How microbes hold the key to next-generation dairy alternatives

Environment and sustainability 11. jul 2022 3 min Assistant Professor Erica Pontonio Written by Eliza Brown

Global climate change and increased focus on animal welfare have created a demand for more sustainable and ethical alternatives to dairy. Researchers in Italy have made it their mission to create dairy products without the climate burden of milk-based products. But to create a convincing vegan dairy alternative, researchers have to re-engineer how milk becomes yogurt, cheese or butter in the first place.

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Erica Pontonio is determined to change the way you eat.

With demand rising for more sustainable and ethical alternatives to dairy products, she studies food microbiology as an Assistant Professor at the University of Bari Aldo Moro in southern Italy. Her entrance into the world of vegan food development was sourdough, which is naturally dairy-free. “At some point, we decided we could use the same plant-based ingredients to make something else,” Erica Pontonio explains.

She and her lab pivoted to vegan dairy replacements about 5 years ago. Pontonio made it her mission to create an almost-yogurt without the climate burden of milk-based yogurt, yogurt-ish without the allergens in dairy – “yogurt-like” in food industry parlance.

With a lot of microbes and a little faith on the part of consumers, Erica Pontonio is convinced the future is bright for plant-based alternatives to dairy products.

Reinventing the (cheese) wheel

To create a convincing vegan dairy alternative, researchers have to re-engineer how milk becomes yogurt, cheese or butter in the first place.

Microbes are the architects of texture in dairy products like yogurt and cheese, Pontonio explains. Adding specific strains of bacteria – usually Lactobacillus delbrueckii subsp. bulgaricus and Streptococcus thermophilus – to milk begins the process of fermentation, in which the microbes gobble up sugar in the milk and release lactic acid as they convert it into usable energy.

The lactic acid lowers the pH of the milk, causing proteins called caseins to denature, or lose their structure. These mashed-up caseins coagulate, thickening the mixture. The microorganisms also produce chains of sugar called polysaccharides, which lend fermented dairy products their creamy texture.

To create a vegan alternative, plant products – such as ground-up flour from peas or grains – replace milk as the main input. Not only do these alternatives have a lower protein content, but the proteins that are present are also structurally very different from casein. “When these plant proteins are destabilised, they do not coagulate – they do not form any consistent network,” explains Erica Pontonio.

No one-size-fits-all bacteria

To get the ball rolling, Pontonio says researchers instead turn to starch. By heating the mixture at a balmy 80°C for 10–15 minutes, starch granules swell until they burst, coagulating into a gelatinous substance closer to the consistency of yogurt.

But the determining factor for the texture and “mouth feel” of the product is the choice of microbes, Pontonio says. Researchers consider various bacterial strains that are specialised to grow on the plant inputs – for instance, chickpea or lentil meal. These candidate bacteria are closely related to the ones used to ferment milk, and although they cannot work thickening magic in plant products because they lack casein proteins, they can produce the polysaccharides to make it creamier.

Bacteria can also help eliminate what researchers call anti-nutritional factors in the plant mix –digesting saponins, which reduce the absorption of vitamins, or degrading components that would otherwise give the yogurt-like a funky or plant-like taste.

But there are no one-size-fits-all bacteria for vegan dairy replacements, and choosing between a host of microbes that seem like good candidates eventually comes down to trial and error. Pick the wrong one and your pea-based cream cheese comes out slick and slimy, and another bad fit could make it clumpy and hard.

Yogurt-like and the art of close enough

There are two competing yet complementary philosophies to making vegan dairy product replacements – trying to approximate as closely as possible the original milk-based product or aiming to create something new and distinct that is just as palatable. Currently, Erica Pontonio’s lab is working to develop a true yogurt duplicate.

She and her team at the University of Bari Alba Moro keep an 80-litre tank humming with new yogurt-likes in their experimental kitchen. They have a viscosimeter to assign a numerical value to the yogurt-like’s texture, but ultimately nothing can replace a human taste test. A trained panel of 12–15 tasters evaluates each attempt based on factors such as flavour and texture.

“Very rarely does a yogurt-like actively taste bad,” Pontonio says. If anything, it just tastes or feels different than traditional milk yogurt.

Right now, their biggest headache is stubborn graininess. “When we start to form a mixture of flour and water, it is not completely solubilised – you can actually feel this problem,” she explains. It is also challenging to mask the sensory profile of the raw material. “If you are working with chickpea flour, you can link the sensory evaluation to chickpea. That is probably not what you are looking for by eating a yogurt.”

“Using other ingredients like chocolate or fruit that can cover or at least reduce the sensation coming from the plant-based ingredients” goes a long way, she adds.

Erica Pontonio and her lab collaborated with an industrial team on developing a vegan ice cream alternative made from a frozen yogurt-like. She says she could not tell the difference between normal ice cream and the chocolate flavour of the vegan treat made from chickpeas, lentils and rice – not exactly what comes to mind when you think of dessert.

Visions of a plant-based future

Some people have a cognitive block against dairy alternatives – maybe they tried an early generation years ago that missed the mark on texture or reminded them of a spoiled version of the dairy product it claimed to emulate. Pontonio hopes that consumers can be adventurous enough to at least try new plant-based formulations. “They are not what people imagine,” she says.

Erica Pontonio understands why consumers may be reluctant to switch to something new when they have no problem with the dairy products they grew up with – if it ain’t broke, don’t fix it. But with the climate emergency, we must urgently shift our diets.

“We do not have to make that complete substitution, but we can actually increase a little bit at a time,” Pontonio says. “We can eat the milk-based yogurt one day and the plant-based yogurt another day.”

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