Potencial Antifúngico de Bioinsumos: Aplicações de Óleos Essenciais e Líquido da Casca da Castanha de Cajú na Preservação de Frutas

Abstract

The antifungal potential of natural bioinputs, such as essential oils and cashew nut shell liquid (CNSL), has emerged as a sustainable and effective alternative for controlling phytopathogenic fungi and preserving tropical fruits post-harvest. The growing demand for natural, safe, and environmentally responsible foods drives the search for innovative strategies to replace the intensive use of pesticides and chemical preservatives, whose continuous application causes environmental impacts, human health risks, and promotes the emergence of resistant microbial strains. In this context, essential oils from clove (Syzygium aromaticum), peppermint (Mentha piperita), tea tree (Melaleuca alternifolia), and babassu oil (Attalea speciosa), as well as CNSL, have shown promise due to the presence of bioactive compounds capable of inhibiting fungal growth, exhibiting low toxicity, and being biodegradable, constituting ecologically responsible and economically viable alternatives. The main objective of this thesis was to evaluate the antifungal potential of these bioinputs against Aspergillus sp. and Colletotrichum gloeosporioides, as well as to assess their effectiveness when incorporated into biodegradable coatings for the preservation of guavas (Psidium guajava L.). The specific objectives included investigating the inhibitory action of essential oils and CNSL on the selected fungi; evaluating the performance of carboxymethylcellulose (CMC) and pectin-based coatings containing these compounds in preserving the physicochemical, microbiological, and sensory attributes of the fruits; and discussing the feasibility of using bioinputs as sustainable alternatives to conventional conservation and phytosanitary control methods. Article 1, titled “Antifungal Efficacy of Essential Oils (Clove, Peppermint, Tea Tree, Babassu) and Cashew Nut Shell Liquid against Aspergillus sp. and Colletotrichum gloeosporioides,” investigated the antifungal activity of essential oils and CNSL through in vitro assays, including minimum inhibitory concentration, conidial germination, and mycelial growth inhibition. Clove essential oil demonstrated the highest efficacy, showing fungicidal potential even at low concentrations, followed by peppermint and tea tree oils, which primarily acted as fungistatic agents. CNSL and babassu oil exhibited more significant antifungal effects at higher concentrations. Additionally, Colletotrichum gloeosporioides was generally more sensitive to treatments than Aspergillus sp., which showed greater intrinsic resistance. The results confirm that these natural compounds represent effective and eco-friendly alternatives for managing fungi in tropical fruits, reducing contamination risks and economic losses. Article 2, “Application of Biodegradable Coatings Containing CNSL and Clove and Peppermint Essential Oils for Guava Preservation,” evaluated CMC and pectin-based formulations incorporating CNSL and essential oils for post-harvest preservation of guavas during storage. The coatings significantly slowed fruit degradation, maintaining parameters such as pH, soluble solids, acidity, vitamin C content, and inhibiting microbial growth. The formulation combining clove oil and CNSL stood out for preserving visual appearance, texture, and nutritional quality, demonstrating the synergistic effect of natural compounds in post-harvest conservation. The final considerations indicate that essential oils and CNSL are promising strategies for controlling phytopathogenic fungi and preserving tropical fruits, offering sustainable alternatives to pesticides while meeting the growing demand for natural, safe, and environmentally responsible foods. The results reinforce the applicability of these bioinputs in the agroindustry and highlight the need for continued research on their mechanisms of action, formulation stability, and validation under commercial conditions, consolidating their use as an innovative and ecologically sound solution for tropical fruit preservation.