Microplastic accumulation dynamics and risk assessment in dried fish processed with sea salt at different salting ratios

Global food security, particularly in South Asia and low-income coastal regions like India, relies on seafood consumption, both fresh and dried. Seafood, encompassing small pelagic fish, dried varieties, and salt-cured fish, absorbs xenobiotics like micro/nanoplastics and their associated contaminants during processing. This occurs due to factors such as processing conditions, the status of fish muscle biochemistry, and the additives used, presenting largely unexplored health risks that have received minimal study attention. This study investigates the impact of salting on microplastics (MPs) contamination in cured fish, exploring the intricate relationship between salting, muscle biochemistry, and MPs under controlled conditions. Commercial solar salt used for curing contained an average of 40.72 ± 5.97 MPs/g. Microplastic abundance in cured fish decreased significantly, from 65.7 ± 6 to 3.36 ± 1.5 MPs items/g, with a lower salt-to-fish ratio of 1:10. Characteristics of MPs such as morphotype, size, colour and polymer type in both cured fish and curing salt exhibited similar trends. Protein content and MPs showed a strong negative correlation, while the lipid content correlation with MPs presence was weak. Various MPs indices such as contamination factor, load index and polymer induced risk index emphasized salt's significant role in enhancing contamination in cured fish, posing safety risks to consumers. Given the limited number of studies conducted on comprehending the uptake of microplastics in processed seafood, a critical aspect of food safety, the present study aims to illuminate the intricate interplay between fish biochemistry and microplastic characteristics. Additionally, it explores the role of salt in this dynamic, highlighting implications for both food safety and human health.