Desenvolvimento e aplicação de revestimento biodegradável à base de alginato de sódio e cultura mista de bactérias láticas para biocontrole da antracnose em frutas

Abstract

Mango (Mangifera indica L.) and guava (Psidium guajava L.) are climacteric fruits, which have accelerated respiration and maturation, making them more susceptible to the development of anthracnose, a post-harvest disease caused by fungi belonging to the Colletotrichum spp. genus. Chemical fungicides have traditionally been used to control anthracnose; however, the risks associated with their excessive use have driven the search for alternatives. From this perspective, the application of biocontrol agents, in combination with coating materials, is considered an innovative approach to biopreservation. Thus, the present study aims to evaluate the effectiveness of sodium alginate-based coating added with a mixed culture of lactic bacteria (LAB) in controlling anthracnose in guava and mango. For this purpose, a mixed culture of LAB strains (9 -10 log CFU/g), composed of Levilactobacillus brevis 59, Lactiplantibacillus pentosus 129, and Limosilactobacillus fermentum 263, was lyophilized and added to the sodium alginate (SA) coating (1.5%). The viability of the cells added to the sodium alginate coating was evaluated under different storage conditions (4 and 25 ± 2 °C; 15 days), and the biodegradability of the SA films with and without the BAL addition was evaluated. The formulated coatings (SA + LAB, SA, and negative control) were applied to the fruits, which were subsequently artificially contaminated by different Colletotrichum species. The anthracnose lesion diameter reduction percentage (ALDR%) and the fruit’s physical and physicochemical parameters (total soluble solids (TSS), titratable acidity (TA), pH, ascorbic acid, weight loss, and fruit color) were evaluated on days 6, 9, 12, and 15 of storage at 25 ± 2 °C. The LAB remained viable in the coatings during the 15 days of storage, exceeding 7 log CFU/g or CFU/mL when stored at 4 °C ± 2 °C. The biodegradation of the tested materials was observed in water (drinking and seawater) and in soil, with emphasis on rapid biodegradability in drinking water. The ALDR% ranged from 22.92% to 78.61% in guavas and from 29.13% to 79.94% in mangoes. During the storage period, there was an increase in TSS and pH; a reduction in TA, ascorbic acid, and weight; and maintenance of color parameters, with greater preservation of physical and physical-chemical parameters in fruits coated with SA + LAB and SA. The coating produced was effective in maintaining viable LAB cells throughout storage, demonstrating potential for controlling anthracnose and preserving quality characteristics in guavas and mangoes, contributing to a longer shelf life for the fruits in the post-harvest period.