Characterization and flavour enhancement of protein hydrolysate generated from enzymatically hydrolyzed clam (Polymesoda erosa) / Noorasma Mustakim

An enzymatic hydrolysis of the bivalve species to produce value-added hydrolysate products has emerged as a priority area for the global seafood industry development However research on protein hydrolysates from bivalves are still very limited and some of them have been showed to impart undesirable flavours which limit its application for human consumption. Therefore, this research was conducted to characterize the mud clam (Polymesoda erosa) hydrolysates produced using two different enzymes; alcalase and flavourzyme. The selected hydrolysate was then modified by Maillard reaction and analysed. Mud clam was hydrolysed using alcalase at pH8.5, 60°C, 3% enzyme substrate (ES) ratio and flavourzyme at pH 7, 55° C, 3% ES ratio for 2 hours. The hydrolysate was then characterized for physicochemical, functional and sensory properties. The sensory properties of hydrolysate were evaluated through Quantitative Descriptive Analysis (QDA), volatile compounds, amino acids and sodium dodecyl sulfate polyacrylamide gel electrophoresis (SDS PAGE). The result showed that the type of enzyme used gave significant impact on the hydrolysate properties. Hydrolysis using alcalase resulted in 20.28% DH, 25.06 % yield and 45.37 % protein while flavourzyme hydrolysis resulted in 22.93 % DH, 46.67 % protein and 30.68% yield. Better emulsifying properties, foaming properties and water and oil holding capacity were exhibited by flavourzyme hydrolysate compared to alcalase hydrolysate. Alcalase hydrolysate was more bitter compared to flavourzyme based on QDA result the presence of more bitter like amino acids and higher content of 2-piperidinone volatile compound. Based on these observations, alcalase hydrolysate was produced and further subjected to Maillard reaction process. The Maillard reaction products (MRPs) from alcalase hydrolysate produced in the presence of xylose (AH-x) and alcalase hydrolysate with the presence of xylose and L-cysteine (AH-mx) model system were evaluated and compared to the original alcalase hydrolysate. Findings from amino acid analysis showed that AH-x and AH mx were more umami·and bitter taste was reduced. 2- piperidinone that contributed to bitter taste was reduced in AH-x and not detected in AH-mx. Furthermore, the QDA result showed that AH-mx had greater umami taste and reduced in bitter taste and fishy flavour compared to alcalase hydrolysate and AH-x due to highest content of furfural.