Every food manufacturing process creates solid waste. What to do with that waste is a perpetual question in the industry.

Unfortunately, it hasn't been a very high-priority question. Respondents to Food Processing magazine's 2014 annual manufacturing trends survey ranked solid waste and wastewater management among their lowest priorities.

It makes sense, perhaps, that companies focus more on production of finished goods. But by downplaying the importance of waste management, they're missing out on opportunities to improve their sustainability practices — not to mention the potential for new streams of revenue.

Fortunately, the industry has people like Chris Simmons, who has devoted his career to researching the best solutions to the problem of waste in food processing. Simmons is a food engineer in the Department of Food Science and Technology at the University of California, Davis. Simmons works primarily with the solid residues that accumulate from fruit and vegetable processing.

We spoke to Simmons about the current state of sustainable management solutions for food processing waste. In this article, we explore how the industry is rising to meet the solid waste challenge.

Why Waste Matters

The amount of food wasted each year in the United States is staggering. 133 billion pounds of food are disposed of by consumers, groceries, and restaurants, as well as manufacturers.

Most of this waste winds up in landfills. Food Engineering reports that “disposed U.S. municipal solid waste and accounts for a significant portion of U.S. methane emissions.” Reducing this waste would have considerable environmental benefits.

Finding innovative avenues for solid waste can also provide financial benefit to food processing companies. Many manufacturers of fruit and vegetable products sell their by-products to dairy farms and ranchers for feed supplements.

But Chris Simmons' research shows that animal feed is only the tip of the iceberg when it comes to lucrative — and environmentally friendly — solid waste opportunities. As Simmons says: “Anything that routes materials away from the landfill improves the sustainability of that processing pipeline.”

The Whole Tomato

Simmons' research focuses primarily on produce grown and processed in California, primarily tomatoes.

Tomatoes are one of the state's major exports. California produces 90% of the tomatoes in the United States. The bulk of the tomato yield is made into tomato paste, but that leaves countless pounds of skin and seeds, also known as pomace, that needs to be disposed of.

While many tomato processors sell pomace for feed supplements, Simmons and his colleagues are investigating other avenues, such as extracting high-value compounds out of waste materials or transforming them into whole new products.

For example, waste can be used in biofuel production. Researchers have optimized anaerobic digestion processes to produce high amounts of renewable methane. This methane can be burned to generate electricity, heat, or power for vehicles.

Tomato waste can also be used to improve soil quality. Waste materials provide soil amendments that promote the soil's ability to hold water and improve fertility. Simmons' lab has developed ways to use the fruit residue to feed specific bacteria in the soil. They then promote the activity of the bacteria to create compounds that eradicate particular pests — thus replacing the need for traditional herbicides and fumigants.

Waste from tomatoes is making inroads in the medical arena, as well. Tomato skin is rich in lycopenes, which are antioxidants that help prevent cancer. Scientists have been able to extract lycopene from tomatoes to use as a nutraceutical. This value is lost if the skin is simply used for animal feed.

Unsurprisingly, as a California-based researcher, Simmons also works frequently with the wine industry.

While grapes share many chemical similarities with tomatoes, grape pomace can be harder to manage because it contains more phenolics, such as lignins. (Lignin is, essentially, the “cement” that holds the plant wall together.) Animals can only tolerate limited amounts of phenolics, so the use of grape pomace in animal feed is limited.

It's because of challenges like these that Simmons works to “develop as many avenues to value as we can from a single waste stream in food processing.”

Implementing Innovations

Despite these exciting emerging alternatives for solid waste, the majority of tomato processors are still selling their pomace back to farmers. What will it take for the infamously slow-to-change food processing industry to look beyond this tried-and-true method?

To a large extent, it comes down to value. If one of the newer waste innovations provides a value that exceeds what processors currently get for feed, then it's likely that that new method will gain in popularity.

And Simmons strongly believes that the most environmentally friendly solutions can also be the most cost-effective. The soil amendment technology described above is a case in point. When the soil amendment technology matures, it could allow pomace to be sold to any grower in the region — not just the proximal dairy or beef farm that needs pomace for feed.

But, Simmons warns, it's important to remember that “sustainability is system-wide.” If processors route their waste away from animal feed, then something else will be needed to feed the animals. And the new method of producing feed could have a greater or a smaller footprint. That's why it's critical to look at solid waste solutions from a whole systems perspective.

Zero Waste Future?

It looks as if, slowly but surely, waste reduction is catching on. A recent article from Food Engineering highlights several large food processing companies that have achieved zero waste to landfill. Smithfield Foods currently has four zero-landfill facilities, and Mars, Nestle, Sunny Delight, and MillerCoors have all achieved landfill-free status.

Of course, no company goes from landfill-dependent to landfill-free overnight. Industry professionals recommend starting small and moving forward pragmatically. Each plant needs to identify its various waste streams and determine which solutions are right for each, be they recycling, composting, waste-to-energy, and so on.

Government agencies are getting on board as well. Last year, the USDA and EPA called for a 50% reduction of food waste nationally by 2030. This goal builds on the U.S. Food Waste Challenge, a 2013 initiative of the two agencies that encourages players from throughout the food chain to share best practices around reducing and reusing food waste. The Challenge was initially intended to reach 1,000 participants by 2020. It blew that expectation out of the water, by the end of 2014, by which time 4,000 participants had already signed on.

To Chris Simmons, this new enthusiasm is on-trend. He predicts that 10 years down the road, we “won't see any solid waste from fruit and vegetable processing going to landfills.” With the help of labs like his at UC Davis, food processing pipelines will accelerate the pace at which they adapt to and incorporate novel waste treatment technologies.

As the economic and environmental benefits of sustainable waste management become ever more apparent, we can confidently project that the issue will be low-priority no more.

Learn more about sustainable waste management from our Expert in Residence, Chris Simmons.