Effect of pitahaya (Hylocereus spp.) peel based biopolymer films on postharvest quality of strawberries (Fragaria × ananassa)

The objective of this study was to evaluate the effect of biopolymer films made from pitahaya fruit ( Hylocereus spp.) peel with different concentrations of cassava starch (0 and 2% w/w) on the postharvest quality preservation of strawberries ( Fragaria × ananassa ) stored under refrigeration at 4°C for 10 days against a commercial polylactic acid (PLA) film. The physicochemical characterization of the biopolymer films included tensile testing, Fourier-transform infrared spectroscopy (FTIR), colorimetric parameters (L*, a*, b*, ΔE*, hue, saturation, and opacity), thickness, weight, water vapor permeability, moisture content, and ultraviolet light barrier properties. Both formulations produced homogeneous films with high UV-light barrier capacity (>95%), comparable mechanical strength (tensile strength 0.4 ± 0.2 MPa; elongation at break 6 ± 3%), low WVP (9.0 × 10⁻¹¹ g Pa⁻¹ s⁻¹ m⁻¹), and similar thermal stability (Tg = 74.08°C); starch incorporation altered optical and structural properties without compromising functional performance. During strawberry storage, no significant differences were detected between the pitahaya-based films and PLA packaging in pH, and total soluble solids, firmness (statistically indistinguishable among treatments), with microbial growth (total aerobic count +2.5 log CFU/g; yeasts and molds +1.5 log CFU/g over 10 days) remaining within ranges reported as microbiologically acceptable for fresh strawberries. These results demonstrate that pitahaya peel-based biopolymer films can match the postharvest performance of commercial biodegradable packaging, positioning strawberry preservation as a viable new application for agricultural by-product valorization.