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As interest grows in healthier alternatives to traditional wheat-based foods, scientists are exploring new ingredients that can improve nutrition without sacrificing practicality. One promising option is partially defatted sunflower seed flour (SF), a residual material left over from sunflower oil production. This underutilised byproduct has shown strong potential to enrich bread with protein, fibre and antioxidant compounds.
"Our goal was to improve the reuse of sunflower seed flour given its high protein and chlorogenic acid content," says biologist Leonardo Mendez de Souza Mesquita, currently based at the Institute of Biosciences at the University of São Paulo (IB-USP) in Brazil. He is the lead author of a study published in the American Chemical Society's journal ACS Food Science & Technology.
Testing sunflower flour in bread recipes
To evaluate how sunflower seed flour performs in bread, the research team prepared bread recipes that replaced wheat flour with sunflower seed flour at ratios ranging from 10% to 60%. Each version was carefully analysed for its chemical composition, dough behaviour and the physical properties of the finished bread.
"Sunflower seed flour has been shown to contain a very high proportion of protein, ranging from 40% to 66%, as well as dietary fibre, iron and calcium, and high levels of chlorogenic acid, a phenolic compound linked to antioxidant, anti-inflammatory and blood-sugar-lowering effects," Mesquita explains.
He adds that using this byproduct increases the nutritional value of bread while reducing the environmental footprint of sunflower oil production. Because it is sold cheaply to avoid disposal, sunflower seed flour is also a low-cost ingredient.
Major gains in protein and antioxidants
The results showed clear nutritional improvements. Bread made with sunflower seed flour contained far more protein and fibre than regular wheat bread. At the highest substitution level, the bread reached 27.16% protein, compared with 8.27% in conventional bread. Antioxidant levels rose alongside the protein content.
Antioxidant activity was measured using Trolox, a water-soluble vitamin E analogue used as a reference standard. The values recorded in sunflower flour bread were significantly higher than those seen in bread made entirely from wheat flour.
"The finding reinforces the potential of sunflower seed flour to promote health benefits associated with reducing oxidative stress," Mesquita says. He also points to strong inhibition of digestive enzymes, including alpha-amylase (92.81%) and pancreatic lipase (25.6%), suggesting that bread containing sunflower seed flour or its aqueous extract may help slow the digestion of starches and fats.
Clean processing and food safety
Another key finding relates to how the sunflower oil is produced. According to the researchers, industrial extraction relies on mechanical pressing rather than chemical solvents. As a result, the residual flour is free of processing contaminants, apart from residues already present from sunflower field cultivation.
While the nutritional benefits were clear, high amounts of sunflower seed flour affected the appearance and texture of the bread. When sunflower seed flour made up 20% or more of the recipe, the loaves became smaller and firmer. Changes in crumb structure also resulted in denser, less soft bread.
"However, adding the aqueous extract successfully preserved the bread's structure and texture, keeping it close to that of conventional wheat bread," Mesquita says. He explains that this approach allows bakers to obtain the nutritional advantages of sunflower flour while minimising the negative effects on texture.
Using sunflower extract to improve bread quality
The aqueous extract is produced by mixing sunflower seed flour with water and filtering it, without requiring any additional physical or chemical treatment. Mesquita suggests that future work could explore whether the aqueous extract could fully replace the flour or be blended with it in various proportions. Commercial bakeries could then determine which formulations work best at scale.
Sustainable innovation and the circular economy
This research is part of a broader effort to find productive uses for industrial waste. "Turning waste into products is a key strategy for promoting the circular economy and reducing resource waste," Mesquita says. He notes that partially defatted sunflower seed flour supports human health while also offering environmental and economic benefits, addressing all three pillars of the circular economy.
The circular economy seeks to move away from the traditional "extract, produce, dispose" approach. Instead, it aims to keep materials in circulation longer, maximise their value and regenerate resources at the end of each cycle. In this case, a discarded byproduct has been transformed into a functional ingredient that enhances the nutritional value of bread while reducing waste.
Source: ScienceDaily