Comparative efficacy of GRAS chemicals, botanicals and yeast in controlling green mould and fruit nutritional quality enhancement in Kinnow mandarin (Citrus nobilis Lour x Citrus deliciosa Tenora)

• GRAS salts were evaluated in Kinnow mandarin against post-harvest losses caused by penicillium digitatum sacc. • Seven yeast isolates, nine local botanicals and six GRAS salts were tested. • GRAS salts exerted a substantial enhanced nutrient composition and fruit quality. • The study demonstrated multifaceted approach as a viable alternative to synthetic fungicides. Green mold caused by Penicillium digitatum Sacc. is a serious disease of Kinnow mandarin fruits, causing up to 90 per cent fruit rot. The use of chemical fungicides has raised concerns about residual toxicity in edible fruits. To find effective alternatives to chemical fungicides, yeasts, plant leaf extracts, and GRAS salts were investigated to determine post-harvest losses. Seven yeast isolates from different sources, nine locally available plant leaf extracts, and six GRAS salts were tested for resistance against P. digitatum under in vitro conditions. S accharomyces cerevisiae (yeast) isolates, namely, R, BK 6, and BK 4, inhibited the pathogen hyphal growth by 66.66, 53.5 and 48.14 per cent, respectively. Aqueous plant extracts of Roylea cinerea (D. Don) Baill (Ash Roylea, 84.81 %), Murraya koenigii (L.) Sprengel (Curry Leaves, 78.70 %) and Mentha piperita L. (Mint, 76.47 %) were found to be effective in inhibiting the mycelial growth of the pathogen. Among the GRAS salts, salicylic acid (0.25 %), sodium bicarbonate (0.50 %) and potassium sorbate (0.75 %) completely inhibited the mycelial growth of the pathogen. The yeast, plant leaf extract (10 %) and GRAS salt (0.25 %) found to be effective under in vitro conditions were further investigated under in vivo conditions as fruit protectants to determine their effectiveness against Dactylopius digitatus to examine the target damaged areas on the fruit surface and also as fruit pastes. In fruits treated with S. cerevisiae isolate BK 6, Ashy Roylea, and salicylic acid at the affected lesion sites, the incidence was reduced by 50, 33.3, and 66.7 per cent, respectively. Similarly, fruit dip containing broth of S. cerevisiae isolate BK 6, Ashy Roylea aqueous extract, and salicylic acid reduced disease severity by 63.3, 33.3 and 78 per cent, respectively. The study found that yeast isolates and GRAS salts had a significant impact on the nutritional composition of the fruit, thereby improving the quality of Kinnow fruits. The results obtained in this study using various biological and chemical agents demonstrate the potential of a multifaceted approach as a viable alternative to synthetic fungicides. It is concluded that application of GRAS salts, botanicals and yeasts can be a promising integrated approach to manage postharvest diseases in the Citrus industry, ensuring better fruit quality and promoting environmentally friendly practices through synergistic effects, increasing the overall effectiveness of controlling postharvest diseases.