Title: Adjustment of freshness grading scheme to commercially important shrimp species in Nigeria.

This study aimed to improve the quality and freshness grading of commercially important shrimp species in Nigeria. This was done by developing preliminary Quality Index Method (QIM) schemes for thawed brown (Parapenaeopsis atlantica), white (Peneaus notialis), and tiger (Penaeus monodon) shrimp species. To facilitate the implementation of quality and freshness grading practices, a shelf-life study on thawed fjord shrimp was conducted, and protocols for training assessors within the quality assurance unit of the Federal Department of Fisheries and Aquaculture were established. Thawed brown, white, and tiger shrimp species were stored on ice and photographed on storage days 0, 2, 4, 7, and 9. Changes in specific visual sensory attributes were also observed. The observed changes were used to draft a preliminary QIM scheme for each of the specie. A QIM scheme for thawed fjord shrimp was developed, and sensory, microbial, and chemical analyses were carried out on thawed fjord shrimp stored on ice for 0, 1,3, 5, 6, and 8 days after thawing to determine its shelf life. The Quality index (QI) increased linearly with storage time (R²=0.9487). Microbial tests showed an increase in TVC and H₂S spoilage-producing bacteria as storage progressed, but the measurement of TVB-N did not show a linear correlation with storage in ice. Based on the results of the sensory and microbial tests, shrimp became unfit for human consumption on storage day 5. Based on the knowledge and experience gained, protocols for the implementation of quality and freshness grading practices and guidelines for training fishery assessors in Nigeria were established. Preliminary QIM schemes need to be finalized and implemented in Nigeria, as this would help strengthen the quality assurance of fish inspection services and improve shrimp quality management nationally.