of odour characteristics of mussel stored at 4 1C. Sensory scores are given as mean (n=10). Sensory characteristics are intrinsic fresh odour (&), off-odour (&), putrid ( ) and offensive ( ).

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Fig. 2 Sensory scores of colour characteristics of mussel stored at 4 1C. Sensory scores are given as mean (n=10). Sensory characteristics are bright colour (&), orange (&), opaque ( ) and grey discolour ( ).

Fig. 3 Sensory scores of texture characteristics of mussel stored at 4 1C. Sensory scores are given as mean (n=10). Sensory characteristics are firm (&), elastic (&), tight ( ) and soft ( ).

Fig. 4 Sensory scores of appearance characteristics of mussel stored at 4 1C. Sensory scores are given as mean (n=10). Sensory characteristics are glossy (&), moist (&), smooth surface ( ) and dull ( ).

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Various sensory analysis methods have been used in several studies to evaluate the quality of mussels (Krzynowek and Wiggin, 1979; Ablett et al., 1986). A sensory analysis scale pertaining to mussels in evaluating their sensory quality was not available previously. The results of sensory analysis for mussel stored at 4 1C have shown that the sensory scale generated in this study could be used to evaluate the freshness of mussel meat.

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HAARD, N. F. Control of composition and food quality attributes of cultured fish. Food Research International, 25, 289–307 (1992) HANNA, J. Rapid microbiological methods and fresh fish quality assessment. In: HALL, G. M. (Ed.), Fish Processing Technology. London and New York: Blackie Academic & Professional and VCH Publishers, Inc., pp. 275–300 (1992) HUSS, H. H. Fresh fish quality and quality changes. A training manual prepared for the FAO/DANIDA training programme on fish technology and quality control. FAO Fisheries Series, 29, 61–103 (1988) KRZYNOWEK, J. AND Wy´GGY´N, K. Seasonal variation and frozen storage stability of blue mussel (Mytilus edulis). Journal of Food Science, 44, 1644–1645 (1979) SAWYER, F. M. Sensory methodology for estimating quality attributes of seafoods. Proceedings of an International Symposium, Sea Grant College Program, Anchorage, AK, U.S.A., 10–14 November (1986) SOKAL, R. R. AND ROHLF, F. J. Introduction to Biostatistics, 2nd Edn. New York: W. H. Freeman and Company, 363pp. (1987) YORK, R. K. AND SEREDA, L. M. Sensory assessment of quality in fish and seafoods. In: SHAHADI, F. AND BOTTA, J. R. (Eds), Seafoods; Chemistry, Processing, Technology and Quality. London: Blackie Academic & Professional and Chapman & Hall, pp. 233–257 (1994)

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