Pizza with leftover olive leaves. Bread doctored with rice waste. Banana peels turned into snacks. These are examples of a trend called upcycled food — and soon they are coming to our plates.

Upcycling used to be about redoing old clothes to make them fashionable again or revamping aged furniture. Now, however, amid concerns about how much food waste there is in the world, upcycling is coming to the food industry.

What qualifies as upcycled foods? According to a newly coined definition, they are ones that “use ingredients that otherwise would not have gone to human consumption, are procured and produced using verifiable supply chains, and have a positive impact on the environment.” Basically, it means no longer putting agricultural leftovers in the trash and into incinerators and landfills, but back on our plates.

Disgusting? Not necessarily.

Consider the coffee plant fruit — the red or purple cherry-like fruit that contains the coffee bean. They normally get thrown away in enormous quantities as a byproduct when coffee beans are harvested. But they can be collected and made into a gluten-free flour and used in foods such as cookies or tortillas. Since the fruits are full of fiber, potassium and antioxidants, upcycling promoters say they could turn them into nutritious superfoods.

Producers of upcycled foods say consumers will soon be seeing more of them in grocery stores.

The Upcycled Food Association, a nonprofit group formed in 2019, recently created certification standards and a logo that producers can display on packaging to show shoppers that their purchase can help fight food waste. The logo — black and white with a small green leaf — signifies that at least 10 percent of the product’s ingredients by weight have been upcycled. According to the Food and Agriculture Organization of the United Nations, some $1 trillion worth of food is wasted per year, making the market value of upcycled foods potentially huge, experts say. One study suggests that one-third of the food produced globally for consumption is lost or wasted every year.

The Whole Foods Market chain recently called upcycling one of the top 10 food trends of 2021, and some upcycled products already can be spotted on the shelves of specialty markets: upcycled chocolate chip cookies by Renewal Mill, upcycled barley milk by Take Two Foods and upcycled veggie chips by Pulp Pantry.

Take Two Foods, based in Portland, Ore., makes its barley milks with spent grain from beer production — what is left after squeezing out the flavor and nutrients during the brewing process.

According to one estimate, some 38 million tons of such spent grain end in landfills or, at best, composted or fed to animals. Yet from an upcycling perspective, those spent grains are a gold mine, since they are rich in protein and antioxidants, as well as dietary fiber, which has been shown to offer protection against diabetes, coronary heart disease and stroke.

By adding the spent grains, “we can create basically new products that can also carry nutritional benefits,” says Simona Grasso, a food scientist at University of Reading in England. A 2019 study, for instance, showed that pasta with up to 20 percent of wheat flour replaced by brewers’ spent grain had 135 percent more fiber and 19 percent higher antioxidant activity than regular pasta.

Scientists have experimented with adding a variety of other upcycled products to pasta, including onion skin powder, carrot peel and shavings (a waste stream from making “baby carrots,” for instance), apple peel, and olive or grape pomace (leftovers from juicing), showing significant increases in dietary fiber and antioxidant capacity.

Another upcycled ingredient for making healthy pasta is okara — the pulpy byproduct of soy milk and tofu production, and a traditional ingredient in Japanese, Chinese and Korean cuisine. It is often thrown out by major producers of tofu or soy milks.

“It has recently become a waste product, and it really shouldn’t be,” says Jonathan Deutsch, food scientist at Drexel University.

Research shows that substituting half of wheat flour in pasta with okara can increase by 68 percent the content of phenolics, compounds which have antioxidant properties and may play a role in the prevention of cardiovascular disease. Okara can also be added to cookies or baking mixes, as Renewal Mill is doing with some of its cookies, baking mixes and flour.

So far, most of the applications for upcycled food waste ingredients have been in breads, muffins, biscuits and other bakery products. But Grasso says that “that’s just the beginning.” Scientists are studying the upcycling potential of berry pomace from black currant juice production, rice bran leftover from milling and polishing rice grains, and olive leaves — a waste from olive oil production that can be ground into flour and made into pizza dough. A San Diego company, SoulMuch, makes granola from upcycled almond pulp, a waste product of almond milk production. From an environmental perspective, it makes sense: A 2019 study found that just one California almond uses up an astounding 3.2 gallons of water.

Consumer acceptance may be a challenge, however.

One issue may be the flavor or texture if too much of the upcycled ingredient is added to the product, as is the case with okara. Another is psychology: Some people react with disgust to the idea of eating stuff with “waste” in it. A 2021 review of studies showed that people are unwilling to pay more for upcycled foods than they do for regular products, with the exception of those consumers who are more environmentally conscious.

“People that are already more interested in being more sustainable, people who are already trying to reduce their plastic usage — definitely those would be the people who might be interested in these products,” Grasso says.

The third challenge is the supply chain and the cost of production. Even though it’s stuff being discarded, getting ahold of food waste and reprocessing it into something usable is not cheap. For instance, “grain and soy beans are low cost commodities to begin with, so if you are making something from spent grain, you may end up paying more to stabilize it and transport it and work with it, than you would if you bought grain outright,” Deutsch says.

Reusing food waste instead of dumping it into landfills may seem like an obvious improvement from an environmental perspective, and producers bank on it by advertising their products with slogans such as “Fight climate change from your kitchen.” But more studies need to be done on how much upcycling could lower carbon footprints of various food products, Grasso says.

Deutsch says he believes that upcycling alone is not enough to dramatically minimize food waste. Instead, we have to work on prevention in the first place, including in our own kitchens. Yet although upcycling food waste is “not a silver bullet,” he says, “it’s the right thing to do.”