Managing a sensory panel for day-today QC activities. Sensory Evaluation of Fish Freshness

Transcription

1 Managing a sensory panel for day-today QC activities Sensory Evaluation of Fish Freshness Emilía Martinsdóttir Matis Skúlagata 4, IS- Reykjavík, Iceland Tel: , emilia@matis.is

2 The content of the lecture Methods for sensory evaluation of fish importance of freshness use of sensory evaluation The QIM-method How to develop a QIM-scheme Reference manual Use in industry Conclusions

3 Why is sensory evaluation of fish important! Sensory evaluation of fish freshness gives valuable information on quality Fish is very perishable, can be kept on ice 8- days depending on species Spoilage is species related - Many different species Freshness and changes in sensory attributes are critical parameters during food production Time and temperature is of main importance Fish is transported all over Fish is sold via e-commerce

4 Sensory evaluation in the fishery chain Fishing vessel Landing FIsh auction Fish processing plant Fresh fillets Frozen fillets Retailers Retailers Consum ers Consumers Sensory evaluation of whole fish Sensory evaluation of raw and cooked fillets Sensory evaluation of cooked fillets

5 Methods for sensory evaluation of fish freshness in the industry EU scheme Grading scheme for whole fish EU scheme is commonly accepted in the EU countries E, A, B / unfit QIM (Quality Index Method) Bremner,985 Demerit points -3 added to give an index Torry scheme for both whole and cooked fish Shewan, 953 scoring system (-)

6 Criteria Not Admitted Freshness category EU-scheme Extra Skin A B B right, iridescentpigment Pigmentation brightbut Pigmentation in the (save for redfish)or process ofbecoming notlustrous opalescent; no D ull pigmentation discoloured and dull discolouration Skin mucus White fish: Haddock, cod saithe, pollock, redfish, whiting, ling, hake, Ray s bream, anglerfish pouting and poor cod, bogue, picarel, conger, gurnard, mullet, plaice, mergrim, sole, dab, lemon,sole, flounder, scabbard fish A queous, transparent S lightly cloudy M ilky Y ellowish, grey, opaque mucus Eyes Gills C onvex (bulging), black, C onvex and slightly Flat, opalescentcornea, C oncave in the centre, brightpupil, transparent sunken; black, dull pupil, opaque pupil grey pupil, milky cornea slighly opalescentcornea cornea B rightcolour, no mucus L ess coloured, B rown /green becoming Y ellowish, milky mucus transparentmucus discoloured, thick, opaque mucus Peritoneum on gutted fish Smell of gills and abdominal cavity >whitefish other than plaice: >plaice: Flesh S mooth, bright, difficult S lighly dull, can be S peckled, comes away D oes notstick to detach from flesh detached from flesh easily from flesh S eaweedy N o smell ofseaweed, Fermented, slightly sour S our neutral smell Fresh oily, peppery O ily, seaweedy or O ily, fermented, stale, earthy smell slightly sweetish slightly rancid S our Firm and elastic, smooth L ess elastic S lightly soft(flaccid), S oft(flaccid), scales surface less elastic, waxy easily detached from (velvery)and dull skin, surface rather surface wrinkled

7 Disadvantages of grading schemes like the EU-scheme Grouping several, different sensory terms into one quality grade Sensory characteristics disagree with other subdescriptions of the quality grade confusion of the grader, increased time decreases the objectivity of the evaluation Not species related

8 QIM-scheme for Sea bass Quality parameter Description Skin Bright, iridescent pigmentation Colour/ appearancerather dull, becoming discoloured (head) Green, yellowish, mainly near the abdomen Odour Fresh seaweedy, neutral Cucumber, metal, hey S our, dish cloth Rotten Texture In rigor Finger mark disappears rapidly Finger leaves mark over 3 seconds Eyes Pupils Clear and black, metal shiny Grey Mat, grey Form Convex Flat S unken Gills Colour Blood red/orange Pale red, pink/light brown Grey-brown, brown, grey Mucus Transparent Milky, clotted Brown, clotted Odour Fresh, seaweed, neutral Metal, grass S our, mouldy,dish cloth Rotten Flesh, fillets Colour Translucent, bluish Waxy, milky Opaque, yellow, brown spots Viscera Solution Whole Beginning to dissolve Viscera dissolved Quality Index Score 3 3 -

9 Advantages of the Quality Index Method (QIM) The relevant attributes are all evaluated and given scores according to their imporance The inspector has to evaluate each attribute Minor differences in judgements in one attribute do not influence the total score Useful to teach inexperienced people Useful to train and harmonise inspectors Linear relationship between Quality Index and storage time in ice

10 QIM scheme is developed for a new each fish species Development of QIM scheme selection of experienced QIM assessors purchasing of super fresh fish controlled storage experiment day-to-day description of the sensory attributes draft scheme validation and linear regression end-of-shelf life practical implementation QI score 4 y =,69x +,5676 R =, Days in ice 5

11 Practical session With max 5 experienced QIM assessors experienced in sensory assessments good vocabulary experienced panel leader day-to-day description five fishes a time (do not re-use them) discussion during observation write down all comments from everyone continue one day after fish is definitely spoiled

12 Draft scheme Select the attributes which changed during the storage time group the descriptions with major changes add scores very fresh, to max 3 at end of changes make a draft QIM scheme

13 Changes in sensory attributes during storage of ocean perch Eyes Gills Cornea: Clear Colour : Blood red Score = Score = Form: concave Score = Eyes Cornea: milky Score = Form: sunken Score = Mucus: Clear Score = Mucus: Discoloured, clotty Score =

14 Validation new storage experiment use the draft QIM scheme individually discuss the scoring after every session adjust the descriptions and scores determine end-of-shelf life simultaneously use sensory evaluation of cooked samples by expert panel Torry scheme Quantitative Descriptive Analyses (QDA)

15 Finalising the QIM scheme Firm texture Describe the assessment of the fish Make professional photographs on relevant attributes use one batch, make photographs every day no commercial pictures calculate reliability of the calibration curve how many fishes per batch prediction of storage time st.dev. Con vex f orm of ey e

16 QIM in Quality and Production Management 3 Plaice Quality Index 5 Salmon 5 5 Remaining shelf- life Remaining shelf-life 5 5 Predicted storage time in ice Estimated shelf life

17 QIM-manual in languages English, Dutch, Danish, French, German, Greek, Icelandic, Italian, Norwegian, Portuguese and Spanish Sensory evaluation of fish The Quality Index Method (QIM) for fish species Guidelines for sensory evaluation of fish Facilities for sensory evaluation Sample preparation of cooked samples and procedure for the sensory evaluation Selection and training of panellists Shelf life of whole fish Using QIM in process- and quality management

18 Conclusions QIM is developed and recommended by fish research institutes Rapid, objective sensory method QIM is used in research Use in fish auctions has increased Interest of the fish sector has increased For further progress and development of QIM Implementation in fish auctions and fish processing plants training of assessors implementation of QIM (at the first point of sale) stimulated if the EU Council regulation (46/996) would incorporate QIM Develop schemes for more fish species!!

19 Conclusions QIM-schemes could be developed for other food quality control same language for buyers and sellers photographs

20 QIM-homepage QIM-EUROFISH QIMCHAIN-project Information on QIM method All QIM-schemes presented New articles on QIM Attribute Appearance Skin Description Bright, iridescent pigmentation Rather dull, becoming discoloured Dull Stiffness In rigor Firm, elastic Soft, Very soft Eyes Cornea Clear Opalescent Milky Form Convex Flat, slightly sunken Sunken, concave Pupil Black Opaque Grey Gills Colour Bright Less coloured, some discoloured Discoloured, brown spots Brown, discoloured Smell Fresh. seaweedy, metallic Neutral, grassy, musty Yeast, bread, beer, sour milk Sulphuric, very sour Mucus Clear Milky Milky, dark, opaque Flesh, fillets Colour Translucent, bluish Waxy, milky Opaque, yellow, brown spots Blood Colour Red Dark red Brown Quality index Score

21 Thank you for your attention! Acknowledgements : Rian Schelvis-Smit and Joop Luten RIVO Grethe Hyldig DIFRES Kolbrún Sveinsdóttir IFL