Abstract—The work explores the feasibility of supercritical carbon dioxide (SC-CO₂) as alternative drying food process. Experiments carried out with apple pieces at 10 MPa and 35°C, aimed to investigate the effect of the drying time (5÷120 min) and the addition of a pre-dehydration step in graded ethanol (EtOH) solutions on the dehydration of the final product in terms of weight loss and structure. The treatment with pure EtOH leaded to a weight reduction of 50.0 ± 0.2 % after 120 min while SC-CO₂ induced a reduction down to 18.53±1.57 % after the same drying time. Significant improvements in terms of weight loss were obtained when apples were first dehydrated in pure EtOH for 40 min, and subsequently in SC-CO₂ for 10 min reaching a final reduction of 11.67±2.55%. Color measurements indicated that both SC-CO₂ and EtOH-SC-CO₂ drying treatments induced a significant increase of L*, while an increase of a* and b* parameters was detected only for SC-CO₂ dried apples. The overall changes in color ΔΕ did not shown significant differences between the two dried samples. SEM images indicated that the EtOH-SC-CO₂ dried apples presented more shrinking and a wider pore distribution compared to the SC-CO₂ dried ones. EtOH-SC-CO₂ drying confirmed the potential to apply the technology for drying apple slices in short time.
 

Index Terms—apple; drying, supercritical carbon dioxide, weight loss, microstructure, color

Cite: Massimo Vetralla, Giovanna Ferrentino, Alessandro Zambon, and Sara Spilimbergo, "A Study about the Effects of Supercritical Carbon Dioxide Drying on Apple Pieces," International Journal of Food Engineering, Vol. 4, No. 3, pp. 186-190, September 2018. doi: 10.18178/ijfe.4.3.186-190