Method validation for protein quantitation of fish muscle tissues from Lake Taal, Batangas

Abstract

Lake Taal is one of the largest producers of inland fish in the Philippines and has one of the largest freshwater wet markets in Luzon. These unregulated wet markets sell fishes in unreasonable prices and thereby, exploit the knowledge of consumers on the validity of the prices. This study was designed to quantify the proteins in fish muscle tissues and to validate the effectivity of the various protein quantitation methods. Twelve different species of fish samples were freshly collected from Lake Taal. Muscle tissues were removed and lyophilized before subjecting to comparative protein quantitation methods using direct photometry, ovalbumin assay, and Bradford’s assay. These techniques were selected due to their accessibility and the use of photometry for quantitation. The results show that the means were significantly different for all the methods according to ANOVA. These results were confirmed with post-hoc Tukey HSD test, Scheffe test, and Bonferroni and Holm multiple comparison (BHMC) tests with p < 0.01. Bradford’s Assay was the ideal method with an RSD of less than 1% for all the samples, with no negative concentrations, and with concentration ranging from fifteen to twenty percent. P. leopardus had the highest amount of proteins, followed by M. cephalus, L. plumbeus, C. chanos, H. quoyi, and A. semipunctata. Interestingly, the study revealed that O. niloticus, which is one of the species with a high market price had the lowest protein concentration. With these results, the lowly commercialized fishes such as M. cephalus, L. plumbeus, H. quoyi, and A. semipunctata which are used as gamefish, fish bait, and aquarium displays should be commercialized more than the unstable populations of P. leopardus and C. chanos. Overall, this study revealed comparative information on protein quantitation methods, and market price-nutritional values correspondence.