Nutritional profile of nigiri sushi meal and the usage of citrate synthase activity as freshness parameter

The aim of the study was to access the influence of nigiri sushi meal ingredients ratio on its weight, nutritional profile, physic-chemical characteristics (crude protein, lipid content, ash content, salt content, phosphorus content and thiobarbituric acid assay) and to estimate the usage of citrate synthase activity as freshness index of seafood used for sushi preparation. Nutrition composition of nigiri sushi is highly influence by rice/seafood ratio. Inclusion of processed seafood in sushi can influence significantly weight and consequently nutritional profile of nigiri sushi meal as well. Shrimp cooking resulted in 16.45±3.29% weight loss in whole non-deveined shrimp and 13.03±3.40% in non-deveined shrimp tail. Nigiri sushi meal prepared with salmon and tuna fish can be recognized as good sources of seafood. Nigiri sushi meal can be considered as a low-calorie meal (nigiri salmon: 716.13±24.18 kJ/100g; nigiri tuna: 638.12±10.64 kJ/100g; nigiri shrimp: 672.06 ± 8.72 kJ/100g) but on the contrary it cannot be considered as low salt content meal (nigiri salmon: 0.97±0.04%; nigiri tuna: 0.89±0.10%; nigiri shrimp: 1.06±0.13%). Citrate synthase activity (CSA) increases after each freezing/thawing cycle and at the end (4th cycle) were 5.29±0.67 μmol/mL/min and 6.67±0.63 μmol/mL/min in tuna and salmon samples, respectively. CSA can be recognized as reliable enzymatic kit indicator for fish freshness determination in nigiri sushi meal.