Imitating animal protein products with plant-based alternatives is a growing trend. For example, plant-based burgers such as Beyond Meat and the Impossible Burger have established brand name recognition and are available at some major fast-food chains. Plant-based imitations are not limited to burgers; Just Egg imitates omelets and scrabbled eggs and has appeared on Tim Horton's menu. These plant-based products need to aim a larger market than the vegan one, which remains low at less than 2% of the population. Thus, they are also marketed as an environmentally friendlier alternative. For instance, Just Egg website claims that its product use 77% less water and has a 40% lower carbon footprint than eggs. In this short note, we argue that these environmental claims, when put in perspective, are misleading the consumer.
The claims of Just Egg sustainability are based on a life-cycle analysis (LCA) study. Such studies examine the impacts of all the inputs needed to produce a final product, in this case Just Egg and eggs. In other words, to calculate the impact of Just Egg, the environmental impact of the production of the raw ingredients, including mung beans (the source of protein), canola oil and small amounts of 14 other ingredients are considered. In the case of eggs, the LCA considers the grains needed to feed the laying hens as well as the environmental impacts of hens and their manure. LCA analyses are widely used and are scientifically approved methodologies.
The first issue we have is related to the segments of the value chain for which LCA for Just Egg and eggs are compared. The LCA analysis used is limited to the production of the inputs for the Just Egg product, which is compared with the LCA of eggs[1]. So, the comparison is between raw products before their transformation into Just Egg and eggs at the farm. Thus, the manufacturing impact of Just Egg is not taken into account, while it is for eggs (hens process inputs into eggs). This omission is important given that the ingredients to make Just Eggs need extensive processing. The protein isolate extracted from the raw mung beans is obtained through several manufacturing processes, including grinding the mung beans into flour and soaking them with sodium hydroxide to solubilize the protein. The protein extract is separated using a centrifuge followed by addition of sodium chloride to create a curd precipitation. This protein concentrate is then washed, pasteurized and spray dried. This manufacturing process uses water and energy, increasing the carbon footprint of the final product.
Packaging and transportation, which are not taken into account in the comparisons made by Just Egg, also seem to favor eggs. All Just Egg products are transported from one plant in Minnesota to various locations in North America. At the opposite, egg farmers are located all over North America, reducing the transportation footprint of eggs relative to Just Egg. Just Egg is liquid and comes in 355 ml plastique bottles, while eggs are packaged in low-grade carton crates at the end of their recycling purposing.
The second issue we have concerns the unit of comparison. The calculated environmental impacts from the LCA are expressed in weight (kg) of final product.
However, weight does not capture the functional unit of the product consumed. Omelets and eggs are normally consumed for their nutritional contribution in protein to diet. The protein content of Just Egg, using values available on their website, is 109 grams of protein per kilograms of Just Egg. This compares to 130 g of protein per kilogram of eggs. However, the availability (digestibility) of protein in eggs differ from the one from pulses (i.e. mung beans). International nutritional guidelines, set out by the FAO, provide methodologies to correct protein contents according to how they contribute to human health[2]. Table 1 reports the digestibility scores for eggs, tofu and mung beans. These scores express, in percentage, the quality of the protein content for human nutrition[3].
After adjustments as prescribed by the FAO (Table 1 data), one kilogram of Just Egg and one kilogram of eggs contain 63 g and 147 g of available proteins, respectively. Thus, comparisons based on available proteins for human nutrition greatly reduce the footprints of eggs relative to Just Egg. In fact, using the numbers put forward by Just Egg and adjusting them for available proteins results in eggs having a carbon footprint 25% lower than Just Egg.
Table 1: Protein quality scores for Eggs, Tofu and Cooked peas
Product DIAAS(%)
Eggs 113
Tofu 52
Cooked Peas 58
Source: Values from Phillips (2017).
This information implies that a plastic bottle of Just Egg contains 23.2 g of available proteins, compared to 176.28 g per dozen eggs. In other words, more than seven plastic bottles of Just Egg are needed to transport the same quantity of proteins contained in a carton crate of twelve eggs. Obviously, the environmental footprint of seven plastic bottles is larger than one low grade carton crate. The plastique bottles also take larger space in transports and in disposable bins, contributing negatively to the environmental footprint of Just Egg.
In summary, the claims put forward by Just Egg regarding their lower environmental footprint relative to eggs are misleading consumers for the following reasons: 1-the LCA analysis does not consider the numerous manufacturing operations involved in producing Just Egg; 2-The comparison does not take into account the environmentally friendlier packaging of eggs (carton crates) relative to Just Egg (plastic jugs); 3-The comparison is based on 1 kg of products instead of 1 kg of available protein for human nutrition. This correction alone reverses the conclusion of Just Egg regarding the environmental performance of their product; 4-The comparison does not take into consideration transportation impacts of the final products. Seven plastic jugs of Just Egg transported all over North America from one plant in Minnesota compared (on an available protein basis) to one dozen eggs in a carton crate transported for numerous production points across North America.
There might be many reasons to consume Just Egg, but reducing one’s environmental footprint is not one of them.
References.
FAO 2013, Dietary protein quality evaluation in human nutrition: Report of an expert consultation. FAO Food and nutrition Paper. FAO : Rome. 66 p.
Mathai, J. K., Liu, Y., & Stein, H. H. (2017). Values for digestible indispensable amino acid scores (DIAAS) for some dairy and plant proteins may better describe protein quality than values calculated using the concept for protein digestibility-corrected amino acid scores (PDCAAS). British Journal of Nutrition, 117(4), 490-499.
Phillips, S. M. (2017). Current concepts and unresolved questions in dietary protein requirements and supplements in adults. Frontiers in nutrition, 4, 13.
Sheldon, S., Giles, D., & Lazimy, U. (2017). JUST, Inc. Sustainability KPI Calculation Methodology. San Francisco, CA, USA.
[1] In the study Just Eggs is compared with liquid eggs. Given that a vast majority of sales at the retail level are for eggs and not liquid eggs, we pursue our comparison with eggs.
[2] Until recently, protein digestibility-corrected amino acid scores (PDCAAS) was the recommended method to evaluate the quality of the protein with regards to human needs and the digestibility of each amino acid. However, it has been shown that PDCAAS underestimates the value of high-quality proteins and overestimates the value of low-quality proteins (Mathai et al. 2017). To avoid these shortcomings the Food and Agriculture Organization (FAO) now recommends using a new procedure called digestible indispensable amino acid score (DIAAS) (FAO 2013)
[3] DIAAS ≥100% = Excellent or High protein quality