Abstract:
The aims of the research were to produce hydrolysates derived from abalone Haliotis asinina using Flavourzyme[Registered sign] and Alcalase[Registered sign] and to study the functional properties of the obtained protein hydrolysates. Conditions for protein hydrolysis using Flavourzyme[Registered sign] and Alcalase(R) were fixed at 60 ํC pH 6.0 and 60 ํC pH 8.0, respectively. Five levels of Flavourzyme[Registered sign] were used (0-1.50% w/w) and digestion time was varied from 0 to 4 hours. Five levels of Alcalase[Registered sign] were used (0-0.20%) with 5 levels of digestion time as above. Enzyme quantity and digestion time significantly affected the degree of hydrolysis (DH) and the quantity of free amino acids (p [is less than or equal to] 0.05). The results showed that DH obtained by Alcalase[Registered sign] was higher than that obtained by Flavourzyme[Registered sign] ; however, using Alcalase[Registered sign] yielded a lower quantity of free amino acids. Based on maximum DH and minimum quantity of bitter taste free amino acids, four optimal conditions for digesting protein from abalone were selected. These conditions were: using 0.50% Flavourzyme[Registered sign] for 4 hours; 1.00% Flavourzyme[Registered sign] for 4 hours; 0.05% Alcalase[Registered sign] for 3 hours; and 0.10% Alcalase[Registered sign] for 2 hours. Freeze dried powder obtained from each of the four optimal conditions were analyzed for their solubility, foaming and emulsifying properties. Regarding solubility, the solubility of protein hydrolysates were not affected by pH (p > 0.05). Protein hydrolysates from Flavourzyme[Registered sign] and from Alcalase[Registered sign] had a good solubility over the wide pH range (2-10). The solubility was about 55-61% and 50-61%, respectively. Protein hydrolysates by Alcalase[Registered sign] exhibited a superior foam expansion (FE) and foam stability (FS) to protein hydrolysates by Flavourzyme[Registered sign]. FE and FS of protein hydrolysates by both enzymes were affected by pH values (4.5-7.5) and salt concentration (0.10M) (p [is less than or equal to] 0.05). These protein hydrolysates had better FE than BSA did. However, protein hydrolysates by both enzymes showed a higher FS than BSA did. The protein hydrolysates by Flavourzyme[Registered sign] had a better emulsifying activity index (EAI) and showed a higher emulsion stability index (ESI) than protein hydrolysates by Alcalase[Registered sign]. EAI and ESI of protein hydrolysates by both enzymes were significantly affected by salt (0.10M) (p [is less than or equal to] 0.05). Protein hydrolysates by both enzymes had a better EAI than BSA did; however, ESI of protein hydrolysates obtained by both enzymes and BSA were very similar.