Potensi Ekstrak Umbi Bawang Lokio (Allium chinense G. Don) dalam Menghambat Escherichia coli dan Meningkatkan Masa Simpan Ikan Nila (Oreochromis niloticus L.)

Abstract

Bawang Lokio (Allium chinense G. Don) grows extensively in North Sumatera, Indonesia, so called as “Bawang Batak” by the Batak tribe. Exploration of the natural compoundpotency of this plant in fresh food preservation is rarely reported. The aim of this research were to determine the minimum inhibition concentration of bawang Lokio bulb extract with ethanol againsts Escherichia coli isolated from Tilapia fish and to extend the self life of fresh Tilapia fish. Antimicrobial activity was examined by disc diffusion method in concentration of 0, 7.5, 10, 20, 30, 40 and 50% (w/v). For fresh fish preservation, the gutted Tilapia fish were soaked in concentration of 100% bawang Lokio bulb extract. Tilapia fish were stored for 36 hours at ambient (27 °C) and fridge (4 °C) temperatures with 6 hours interval of observation. The observation parameters were organoleptic test, Total Bacterial Count (TBC) and Total Volatile Base Nitrogen (TVBN). The Minimum Inhibition Concentration (MIC) of ethanol extract of bawang Lokio bulb was 10% against E. coli with medium antimicrobial category.Based on Standard Nasional Indonesia (SNI), the organoleptic test of Tilapia fish was still accepted until 30 hours of storage while TBC and TVBN 18 hours. If it was compared by negative control (without addition of extract, ambient temperature storage) which could stay for 6 hours. The different activities of antimicrobial compound and temperature of storage were assumed as the cause of decreasing fish quality. It could be concluded that ethanol extract of bawang Lokio bulb was against Escherichia coli in minimum inhibition concentration of 10% and maximum self life of Tilapia fish were 18 hours at ambient temperature.