Citrus peels may be more valuable than they look: 2026 USDA-backed study of 22 Florida-grown varieties and hybrids finds antioxidant, anti-inflammatory and potentially anti-cancer compounds

For most people, a citrus peel is something to remove and throw away before eating the fruit. But for researchers studying the future of citrus farming, that bitter outer layer may hold value of its own.

A 2026 study published in ACS Agricultural Science & Technology, involving USDA researchers, examined the peels of 22 citrus varieties and unique hybrids and found distinct combinations of compounds with antioxidant and anti-inflammatory properties. The findings suggest that some of these fruits could eventually have uses beyond food and juice, including precision nutrition and health supplement applications.

Citrus peels are good sources of antioxidants

Citrus peels are rich in compounds that companies are interested in for health and pharmaceutical products. Researchers are now looking more closely at what different varieties and hybrids contain and whether their distinct chemical profiles could offer additional uses.

Christina Dorado, lead scientist and chemist at the US Horticultural Research Laboratory’s Citrus and Other Subtropical Products Research Unit in Fort Pierce, Florida, said developing commercially viable citrus varieties is important for farmers.

“It’s important to develop varieties and hybrids that are viable for commercial production,” Dorado said to USDA’s Agricultural Research Service (ARS). “For citrus farmers, it is not just about growing fruits for food or juicing. The citrus peels are valuable too because they are good sources of antioxidants and anti-inflammatory compounds.”

The study looked at 22 citrus varieties and hybrids

In the study, Dorado and researchers at the US Horticultural Research Laboratory assessed 22 citrus varieties and new hybrids. The trees examined in the study were grown at two Florida locations: the USDA Picos Farm in Fort Pierce and Whitmore Foundation Farm in Groveland.

They examined the phenolic profiles of the fruit peels, looking specifically at antioxidant and anti-inflammatory compounds. The researchers found that different citrus varieties contained different combinations of potentially beneficial compounds. That variation could eventually help researchers identify citrus materials suited to specific nutrition or health-related applications.

Mandarins stood out for their flavonoids

The mandarin varieties examined in the study had high levels of polymethoxylated flavones, or PMFs. Two of the compounds that stood out were nobiletin and tangeretin, with anti-cancer properties. In a 2025 study published in Pharmacological Research - Natural Products, Tangeretin has shown ‘remarkable potential to impede cancer cell progression.’

The researchers also found a different combination in mandarin x pummelo hybrids. These hybrids contained both PMFs and coumarins, compounds that are largely absent in citrus and have shown potentially beneficial biological actions.

Different hybrids produced different chemical profiles

The two trifoliate oranges studied, Flying Dragon and Gotha Road, also showed notable differences. Gotha Road had more coumarins, while Flying Dragon had more psoralens, which are structurally related to coumarins.

The researchers also found that hybrids created by crossing mandarins with trifoliate orange parents often combined compounds from both species. This produced chemical profiles that were not found in traditional citrus varieties.

What this could mean for citrus farmers

The research comes as Florida's citrus farmers and producers continue to deal with Huanglongbing, commonly known as citrus greening. The disease was first found in Florida in 2005 and is now endemic there. It has also been reported in Arizona, Texas and California. Citrus greening affects citrus trees and fruit, reducing production and increasing bitterness, resulting in economic losses for farmers and producers.

One way the ARS is responding is by developing citrus varieties and hybrids that show tolerance to citrus greening. For farmers, the potential value of these varieties could extend beyond the fruit itself. If varieties can eventually be commercially produced and their peels prove useful for health-related applications, the peel could become another valuable part of the crop.

The research is promising, but the fruits are not yet commercial

The citrus varieties and hybrids examined in the study are not currently available for commercial production. That means the findings do not yet translate into a new commercial crop for farmers. Still, the researchers see potential in the unusual chemical profiles they identified.

“We found that these hybrids and varieties have a lot of beneficial compounds that are not found in traditional citrus fruits like oranges, limes, lemons, and grapefruits,” Dorado said. More research is now underway to examine the health effects of the compound mixtures found in these fruits.