MODELING THE HYDROLYSIS PARAMETERS OF HALF-CRENATED ARK USING RESPONSE SURFACE METHODOLOGY

PMASNI

Abstract

Studies on the processing of the bivalve mollusc Anadara kagoshimensis (half-crenated ark), inhabiting the Azov and Black Sea Fishery Basin, are of immediate relevance due to its biomass reaching volumes sufficient for its commercial exploitation. This necessitated research aimed at identification of the parameters for enzymatic hydrolysis of half-crenated ark using Response Surface Methodology; the molluscs subjected to hydrolysis are ground with their shells, which ensures their rational processing without preliminary dressing. A regression equation has been derived to descibe the accumulation of formol-titratable nitrogen (the response function) in the hydrolysate depending on the process duration, the dosage of alcalase enzyme, and a hydromodulus. The optimal hydrolysis regime for a three-factor experiment has been identified: duration of 449 minutes, alcalase enzyme dosage of 1.7 % relative to the weight of half-crenated ark soft tissues with perivisceral fluid, and a hydromodulus of 3 %. A two-factor experiment was conducted to determine the feasibility of adding 3 % of water, and its results indicate that a hydromodulus does not exert a significant effect on the hydrolysis outcome due to the presense of molluscan perivisceral fluid in the pulp subjected to hydrolysis. Thus, the optimal hydrolysis regime without a hydromodulus involves the process duration of 141 minutes and the alacalase enzyme dosage of 1.7 %, which ensures the accumulation of 479 mg% of formol-titratable nitrogen and the hydrolysis degree of 46.1 %. Considering the high energy demand associated with the 7-hour-long hydrolysis process, the analysis of experimental data on the accumulation of formol-titratable nitrogen and the degree of hydrolysis provides the ground to recommend as rational for half-crenated ark the following regime: process duration of 230 minutes and alcalase enzyme dosage 1.3 % at the temperature of 55±2 °С and pH=6.5. The hydrolysate obtained following the specified regime, after its concentration to 50 % of dry matter content, is characterized by a relatively high protein content (≈30 %) and degree of hydrolysis 44.1±1.4 %.