Enhancing the shelf life of guava (Psidium guajava L.) using edible coating derived from yellow passion fruit (Passiflora edulis forma flavicarpa) peel pectin

Abstract

Guava (Psidium guajava L.) is a major commercial fruit with great export potential in Sri Lanka but has a shorter shelf life due to its climacteric nature. Therefore, this study aimed to investigate the potential of yellow passion fruit (Passiflora edulis forma flavicarpa) peel pectin as a base material for an edible coating in extending the shelf life of guava. Pectin was extracted using an acidified aqueous method (citric acid, pH 2; solvent: solute ratio 40:1; 75 min at 85°C), identified using Fourier Transform Infrared Spectroscopy (FTIR) and characterized for yield, equivalent weight and degree of esterification. Matured apple guavas were coated with pectin solutions (1%, 2%, 3%) and stored at 25 ± 3°C, 75% RH for 16 days. The quality parameters of guava including appearance, weight loss, firmness, pH, titratable acidity, total soluble solids, total chlorophyll content were monitored at regular intervals of 4 days. The pectin yield from passion peel was 25.25% (dry basis), indicating the potential value-addition of this agro-industrial by product. The moisture content (8.00%), ash content (7.20%), equivalent weight (806.04 mg), and the degree of esterification (64.25%), exhibited the suitability of pectin for gel formation. The FTIR data confirmed characteristic peaks at 3359 cm⁻¹ (O-H stretching), 2924 cm⁻¹ (C-H stretching), 1718 cm⁻¹ (C=O stretching), and 1629 cm⁻¹ (C=C stretching), corresponding to the functional groups. The 3% coating solution was effective until the day 16, and significantly (P ≤ 0.05) reduced weight loss (13.42%), maintained firmness (43.00 kPa), and preserved quality parameters (pH 4.30, soluble solids 12.40°Brix, chlorophyll 81.30 µg/g, titratable acidity 7.20%) of coated guava compared to control (treated with distilled water). The 2% solution was effective until day 8, while 1% showed no significant difference from the control (P≥0.05). Therefore, this study concluded that the passion peel-derived pectin has a significant potential in preserving the postharvest quality of guava by regulating various physiological processes.