Effect of Biosurfactants Extracted from a Locally Fermented Milk (Pendidam) on Its Shelf Life

Abstract

Biosurfactants was extracted from a locally fermented milk (pendidam), characterized and their antimicrobial activity on Candida spp. and E. coli were determined. The results obtained show that the crude extract of biosurfactants exhibit emulsifying activity with an emulsification index of 61.11±1.37% and can reduce the surface tension of water from 69.22±0.35 mN/m to 59.41±0.59 mN/m. Their properties were not affected by exposure to high temperature (100ºC for 15 min), to high salinity (20% NaCl) and to a wide range of pH (2 to 12). Furthermore, the biosurfactants extracted showed antimicrobial activity against Candida spp. and E. coli with a Minimum Inhibitory Concentration (MIC) of 50 mg/mL and a Minimum Bactericidal and Fungal Concentration (MBC/MFC) of 100 mg/mL. The obtained biosurfactants reduced the microbial load of pendidam in a rate ranging from 12.97% to 62.21% depending on the concentration used, the type of microorganisms and the time. The higher reduction of the microbial load of pendidam was recorded with biosurfactants concentration of 100 mg/mL against total aerobic flora after 72 hours of preservation at room temperature. Considering the results obtained, biosurfactants are able to improve the microbiological quality of pendidam, increase its shelf life and these facts confirm their eventual use as food preservatives.