Whey-ing Greek yoghurt’s environmental impact

The disposal of acid whey is a problem in the Greek yoghurt processing industryIn the US, Greek yoghurt is a booming $2 billion a year industry, but it produces millions of litres of waste that’s proving a problem in disposing.

Fuelled by the growing appetite for rich, creamy, protein-packed Greek varieties, yoghurt was one of the fastest-growing grocery categories in the US in 2010, according SymphonyIRI. What’s remarkable, Greek yoghurt is driven almost entirely by changing consumer tastes and without the corporate hype that normally surrounds growing categories. ‘It wasn’t as if there was an obvious sort of marketing push,’ states Mintel’s Bill Patterson. ‘It just kind of leapt on the scene. It truly was consumer-driven, which is really quite unusual.’

In its report The Yogurt Market and Yogurt Innovation: Greek Yogurt and Beyond, Packaged Facts estimated the US retail market for yoghurt at $7.3 billion in 2012, with the Greek yogurt segment singlehandedly responsible for these respectable sales gains in a very large and mature product category. It’s emerged as a platform for innovation in other product categories. Frozen yoghurt has become a big early adopter, with a plethora of new Greek yoghurt product introductions. Some yoghurt makers have begun to pay more attention to foodservice, with Chobani and Dannon opening up their own yoghurt shops in the US.

Acid milk serum

To produce the thicker, creamier yoghurt, which also has the benefit of containing twice the proteins of ordinary varieties, Greek yoghurt is strained through a cloth or filter or in industrial operations, placed into mechanical separators that use centrifuges to remove the milk serum. The byproduct is a thin, runny, acid whey (roughly as acidic as orange juice) containing lactose (milk sugar), lactic acid from the fermentation and a small amount of dairy proteins and milk salts like calcium. It’s illegal to dump acid whey as it becomes toxic as it decomposes. It robs rivers and streams of oxygen, turning them into what one expert calls a ‘dead sea’ and destroying aquatic life.

In an article that’s set the cat among the pigeons in Modern Farmer, the scale of the problem is daunting. New York’s Greek yoghurt industry has tripled in size between 2007 and 2013. The Greek-style bonanza has been huge because of the expansion of yoghurt production by Chobani and Fage (pronounced fa-yeh) giving New York a total of 29 yoghurt plants. Dubbed the Silicon Valley of Yoghurt, the state now surpasses California in yoghurt production by more than 45 million kilogrammes. The downside is that yoghurt manufacturers in the state produced almost 600 million litres of acid whey last year.

Mintel reports that the average American eats yoghurt 7.5 times a month, but that’s still a fraction of the frequency by European consumption.

An increasing problem

Typically, companies produce 30ml of creamy yoghurt from 80-100ml of milk. The remaining 50-70ml becomes acid whey. Sour whey can’t be sold to sports-nutrition companies because it isn’t like the sweet whey produced by cheesemaking, which is richer in protein. Much of it is being returned to the dairy farmers, who have been experimenting with it, mixing it with manure, into cattle feed and converting some of it into biogas that powers their farms and even supplies local utilities with power. (Biogas refers to a gas produced by the breakdown of organic matter in the absence of oxygen, thus creating a renewable energy source.)

But this is still problematic. Silage can only soak up so much acid whey before becoming unmanageable slop, and farmers must take care not to feed their cows too much whey as it’s similar to feeding them candy bars. Converting whey into biogas requires expensive anaerobic digesters installed below ground (reportedly around $4.5 million), something small farms cannot easily afford.

Chobani and Dannon – which produces Okios, Activia Green yoghurt, and Dannon Light & Fit Green – return the majority of the acid whey to farmers, who use it as part of a fertiliser or as a protein supplement in their animal feed. A small percentage is also sent to community digesters, where the whey is used to produce energy. Up to 80 per cent of the whey from Fage is piped directly to a wastewater treatment plant, where it goes into a four million litre tank filled with anaerobic bacteria, called an anaerobic digester. The resulting methane gas becomes combustible fuel that generates nearly enough electricity to power the plant. ‘The rest goes to farmers with anaerobic digesters for energy or feed,’ states Fage spokesman Russell Evans.

Dairy scientists at Cornell University and elsewhere have been exploring ways to extract the protein contained within the whey in an economical manner so it can be used in infant formulas. Another angle being explored by scientists is extracting lactose, which has many uses, from the whey.

Conflicting views

The issue has caused contention, with widely opposing opinions.

‘There’s nothing environmentally hazardous about it when it’s reused or disposed of properly,’ Michael Neuwirth, Dannon’s senior director of public relations told CNN. ‘We’ve been disposing of and finding ways to use whey in environmental and sensible ways since we’ve been making yoghurt.’ James McWilliams, food and agriculture writer as well as a history professor at Texas State University, argues the damage could be much worse than we know. ‘Producers typically hire farmers to haul it off and dispose as they see fit. At the level at which it’s produced and disposed, it’s toxic enough to rob aquatic ecosystems of enough oxygen to harm fish and other species.’

Muller Quaker Dairy and Ultima Foods have moved to distance themselves from the building fray over whey. New York-based Muller Quaker Dairy – the joint venture between PepsiCo and German dairy giant Müller – states the manufacturing process used to produce its Muller Greek Corner range ‘doesn’t generate whey waste’. Canada-based Ultima Foods explains it employs an ‘ultrafiltration process’ to manufacture its iögo Greko Greek yoghurt range – rather than the traditional acid whey-producing centrifugation process employed by many Greek yoghurt manufacturers.

Torben Jensen, application manager at Arla Foods Ingredients, also responds to the controversy, stating it highlights that the inefficiency of traditional Greek yoghurt making techniques is unsustainable both from an ecological and a commercial point of view. ‘This emphasises the importance of adopting new manufacturing techniques to allay consumer concerns and ensure this vibrant market continues to grow as strongly as it has done in recent years, and even more so in the past six months,’ he maintains. ‘To address this very issue, we have developed a Nutrilac protein solution that enables yoghurt manufacturers to produce Greek and Greek-style yoghurt on their existing plant, completely eliminating acid whey without compromising quality or taste.’

Nutrilac proteins are designed for use in conjunction with the company’s ‘Quick’ process – a manufacturing technique that eliminates the need for the whey separation step associated with traditional Greek yoghurt making. This means that virtually 100 per cent of the milk used in the manufacturing process ends up in the final product.

There’s no telling when the industry will develop a better solution for the acid whey, but until then, consumers will eat Greek yoghurt until the cows come home.