Producción de compuestos volátiles y evaluación sensorial de queso tipo panela incorporado con Lactococcus lactis UQ2 rif L+ como cultivo protector

Panela cheese is a traditional fresh product which can support the development of pathogenic or spoilage microorganisms due to its composition. There is some consumer preference for panela cheese made from unpasteurized milk because of its specific flavor and aroma characteristics. Biopreservation is defined as the use of bacteria or their metabolites such as bacteriocins, as natural agents for food preservation. Nisin is a bacteriocin with GRAS status, which is synthesized by certain strains of L. lactis. L. lactis UQ2 rif L+, is a modified strain that has the ability to grow in a complex medium such as milk and promotes the synthesis of nisin and volatile flavor compounds when incorporated in panela cheese. In this study, panela cheese was added with L. lactis UQ2 rif L+ as biopreservation method. To verify beneficial properties of the strain a 22 experimental design was conducted, where population of L. lactis UQ2 rif L+ and the initial level of fat in milk were included as factors. Response variables were nisin activity, consumer acceptance and the volatile compounds profile during a 28 day storage period at refrigeration temperature. L. lactis UQ2 rif L+ showed a maximum population of 9.2 ± 0.1 log CFU/g of cheese and a nisin activity of 1.53 ± 0.4 mg/kg of cheese after 21 days of storage for cheese with a high level of inoculum = 107 CFU/mL and 3.5% of milk fat. Statistical analysis showed that texture and flavor were best rated for cheeses that were made with high fat level (3.5%). 37 volatile compounds were identified, of which 3-methyl-1-butanol, hexanal, 3-methyl-butanal and 2-methyl propanol are compounds produced by Lactococcus strains. These results suggest that the addition of protective culture to panela cheese promotes microbiological stability and flavor improvement and sensory acceptance is highly influenced by the fat content in milk