Moving toward carbon neutral cheesemaking
Membrane filtration, renewable energy lessens impact on environment.
Photo courtesy of Kemter via gettyimages.com
John A. Lucey is a professor of food science at the University of Wisconsin, Madison, and the director of the Center for Dairy Research.
Cheesemaking is a traditional process that has been around for thousands of years. Originally, cheesemaking was done at a small farmstead scale with low inputs like energy or water. But cheese factories have grown, and these modern plants require significant mechanization, and process steps like pasteurization, clean in place (CIP), and refrigeration.
Water and energy requirements also have significantly increased. Across the industry, there is growing interest in lessening the climate impacts of food production. Some small cheese plants are already claiming that they are carbon neutral. So, what can the cheese industry do to lessen its impact on the environment?
First, what does it mean to be carbon neutral? Carbon neutrality for a business can be achieved by first calculating a carbon footprint for their processes and then reducing that footprint to zero through a combination of efficiency improvement techniques within the business as well as supporting external emission reduction projects (such as production of renewable energy or forestry restoration projects that can sequester carbon). The carbon credit system is an approach that is becoming common overseas. Unfortunately, no national markets or federally regulated carbon credit system exists in the U.S. Similarly, some overseas cheese plants that are cooperatives can count any efforts by their farmers to produce biogas or other forms of renewable energy as carbon offsets.
When we look at cheese, we should recognize that most of the environmental impact is derived from the farm level due to milk production, which contributes more than 90% of the greenhouse gas emissions associated with cheese. On the farm, greenhouse gas emissions come from sources like the release of rumen or enteric methane from cows, nitrous oxide from fertilizer, and methane from manure. Internationally, there is a lot of research focused on feed supplements for cows that significantly reduce enteric methane. We need to quickly get approval for their use in the U.S. as long as they do not impact milk quality/safety. Research is also focusing on soil practices that trap/retain carbon, and manure management (e.g., production of biogas from a biodigester, which could replace fossil-based energy for powering the farm). Production of renewable energy, like solar or wind, is also another approach that is occurring at the farm level.
At the cheese plant, some of the major inputs include electricity (for operating cheesemaking equipment), typically fossil fuels for steam-powered heating (of milk, water, and curd; evaporators and dryers if making sweet whey powders), and refrigeration/cooling. Some smaller dairy plants that do not have whey processing capability, or plants that produce acid whey, can feed their whey to an anaerobic biodigester that produces biogas, which can then be used to generate electricity and hot water.
Cheese plants utilize a lot of energy to heat milk, but most modern pasteurizers operate with very high heat regeneration rates. Heat recovery is an important strategy in most plants. Some small cheese plants have gone back to the idea of using underground storage rooms to ripen their cheese (like old-fashioned caves), as this helps maintain a cool, constant temperature, and thus lowers refrigeration costs. Some additional cooling may be required but this would be much less than if the storage facility was entirely above ground.
In addition to reducing energy inputs, we should also be looking at technologies or strategies to re-use water. About 90% of milk is water so if a plant is bringing in a million pounds of milk a day, then around 900,000 pounds of that is water. In a cheese plant, a lot of this water is released in the whey, and much of that water can be recycled with membrane filtration.
Yet, it depends on how pure we want to make this water; fully potable water is a bit more expensive to produce but many plants already use their recycled water for initial rinses, CIP, and boiler make-up water purposes. Reducing or eliminating the use of groundwater is an important topic in many parts of the U.S. with limited local water availability. Reducing milk trucking distances and having very local dairy farms should also reduce transportation costs.
Finally, packaging should also be part of this discussion. A growing number of food/beverage companies are interested in moving to renewable and recyclable packaging. Currently only about 1% of plastics are bio-based. There are ongoing research studies trying to develop bioplastics (and other fossil-derived chemicals) from the fermentation of dairy coproducts like whey. However, at the moment most retail cheese packaging is not recyclable and is not made from renewable sources, so we have a lot of work to do.
Over the past 10 years I have seen many dairy companies adopting sustainability plans and publishing annual reports on their progress towards their goals. By tackling some of these challenges we can demonstrate that the dairy industry not only helps feed the world but is also playing an active role in achieving climate neutrality goals.
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