Translational Application of Chia (Salvia hispanica) and Nopal (Opuntia ficus-indica) Mucilage-Based Edible Coatings for the Postharvest Preservation of Cherry Tomato and Carrot

Introduction: Postharvest losses (~23%) arise from physicochemical and microbial decay. Edible biopolymer coatings offer sustainable alternatives to synthetic waxes, yet their efficacy depends critically on water-vapor permeability (WVP) and water activity (aw). This translational study formulated coatings from chia and nopal mucilages, with/without Isomalt as a matrix modifier/aw reducer, for climacteric (cherry tomato) and non-climacteric (carrot) produce.

Methodology: Five groups (control, Chia, Chia+Isomalt, Nopal, Nopal+Isomalt) were stored at 25±1 °C/65±5% RH for 15 days. Films were characterized for barrier properties; weight loss (WL), TSS (°Brix), pH, and titratable acidity (TA) were monitored every 3 days and analyzed via two-way ANOVA/Tukey's (p<0.05).

Results: Isomalt reduced nopal film WVP by 32% (p<0.05) via hydrogen-bond networking, unlike chia films which exhibited structural micro-fractures and higher hygroscopicity. In vivo, Nopal+Isomalt outperformed all treatments, restricting tomato WL to 5.2±0.3% (control: 15.7±0.6%), maintaining TA (0.48±0.02% vs. 0.31±0.03%) and pH (4.1±0.1). For carrots, WL was 8.3±0.4% (control: 22.5±1.1%), with stable pH (6.1±0.1). TSS remained stable at 5.9±0.2 °Brix (tomato) and 7.2±0.3 °Brix (carrot), versus control fluctuations >±2.0 °Brix (p<0.05). This high stability indicates an effective reduction in the respiration rate and metabolic carbon consumption of the treated tissues. Synergy arises from nopal's galacturonic acid (enhancing continuity) and Isomalt's aw-depression, improving moisture/O2 barriers without sacrificing transparency.

Conclusion: Tailoring nopal mucilage with Isomalt effectively delays senescence and moisture loss across distinct metabolic models, validating its scalability as an eco-friendly postharvest technology with translational supply-chain applications. Furthermore, these bio-polymeric systems demonstrate an outstanding potential to replace commercial synthetic coatings, representing a viable, high-throughput, and cost-effective strategy to mitigate agricultural economic losses while strictly preserving fresh-like organoleptic attributes during retail distribution.