Fermented papaya is recognized as a nutraceutical with a diverse and rich composition. Fermentation of fruit with desirable microorganisms could be a strategy to improve the nutritional quality and profile of the fruit. Despite the popularity of fermented papaya, there is still a lack of knowledge on the effects of various fermentation parameters. The goal of this study was to screen the antioxidant and other properties of the products obtained through a variety of fermentation experiments, as well as the impact of adding Gluconobacter oxydans on their physicochemical properties. The strategies used to produce the fermented papaya extracts were spontaneous fermentation and bioinoculation with G. oxydans. Different fermentation tests were performed to measure pH, total soluble solids, reducing sugars, sodium pyruvate content, total phenolic content (TPC), and ferric reducing antioxidant power (FRAP). There was a decrease in TPC during spontaneous fermentations (five assays). However, it can be observed that in the fermentation assays with G. oxydans, there was an increase in TPC and antioxidant properties. The highest content of TPC was observed on the eighth day of P7 (260.18 ± 0.02 µg gallic acid equivalents mL⁻¹) which was fermented with the bacteria and supplemented with glucose. Therefore, phenolic compounds in fermented papaya were found to increase antioxidant capacity as a result of bioinoculation with G. oxydans.

Background: Domestic refrigeration and egg handling are key factors in ensuring household food safety. Inadequate temperature control and poor hygiene in refrigerators can promote the survival and growth of foodborne pathogens. This study aimed to (i) characterize refrigerator temperature profiles and surface microbial contamination and (ii) screen eggs and egg-storage areas for the presence of Salmonella spp. and Campylobacter spp. Methods: Fifty domestic refrigerators were monitored twice in 2024 and 2025 in Porto, Portugal. The temperatures were continuously logged on the lowest shelf, which was swabbed for microbiological analysis. Surface hygiene was evaluated using total viable counts (TVC), Enterobacteriaceae, and Escherichia coli enumerated following ISO methods. Detection of pathogens Listeria monocytogenes, Salmonella spp., and Campylobacter spp. was performed using real-time PCR. Eggs (n = 92 in 2024; n = 88 in 2025), and domestic egg storage areas (total n = 76) were screened for Salmonella and Campylobacter. Results: The mean refrigerator temperatures were 6.0 ± 0.5 °C in 2024 and 6.1 ± 0.5 °C in 2025; 44% and 50% of the units, respectively, exceeded the recommended 6 °C threshold. In 2025, 31 (62%) and 33 (66%) refrigerators showed higher TVC and Enterobacteriaceae counts compared to 2024, whereas E. coli was only detected sporadically. L. monocytogenes, Salmonella spp., or Campylobacter spp. were not recovered from the refrigerator surfaces. Likewise, Salmonella and Campylobacter were not detected in any of the eggs or egg-storage sites. Indicator microorganism’s counts were not associated with the mean temperature. Conclusions: The absence of correlation between ΔT and Δ microbial counts suggests that behaviour-driven hygiene factors, rather than the relatively small year-to-year temperature differences observed, are more influential in determining household bioburden. Maintaining refrigerator temperatures ≤ 6 °C together with simple hygiene practices remains essential for reducing household food safety risks.