Control of Listeria monocytogenes by Monoglycerides in Foods

Monoglycerides (MCs) including MC₁₀, MC₁₂, and coconut MCs were tested for inhibitory activity against Listeria monocytogenes strain Scott A in culture media and in several foods. MCs were inhibitory to L. monocytogenes in certain foods including beef frank slurries (pH 5.0 and 5.5) and seafood salad (pH 4.9) at 4°C, but were less active at 12 than at 4°C. MCs were less inhibitory to L. monocytogenes in other foods tested including turkey frank slurries (pH 5.5), imitation crabmeat, cooked shrimp, summer sausage, yogurt, cottage cheese, and Camembert cheese. Combinations of MCs, particularly MC₁₀ and MC₁₂, showed increased activity in certain foods. The combination of MC₁₀ (250 to 500 μg/ml) and MC₁₂ (250 to 500 μg/ml) or a mixture of coconut-derived MCs (500 to 1,000 μg/ml) were inhibitory against L. monocytogenes in beef and turkey frank slurries. Certain Chemical factors affected the degree of inhibition by the lipid compounds including pH, acidulants such as lactic acid, certain antioxidants, and lipid carriers. The results suggest that MCs could be used as preservatives in certain classes of minimally processed refrigerated foods when intrinsic antimicrobial activity is inadequate.