Effects of Frying, Freezing, Boiling, and Thawing Processes on Proximate, PH and Energy Values of Fresh (Oncorhynchus mykiss)

Objective/Background: Oncorhynchus mykiss is the most popular type of freshwater fish consumed by Iranians. It has delicious taste and high nutritional value. The purpose of processing and preserving fish is to get it to the end consumer in a good, usable condition. Methods: This study is a descriptive study that compares and determines the analysis results of proximate, protein, and fat between fresh and processed fish using the standard method of AOAC and compares the analysis of this study with that of other studies. The effect of the processing methods’ nutritional composition is determined. In addition to fresh fish, 5 treatments are used for the 5 different methods of fish processing. Results: The fresh fish and the different processed samples were analyzed by standard AOAC methods, and their pH was measured. After analyzing the macronutrient compounds of different samples, the energy values were then calculated in kcal. The moisture content ranged from 72.50% for fresh fish to 19.50% for frozen fish, while the fat content ranged from 8.09% for fresh fish to 64.47% for frozen fish. The ash contents were found to range from 4.82% to 5.82%, while the protein contents were found to range from 10.47% to 13.59%. The results showed that quick freezing of fish preserved nutrients with a high percentage of energy. This sample was recommended for consumption, followed by samples thawed in oven and in hot water. The fried and boiled samples were in the next stages of quality and energy values. Conclusions: Because the fat content of this type of fresh fish is high, and if fish feed and its nutrition are protein materials with high biological value, it will be useful to increase the percentage of meat protein for it to grow.