The effect of hydrolysis duration on the antibacterial activity of swamp eel head protein hydrolysate produced by papain against histamine-producing bacteria

Swamp eel (Monopterus albus) processing produced byproducts such as heads that possess a high protein, carbohydrate, lipid, and energies content. Swamp eel heads were hydrolyzed (SEHPH) and tested for their antibacterial activity against histamine-producing bacteria (HPB) to explore the potency. The hydrolysis was conducted by a commercial papain enzyme PAYA (concentration 4) with various hydrolysis times (0, 60, 120, and 180 minutes) at 60o C with pH 5. The results indicated that increasing hydrolysis time increased solubility and the degree of hydrolysis. The inhibitor concentration 50 test using microdilution of SEHPH inhibited 50 against three HPB named Citrobacter sp. (CK1), Klebsiella sp. (CK13), and Morganella morganii (TK7) at 20 mg/ml. The optimum antibacterial activity test by disk diffusion method was formed by each minute of hydrolysis with the best inhibition zone to Klebsiella sp. (CK13). The macrodillution method showed the highest inhibition was produced by 180 hydrolyses with 45 on CK1, 54 on CK13, and 48 on TK7. These results indicated that SEHPH has potency as an antibacterial agent to reduce histamine-producing bacteria.