Quality Indicators of Northern Shrimp (Pandalus borealis)

Qingzhu3.2 Sensory evaluationA Quality Grading Scheme was used to evaluate the quality of whole shrimp (Table 3).Duplicate samples from each of the four storage conditions were taken at regular intervals(on days 0, 1, 4 and 6 of storage) for each group and placed in two clean transparent glasscontainers, after 20 min the assessment was carried out under room temperature andadequate fluorescent light. The samples were coded with a random three digit number.The panalists were not aware of the number of storage days of the shrimp and did notknow which two containers were the same group prior to assessment. The panelconstituted of eight members who had been trained in evaluating quality of shrimp andthe characteristic sensory attributes.Table 3: Score sheet for quality grading scheme of whole shrimp (IFL 2003).Score / GradingDescription5 Excellent Colour is dark red to bright pink. Roes are blue-green (copper). Strong seaweedy,marine odour. Strong sweet shrimp taste.4 Good Colour is natural light pink. Roes are blue-green (copper). Weak characteristicshrimp odour. Weak sweet shrimp taste.3 Moderate Marine/shrimp odour is diminishing, weak “fishy odour”, even slight ammonia.Colour is natural light pink with grey-greenish or yellowish discoloration.Roes are light green. Taste is natural not sweet to weak “fishy taste”.2 Borderline----Clearly not FreshWeak ammonia odour. Colour is natural light pink with grey-greenish oryellowish discoloration. Roes are discoloured. Blackening on the head canbe spotted. Distinct fishy taste with bitter aftertaste.1 Unfit Spoiled Ammonia odour. Colour is natural light pink with grey-greenish or yellowishdiscoloration. Roes are Dark. The blackening on the head is extensive.Spoiled, taste with strong, bitter aftertaste.3.3 Protein measurementProtein content in shrimp meat was determined by the Kjeldahl method (ISO 1997). Asample of 5.00 g was digested in sulphuric acid in presence of copper as a catalyst.Thereafter, the sample was placed in distillation unit, 2400 Kjeltec Auto Sample System.The acid solution was made alkaline by a sodium hydroxide solution. The ammonia wasdistilled into boric acid and the acid was simultaneously titrated with diluted H 2 SO 4 . Thenitrogen content was multiplied by the factor 6.25 to get the ratio of crude protein.UNU-Fisheries Training Programme 13