ε-Polylysine is widely used as a natural biological preservative in meat, dairy products and other foods for its characteristics of high safety, stability, efficiency, solublity in water and broad-spectrum antibacterial activity. In this paper, physiological and biochemical characteristics of Streptomyces albulus UN2-71, a strain capable of producing ε-polylysine, were studied. The ε-polylysine production increased from 1.64 to 2.37 g/L after optimization of fermentation conditions. The optimized conditions were defined as: 30 mL of the liquid medium in a 250 mL shake flask, inoculum size 10%, temperature 30 ℃, shaking speed 150 r/min and initial fermentation pH 7.0.

This study investigated the effect of addition of acetylated crosslinked starch as a stabilizer on set yoghurt. The presence of acetylated crosslinked starch was effective in controlling the acidity of yoghurt and improving its water holding capacity and freeze-thaw stability; however, excess acetylated crosslinked starch caused in a reduction in flavor compounds, a rough taste and a lack of refreshingness. Addition of 0.5%–1.5% acetylated crosslinked starch in set yoghurt was preferred.