From waste to taste: using hydrolyzation to create a sustainable palatant
Convincing consumers to get on board may be the most challenging hurdle yet in the bid to use food waste hydrolysates as ingredients in pet food.
Waste created by food production is one of the most difficult waste streams to tackle as it cannot be easily converted to energy because it is too wet to burn. However, hydrolysis may offer a way of not only avoiding food waste, but utilizing it to add value to pet food.
Ways of working with waste
CSS Pet Nutrition CEO Dan Morash has a long history of working with the adaptive reuse of waste as an investor in waste-to-energy projects. He notes that a typical grocery store will throw out some 225 kg of viable food per day, including fruits and vegetables that are removed from the sales floor for cosmetic reasons.
“Burning, anaerobic digestion or composting of food wastes the nutritional value of food,” Morash says. “It’s much more productive to recover food no longer offered forsale or donation for beneficial use.” And that’s how an investment banker and energy expert came to found a pet food ingredient company.
Morash, alongside a growing number of experts around the globe, believes that hydrolysis could convert food waste and other agricultural byproducts into valuable ingredients for pet food.
The hydrolysis process can improve protein digestibility, improve ingredient shelf life and even imbue otherwise mundane ingredients like vegetable trimmings or corn gluten with interesting bioactive properties.
But while the environmental benefits of more circular pet food could appeal to consumers in some markets, the concept of including waste in pet food could encounter resistance in countries such as the US, where consumers have moved toward human-quality foods for their pets.
“With the selection of cheaper enzymes, there is potential. It could be economically accessible, so I think the thing is to educate the consumers and the customers, and to make sure we meet the safety requirements,” says Yonghui Li, an Associate Professor of protein science at Kansas State University (KSU).
What is hydrolysis?
Speaking broadly, hydrolysis is the process of using enzymes or chemicals such as acids or alkalis to break larger molecules, like proteins, into smaller molecules.
According to Li, this is commonly done to improve protein digestibility and can work with various enzymes or starting feedstocks. There are several hydrolysates already on the market today, including wheat gluten hydrolysates and pea protein hydrolysates.
However, most of these existing hydrolysates rely on food-quality feedstocks like wheat or peas. For people who want to bring about a more circular economy – a concept in which all usable materials are ultimately recycled – the potential hydrolysis of food waste and agricultural byproducts holds special appeal.
The enzymatic hydrolysis process itself is environmentally friendly and it could add value to products that might be cheaper to throw away under normal circumstances, according to Li.
Hydrolysis can also unlock nutrients from waste streams like chicken feathers by breaking down indigestible molecules like keratin. “Chicken feather is an underutilized byproduct that can often cause environmental issues if mismanaged,” says Faslu Rahman, a researcher with the ICAR-Indian Veterinary Research Institute (IVRI).
Rahman also notes that generating income from a recycled product can be a sustainable practice as it reduces waste.
Hydrolysates as palatants
CSS Pet Nutrition – founded in 2012 by Morash – collects grocery waste such as vegetables and then sorts, heats, grinds and processes it using a proprietary enzymatic digestion technology to produce hydrolysates at its 5,000-ton-per-year facility in Sacramento, California.
Initially CSS sold these hydrolysates as a liquid fertilizer and it still maintains this line of business. But along the way, it realized that the hydrolyzed fruits and vegetables could also serve as excellent palatants for pet food.
The hydrolysis process cooks and concentrates the vegetables, “combining amino acids and simple sugars in the Maillard reaction”, explains Morash, “which is what happens when you sauté something in the pan and deglaze the pan to get the brown bits”.
The CSS product has since outperformed market-leading pet food palatants in multiple feeding trials, and the fact that supermarkets pay CSS to take the waste means it can also beat existing palatants on cost.
Furthermore, the company has conducted a life-cycle analysis that suggests that for every ton of food it recovers, it eliminates 1.7 tons of equivalent greenhouse gas emissions.
“The conventional palatant is hydrolyzed chicken livers, and when you look at the carbon footprint of feeding and growing chickens, versus us taking fruits and vegetables that would otherwise go into landfill, you are substituting something with a big carbon footprint for something that has a small carbon footprint,” says Morash.
Further benefits in pet food
Hydrolysis can come with a variety of other benefits. Depending on the exact process and feedstock used, protein hydrolysates can contain valuable antioxidants or even offer antimicrobial properties that can extend the shelf life of pet food.
Some offer better technical functions, such as improved solubility or texture, while some offer a better nutritional profile, with more digestible proteins and bioavailable amino acids.
Most of the differences come from variations in potential feedstocks. In studies by Li’s research team, hydrolyzing corn gluten meal and distillers’ dried grains with solubles produced hydrolysates high in antioxidants with interesting emulsification properties.
A 2024 study led by Rahman at the IVRI demonstrated that hydrolyzing chicken feathers yielded a protein rich in histidine, arginine and lysine.
Potential drawbacks
While promising, hydrolysates are not without potential drawbacks. KSU’s Professor Li states that not every hydrolysate will perform well as a palatant – the process worsens the flavor of some feedstocks even as it improves the flavor of others.
Cost, Li notes, could also be an issue. “You could use some acid or alkali to break down the protein,” he says. “Acid or alkali would be cheaper, but the enzyme is more specific and we can better control the process.”
Furthermore, in Rahman’s research, feeding large quantities of hydrolysates triggered diarrhea in pets, which could potentially limit inclusion rates.
But at least within the US, consumer acceptance could prove the biggest challenge. Rahman doesn’t think hydrolysates made from ingredients such as corn or chicken should pose an issue, but the inclusion of food waste could be where some consumers draw the line.
Some advocacy groups have decried the use of waste products in pet food and complained that hydrolyzed food waste products lack transparency. These concerns mean that consumer education – and quality control – will be key to accelerating the use of hydrolysates in pet food.
“In other countries utilizing byproducts or waste can be more acceptable than in the US,” says Li. “We definitely need to make the consumer aware that this can be safe and even better quality, but at the same time we have to ensure the raw materials and the products are safe.”
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