Efficacy of Herbal Extracts-Based Nano-Formulations in Extending Guava Fruit Shelf-Life

The guava (Psidium guajava L.), known as ‘Apple of the Tropics’ is a rich source of polyphenols, pectin, dietary fiber, and carotenoids. Guava comes under climacteric types of fruits; due to its high transpiration and respiration rate it experiences high post-harvest losses. Giloy leaf and ajwain seed herbal extracts-based nano-formulations (NFs) were synthesized using biopolymer sodium alginate and CaCl2, viz., T1 (Alginate: CaCl2), T2 (Alginate: CaCl2: Ajwain extract), and T3 (Alginate: CaCl2: Giloy extract). Antibacterial and antioxidant activity of the NFs were examined to check their efficacy as antibacterial agents, which was checked against E. coli, P. aeruginosa and B. cereus bacterial culture. The zone of inhibition against bacteria ranged from 6 ± 0.42 mm to 14 ± 0.92 mm. Antioxidant activity was 93.27%, 71.67%, and 67.04% for T2, T3 and T1 NFs and 89.90% and 67.05% for ajwain and giloy extracts. NFs treated fruits showed minimum loss in physiological weight, firmness, and color change compared to control fruit (uncoated). Physiological loss in weight ranged from 3.16 to 17.21% and 3.23 to 15.57% and fruit firmness ranged from 4.47 to 8.41 kg/cm2 and 4.84 to 8.37 kg/cm2 during storage at 25 ± 2 °C (incubation) and 32 ± 2 °C (room temperature), respectively. Among NFs, T2 showed the best results in preventing ripening and maximum loss of quality was observed in control (uncoated) fruits. Thus, NFs are an effective method of extending the shelf-life of fruits and ajwain based NFs increased shelf life of guava from 4–5 days to 7–8 days. Fruits storage at 25 ± 2 °C showed better results compared to storage at 32 ± 2 °C. Thus, NFs treated fruits storage at lower temperature controls the ripening related changes maximally.