Effects of chitosan coatings fused with medicinal plant extracts on postharvest quality and storage stability of purple passion fruit (Passiflora edulis var. Ester)

Chitosan edible coating (Ch; 2%, mass concentration) enriched with 2% of 0.1 mg/L Bidens pilosa (Ch+B), Lippia javanica (Ch+L), Syzygium cordatum (Ch+S), or Ximenia caffra (Ch+X) was applied as a composite edible coating in alleviating shrivel and maintaining the quality of purple passion fruit (Passiflora edulis var. Ester). Treated fruit was dipped for 3 min in the coating solution, and control fruit was dipped in distilled water. The fruit were stored at (8±2)°C and 90%±5% relative humidity (RH) for 32 d. Sampling was done every 8 d plus 3 d ((20±2)°C and (50%±5%) RH) to simulate retail conditions. Efficacy of medicinal plant extracts in the chitosan matrix varied; lower ethylene production (82.42 μL C2H4/(kg h)) was seen in fruit coated with Ch+S, and the lowest respiration rate (75 mL CO2/(kg h)) was observed in fruit coated with Ch+B. The control fruit showed the highest ethylene production (84.90 μL C2H4/(kg h)) and respiration rate (117.98 mL CO2/(kg h)). Fruit coated with Ch+B had the lowest weight loss (41.67%), higher juice content (60.13%) and BrimA (3.31); while the control fruit had the highest weight loss (88.03%), lowest juice content (21.90%), and BrimA (2.49). Shrivel incidence was lowest (23.70%) on fruit coated with Ch+L and highest (83.30%) on the control fruit. Fruit coated with Ch+X had the lowest electrolyte leakage (71.40%), while the control fruit had the highest (91.97%). Fruit coated with chitosan alone performed better than the control fruit but did not exceed the quality of composite chitosan-coated fruit. Based on the principal component analysis, it can be concluded that passion fruit coated with Ch+B was more effective in alleviating shrivel incidence, better maintained the quality of passion fruit during storage, and shows potential for commercial applications.