Annual Variation in Proximate Chemical Composition of Fish Sold in Ludhiana Market: Punjab, India

Abstract

A study was carried out to investigate the nutritional composition of four different fish species (Wallago attu, Labeo rohita, Pangasianodon hypophthalmus, and Rastrelliger kanagurta) sourced from the inland and marine sector comprising both culture and capture fisheries marketed in Ludhiana fish market from September 2021 to August 2022, encompassing four distinct seasons: post-monsoon, winter, pre-monsoon, and monsoon. The proximate parameters including protein, lipid, carbohydrate, ash and moisture content were analysed following the standard methods. The moisture content across the four species ranged from 72.48% to 81.08% in selected fish. Lowest moisture content was recorded during the pre-monsoon season, contrasting with their highest levels during the monsoon season. Protein levels ranged from 9.72% to 18.36% across different seasons. Specifically, P. hypophthalmus displayed the lowest protein content (9.72±0.18%), while R. kanagurta exhibited the highest (18.36±0.18). W. attu, L. rohita, P. hypophthalmus, and R. kanagurta exhibited their lowest lipid content in flesh during the monsoon season, measuring at 0.69%, 1.59%, 9.33%, and 2.47%, respectively, contrasting with their highest levels during the winter season at 1.07%, 2.05%, 11.04%, and 4.05%, respectively. Across different seasons, carbohydrate content varied from 0.23% to 2.04%. R. kanagurta exhibited the lowest carbohydrate values; while L. rohita displayed the highest. Across different species, ash content varied from 1.62% to 4.34%, with the lowest observed in P. hypophthalmus and the highest in W. attu. Overall in fish muscle, water content reached its peak levels while muscle protein content decreased during the monsoon. The decline in protein and the rise in water content of the muscle were attributed to gonadal development and maturation, which depleted muscle protein reserves during the monsoon season. Inverse relationship between moisture and fat content in fish were observed, suggesting that fatty fish typically exhibit relatively lower moisture content. Lower levels of carbohydrate content are found in the total proximate composition of fish muscle, indicating that most of the glycogen in freshwater fish does not significantly contribute to body reserves.