Microbiological Characterization of Baru Nuts From the Cerrado Biome, Brazil

This study aimed to microbiologically characterize baru nuts, a seed widely consumed in Brazil with growing relevance in the export market. Analyses were conducted for mesophilic and thermophilic aerobic spore-forming bacteria, total mesophilic aerobes, Enterobacteriaceae, Salmonella, Staphylococcus aureus, lactic acid bacteria, molds, and yeasts. Subsequently, Enterobacteriaceae isolates were identified by MALDI-TOF. It was found that in all baru nut samples, counts of S. aureus, lactic acid bacteria, and thermophilic aerobic spore-forming bacteria were below the quantification limits (< 2log₁₀ CFU/g, < 1log₁₀ CFU/g, and 1log₁₀ spore/g, respectively). All samples had counts above the quantification limits for mesophilic aerobic spore-forming bacteria (> 1log₁₀ CFU/g) and total mesophilic aerobes (> 2log₁₀ CFU/g). Enterobacteriaceae counts were below 2.22log₁₀ CFU/g, while molds and yeasts reached up to 2.70log₁₀ CFU/g. Identification of 17 species from the Enterobacteriaceae family revealed potentially pathogenic microorganisms that serve as important biological markers, including emerging and multidrug-resistant species. Franconibacter pulveris was the most abundant, representing 41.9% of all isolates, followed by Pseudescherichia vulneris and Pantoea septica, each accounting for 10.5%. In addition, Cronobacter sp. (3.8%) and Salmonella sp. (1.0%) were identified-both pathogens commonly associated with nuts and low-water-activity products. The presence of these sanitation-relevant and understudied species highlights the need for ongoing microbiological monitoring and a better understanding of the microbial ecology in food products. PRACTICAL APPLICATIONS: This study provides information on the microorganisms found in baru nuts. These results can help producers improve handling and processing practices, contributing to safer products for consumers and supporting the development of quality standards for this native Brazilian nut.