By: Alejandro Leiva Arrieta

Plant-based meat alternatives (PMA) have increased in popularity after the Beyond Burger® and Impossible Burger® became available in restaurants and supermarket shelves. These companies made a big statement; they can make plants taste and feel as good as meat. The trend is also on the rise in part because these companies turned to a vast new consumer group known as “flexitarians,” who reduce, not eliminate, their meat consumption in their daily diet ^[1]. As a naturally curious person, I wondered what the major food safety risks associated with PMA would be.

A quick search on the web results in food safety concerns around the high number of weird-to-pronounce ingredients and genetically modified organisms (GMOs). Speaking of GMOs, recently, the Center for Food Safety, a non-profit consumer group, issued a 12-page letter asking the FDA to demand Impossible Foods to recall and stop selling all their “adulterated” burgers because of its GMO ingredient, soy leghemoglobin ^[2]. This strategy was futile because Impossible Foods has already provided compelling evidence that soy leghemoglobin is safe to consume ^[3].

As a food scientist in the making, you live long enough to understand that just because an ingredient is made from a GMO or just because an ingredient has a name that is difficult to pronounce, it does not mean it is unsafe to eat.

Could there be a more compelling food safety risk?

PMA manufacturers claim that their products are less susceptible to bacterial contamination than the real thing. While this may be true because 89% of meat is sold as uncooked fresh meat ^[4], plant-based meat alternatives can be highly susceptible to microbiological spoilage due to their almost neutral pH, and high protein and moisture content ^[1]. Another potential food safety risk is aflatoxin contamination because the primary ingredient in meat alternatives is derived from legumes. Despite these two potential hazards, they are controlled in the extrusion process.

Extrusion is the process in which plant proteins are subjected to high pressure and high temperature to rearrange the proteins at a molecular level to produce a meat-like texture ^[5]. Through this step, endospore-forming bacteria such as Clostridium spp and aflatoxins are eliminated. However, all postprocessing steps are critical regarding product hygiene, handling and packaging to avoid a re-contamination risk ^[1]. Here is where a food scientist’s safety bible comes into play, “The HACCP.”

Allergens

Allergens could be a safety risk in meat alternatives. This is true for soy, which is found in many plant-based food products and is considered one of the eight most common foods associated with food allergy ^[6]. However, allergenicity is not only associated with the nature of the ingredient, but also how the ingredient is processed.

Legumes like soy and pea are the main ingredient in plant-based burgers

Source: https://www.ars.usda.gov/oc/images/photos/k3245-1

Before we make a fuss about these potential contaminants, we need to understand that any food containing protein may induce an allergic reaction ^[7]. This means that any food, not just a plant-based meat alternative, has the potential to cause a food allergy. A food allergy is a violent reaction of the immune system towards a protein present in food. Food allergies are estimated to affect 3% of adults, and between 6-8% of infants ^[8]. Although they are relatively rare, they can be fatal.

Food allergy incidences have doubled in the past 30 years, so researchers have focused on finding ways to eliminate or reduce the presence of allergens through various thermal and non-thermal approaches like genetic engineering, thermal processing and enzyme treatment ^[8]. Among these, food allergen reactivity due to thermal processing (extrusion is considered a thermal process) is the most studied. These approaches are not a silver bullet; removing a food protein allergy is complex, and sometimes the same fundamentals of a process used to reduce or eliminate an allergy result in the exact opposite. In most cases, thermal treatment has shown to decrease allergen reactivity, yet in others, they increase ^[8,9].

Heat-induced allergenicity is not something recently discovered. In 1921, Prausnitz & Kustner published the first scientific article about this matter ^[7]. Today, their work is considered the first meaningful research on food allergy. In their published work, a patient allergic to fish was found to be unaffected by raw fish, even though he suffered severe reactions to cooked fish. It was later found that cooking (in other words, the thermal process) was responsible. Why? Because heating alters proteins by rearranging their molecular structure (known as crosslinking), and can lead to an increase in allergenicity ^[8].

Because soy is an important allergen in the food industry, and because thermal processes cannot guarantee that soy-based products are free from allergens, manufacturers have turned to chickpea, bean lentil, or pea as their main plant protein ingredient (like the Impossible Burger). Although pea, chickpea, bean and lentil are not classified as significant allergens, they are known to be allergenic and to be cross-reactive with other allergens. For example, convicilin, a pea protein allergen, has been shown to interact with vicilin, a lentil protein allergen ^[10]. Cross-reactivity of allergens may explain a study in Sweden that reported three anaphylactic deaths after the consumption of meat products fortified with soy protein. These patients had a previously known allergy to peanuts but not to soybeans ^[7].

Legumes are an excellent source of plant proteins

Source: https://pixabay.com/photos/string-bean-beans-assortment-3861864/

In most cases, cross-reactivity between proteins does not cause an allergy but can be presented in highly sensitive individuals, and this can be lethal ^[10]. Furthermore, allergies from pea, chickpea, bean and lentil have been confined mostly to Europe, Asia and the Mediterranean. Thus, thermal treatment is not entirely responsible for an increase or decrease in allergenicity; it is also dependent upon the type of protein involved and on the population type ^[7].

Our current knowledge of the impact of food processing on allergen structure is not enough to guarantee food free from allergens. Furthermore, food allergy is a multifactorial issue, even involving the genetics of a population. This uncertainty is why we have “hypoallergenic” in the food label, but that by itself is not enough. What happens when novel plant proteins come out to the market, and there is no history of safe use regarding allergens? Before novel food proteins can be brought to market, we need to take precautions to avoid novel food proteins that add to the burden of food allergy. Understanding the mechanisms of protein allergens in food is central to managing allergen risks in the food supply chain.

The current allergenicity risk assessment (ARS) in food is based on homology (how allergen proteins are similar among each other) in GMOs ^[9,11]. Nevertheless, it does not include guidelines to consider the risk of processed induced allergenicity and cross-reactivity of allergen proteins. Several experts say that the current model for ARS should have a combination of methodologies that includes techniques from genetics, immunology, food science, chemistry and biochemistry as well as defined guidelines for interpreting results ^[12].

As we have seen, food allergies are multifactorial; they can be dependent on geography (genetics of a population), ingredients and processing conditions. We still do not know how all these factors interact with each other to produce a food allergy, but what we do know is that the race for plant-based meat alternatives has just begun. New products, novel plant protein sources and new processing technologies are going to come out. Unless the absence of a protein allergen can be demonstrated, it is reasonable to assume that there is the potential for an allergic response in certain individuals ^[7].

Indeed, developing an ARS is difficult, but this just goes to show how little we know about the mechanisms of protein allergenicity. It is in the interest of both the manufacturer and the consumers to accurately predict the allergenicity of a product to avoid withdrawal of the novel food and to prevent potentially lethal allergies. Individuals also have the right to expect the food that they eat is safe. After all, food safety is the concept that “food will not cause harm to the consumer when it is prepared and eaten according to its intended use” ^[13].

Despite all this, let us be practical as well; the probability of allergen risk from thermal processing methods is very low. We should not be afraid of the Beyond or Impossible burgers. In fact, I wrote this post while eating a delicious Beyond Burger, carefree.

I am sure the planet will be happy with this too.

References

1. Wild, F. et al. The evolution of a plant-based alternative to meat. Agro Food Ind. Hi Tech 25, 45–49 (2014).
2. Burton, M. Impossible Foods Issues First Impossible Burger Recall – Eater. https://www.eater.com/2019/3/22/18277642/impossible-foods-burger-recall-plastic (2019).
3. FDA. FDA In Brief: FDA approves soy leghemoglobin as a color additive | FDA. https://www.fda.gov/news-events/fda-brief/fda-brief-fda-approves-soy-leghemoglobin-color-additive (2019).
4. IFT. Fresh meat still popular despite consumers’ desire to limit intake – IFT.org. https://www.ift.org/news-and-publications/news/2019/october/18/fresh-meat-still-popular-despite-consumers-desire-to-limit-intake?utm_campaign=Weekly Newsletter&utm_source=hs_email&utm_medium=email&utm_content=78465351&_hsenc=p2ANqtz—2cPvQrzlw3t8OhwRC34K (2019).
5. Wilson, S., Blaschek, K. & Gonzalez De Mejia, E. Special Article Allergenic Proteins in Soybean: Processing and Reduction of P34 Allergenicity. 47–58 (2005) doi:10.1301/nr.2005.feb.47-58.
6. Sadler, M. J. Meat alternatives – Market developments and health benefits. Trends Food Sci. Technol. 15, 250–260 (2004).
7. Davis, P. J. & Williams, S. C. Protein modification by thermal processing. Allergy: European Journal of Allergy and Clinical Immunology vol. 53 102–105 (1998).
8. Ogawa, T., Samoto, M. & Takahashi, K. Soybean allergens and hypoallergenic soybean products. Journal of Nutritional Science and Vitaminology vol. 46 271–279 (2000).
9. Verhoeckx, K., Broekman, H., Knulst, A. & Houben, G. Allergenicity assessment strategy for novel food proteins and protein sources. Regulatory Toxicology and Pharmacology (2016) doi:10.1016/j.yrtph.2016.03.016.
10. Boye, J., Zare, F. & Pletch, A. Pulse proteins: Processing, characterization, functional properties and applications in food and feed. Food Research International vol. 43 414–431 (2010).
11. FDA. Statement of Policy – Foods Derived from New Plant Varieties | FDA. https://www.fda.gov/regulatory-information/search-fda-guidance-documents/statement-policy-foods-derived-new-plant-varieties (1992).
12. Verhoeckx, K., Broekman, H., Knulst, A. & Houben, G. Allergenicity assessment strategy for novel food proteins and protein sources. Regulatory Toxicology and Pharmacology vol. 79 118–124 (2016).
13. Wallace, C., Manning, L. & Luning, P. The Evolution and Cultural Framing of Food Safety Management Systems – Where from and Where next? Compr. Rev. Food Sci. Food Saf. 00, (2019).
14. Featured Image: Photo by Maude Frédérique Lavoie on Unsplash

Alejandro Leiva Arrieta | Linkedin

Guest Blog Writer

Alejandro obtained his B.S in Biotechnology Engineering from Tecnológico de Monterrey in Mexico. He is currently an M.S. Food Science Student at The University of British Columbia. His research focuses on food processing and food fortification, specifically microencapsulation technologies. Alejandro’s main interests in food science are food processing, food safety, statistical quality control and data science for new food product development.