Effects of bioprotective cultures on the microbial community during storage of Italian fresh filled pasta

Filled pasta is a typical Italian product consisting in a thin dough stuffed with dairy, meat or vegetable ingredients. When industrially produced, its microbial stability relies on thermal treatment, proper storage temperature and modified atmosphere packaging. Since these processes can strongly affect the traditional features of pasta (mainly flavor and texture), alternative strategies have been investigated. In this study, milder heat treatments were applied and combined with the addition of bioprotective cultures (Lactobacillus rhamnosus and Lactobacillus paracasei) in the filling of Ricotta based Tortelloni to assure microbial quality and safety. Their effects on microbiological patterns during storage at 6 °C was studied through culture dependent and independent methods; in addition, the influence on organoleptic profile (through SPME-GC-MS and sensory evaluation) was also assessed. The results demonstrated that bioprotective cultures had a relevant quantitative and qualitative effect on the microbiota of Tortelloni during storage: although they were not dominant, their presence reduced the initial microbiota associated with raw materials and gave a competitive advantage to safer or organoleptically acceptable LAB species, such as leuconostocs. Although these LAB cultures influenced the aroma profile of filled pasta (i.e. increase of alcohols, esters and acids), the sensory evaluation confirmed the overall acceptability of the product. The addition of bioprotective cultures can therefore be considered a helpful strategy to reduce thermal treatments and to better maintain the traditional textural and flavor characteristics of this product.