Impact of Convective, Infrared, and Freeze‐Drying on the Kinetics and Quality of Prickly Pear

Abstract

The fruits of the prickly pear ( Opuntia ficus‐indica ) are seasonal products with varying shades, ranging from yellow to deep red. Their pigments, rich in bioactive compounds, are highly sensitive to thermal processing methods used for preservation, particularly drying. This study aims to evaluate the effect of different drying methods convective drying, infrared drying, and freeze‐drying on the bioactive and sensory properties of prickly pear fruits harvested in the Mahdia region of Tunisia. Sliced fruits were dried using convective drying, infrared drying at 50°C, 60°C, and 70°C, and freeze‐drying at −40°C and 0.25 Torr. Several parameters were measured, including total polyphenol content (TPC), sugar content (SC), antioxidant activity (AA), colorimetric coordinates ( L * a * b *), color index (CI*), Fourier‐transform infrared FTIR spectra, and carbon content. Additionally, the impact of drying techniques on drying kinetics was analyzed, focusing on the temporal evolution of the dimensionless moisture content, drying rate, and moisture diffusion coefficient. Regardless of fruit color (red, orange, or yellow), the results show that infrared drying at 60°C is the most suitable method among the tested conditions, considering phytochemical composition, physicochemical properties, and biological activities. Although freeze‐drying produced results closest to those of the fresh samples, infrared drying at 60°C yielded values very similar to freeze‐dried samples, making it a promising, faster, and more accessible alternative.