Fast-forward to the noughties, and soy milk was still the dominant alternative to dairy. Yet, in the past decade, other contenders have appeared – oat, almond, rice and more.
About 40 per cent of Australian households bought plant milks as well as dairy in 2021, up from 30 per cent in 2016, according to research by Nielsen Data. In the year to July 2021, plant milk made up 15.5 per cent of milk dollar sales globally, says consumer data company NielsenIQ, which notes the pivot to plant milks is part of a trend towards animal-free “alt-protein” foods. Plant milks’ appeal extends beyond lactose-intolerant consumers to those aiming to make “green” choices.
So are plant milks greener than dairy? Which ones are the greenest? And what’s brewed milk?
What are plant milks?
Plant milks are made by breaking down a plant and homogenising the fats and proteins, which means the molecules are made into smaller, uniform particles – any particles larger than 50 micrometres leave a gritty texture on the tongue. Plant milks can be made from cereals (from oats to rice), nuts (from pistachio to pecans), legumes (soy and peas) and seeds (hemp and sunflower seeds).
Soy milk, for example, starts with dry soybeans hulled, pressure cooked with water or steam (raw soybeans are inedible) and pulverised into a white slurry. A centrifuge removes the larger particles and soybean fibre, called okara, which is often used for animal feed. The remaining liquid is forced at high pressure through tiny passages that shrink the fat into molecules that will emulsify with water to give the soy milk its silky texture. Cereal milks, such as oat, follow a similar process but an added enzyme breaks down starch into simpler sugars, which sweeten the milk. Without the enzyme, the oat starch swells with water and becomes slimy.
Plant milks, as with cow’s milk, are pasteurised – treated with high temperatures – to sterilise them and improve their shelf life. Nut milks can be made in this way, too, but don’t require cooking or enzyme treatment, and can be made using nuts milled into a powder or paste rather than a blended slurry.
Why are they becoming so popular?
Most of the 10 cafes interviewed for this explainer say about a quarter to a third of their customers order a dairy-alternative milk, echoing a 2021 survey of 900 cafes by research company Cafe Pulse, which found a quarter of coffee drinkers have ditched dairy. Almond, soy and oat were the most popular milks in cafes, it found.
A North Sydney cafe we visited, where relative newcomer hemp milk is popular, estimated 90 per cent of its customers choose plant milk. And for some customers, one plant milk isn’t enough. “One person orders half oat, half soy, and decaf,” says the barista. “I cannot justify that. Just have a Diet Coke!”
One of the main drivers, particularly among some younger consumers, is concern over the environmental impacts of cow’s milk.
Professor Nitika Garg flirted with coconut milk coffee after a tip from a friend before settling on oat milk for its consistency and taste. As a consumer behaviour researcher at UNSW, she has looked into other people’s choices, too. Consumers are generally concerned about cost then health, she says, but products’ environmental impacts are increasingly important. (As to cost, a litre of cow’s milk starts at $1.60 at supermarkets while home-brand plant milks go for about $2 a litre, most ranging between $2.50 and $4, with fancier lines costing up to $5.50. Some cafes charge a little more for plant-milk coffees.)
“I think that the reason why non-dairy or plant-based milk came into the marketplace is health,” Garg says. Many plant-milk drinkers are lactose intolerant, which means their body can’t break down the lactose sugar in cow’s milk, but others seek out plant milk because it’s lower in fat and kilojoules. Soy milk fortified with calcium and vitamins A and D has the closest nutrient profile to cow’s milk, which is naturally high in these and other nutrients, including B vitamins. Other plant milks, including almond, rice and oat, are relatively low in protein. Plant milks can also contain added sugars.
“But we [also] have a growing awareness regarding sustainability and the need for environmentally friendly consumption,” Garg says. “So I think it’s like a perfect storm – a positive storm – for this industry, where a lot of factors have collided to drive the demand for the substitutes.
“Millennials are very tuned into these issues of animal welfare and climate change. Generation X is also a big factor because they have witnessed some of the key changes [in the environment] and they have the resources to support this movement. A lot of these coffee purchases you’re seeing in cafes switching to plant-based milk is driven by that generation.”
So, which milk is the greenest?
Scientists at Oxford conducted a meta-analysis of data from 38,700 farms across the globe in 2018 and about 1000 “post-farm processes”, including processing and packaging, to establish the environmental impacts of various foods and drinks including dairy, almond, rice, oat and soy milk.
They found plant milks do better than cow’s milk on every environmental metric, including land and water use and global warming potential (measured as CO2 equivalent, which converts other greenhouse gases such as methane to the equivalent amount of CO2). Eckard says much of the environmental impact of cows comes from their water and feed needs. “If you want to generate human protein and energy per hectare on the most efficient mechanism, it’s crops fed straight to humans, not crops grown to feed to animals to feed to humans – because there’s energy loss at each step,” Eckard says.
Cow’s milk uses the most water: 628 litres to make a litre of milk (most water is used for growing feed and irrigating pastures, although a lactating dairy cow in hot weather can drink 200 litres a day). And cow’s milk has the highest “eutrophication factor”, which refers to how much a certain crop or animal contributes to nutrient run-off from fertilisers or urine into waterways, causing algal blooms. The dairy industry in New Zealand is on notice about this issue after a government report in 2020 found that between 95 and 99 per cent of New Zealand’s rivers running through urban and farming areas are polluted.
But there is no one plant milk that leads the pack on all green measures.
Almond milk sucks up carbon but is intensely thirsty. “Almond milk has almost negligible greenhouse gases,” Eckard says. “In fact, a lot of almond production could be carbon positive.” As a permanent crop, though, almond trees have to be watered year-round. Growing one almond in California, where most of the world’s almonds are farmed, takes 12 litres of water on average. One litre of almond milk takes 371 litres of water to make, according to the Oxford analysis. The practice of bringing in billions of bees each year to pollinate almond trees could also be contributing to mass bee die-offs.
The chief executive of Australian Almonds, Tim Jackson, says growers use less water in Australia than in the United States and have introduced practices to improve sustainability in response to public concern, such as recycling the hull and shell of almonds as stock feed and fertiliser. And many almond farms have also changed the way they work with bees. “More than 50 per cent of our farms are now bee-friendly farms,” Jackson says. “We’ve got this internationally certified, bee-friendly farming certificate, which means that the growers have to do everything they can to comply with conditions around being bee-friendly.” This includes avoiding spraying chemicals toxic to bees around the time the hives are brought in and planting other flowering species around the almond trees so the bees have a diverse diet.
While rice milk is the most efficient plant milk in terms of land use, it does badly on all other factors. It’s not all that far behind almond milk for water use because the crops are partially submerged – and that method affects its climate credentials, too. The flooded fields, littered with decomposing rice straw residue, create the perfect conditions for methane-producing bacteria called methanogens – the same kind that produce the methane in cow stomachs. This process unleashes about 11 per cent of the world’s man-made methane.
Coconut milk is water-efficient and has low emissions, but coconuts are grown commercially in tropical areas vulnerable to deforestation, and experts have warned that increased demand for coconuts could lead to habitat destruction and species loss.
An outlier, hazelnut milk, is poised to dethrone almond milk as the “greenest” nut milk. Hazelnuts also grow on trees, which absorb carbon, but are less thirsty than almonds. And they are pollinated by wind, eliminating the need to bring in bees.
But did we get it right the first time with soy milk? Soy is easy to grow, uses the least water and releases a third of the carbon emissions of dairy. As with all legumes, soy plants have bacteria in their roots that convert atmospheric nitrogen into ammonia used by the plant to grow. This process reduces the amount of fertiliser required for the crop, which is why soy contributes the least to waterway pollution and algal blooms.
The biggest concern with soy milk globally is deforestation. Soya crops, for example, are driving record deforestation in the Amazon. Yet three-quarters of soy is used to feed meat and dairy livestock. Reducing consumption of animal products would ease the demand for cheap soy that’s behind much of the land-clearing.
For both oat and soy, brands that use Australian-grown crops have lower carbon footprints, too. (Cafe staple Bonsoy uses US-grown soybeans, and pioneering oat-milk brand Oatly uses oats grown in Sweden and Finland.)
Oat is similar to soy for emissions and land use, and uses more water than soy and far less than almonds and rice but contributes more than soy or almond to eutrophication.
Interested in which makes the best coffee? Keep reading on Sydney Morning Herald
Article Attrition: Sydney Morning Herald, Angus Dalton