Study On Enzymatic Hydrolysis Technology Of Tuna By-products

Many kinds of Tuna food was produced every year. However, during processing procedure, a lot of by-products are generated. At present, these by-products have not been developed and used, which bring both environmental pollution and resources wasting. This paper takes tuna by-products as the object of study in order to provide some basic information for further comprehension utilization of tuna and enhance its economic value. The main contents were as follows:1. Through analysis of Tuna by-products it was found that the content of water was about 41.3%, crude protein 42%, fat 2.13% and ash 10.02%.Papain, Alcalase, Protamex and Flavourzyme were chosen to hydrolyze tuna by-products. Results showed that the degree of hydrolysis of tuna hydrolysate were higher by Alcalase and Flavourzyme than that of Papain and Protamex through single-factor tests.2. Hydrolysis time, temperature, initial pH, liquid-solid ratio, and enzyme quantity were selected as the five orthogonal factors. The orthogonal test results by using Alcalase to hydrolyze tuna by-products were as follows: time 42h, temperature 60℃, initial pH8.0, liquid-solid ratio 6:1 and enzyme quantity of 1%. The DH reached to be 29.68% under these conditions. Otherwise, the orthogonal test results by using Flavourzyme were as follows: time 30h, temperature 50℃, initial pH7.0, liquid-solid ratio 12:1, enzyme quantity of 1%. The DH was 31.79% under these conditions.3. Based on the different hydrolyzing manner between Alcalase and Flavourzyme, dual-enzyme hydrolyzing technology was used for hydrolyzing of tuna in order to get a higher DH. A dual quadratic rotary combinative design scheme was used for analysis. A dynamic mathematic model was designed which showed the connection between hydrolysis degree (Y) and hydrolysis time (A), enzyme ratio(B) as well as initial pH(C).Meanwhile response surface methodology was used to further optimize the process parameters to get the optimum conditions. The optimized conditions were as follows: time 37.22h, enzyme ratio 2.68, initial pH7.87. Under these conditions, the theoreticy DH was 41.81%. The actual value of 40.97% was received from three times of experimental repeatment under these optimal conditions, which showed highly similar to the theoretical value, and means that the response surface method could make a good forecast to the degree trend. Through dual-enzyme hydrolysis of tuna by-products, it was found that the hydrolysate was rich in taste amino acids, including aspartate 4.82mg/100ml, glutamic 7.6mg/100ml, glycocoll 11.12 mg/100ml,aminopropionic 18.51 mg/100ml and arginine 4.51mg/100ml.