Sustainability of plant-based meat alternatives

[music] Welcome to Science Sessions, the podcasts of the proceedings of the National Academy of Sciences, where we connect you with Academy members, researchers, and policymakers. Join us as we explore the stories behind the science. While meat and other animal-sourced foods can provide essential nutrients, overconsumption can contribute to human diseases, and the production of meat is associated with significant greenhouse gas emissions. To reduce the amount of meat people consume, a variety of plant-based alternatives have entered the consumer market in recent years. Many of these products are intended to replace ground meat, including traditional veggie burgers, and more sophisticated products that attempt to replicate the taste, texture, and even juices of a beef burger, while the raw plant ingredients that go into these products might be preferable to meat from a sustainability perspective. Many of these products also undergo extensive processing, but is not always considered in such comparisons. I'm Matthew Hardcastle, and in this special future episode, we will hear from biologists, food scientists, and economists, taking an in-depth look at the broad health and environmental impact of plant-based meat alternatives. Rudolph Barangu, a biologist at North Carolina State University in Raleigh, is an organizer of a recent PNES special feature on the sustainability of animal-sourced foods and their plant-based alternatives. Barangu explains the potential opportunities and challenges for plant-based meat alternatives to help mitigate the environmental impact of meat. We all appreciate how important animal sources foods are for our diets and the many benefits that they have had over the past few millennia in terms of promoting human development and health. The inordinate amount of resources and land and energy that has to go into the breeding and development of livestock for animal-sourced foods is a major challenge that we have to address and the rise of plant-based alternatives is certainly a sign of some solutions that beckon before us. There are specific brands and specific kinds of products that have captured the imagination of some of the customers that have also maturely captured their interest and literally addressed their appetite for alternatives. If we go beyond and outside, the developed Western world, there's been very limited interest and limited availability and affordability of some of those products. How we balance land and emissions and water on the operational side with the needs that we have in the tradition side and economic development side is really the challenge that we're trying to address. There's not one solution necessarily to the different challenges that we have here. I think we'll be naive and overly simplistic to presume that one set of solutions to one set of problems can be addressed and deployed equally evenly, unilaterally in all those different jurisdiction and contexts. In comparing meets to plant-based alternatives, there are a variety of factors to consider, including their respective nutrition, health, environmental and cost impact. In a PNAS article in the special feature, Marco Springman, an environment and health researcher at the University of Oxford and University College London and his colleagues, compared 24 plant-based meat and milk alternatives with both animal source foods and unprocessed plant-based foods across multiple metrics. Traditional meats and milks, they're usually fairly high sources of both calories and saturated fat, meat and milk replacements have much lower levels on saturated fat, higher levels of fiber, and they often also good sources of iron zinc and sometimes also ribofliving. In general, we find that replacing meat and milk with alternative products could actually reduce nutritional imbalances from around 10% to 5%. The next analysis we did was a health analysis. Animal source foods, they had on average negative health impacts because they had hemiron, they had cholesterol and so on. We found that things like peas, tempeh, soybeans and so on reduced the risk more. Processed meat alternatives like veggie burgers still had a good impact here. If you put everything together there, there was a reduction in total risk by around 4% if you replace all of this. You might have heard that veggie burgers are much more climate-friendly than normal burgers and that is indeed what we found as well. We didn't only look at greener scarce emissions, we also looked at land use and water use. Processed meat replacements reduce averaged impacts by around a factor of 20, whereas unprocessed products like soybeans or peas, they can double that still. On a cost level, we did find that many of those processed alternatives, they are more costly. Sometimes double the price when we look at certain meat alternatives like some veggie burgers, for example. Compared to less processed plant-based foods, such as beans, nuts and grains, the plant protein ingredients used in meat alternatives undergo additional manufacturing steps after harvesting. In another PNAS article in the special feature, Bill A. Mutus, a food scientist at North Carolina State University, and his colleagues highlighted the potential environmental impact of producing plant-based proteins. A Mutus is the executive director of the North Carolina Food Innovation Lab, which has worked with several companies in this industry. He is also an advisor for BarVQ, an alternative meat company in Cornelius, North Carolina. Once the crops have been harvested from the field, then they need to be usually dried and then transported to a manufacturing plant where they're actually extracting and concentrating the proteins. They then, from there, are ground up into a fine meal, and then the proteins are extracted from that ground meal. The more traditional way has been to take the meal, suspend it in water, and then either add sodium hydroxide to raise the pH and start precipitating some of the proteins, or they add acids and precipitate proteins using acid extraction. They usually then reverse the order after they've done both those steps. They bring it back to a neutral pH of around seven. From there, they can go to a spray dryer, which is, as you might imagine, a fairly intensive use of natural gas and electricity. You have a lot of chemicals being utilized that are rather harsh. The only metals that really stand up to those types of chemicals are stainless steel. And stainless steel is, of course, a very energy-intensive process to manufacture that product. So as we look at the life cycle for plant-based, protein, concentrated, protein isolates, there's several steps that are missing along the way. So, Immutus says the manufacturer of plant-based meal alternatives can produce significant environmental impact. However, scaling up manufacturing could potentially mitigate some of the sustainability costs. This would require a certain level of consistency and quality in plant-protein ingredients. And yet another PNAS article in the Special Feature would advise a life scientist at the Technical University of Munich in Germany and her colleagues found significant variability in the amino acid scores and functional properties of 61 commercially available plant-protein ingredients. We found significant differences in the amino acids course of individual protein ingredients derived from the same raw material. We focused on functional properties that are important for the later use of protein ingredients in food applications. The first property we examine was protein solubility. We also investigated emulsifying characteristics which are important for producing products like vegan mayonnaise and foaming properties which are essential for making vegan barista drinks. The variations in the individual properties even within ingredients from the same raw material group are significant. For example, within the group of far-bubbin ingredients, we found some that could not form stable foams and others that produced two liters of foam from 100 milliliter of protein-dyspersion that remained stable for 60 minutes. We documented significant variability even among batches of the same product. This inconsistency makes it difficult to produce standardized food products with reliable quality and performance. While the popularity of these products has rapidly increased over the past decade, adoption has stalled in recent years for where they're limiting their potential benefits. In article published in Scientific Reports, Zach Rene-Ihofer, an agricultural economist at Purdue University in Indiana and his colleagues analyzed trends in plant-based meat alternative consumption based on two years of grocery stores gaining data from 38,966 households. We did find that most of the plant-based meat alternative buyers also bought meat. So these households were not really making a substitute. In fact, to confirm that, we found that their expenditure on ground meat actually increased on average weekly expenditure after that first meal alternative purchase. So yes, while households bought it and may have bought it again on multiple occasions, they did not decrease their expenditure on meats. We found that younger people, single, female, college educated, higher income and non-white individuals were more likely to purchase a plant-based meal alternative than older people married households, male households, non-college educated, lower income groups and white households. The percentage of households that bought a plant-based made alternative was a little under 20% of that limited sample. A little over 60% bought them again. That means about 40%, it was a novelty they bought at once and didn't buy it again. Some plant-based meat alternatives are sold in a state resembling raw meat. It must be cooked before consumption. Consumers may be unfamiliar with the proper cooking and handling of these products, potentially contributing to food safety risks. In an article published in Science of Food, Evelyn Selberher, a microbiologist at the University of Veterinary Medicine in Vienna, Austria, and her colleagues analyzed the microbial communities found in 32 plant-based meat alternative products. We found it complex and for us really highly interesting microbial landscape, we found significant populations of pseudomonatoda. This bacteria very well recognized for its biological capabilities in perishable food items where they can produce off-flavorous discoloration or full orders. We found lactic acid bacteria. They have several really positive health effects. They have balancing the gut flora, they improving digestion, the boost in one system. We are also found potentially pathogenic bacteria. And these pathogenes carry viralance factors and antimicrobial resistance genes. We found also presence of better lactic acid producing clipsylla asolates and pizzylose asolates that havered and there are toxic genes that could cause food poisoning symptoms like diarrhea. Unlike traditional meat products, the plant-based meat alternatives do not provide visual cues such as color change to indicate that they are done. This makes it difficult for the consumer to judge whether the product has been adequately cooked or not. So this uncertainty alone can lead to under-cooking. Another important aspect of sustainable plant-based meat alternatives is access. The availability of many plant-based meat alternatives has largely been confined to wealthier countries. In the context of lower-income countries, meat consumption often provides essential nutrients that cannot readily be replaced by available plant-based foods. Matin Kaim, an economist at the University of Vaughn in Germany, is another organizer of the Special Feature. In a PNIS article in the Special Feature, Kaim and his colleagues analyze the impact of animal-sourced foods on child nutrition in five sub-seherent African countries, based on more than 32,000 observations of children below the age of five. The most recent numbers are telling us that around 22% of the children in the world are affected by stunted growth, the serious development issue. We're finding after controlling for any confounding factors that if the households and the children eat animal sourced foods, even occasionally, then these children are less affected by stunting and have higher growth rates in terms of physical growth, eating versus not eating animal sourced foods reduces the likelihood of a child being stunted by seven percentage points. And that's quite a substantial number if we're looking at can plant-based foods alone lead to the same types of positive nutrition effects on the average they can't. Plant-based foods such as foods and vegetables have a lot of seasonality. We're looking at households that are often located in remote villages in rural areas where access all year round to all types of foods is not necessarily given. The reduction of meat and animal sourced food consumption in the rich world is definitely good for sustainability at the same time an increase in improving access for poor people in Africa to these foods is also good for sustainability in terms of improving child health and nutrition. A growing body of work suggests that the production of plant-based meat alternatives can produce environmental effects that are not always considered would weigh in their sustainability costs and benefits. High prices and limited availability have further constrained the adoption of these products. In some regions the nutritional benefits provided by meat continue to outweigh the environmental costs. Ultimately adopting a diverse diet and incorporating less processed plant-based foods might prove beneficial to health and the environment. Thanks for tuning in to science sessions. You can subscribe to science sessions on iTunes, Spotify, or wherever you get your podcasts. If you liked this episode please consider leaving a review and helping us spread the word.