Microbial Load and Morphological Characterization of Bacteria and Fungi in Dough Stored at Different Temperatures and a Contaminated Pickle Sample
Year: 2026
Type: article
Abstract: Wheat dough is often kneaded in advance and held before use in south Asian households, yet little is known about how holding conditions affect its microbial load. This study isolated, enumerated and characterized bacteria and fungi from homemade kneaded wheat dough held for 24 h under refrigeration (4 °c; S1) or at room temperature (S2), and from a visibly contaminated homemade pickle (S3). ten-fold serial dilutions were spread on nutrient agar (NA; 10⁻⁵ and 10⁻⁶) and potato dextrose agar (PDA; 10⁻⁴ and 10⁻⁵), colonies were counted, pure bacterial cultures were obtained by streak plating, and four isolates (b1–b4) were described by colony morphology and gram reaction. only the 10⁻⁶ NA dilution gave countable plates for all samples. from these plates, the estimated bacterial load was highest in room-temperature dough (1.5 × 10⁹ CFU g⁻¹; 9.18 log CFU g⁻¹), lower in refrigerated dough (8.5 × 10⁸ CFU g⁻¹; 8.93 log CFU g⁻¹) and lowest in the pickle (4.8 × 10⁸ CFU g⁻¹; 8.68 log CFU g⁻¹). the pickle yielded the highest fungal count (72 colonies at 10⁻⁴; about 7.2 × 10⁶ CFU g⁻¹), and large, dark, spreading molds were evident on PDA from room-temperature dough. Three of the four bacterial isolates were gram-positive, and one was a gram-negative rod. fungal colonies were morphologically consistent with Aspergillus species (A. candidus- and A. niger-like). These identifications are presumptive because no molecular or other confirmatory tests were performed. because several Aspergillus species are potential mycotoxin producers, these observations have food-safety relevance, although mycotoxins were not measured in this study. Under the conditions examined, refrigeration was associated with a lower estimated bacterial load in kneaded dough; the study also illustrates a simple, low-cost culture-based workflow for teaching and screening laboratories and identifies the replication and confirmatory identification needed in future work.
Language: English
Topic: Food Safety and Hygiene
Subfield: Food Science
Domain: Life Sciences
Open Access status: diamond
OpenAlex ID: W7223558911