The antibacterial activity of sunflower pectin oligosaccharides (SPO) and citrus pectin oligosaccharides (CPO) was evaluated in this paper. The antibacterial activities of these two pectin oligosaccharides with different polymerization degrees were examined by determination of the minimum inhibitory concentrations against Escherichia coli, Staphylococcus aureus and Bacillus subtilis in food. The results showed that the 15 -50 polymerization degree of SPO and CPO displayed the best antibacterial activity. Under the same concentration, the antibacterial activity of CPO against Escherichia coli and Bacillus subtilis was higher than that of SPO. However, the antibacterial activity of CPO against Staphylococcus aureus was lower than that of SPO. The
minimum inhibitory concentration of SPO and CPO against these three kinds of bacteria was 0.06- 0.6 mg/mL.