Promoting the preservation of strawberry by supercritical CO2 drying

This work aimed to investigate the supercritical CO2 (ScCO2) drying of strawberries and its effect on enzymatic, chemical and microbial stability. Process conditions influenced the final weight loss (WL), water activity (aw) and the inactivation of polyphenol oxidase (PPO) and peroxidase (POD). At 40 °C, an efficient drying (WL > 92 %, aw < 0.34) and a complete enzymatic (POD and PPO activity) inactivation can be achieved using several combinations of pressure, time and flow rate. ScCO2 dried strawberry at 40 °C, 13.3 MPa, 7 h and 19 kg/h flow rate maintain the total content of Vitamin C (358.5 mg/100 g), 95 % of total anthocyanin (61.68 mg/100 g) and 76 % of total flavonoids (25.85 mg/100 g) in comparison with fresh samples. Foodborne pathogens (E.coli O157:H7, Salmonella enterica and Listeria monocytogenes) inoculated at high concentration (≥6 log CFU/g) were undetected after the process. Overall results are promising for the development of a novel low temperature drying process for the production of healthy and safe snack.