Effects of PBS-based packaging on the shelf-life and spoilage profiles of soft cheeses

The intense use and accumulation of non-degradable plastics, which leads to the growing problem of waste disposal, and the lowering in the availability of fossil resources have strongly increased the interest and efforts in using renewable resources to develop biodegradable-based packaging materials. A number of bio-based materials and their innovative applications in food-related packaging have therefore gained much attention over the past several years. The main bio-sourced polymer currently used in food packaging is polylactic acid, but polybutylene succinate (PBS) can be considered a promising polymer from renewable resources for packaging industry for the coming years due to the prediction of a large development of succinic acid production by fermentation of gluco-based resources. The potentialities of PBS in this area are explored within the EU project SUCCIPACK (Grant agreement 289196) which aims to develop sustainable, active, and intelligent food packaging materials based on green PBS that can be flexibly used by packaging and food industries. Aspect that are taken into consideration include the optimization of the synthesis and compounding of polymer and copolymer grades for industrial plastic transformation processes to obtain films, trays and pouches. Also tailored packaging functionalities are obtained through surface treatments to control gas barrier properties and introduce antimicrobials. The performance of the novel packaging materials are assessed for selected food products, including soft cheeses, raw meat, fish products, ready-to-eat vegetables and ready meals for vegetarian. The objective of this preliminary work was to test the effects of PBS packaging material on the shelf-life of two soft cheeses such as ricotta and squacquerone. In particular microbial populations, volatile organic compounds, color and sensory properties were monitored over a 20-days storage at 4°C and compared to control products packaged with the traditional materials. Microbial data of the evolution of main spoilage microorganisms were modelled with the Gompertz equation to calculate the products shelf-life and evaluate possible shifts in microbial population due to the innovative packaging. Volatile microbial metabolites were determined by electronic nose and solid-phase micro-extraction gaschromatography/mass-spectrometry (SPME/GC-MS) analysis. Also the real oxygen permeability of the whole packaged products was measured. The comparison of all the data collected showed that the packaging material and conditions used affected the microbiota and its evolution during storage resulting in significant differences in the volatile metabolites released with a potential impact on cheese sensory attributes.