Bactericidal activity of lauric arginate in milk and Queso Fresco cheese against Listeria monocytogenes cold growth

Abstract

Lauric arginate (LAE) at concentrations of 200 ppm and 800 ppm was evaluated for its effectiveness in reducing cold growth of Listeria monocytogenes in whole milk, skim milk, and Queso Fresco cheese (QFC) at 4°C for 15 to 28 d. Use of 200 ppm of LAE reduced 4 log cfu/mL of L. monocytogenes to a nondetectable level within 30 min at 4°C in tryptic soy broth. In contrast, when 4 log cfu/mL of L. monocytogenes was inoculated in whole milk or skim milk, the reduction of L. monocytogenes was approximately 1 log cfu/mL after 24 h with 200 ppm of LAE. When 800 ppm of LAE was added to whole or skim milk, the initial 4 log cfu/mL of L. monocytogenes was nondetectable following 24 h, and no growth of L. monocytogenes was observed for 15 d at 4°C. With surface treatment of 200 or 800 ppm of LAE on vacuum-packaged QFC, the reductions of L. monocytogenes within 24 h at 4°C were 1.2 and 3.0 log cfu/g, respectively. In addition, the overall growth of L. monocytogenes in QFC was decreased by 0.3 to 2.6 and by 2.3 to 5.0 log cfu/g with 200 and 800 ppm of LAE, respectively, compared with untreated controls over 28 d at 4°C. Sensory tests revealed that consumers could not determine a difference between QFC samples that were treated with 0 and 200 ppm of LAE, the FDA-approved level of LAE use in foods. In addition, no differences existed between treatments with respect to flavor, texture, and overall acceptability of the QFC. Lauric arginate shows promise for potential use in QFC because it exerts initial bactericidal activity against L. monocytogenes at 4°C without affecting sensory quality.

Applications of Edible Coatings Formulated with Antimicrobials Inhibit Listeria monocytogenes Growth on Queso Fresco

“…After a 24 h lag, L. monocytogenes grew rapidly on the surface of QF without antimicrobial application reaching counts >8 log CFU/g at day 21 with no additional change through 35 days (Figures 1 and 2), which is in agreement with previous studies (Soni et al, 2010;Kozak et al, 2018b effects as well as treatment × time interaction were observed for both PI and PC applications when treatments and controls were compared altogether (P < 0.001). Overall, the surface application of 1% AA to PI cheese (PI-AA control) had a significant effect on L. monocytogenes counts when compared to SDW control (P = 0.004) (Figure 1).…”

Antimicrobial property and microstructure of micro-emulsion edible composite films against Listeria

“…Although the composite film effectively reduced the microbial contamination on meat surfaces, the same film treatments were less effective against the microorganism on meat surfaces than in TSB (Figure 7 vs. Figure 2). Similar phenomena was observed in our previous study and also reported by other researchers, which showed that higher concentrations of antimicrobials or higher treatment doses are required in food systems to inhibit the growth of microorganisms than in growth media (Burt, 2004;El-Shenawy et al, 1989;Guo et al, 2014;Kamat and Nair 1995;Karatzas et al, 2002;Patterson, 1989;Shelef, 1994;Soni et al, 2010). The reduced antibacterial effect of antimicrobials in foods versus in growth media can be explained as follows: 1) The food matrix provides a protective environment to the pathogen as compared with phosphate buffer or other growth media; 2) Food components interfere with antimicrobial activities by binding with antimicrobials; and…”

Effect of Antimicrobials and Sodium Replacement Agents on the Survival of Pathogenic Bacteria in Low Sodium Low-Moisture Part-Skim (LMPS) Mozzarella Cheese

“…The concentration of L. monocytogenes increased by 4-5 log CFU/g after 28-35 days of incubation at 4°C in queso fresco cheese (Leggett et al, 2012;Soni et al, 2012;Soni et al, 2010). When the incubation temperature was increased to 10°C, the same log increase was observed after only 10 days.…”

“…aureus was also severely damaged by the activity of the LAE, however, damage of the membrane progressed much more slowly. LAE initially reduced the populations of L. monocytogenes by up to 2 log CFU/ml in milk and queso fresco cheese (QFC) when incubated at 4°C (Soni et al, 2010). However, there was no subsequent inhibitory effect by LAE; growth resume slowly during long-term storage of QFC at 4°C.…”