Purpose: To control the risk of L. monocytogenes at RTE ravioli, the antimicrobial effects of CSV blend and nisin were investigated.
Methods: Ravioli dough was prepared with 0, 0.1, 0.3, 0.5, and 1% CSV blend and 0, 0.1, 0.2, and 0.3% nisin. Spinach filled raviolis were inoculated with L. monocytogenes for a target population of approximately 2.0 ± 0.5 log CFU/g. Inoculated raviolis were modified atmosphere packaged (MAP) and stored at 4, 10, 17, and 24°C. At selected times after inoculation, the diluted samples were plated onto PALCAM agar in duplicate, and incubated at 35°C for 48 h. The colonies on duplicated plates of each sample were counted with an automated colony counter.
Results: Growth kinetic parameters of the observed data were fit well to a modified Gompertz equation (R2 > 0.95). Generally, lag times (LTs) of L. monocytogenes on spinach raviolis under MAP was longer than those of L. monocytogenes under aerobic-packaged raviolis, regardless of the storage temperature. At the temperatures below 10°C with MAP, the growth of L. monocytogenes was significantly inhibited in raviolis which made with 1% CSV blend or 0.3% nisin during 60 days of storage. The growth rate of L. monocytogenes in raviolis with nisin was slower than that with CSV blend.
Significance: The addition of 1% CSV blend or 0.3% nisin in spinach ravioli with combination of MAP effectively controlled the growth of L. monocytogenes at refrigerated temperature. Thus, very low level of the CSV blend can be applied in manufacturing of natural RTE ravioli to improve the microbial safety and quality of the products.