Controlling anthracnose in mango and guava with antifungal coatings of sodium alginate containing hydroalcoholic extracts of fruit by-products fermented by lactic acid bacteria.

Aim: This study evaluated the efficacy of hydroalcoholic extracts from fruit by-products fermented by lactic acid bacteria (LAB), i.e. a mix of Levilactobacillus brevis 59, Lactiplantibacillus pentosus 129, and Limosilactobacillus fermentum 263, as active antifungal agents in sodium alginate coatings for the control of anthracnose caused by Colletotrichum spp. in mango cv. Palmer and guava cv. Paluma.

Method and results: The hydroalcoholic extracts of fermented and unfermented acerola, cashew, mango, and grape by-products presented variations in acidity, pH, total soluble solids, ascorbic acid, total phenolic compounds, flavonoids, and antioxidant activity. Sixteen chemical constituents were identified, including sugars and organic molecules, in the hydroalcoholic extracts of fermented and unfermented acerola and mango by-products. Hydroalcoholic extracts of fermented acerola and mango by-products caused the highest mycelial growth inhibition % (%MGI: 19.5%-76.31%) against Colletotrichum spp. using the agar-well diffusion method. The fermented extracts (1 g.L-¹) caused the most promising inhibition (%MGI: 35.00%-82.75%) and were identified as the minimum inhibitory concentration. Coatings containing these extracts delayed the development and severity of anthracnose in mango and guava during 15 days of storage (25°C), with a % anthracnose lesion diameter reduction (%ALDR) between 3.93 and 87.01%.

Conclusion: Hydroalcoholic extracts from fermented acerola and mango by-products exhibited notable antioxidant and antifungal activity. Their incorporation into sodium alginate coatings represents an innovative strategy to control postharvest anthracnose in fruits.