Modern trends scrambling with us: Does cooking your meatballs using egg cartons pose a serious health hazard?

Or are we just being over cautious?

Fair enough we know this trend is actually not that new. This all started back in May 2017, when renowned U.S. chef Alton Brown posted an image on his Instagram account of him baking meatballs in egg cartons.  It managed to make an impact on how people, otherwise known as foodies, cook their meatballs. It’s now 2019, and the hack is still being reposted, so it caught our eye. So to start this blog, we decided to verify it against facts, using our science background and our joint passion for food. Let’s start by introducing all of us to the original post.

After this original post, sites like: BuzzFeed (https://www.buzzfeed.com/jesseszewczyk/alton-brown-meatball-cooking-hack), Delish (https://www.delish.com/restaurants/news/a53415/alton-browns-hack-for-meatballs/), Everybody craves (http://craves.everybodyshops.com/alton-browns-genius-meatball-baking-hack-youll-want-to-copy/), among others, broke the news to the rest of the internet (those that do not have an Instagram account). Where the base audience is much wider and can reach to other demographics. This was our cue to add some facts to your life that will make you think twice when you read about “genius hacks” like this one, and would like to try giving them a go at home.

“… in other countries, especially in Europe, the practice of washing eggs is actually discouraged.”

To examine this particular trend, we will take a look at each individual element. Let us start with the egg cartons. In many countries, like the US, eggs are often washed before being transferred into a container for transport to the market. These washes are used to remove harmful pathogens that can infect the eggs and those in contact with them. However, in other countries, especially in Europe, the practice of washing eggs is actually discouraged (“EUR-Lex—32008R0589—EN – EUR-Lex,” n.d.). Why would this be, you may ask? To answer this question, let us start with a brief overview into the structure of the eggshell.

Structure of the eggshell 

The structure of the eggshell starts with a fibrous membrane layer (Chien, Hincke, & McKee, 2009). This layer has a matrix of proteins that functions as a guide for the deposition of calcium salts into the fibrous membrane, resulting in the hard shell that all eggs have and that we are familiar with (Chien et al., 2009). In order to maintain respiratory function with the outside environment, this hard shell is porous (Tyler, 1945).

For commercial food production, the European Council regulation on egg production, No 589/2008 of 23 June 2008, actively discourages the practice because it damages the eggshell allowing contamination to enter the egg.

Beyond this, there is another thin but very important layer of organic matter called the cuticle (Vadehra, Baker, & Naylor, 1970) Its role is crucial for the chick’s survival because it serves as the initial barrier against infection through the hard shell (Mikšík, Ergang, & Pácha, 2014), and here lies the main reasoning against egg washing.

For commercial food production, the European Council regulation on egg production, actively discourages the practice because it damages the eggshell allowing contamination to enter the egg (“EUR-Lex—32008R0589—EN – EUR-Lex,” n.d.). While egg washing can effectively remove pathogens from the egg surface, it leaves the egg much more vulnerable than before because of the damage sustained in the cuticle membrane (Samiullah et al., 2013; Vadehra et al., 1970). This regulation is supported by decades of studies into the practice of washing and rates of trans-shell infection (Vadehra et al., 1970).

Due to the possibility of contamination during the storage and transportation process,… egg containers are considered single-used item by the United States Department of Agriculture (USDA).

In countries where the practice is encouraged, eggs are washed and then immediately put into cold chain storage (Gole et al., 2014; “Shell Eggs from Farm to Table,” n.d.). The emphasis on cold chain storage here is to prevent bacterial growth on the now damaged cuticle. The washing process grants pathogens the ability to cross the cuticle membrane easily (Vadehra et al., 1970). The poultry industry recognizes that eggs can potentially become contaminated during the transportation and storage process, and egg containers are considered single-used items by the United States Department of Agriculture (USDA) (“Meat and Poultry Packaging Materials,” n.d.). However, the container is not sterile. It can have pathogens, bacteria or fungus, from  the egg surface, the transportation process, or the storage environment (Grizard, Dini-Andreote, Tieleman, & Salles, 2014; Soni, Oey, Silcock, & Bremer, 2016; Välsänen, Mentu, & Salkinoja‐Salonen, 1991). The containers themselves are considered an artificial protective layer that is used to protect the eggs from physical damage and further visible contamination. 

Egg containers, aka, egg cartons

Usually made from either plastic, styrofoam, or carton paper, these containers are commonly used and shaped in a way that provides each individual egg with protection against the environment and each other (“Egg carton,” n.d.). For this discussion, we will focus on the paper carton container.

Making a carton paper egg container is a 4-step process. First, the material used for the carton, usually recycled paper and carton, is processed into smooth pulp and corrected in size. The pulp is stored in pools of slurry mixture. This is followed by the molding step, where the pulp is deposited into molds. While a vacuum system forces the pulp into the appropriate molding form, a desiccating process also takes place in order to remove wet products from the formed container shape. The container is then taken out of the molding box for further drying. The drying process can be active drying with high heat or natural air drying.  Finally, when the containers are dried, they are pressed together into the final carton shape that we all know (“Egg Carton Manufacturing Process | Paper Egg Box Making Process,” 2018).

Besides the already discussed cross contamination, flammability of this non-cooking paper material is also a possibility.

As the process above has indicated, the paper used for food packaging is already highly processed and naturally degradable which means that it can be a source of microorganisms (Välsänen et al., 1991). This could even occur during the production process of the containers themselves. Because the paper pulp is stored as slurry pools, this process could potentially also introduce fungal pathogens besides bacteria into the egg carton. 

If the drying process was not done under high temperature, the container is very likely to still harbor pathogens from the original recycled material or the processing environment (Välsänen et al., 1991).  With a high temperature drying process, the surviving microorganisms are often spore-formers identified from the source material used to create the container (Välsänen et al., 1991). These pathogens are often thermoresistant and some can even grow at 4°C. Besides the thermoresistant pathogens, paper is also a porous material which can hide pathogens and reduce effectiveness of conventional sanitization methods. This points to a high possibility of contamination of ingredients stored within this type of paper containers by dormant pathogens (i.e., spores or spore forming organisms) that can survive the production process. 

To continue with the discussion at hand, this would mean the contamination of the meatballs, that we would cook in these carton containers. Besides  cross contamination, flammability of this non-cooking paper material is also a concern. The autoignition point, or combustion temperature without an external flame, of normal paper ranges within 218 to 246 °C, depending on the type used (“T.C. Forensic: Article 10—PHYSICAL CONSTANTS FOR INVESTIGATORS,” n.d.). Considering the type of paper used in common egg container (compressed paper to make the cartons), it would make sense for the temperature to be in the lower half of the autoignition range. 

A potential hidden danger for cooking with non-cooking grade paper material is from the possible temperature inaccuracy of home ovens. You could think that you are cooking at the set temperature, but the oven could be at a higher temperature. Depending on the type of oven, gas or electric, if there is a spark involved in the ignition process of the oven paper can catch fire at an even lower temperature. Therefore, there is a possibility that the common meatball baking temperature of around 400° F (or 205° C) could cause the egg carton to start burning inside the oven.

Meat cooking and meat pathogens

Another factor that adds up to the danger, is the selective evolution caused by the constant presence of low antibiotic concentration from animal waste and feeds runoff.

So, we have come this far in the discussion of this hot topic. Now let us get into matters with how this trend combines not only the possible pathogens from the eggs and the environment (storage of the carton and carton processing), but also risks from meat. We could potentially be looking at a wide range of dangerous pathogens including Salmonella spp., Campylobacter and E. coli. As in the case of meat, many of these organisms can be introduced in different steps from the farm to processing and cooking (Currie et al., 2007; SARTZ et al., 2008). 

In the farm, sources of contamination include  the soil, animal feed, fecal matter, pests, and the animals themselves, as well as environmental contamination (Mor-Mur & Yuste, 2009). Another factor that adds up to the danger, is the selective evolution caused by the constant presence of low antibiotic concentration from animal waste and feeds runoff. That has increased the presence of dangerous antibiotic resistant strains that can contaminate our food (Khachatourians, 1998; Zhang et al., 2014). It is more important than ever to maintain a safe food preparation and cooking practices that reduce our exposure to these pathogens. Antibiotic resistant Salmonella and E. coli, e.g. Salmonella enterica subsp. Enterica serovar Typhimurium (DiMarzio, Shariat, Kariyawasam, Barrangou, & Dudley, 2013) and ESBL-producing ¹Extended-Spectrum-β-Lactamase producing ability gives the pathogen resistance to the most common antibiotic type, β-Lactam. E. coli O64 (Dutta et al., 2013),  can nullify most of our antibiotic arsenal, leading to longer and more damaging infections (Rasheed, Thajuddin, Ahamed, Teklemariam, & Jamil, 2014; V. T. Nair, Venkitanarayanan, & Kollanoor Johny, 2018). 

Due to the mass production nature of commercial food production, contamination of food can spread quickly and extensively through the production chain. Besides the equipment itself, aerosols within the facility are a big source of contaminants due to centralized industrial cooling systems (Mor-Mur & Yuste, 2009). The food industry has developed decontamination processes involving multiple approaches such as steam, vacuum and antimicrobial washes. However, there have also been reports of pathogens surviving the process that also acquired extra resistance against the utilized methods (Capita & Alonso-Calleja, 2013). This further emphasizes the importance of proper sanitization and hygienic food processing as the main microbial control method (Holah, 1992)..

Beyond the processing facility, if all has gone well during transportation, there is the risk of post-process contamination during storage (Bantawa, Rai, Subba Limbu, & Khanal, 2018). Incorrect pest management and control can provide the ideal environment for pests that carry dangerous pathogens to multiply (Boey, Shiokawa, & Rajeev, 2019, “Pests,” n.d.).

One of the most common pests are rats. They are often carriers of many dangerous diseases. A major disease-causing pathogen that can be spread by rats is Leptospira spp. (Boey, Shiokawa, & Rajeev, 2019). Often, the pathogens are spread through the carrier’s urine, in this case, rat urine. These pathogens can contaminate water, soil, or containers (Muñoz-Zanzi, Mason, Encina, Astroza, & Romero, 2014). In this scenario a possible contamination point could also be from contaminated carton containers during storage. Warehouse storage conditions can range from low to little light and dampness. These alongside with the natural carton porosity can provide favourable conditions for the pathogen to survive on their. Leptospira, in case you were not aware, can cause serious diseases ²Most known diseases according to the European Centre for Disease Prevention and Control: Weil’s Syndrome and Severe Pulmonary Haemorrhagic Syndromes diseases and lead to death if left untreated (“Leptospirosis | CDC,” 2019).

We mentioned how the egg cartons themselves can be contaminated. Now let us focus on how food itself, in this case the meat. Meat can be contaminated during processing. After food has already been contaminated by pathogens, these produce toxins. These toxins are also part of the mechanisms of infection of these pathogens (Martinović, Andjelković, Gajdošik, Rešetar, & Josić, 2016).

Bacillus cereus, more specifically B. cereus sensu stricto, is a common food borne pathogen that can be found contaminating raw meat or can be introduced in meat products through contaminated meat additives (Gdoura-Ben Amor et al., 2018; Güven, Mutlu, & Avci, 2006; Smith, Berrang, Feldner, Phillips, & Meinersmann, 2004; Tewari, Singh, & Singh, 2015). The pathogen is particularly common in a wide variety of foods and food products due to its ability to create an endospore that grant it the ability to grow in a wide range of environmental conditions together with its tolerance to common heat sterilization process (Foegeding & Berry, 1997; Gdoura-Ben Amor et al., 2018; Harmon & Kautter, 1991; Soares, Kabuki, & Kuaye, 2012). In meat, it has been reported that the germination of these inoculated endospores can be observed within a temperature range of  10 to 30 °C (Soares et al., 2012). Furthermore, the bacteria also has the ability to form biofilms on industrial surfaces increasing its ability to spread within the food processing chain (Majed, Faille, Kallassy, & Gohar, 2016). The pathogen produces a preformed emetic toxin and several other enterotoxins (Granum & Lund, 1997). The emetic toxin cannot be removed by cooking and can cause nausea and vomiting (Granum & Lund, 1997). Besides the preformed toxins, the pathogen also produces a collection of enterotoxins that can cause diarrhea (Granum & Lund, 1997). For B. cereus, a certain level of bacterial load is allowed (<10³cfu/g or ml), however due to the prevalence of the organism in many steps of food processing, the potential of further contamination within the process as well as the growth potential of the organism make it important to emphasize strict sanitization for prevention of food poisoning (Gdoura-Ben Amor et al., 2018).

Similar to the pathogens, some of the toxins, specifically preformed toxins, can be persistent and require different approaches for decontamination and detoxification. These processes range from heat to gas plasma ³Gas plasma treatment of food is a process where gaseous chemical that can produce free radicals are allowed to permeate the object. An electrical field would then be used to activate the gases and create radical species that would inactivate the toxin as well as destroying the microorganisms. treatment (Karlovsky et al., 2016). However, the presence of the toxin means that unhygienic practices were present  somewhere along the production and process chain. This should warrant caution to any further consumption of the food.

Decision Time

If the carton is already contaminated, it will potentially contaminate the meat.

So far, we have presented to you all the facts that encompass this trend as well as all the potential hiccups that could pose a threat to your health.

With all this knowledge at hand, this trend does seem to pose a potential health hazard because, as we have explained, egg cartons are not made for meatball cooking. They were conceived as a transport and storage device for eggs and so does their production and storage. If the carton is already contaminated, it will potentially contaminate the meat. Some pathogens like E. coli, have the ability to double every 17-20 minutes, for example the strain O157:H7, has a low infectious dose, it can cause illness with exposure to only 20 organisms (Guerini, Arthur, Shackelford, & Koohmaraie, 2006; “Water Treatability Database,” n.d.). Because of their material, carton, there is also the potential of fire and you could say: “but hey I do not have a gas oven for there to be an open flame, I have an electric oven, what about that?” From what we read above, dry heat from an electric oven can also autoignite the paper from the carton. Next time that a trend does come by, think about all the repercussions that it might have and do not let the trends scramble you around!

What if?⁴IMPORTANT DISCLAIMER: We are not endorsing the use of any of these techniques for sanitization of egg cartons at home, we are merely pointing them out for informative reasons.

If despite all of this, we are discussing, you are still willing to use the egg cartons as a cooking device, according to a review on inactivation technology for Bacillus sp. spore formers in food, there are several options that one may use for sanitization of these containers:

Heat-based. Knowing the autoignition point of paper, it is possible to apply a dry heat method at high temperature (121° C) for 1 hour (Soni et al., 2016).

UV-based. Excimer UV ⁵Excimer refers to dimer where the components only bond in excited state. The UV radiation in this case is the resulting energy emission when the components return to ground state and immediately dissociate. radiation has been shown to be able to reduce the number of active spores significantly without applying too much heat into the object. While it is not recommended for actual food, excimer UV radiation treatment works best for surface of cartons and packages, which is relevant for egg carton containers (Soni et al., 2016). The actual problem with this alternative is the fact that conventional households do not have UV emitting devices, making it hard to implement. 

Pressure-based. This is an approach where compression can cause damage to the pathogen proteome and thus kill it. One way that pressure is currently used  is in combination with heat and/or UV based processing (Soni et al., 2016). This powerful combinatory approach may be able to sanitize our carton container but is also highly unlikely to be practical for home usage.

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