Bread comprises one of the earliest foods prepared by humans and has been an integral part of the human diet. Breads are prone to chemical, physical, and microbial spoilages, demanding strategies from food industries to ensure the shelf-life and quality of the product. Bread shelf-life depends on the formulation and storage conditions, reaching 2–4 days when storage is done at room temperature or up to 14 days at refrigeration conditions (Cauvain and Young, 2011). Amongst the spoilage agents, fungi are the most critical causes of shelf-life reduction and considerable losses in the bakery industry.

Contrary to bread, panettones are bakery products with a relatively long shelf life, and their consumption increases during Christmas. Panettones are products with an upward trend because of their sensorial features, which appeal to different types of people in different countries (Consumidor Moderno, 2023; Stefanello et al., 2019a, Stefanello et al., 2019b). During the industrial production of panettone, the main challenges comprise the production of the dough with the capacity to hold fruits and raisins during proofing and baking and the achievement of a shelf-stable product formulation (Benejam et al., 2009).

Deterioration caused by spoilage fungi is a ubiquitous problem for bread and bakery products (Pitt and Hocking, 2009; Garcia and Copetti, 2019). In addition to the economic losses, which are around 5 % in the United States of America (USA) and 10 % in countries like Brazil (Freire, 2011), it may cause the depreciation and rejection of the brand that commercializes the product, as moldy bread represents 2/3 of complaints about moldy food by Brazilian consumers (Hawkins et al., 2007; Lemos et al., 2018).

The contamination of bakery products by filamentous fungi in the industry may occur mainly in the cooling, slicing, and packaging steps (Legan, 1993; Garcia et al., 2019), where the environmental air has been described as an essential source of fungal spores (Andrade and Salustiano, 2008; dos Santos et al., 2016; Garcia et al., 2019). The mold spores spread through the air as aerosols and are mainly responsible for the spoilage of baked goods like bakery products.

One of the ways to avoid spoilage of bakery products is by using food-grade preservatives, such as acetic and sorbic acid and, mainly, propionic acid and its salts (Gioia et al., 2017). However, their use can be limited to the appearance of resistant strains such as Penicillium roqueforti, which can cause bread spoilage at sub-lethal levels of preservative concentrations (Suhr and Nielsen, 2004). Furthermore, the use of these preservatives has called attention to the concerns about their solubility and toxicity (Dengate and Ruben, 2002). As such, several alternative strategies have been studied to extend the shelf-life of bakery products. One of the most promising strategies for application in bakery products comprises microorganisms, given that several are subjected to fermentation.

Several studies have used microorganisms from natural sources, such as dough fermentation, as novel alternatives to avoid bread spoilage (Valerio et al., 2009; Coda et al., 2013; Sun et al., 2020). This process, called biopreservation, consists of using endogenous lactic acid bacteria (LAB) and yeasts isolated from natural sourdoughs, which possess the ability to produce compounds (mainly organic acids) with fungistatic or fungicidal properties (Stefanello et al., 2019a). Lactic, acetic, formic, phenyllactic, and citric acids comprise the primary acids produced by these microorganisms during fermentation (Valerio et al., 2009; Axel et al., 2015; Rizzello et al., 2011).

Although the studies using microorganisms isolated from natural sourdoughs demonstrate satisfactory results on in vitro tests, reports demonstrating the effectiveness of these microorganisms in natural (in situ) food matrices, such as bakery products, are less frequent. Therefore, this study aimed at ascertaining the impact of the individual LAB Limosilactobacillus fermentum IAL 4541 and yeast Wickerhamomyces anomalus IAL 4533 on the growth inhibition of spoilage fungi isolated from bakery products as a means towards the extension of the shelf-life of conventional and multigrain bread and panettones.