Marigold flower protein shows promise as sustainable ingredient for future foods

Researchers have found that marigold flowers could provide a new source of sustainable plant-based protein, after a study showed that dried pot marigold powder contained around 9% protein with functional properties suited to future food applications.

• Researchers analyzed pot marigold flowers and found dried powder contained around 9% protein with functional properties suitable for food applications, including emulsification, heat stability and flavor contribution.
• The study reported that up to 40% of marigold production is discarded after ornamental use, highlighting an opportunity to valorize this agricultural byproduct as a sustainable protein source.
• Laboratory testing showed marigold proteins remained stable at 221F (105C) and demonstrated strong emulsifying capacity, indicating potential use in bakery products, dressings, mayonnaise and dairy alternatives.

The study, Assessing Structural, Thermal, and Functional Characteristics of Marigold Flower Protein as a Sustainable Food Ingredient, has been published in ACS Food Science & Technology.

The research examined whether pot marigold flowers, commonly grown for ornamental use and often discarded after flowering, could be transformed into a food ingredient rather than treated as waste.

“Marigold flowers are widely cultivated, yet an estimated 40% of production is discarded as waste, especially after ornamental use,” said Anand Mohan, corresponding author of the study. “We saw an opportunity to valorize this agricultural byproduct by exploring its protein fraction, given the growing demand for plant-based and sustainable food ingredients.”

The researchers ground pot marigold flowers, Calendula officinalis, into a fine powder and isolated proteins through four sequential liquid extractions. Each extraction collected different protein molecules, allowing the team to assess the composition, stability and functionality of the flower-derived proteins.

Laboratory tests showed that some extracts contained high levels of glutamic acid and aspartic acid, amino acids associated with umami taste. That suggested marigold proteins could contribute flavor as well as nutrition in food formulations.

The study also found that marigold proteins remained stable up to 221°F (105°C), a higher temperature than some other plant proteins, including pea and chickpea. According to the researchers, that heat stability suggested the proteins could better retain their structure in foods exposed to processing or cooking temperatures.

Two of the protein extracts also showed strong emulsifying capacity, meaning they were able to help keep oil droplets dispersed in water. That property could make the proteins useful in products such as salad dressings, mayonnaise and dairy substitutes, where texture and stability are central to performance.

Mohan said the marigold protein’s emulsifying, hydrating and antioxidant effects made it a candidate for nutrient-enriched food formulations. The researchers suggested the ingredient could improve the taste, stability and texture of bakery products and emulsion-based foods.

The work comes as demand for plant-based protein continues to expand across food categories, from meat and dairy alternatives to snacks, beverages and bakery products. Rather than growing crops solely for protein production, the study explored whether an existing agricultural byproduct could be used more efficiently.

The researchers have planned further work to assess the potential health benefits of marigold protein. They also intend to test the ingredient in baked goods and products such as salad dressings, followed by consumer taste testing.

“People are increasingly aware of food waste and are seeking innovative solutions,” Mohan said. “Demonstrating that something as common and overlooked as a flower can be transformed into a valuable food ingredient makes science both relatable and impactful.”

The authors acknowledged funding from the US Department of Energy, Office of Science, Basic Energy Sciences, Chemical Sciences, Geosciences, and Biosciences Division for the protein amino acid identification component of the research.