Assessment of Rhizopus rot control and quality attributes of manik chaman table grapes after post-harvest ozone and sodium metabisulfite treatment

Abstract

An important fruit crop, grapes are vulnerable to fungal degradation, at different points, together with harvesting, post-harvest management, and storage. The effectiveness of ozone at concentrations 4416.6 L L-1, 6624.9 L L-1, & 8833.2 L L-1 in combination with sodium metabisulfite (SMB), at concentrations of 50 mg, 70 mg, and 90 mg per 100 ml of potato dextrose broth (PDB) was investigated to solve this issue. Fumigation, and food poisoning techniques, were used in these treatments to stop R. stolonifer (Ehrenberg) Vuillemin’s radial growth. In a different trial, SMB in the forms of Indian, and African grape guards, as well as SMB powder packaged in pouches (at a rate of 0.5g per 500g of fruit), was examined, for its potential to combat Rhizopus rot in table grapes subjected to cold storage conditions (52 °C, RH-85-95%), over 49 days. The results showed that sodium metabisulfite at 90 mg/100 ml PDA, and ozone at 8833.2 l L-1 strongly reduced the radial growth of R. stolonifer by 94.82% and 98.14%, respectively. While the inoculation control registered 0.89 Disease Severity (DS), fruits treated with O3 and SMB showed, no symptoms of disease severity. Ozone at 7274.4 L L-1 & 5455.8 L L-1 demonstrated, greater firmness retention of the berries (85.09 N; 84.82 N), as well as higher concentrations of ascorbic acid (3.90; 3.88 mg/100 g). Additionally, these treatments reduced, the levels of Total Soluble Solids (TSS) (18.68 N; 18.72 N), Percentage of Loss in Weight (PLW) (7.49; 7.55), and TSS/acid ratio (20.57 N; 21.52 N). In the sensory evaluation, these therapies received the highest overall acceptance ratings (8.04; 7.70). When combined with ozone, the application of SMB powder at a rate of 0.5g per 500g of grapes showed promising results, among the fruits that had been treated with SMB. In addition, compared to ozone, SMB treatments produced significantly higher L* and b* values. The highest L* value (40.53), highest b* value (23.77), and lowest a* value (-1.92) were all found with SMB powder at 0.5g/500g grapes. In conclusion, ozone shows promise in regulating Rhizopus rot effectively and keeping, the qualitative characteristics of table grapes, during cold storage, offering a feasible substitute, for sulfur dioxide treatments in conventional grape production.