Synergistic effect of aqueous ozone and guar gum coating on the quality and shelf life of stored papaya fruit

The study aimed to investigate the sole aqueous ozone (Oz) and guar gum (GG) coating and the combined effects of aqueous ozone and GG coating (Oz + GG) on the quality and shelf life of ‘Red Lady’ papaya. The ozone (2 mg L⁻¹ for 5 min) and 0.3% GG coating were used individually and in combination (Oz + 0.3 GG) on papaya. The various physicochemical parameters were analysed every 2 days up to 8 days of ambient storage. The findings indicated that both ozone treatment and GG coating in isolation demonstrated efficacy in preserving quality and extending shelf life compared to the control group. However, the Oz + 0.3 GG combination treated fruits exhibited significantly lower physiological weight loss (5.23%), decay incidence (30%), and respiration rate (32.15 mL CO₂ kg⁻¹ h⁻¹), along with improved color values compared to the control. These treated fruits also demonstrated reduced levels of malonaldehyde (14.89 µM g⁻¹ FW) and hydrogen peroxide (70.86 µM g⁻¹ FW) content, indicating less oxidative damage. Furthermore, combined treatment maintained around 2-fold higher fruit firmness (9.10 N), total phenols (35.69 mg GAE 100 g⁻¹ FW), flavonoids (12.19 mg CE 100 g⁻¹ FW), antioxidants activity (37.28%), titratable acidity (0.20%) and received higher sensory acceptability compared to the control. In conclusion, the Oz + 0.3 GG treatment extended the shelf life of stored papaya by up to 8 days (2 days more than untreated fruits) without compromising their quality under ambient conditions. The findings suggest practical implications for the fruit industry, catering to both economic and environmental sustainability goals.