Food Irradiation·Food Science
WANG Xiaofang, ZHANG Ruohong, WANG Meijiao, WANG Chun, LIU Shaojun, YANG Yang, CUI Shenghui, GUO Yunchang
To develop the anti-Listeria spp. vegetable salad dressing, the natural bioactive compounds extracted from pomegranate peel, hibiscus calyx, oregano, and others were used as the ingredients, the inactivation effects of the anti-Listeria spp. salad dressing were determined using in vitro antibacterial test against Listeria spp. (108 CFU·mL-1) and microbial challenge test with artificially Listeria spp. contaminated vegetable salads (108, 105, and 102 CFU·g-1) after mixing well, and further standing for different treatment times (30 s, 1 min, 2 min, 3 min, 5 min, and 10 min), and compared with four commercially salad dressings including Kewpie, Berry, Heinz, and Kiihne. The performance of the anti-Listeria spp. dressing was determined using the most probable number (MPN) method specified in the China’s National Health and Family Planning Commission China Food and Drug Administration (GB 4789.30-2016). It indicated that the anti-Listeria spp. salad dressing exhibited significant antibacterial activity against all 81 Listeria spp., with efficacy correlating with contamination level and treatment time. It demonstrated that mixing 1 mL of salad dressing with 108 CFU·mL-1 of Listeria spp. for 30 s resulted in a maximum residual count of 160 MPN·mL-1, which complete inactivation was achieved within 1 min treatment in vitro test. It confirmed that mixing 40 mL of the salad dressing with 400 g of vegetable salads contaminated at high, medium, and low concentrations of Listeria spp. (108, 105, and 102 CFU·g-1) for 30 s resulted in a maximum residual count of 240 MPN·g-1, which complete inactivation of all Listeria spp. was achieved within 3 min treatment based on microbial challenge test. In contrast, none of the four commercial salad dressings exhibited any anti-Listeria spp. characteristics. The study provides the scientific support for ensuring food safety associated with Listeria spp. contamination at the food consumption terminal and reducing the risk of listeriosis outbreaks.