New evidence on Salmonella in eggs is brought into light by a recent study considering the risk factors, from shopping to consumption, using the Critical Consumer Handling (CCHs) steps identified in consumers’ journey. Led by prof. Paula Teixeira from Escola Superior de Biotecnologia, Universidade Católica Portuguesa, Portugal, this study was performed by a team of researchers from the SafeConsume project. The manuscript describing the study results is in the pipe-line for being published in the second-best ranked scientific journal for food science in Web of Science – Comprehensive Reviews in Food Science and Food Safety.
Where does the problem lie?
There are uneven regulations across the European countries regarding the egg storage temperature and this can only add to the unsafe practices, particularly when cold eggs are left outside, at room temperature, and condensation could favour the bacteria growth on the surface and the entrance of pathogenic bacteria inside the egg shell. Thus, consumers should be aware on the benefits of refrigerated storage of eggs that could prevent Salmonella
growth.
Nonetheless, refrigeration at the consumer stage will only be effective if the eggs from the collection time until purchasing are kept at temperatures that prevent the growth of Salmonella. If not, contaminated eggs may reach consumers with high levels of Salmonella. At the moment, although there are countries in Europe where eggs are entering into a cold chain when starting their way to consumers, there are discrepancies in recommendations and legislation regarding temperatures early and later in the chain. The temperature control requirements of existing EU egg handling regulations need a careful reconsideration. Substantial efforts should also be made to harmonise the discrepancies between relevant regulations in Europe, USA and the rest of the world.
Sources of eggs as unsupervised backyard-eggs, resulting of urban farming, farmer markets or eggs bought on side-roads in the rural areas, after being kept in plain sun, are raising concerns due to higher Salmonella prevalence when compared to ones from different production systems.
Advice to consumers
“Inspect eggs when purchasing and avoid buying eggs from unsafe sources, dirty and cracked eggs that might pose risks to consumers! If available, buy Salmonella-free certified eggs or pasteurized eggs!” says prof. Paula Teixeira.
If you have to choose between brown and white eggshells you should know that small brown eggs from caged hens have lower likelihood of being contaminated than large, white, eggs from free-range hens that could also carry more dirt on their surface.
When buying from the store, check the best-before date and ensure that you have enough time to consume eggs while safe and avoid waste. Keep the eggs refrigerated below 4°C!
Should we wash or not the eggshell?
Consumers are advised against washing eggs that could remove the protection cuticles and favour contamination. Better buy eggs with clean eggshell instead of washing them! However, if eggs are dirty on the outer surface, they should be washed before cooking. In this case the water temperature should be 10°C warmer than the temperature of the eggshells to prevent contamination. If one uses fine sandpaper, towel or brushes to remove dirt, be aware that aerosols containing salmonellae are formed.
Other kitchen practices related to eggs
Clean your hands thoroughly with warm water and soap after handling raw eggs! Salmonella may survive weeks on surfaces that are not clean, so carefully wash the utensils and surfaces after handling raw eggs. Avoid recipes with raw eggs or medium cooked eggs! The alternative is to use pasteurized eggs (home pasteurization is possible), only use fresh eggs or take into consideration that hardboiled eggs could be equally delicious. Ensure a proper time and temperature for egg cooking and monitor the practice!
Manuscript
Maria João Cardoso, Anca Ioana Nicolau, Daniela Borda, Line Nielsen, Rui Leandro Maia, Trond Møretrø, Vânia Ferreira, Susanne Knøchel, Solveig Langsrud, Paula Teixeira. 2021. Salmonella in eggs: from shopping to consumption - a review providing an evidence-based analysis of risk factors, Comprehensive Reviews in Food Science and Food Safety, DOI: 10.1111/1541-4337.12753
