Effects of gassericins A and T, bacteriocins produced by Lactobacillus gasseri, with glycine on custard cream preservation

Effects of food-grade surfactants added to milk-based media for gassericin A activity in the culture supernatants of Lactobacillus gasseri LA39. The vertical axis shows the unit of activity (arbitrary units/mL). The milk-based media were 8% (wt/vol) reconstituted skim milk (RSM), RSM containing 0.5% (wt/vol) proteose peptone (PP-RSM), 8% (wt/vol) reconstituted cheese whey (RCW), and RCW containing 0.5% (wt/vol) proteose peptone (PP-RCW). The food-grade surfactants were Tween 80 (TW), glyceryl monooleate (GO), sorbitan monooleate (SO), and yolk lecithin (YL). MRS = de Man, Rogosa, and Sharpe agar. Each bar represents the mean of 3 data points and the error bars are standard deviations.

Changes in cell viability of Bacillus cereus AK1124 (panel A) and Lactococcus lactis ssp. lactis AK1155 (panel B) in custard creams containing glycine, the culture supernatant of Lactobacillus gasseri LA39 [gassericin A (GA) solution], or both. Lactobacillus gasseri LA39 was cultured in 8% (wt/vol) reconstituted cheese whey, 0.5% (wt/vol) proteose peptone, and 0.1% (wt/vol) yolk lecithin medium (YL-PP-RCW). ♦ = preservative-free custard cream; ■ = custard cream containing 0.5% (wt/wt) glycine; ▴ = containing 49 AU(arbitrary units)/mL GA; × = containing 0.5% (wt/wt) glycine and 49 AU/mL GA; ○ = containing 123 AU/mL GA; ● = containing 0.5% (wt/wt) glycine and 123 AU/mL GA. The data show the average values of triplicate determinations and the error bars are standard deviations.