Is homemade mayo safe to eat? (How to avoid contamination)
By
Dr Rafael Frascino Cassaro (PhD)
| Reviewed by
Dr Anny Manrich (PhD)
The contents of this article are fact-based except otherwise stated within the article.
Author bio
Dr Rafael Frascino Cassaro PhD is a Chemist with expertise in Food Technology, extraction of essential oils from food sources, organocatalysis, extraction by supercritical CO2 and organic chemistry. He writes and reviews content on these topics.
Dr Rafael Frascino Cassaro’s Highlights:
- PIPE-FAPESP Project Coordinator for the company Bioativos Naturais Ltda involving the extraction of essential oils from food sources, with supercritical CO2.
- PhD in Chemistry with research in supercritical fluid reactivity.
- Bachelor of Environmental Chemistry at University of São Paulo State (UNESP)/Brazil
Professional Experience:
Dr Rafael Frascino Cassaro’s Experience:
Dr Rafael coordinated a PIPE-FAPESP Project (Company Research and Innovation Project) for the company Bioativos Naturais Ltda, involving the extraction of essential oils with supercritical CO2 from food sources such as turmeric, ginger, hops, orange bagasse, pepper rose, cupuaçu pie, among others.
Dr Rafael has worked on a project, involving studies of the influence of pre-treatment on the recovery of crude food extracts by extraction with supercritical CO2 (Supercritical Fluid Extraction or SFE) and with pressurized liquids (ethanol and water) for food sources, aimed at obtaining oleoresins; determination of global yield and chemical composition of crude extracts. As a postdoctoral fellow for the Food Engineering department at the University of Campinas/Brazil
Dr Rafael Frascino Cassaro has worked as a substitute Professor at the University of São Paulo State (UNESP) on General Chemistry and Thermodynamics II disciplines for the Food Engineering course.
Education:
- 2009 Bachelor in Environmental Chemistry at the State University of São Paulo, Brazil
- 2015 PhD in Chemistry with research in supercritical fluid reactivity University of São Paulo, Brazil
- 2017 Post Doctoral in Food Engineering Research: Influence of Biomass Pre-Treatment on Supercritical CO2 Extraction: Preservation of High Added Value Assets and Reduction of Process Costs at the State University of Campinas, Brazil
The main publications of Dr Rafael Frascino Cassaro are:
RC Bazito, RF CASSARO, LC OLIVEIRA, RA Gariani, CAO Nascimento. (2013). Proline derivatives as organocatalysts for the aldol reaction in conventional and non-conventional reaction media. Green Processing and Synthesis 2, 43-50
TS Bastos, SB Rodriguez Reartes, MS Zabaloy, RF Cassaro, RC Bazito. (2019).Phase Behavior for the System Carbon Dioxide plus p-Nitrobenzaldehyde: Experimental and Modeling JOURNAL OF CHEMICAL AND ENGINEERING DATA 64 (5), 2116-2125
GH Sakae, LM Takata, AS Paulino, RC Bazito, RF Cassaro, C Princival, .(2013). A high enantioselective Proline-based helical polymer catalyst for aldol type reaction. Blucher Chemistry Proceedings 1 (2), 214-214
You can view some of Dr Rafael’s work below and links to his professional profile.
Research Gate: https://www.researchgate.net/profile/Rafael-Cassaro-2
Fapesp: https://bv.fapesp.br/pt/pesquisador/680718/rafael-frascino-cassaro/
Google Scholar: https://scholar.google.com/citations?user=ToO7HIcAAAAJ&hl=en
Linkedin: https://www.linkedin.com/in/rafael-frascino-cassaro-4a156a37/?originalSubdomain=br
ORCID: https://orcid.org/0000-0002-3729-2858
Reviewer bio
Dr Anny Manrich PhD is a food Engineer with expertise in Food Technology, Natural Polymers, Edible Films, Enzymes, and Nanotechnology. She writes and reviews content on these topics.
Dr Anny Manrich’s Highlights:
- Research and Technology at the Brazilian Agricultural Research Corporation
- PhD in Chemical Engineering with a focus on Biochemistry at the Federal University of Sao Carlos/ Brazil and a one-year scholarship at the Technical University of Munich/ Germany
- Bachelor of Food Engineering at the University of Campinas/ Brazil and a one-year scholarship at the Technical University of Munich/ Germany
“To solve a problem, global vision and multifactorial understanding are necessary. Therefore, in addition to expertise, one should seek multidisciplinary thinking connected with science and reality” – Dr Anny Manrich, PhD.
Professional Experience:
Dr Anny Manrich’s Experience Joining the Brazilian Agricultural Research Corporation, as soon as she completed her doctorate,
Dr Anny Manrich has worked on several projects, including the more than three-year partnership project with BRF, a major food producer in Brazil. As a postdoctoral fellow.
Dr Anny Manrich has also contributed to several business consultancies and research projects of the National Nanotechnology Laboratory System in areas such as food technology, fibres, films and coatings and Nanotechnology; in a very determined way, having a great team relationship, being creative and committed.
Growing concerns about the safe introduction of nanomaterials into today’s life emphasises the need to create regulatory documentation in front of characterising, using and testing them. Dr Anny Manrich worked for two years on a characterization project for nanoscale materials, with the aim of exploring their possible health effects.
Despite not having specific academic training in packaging or polymeric films, Dr Anny Manrich works at the Brazilian Agricultural Research Corporation in areas of edible and biodegradable films produced from agricultural waste and in the development of films with greater resistance to water, having articles published in renowned scientific journals, which demonstrates her multidisciplinary understanding and creativity.
In addition, she worked for four years as a consultant to a food company to develop a line of snacks that are healthy and that add functional ingredients, physiologically active compounds that bring health benefits, made from fruits and vegetables, enabling diet improvement, disease prevention and reduction of nutritional deficiencies.
Dr Anny Manrich participated as a member of the examination board for two Master’s exams and one PhD exam at the Department of Chemical Engineering of the Federal University of São Carlos.
Education:
- 2001 Bachelor in Food Engineering at the State University of Campinas, Brazil
- 1999 One year scholarship at the Technical University of Munich
- 2004 Master in Chemical Engineering at the Federal University of São Carlos, Brazil
- 2012 PhD in Chemical Engineering at the Federal University of São Carlos, Brazil
- 2010 One year scholarship at the Technical University of Munich
The main publications of Dr. Anny Manrich are:
Articles
Manrich, A., Moreira, F. K., Otoni, C. G., Lorevice, M. V., Martins, M. A., & Mattoso, L. H. (2017). Hydrophobic edible films made up of tomato cutin and pectin. Carbohydrate Polymers, 164, 83-91.
Mendes, J. F., Norcino, L. B., Martins, H. H. A., Manrich, A., Otoni, C. G., Carvalho, E. E. N., … & Mattoso, L. H. C. (2020). Correlating emulsion characteristics with the properties of active starch films loaded with lemongrass essential oil. Food Hydrocolloids, 100, 105428.
Norcino, L. B., Mendes, J. F., Natarelli, C. V. L., Manrich, A., Oliveira, J. E., & Mattoso, L. H. C. (2020). Pectin films loaded with copaiba oil nanoemulsions for potential use as bio-based active packaging. Food Hydrocolloids, 106, 105862.
Manrich, Anny, et al. Immobilization of trypsin on chitosan gels: Use of different activation protocols and comparison with other supports. International Journal of Biological Macromolecules 43.1 (2008): 54-61.
Manrich, Anny; Komesu, Andrea ; Adriano, Wellington Sabino; Tardioli, Paulo Waldir ; Giordano, Raquel Lima Camargo . Immobilization and Stabilization of Xylanase by Multipoint Covalent Attachment on Agarose and on Chitosan Supports. Applied Biochemistry and Biotechnology, v. 161, p. 455-467, 2010.
Mendes, J. F., Martins, J. T., Manrich, A., Neto, A. S., Pinheiro, A. C. M., Mattoso, L. H. C., & Martins, M. A. (2019). Development and physical-chemical properties of pectin film reinforced with spent coffee grounds by continuous casting. Carbohydrate polymers, 210, 92-99..
Milessi, T. S., Kopp, W., Rojas, M. J., Manrich, A., Baptista-Neto, A., Tardioli, P. W., … & Giordano, R. L. (2016). Immobilization and stabilization of an endoxylanase from Bacillus subtilis (XynA) for xylooligosaccharides (XOs) production. Catalysis Today, 259, 130-139.
Mendes, J. F., Norcino, L. B., Manrich, A., Pinheiro, A. C. M., Oliveira, J. E., & Mattoso, L. H. C. (2020). Development, physical‐chemical properties, and photodegradation of pectin film reinforced with malt bagasse fibers by continuous casting. Journal of Applied Polymer Science, 137(39), 49178.
Mendes, J. F., Martins, J. T., Manrich, A., Luchesi, B. R., Dantas, A. P. S., Vanderlei, R. M., … & Martins, M. A. (2021). Thermo-physical and mechanical characteristics of composites based on high-density polyethylene (HDPE) e spent coffee grounds (SCG). Journal of Polymers and the Environment, 29, 2888-2900..
Mendes, J. F., Norcino, L. B., Martins, H. H., Manrich, A., Otoni, C. G., Carvalho, E. E. N., … & Mattoso, L. H. C. (2021). Development of quaternary nanocomposites made up of cassava starch, cocoa butter, lemongrass essential oil nanoemulsion, and brewery spent grain fibers. Journal of Food Science, 86(5), 1979-1996.
Manrich, A., Martins, M. A., & Mattoso, L. H. C. (2021). Manufacture and performance of peanut skin cellulose nanocrystals. Scientia Agricola, 79.
Nascimento, V. M., Manrich, A., Tardioli, P. W., de Campos Giordano, R., de Moraes Rocha, G. J., & Giordano, R. D. L. C. (2016). Alkaline pretreatment for practicable production of ethanol and xylooligosaccharides. Bioethanol, 2(1)..
Manrich, Anny, de Oliveira, J. E., Martins, M. A., & Mattoso, L. H. C. Physicochemical and Thermal Characterization of the Spirulina platensis. J. Agric. Sci. Technol. B, v. 10, p. 298-307, 2020.
Book Chapter
Terra, I. A. A., Aoki, P. H., Delezuk, J. A. D. M., Martins, M. A., Manrich, A., Silva, M. J., … & Miranda, P. B. (2022). Técnicas de Caracterização de Polímeros. Nanotecnologia Aplicada a Polímeros, 614.
Conference Papers
Ferreira, L. F., Luvizaro, L. B., Manrich, A., Martins, M. A., Júnior, M. G., & Dias, M. V. (2017). Comparação da estabilidade de suspensões poliméricas de amido/tocoferol e quitosana/tocoferol. In: CONGRESSO BRASILEIRO DE POLÍMEROS, 14., 2017, Águas de Lindóia, SP.
Manrich, A., Hubinger, S. Z., & Paris, E. C. (2017). Citotoxicidade causada por nanomateriais: avaliação do micronúcleo. In: WORKSHOP DA REDE DE NANOTECNOLOGIA APLICADA AO AGRONEGÓCIO, 9., 2017, São Carlos. Anais… São Carlos: Embrapa Instrumentação, 2017. p. 655-658.
Manrich, Anny, et al. Immobilization and Stabilization of Xylanase by multipoint covalent attachment on Glyoxyl Agarose Support. The 31st Symposium on Biotechnology for Fuels and Chemicals. 2009.
Manrich, Anny, et al. Application of immobilized xylanase on hydrolysis of soluble wood hemicelluloses after using microwave and organosolv pre-treatments. The 32nd Symposium on Biotechnology for Fuels and Chemicals. 2010.
You can view some of Dr Anny’s work below and links to her professional profile.
Research Gate: https://www.researchgate.net/profile/Anny-Manrich-2
Scopus: https://www.scopus.com/authid/detail.uri?authorId=23103497100
Google Scholar: https://scholar.google.com/citations?hl=en&user=Ea9qpr0AAAAJ
Linkedin: https://br.linkedin.com/in/anny-manrich-20693129
In this brief article, we are going to answer the question “Is homemade mayo safe to eat?”. We will also discuss how homemade mayonnaise can get contaminated and how to properly store it.
Is homemade mayo safe to eat?
It depends on the recipe, some mayo recipes are intrinsically safe while others are not. An unsafe recipe used with raw eggs to prepare mayonnaise has a very high risk of getting contaminated and causing food poison.
While pH levels can be used to assess the microbiological safety of mayonnaise, it’s often impractical for home cooks and caterers to apply these criteria due to limited kitchen facilities.
There have been numerous reported cases of food poisoning, particularly Salmonella outbreaks, associated with the consumption of homemade mayonnaise. It’s possible that in most cases can be attributed to the use of unsafe recipes in mayonnaise preparation.
Eliminating intrinsically unsafe recipes from use could potentially lead to a significant reduction or even the elimination of food poisoning outbreaks associated with homemade mayonnaise consumption. (1)
How can eggs get contaminated?
Salmonella can be present on the outer shells of eggs. This usually occurs when birds lay their eggs or when the eggs come into contact with bird feces after being laid. It is worth noting that handling eggs purchased from a grocery store is not a common source of illness.
The eggs undergo thorough washing before they are made available in stores. Salmonella can penetrate eggs as they are being formed inside the chicken, even before the eggshell is fully developed. Some mayonnaise producers incorporate dried egg products in their recipes.
The drying process effectively eliminates a significant number of bacteria that were originally present in liquid eggs. Once the product reaches its dried state, the microbiological population stabilizes, and any decline in quality occurs gradually over time.
During the drying process, the number of Salmonella bacteria can be greatly reduced. However, Salmonella can still pose a challenge in dried egg products. (2-4)
How can homemade mayo get contaminated?
Major risk factors contributing to foodborne disease outbreaks include improper storage at non-recommended temperatures, extended periods of inadequate storage, lapses in hygiene practices, and the potential for cross-contamination and recontamination.
While eggs can become contaminated with Salmonella through various means, such as infections in reproductive organs or penetration of the eggshell and membranes, this pathogen is more likely to reach harmful levels, often leading to illness, when mayonnaise is stored under unsuitable conditions (5)
What is the role of acidity in homemade mayo safety?
From a microbiological perspective, it is recommended that a minimum of 60 ml of vinegar per whole egg, 40 ml per egg white, or 20 ml per egg yolk (with a 6% w/v acetic acid content) is necessary to create Salmonella-free mayonnaise in a home setting.
It has been observed that the pH level of mayonnaise is primarily influenced by the ratio of egg to vinegar, and it decreases as this ratio decreases.
Even though egg yolk, egg white, and whole egg have distinct pH values, their impact on the pH of mayonnaise is the same when the ratio is less than 2.5.
Additionally, the presence of salt and sugar tends to decrease the pH of mayonnaise, while oil, mustard, and pepper have the opposite effect. A mayonnaise recipe can be considered safe only when the ratio of egg to vinegar is equal to or less than the established safe ratio. (1, 6)
How to store homemade mayo safely?
For safe storage of homemade mayo, it’s important to maintain a pH level of 4.1 or lower. It’s recommended to initially incubate the mayo at room temperature (18-22°C) for 24 hours before refrigeration. This room-temperature incubation is advised as low-temperature incubation affords some protection to the salmonellas against the antimicrobial effects of organic acids.
After that period, homemade mayo should be stored in a refrigerator at 4°C. When handling eggs, it’s crucial to exercise caution. Whenever possible, use fresh eggs and avoid cracked ones. For catering purposes, it’s advisable to prepare mayonnaise using pasteurized liquid eggs.
It’s essential not to mix any unused mayo with fresh batches. Adding other foods to mayo can impact its antimicrobial properties, so this should be considered during preparation. (7)
What are the symptoms of food poisoning?
The majority of individuals who contract Salmonella experience symptoms such as diarrhea, fever, vomiting, and stomach cramps. These symptoms typically manifest within a window of 6 hours to 6 days after infection and typically persist for 4 to 7 days.
Most people recover without requiring antibiotics; however, these medications are essential for patients who are severely ill or at risk of becoming severely ill. Individuals with diarrhea should make a point of increasing their fluid intake. In rare cases, Salmonella can enter the bloodstream and result in a potentially life-threatening infection. (2)
Conclusion
In this brief article, we answered the question “Is homemade mayo safe to eat?”. We also discussed how homemade mayonnaise can get contaminated and how to properly store it.
Was this helpful?
References
1.-
XIONG, R.; XIE, G.; EDMONDSON, A. S. Modelling the pH of mayonnaise by the ratio of egg to vinegar. Food Control, v. 11, n. 1, p. 49-56, 2000.
2.-
Centers for Disease Control and Prevention [CDC]. Salmonella and Eggs. 2023.
3.-
Belyavin, C. G. Eggs: Use in the Food Industry. Encyclopedia of Food and Health, 476–479. 2016.
4.-
Delves-Broughton, J., & Board, R. G. EGGS | Microbiology of Egg Products. Encyclopedia of Food Microbiology, 569–573. 1999.
5.-
DE OLIVEIRA ELIAS, Susana et al. Contributor factors for the occurrence of salmonellosis during preparation, storage and consumption of homemade mayonnaise salad. Food Research International, v. 78, p. 266-273, 2015.
6.-
MIRZANAJAFI-ZANJANI, Mina; YOUSEFI, Mohammad; EHSANI, Ali. Challenges and approaches for production of a healthy and functional mayonnaise sauce. Food science & nutrition, v. 7, n. 8, p. 2471-2484, 2019.
7.-
RADFORD, S. A.; BOARD, R. G. Fate of pathogens in home-made mayonnaise and related products. Food microbiology, v. 10, n. 4, p. 269-278, 1993.