The growing demand for healthy alternatives to traditional wheat products has boosted the search for new functional ingredients. In this context, partially defatted sunflower seed flour (SF) – a by-product of industrial sunflower oil extraction – is a promising option for enriching breads with proteins, fibers, and antioxidant compounds.
"Our aim was to optimize the reuse of sunflower seed flour considering its high protein and chlorogenic acid content," says biologist Leonardo Mendes de Souza Mesquita , currently at the Institute of Biosciences of the University of São Paulo (IB-USP) in Brazil. He is the first author of a related article published in the journal ACS Food Science & Technology.
In order to assess the potential of sunflower seed flour (SF) as a partial substitute for wheat flour (WF), the researchers formulated bread by replacing WF with different proportions of SF, ranging from 10% to 60%. They characterized all the formulations in terms of the chemical composition and rheological parameters (which describe how the material deforms and flows when subjected to external forces) of the dough and the physical properties of the final products.
"Sunflower seed flour has been shown to contain a very high percentage of protein, from 40% to 66%, as well as dietary fiber, iron, calcium, and high levels of chlorogenic acid, a phenolic compound associated with antioxidant, anti-inflammatory, and hypoglycemic effects. Reusing this by-product adds nutritional value to bread and reduces the environmental impact of the sunflower oil industry. In addition, sunflower seed flour is an extremely cheap raw material, which the oil industry sells just to avoid disposing of it as waste," explains Mesquita.
The results showed that adding SF significantly increased the bread's protein and fiber content. For example, the formulation with 60% SF had 27.16% protein, which is more than triple the amount in conventional bread (8.27%). The antioxidant content increased proportionally as well. Trolox, a water-soluble analog of vitamin E, is used as a reference standard in antioxidant tests. The value obtained was much higher than that found in bread made with 100% WF.
"The result reinforces the potential of sunflower seed flour to promote health benefits associated with reducing oxidative stress. In addition, we observed significant inhibitory activity against the enzymes α-amylase (92.81%) and pancreatic lipase (25.6%), indicating that breads with SF or SFE can contribute to modulating the digestion of starches and fats," says Mesquita.
An important fact reported by the researcher is that industrial sunflower seed oil extraction is done by pressing, without the addition of chemicals. This ensures that the resulting flour, a by-product of the process, is free of contaminants other than those left over from agricultural sunflower production.
Despite its virtues, replacing a large proportion of wheat flour with sunflower seed flour compromised some of the bread's sensory characteristics. Starting at 20% SF onwards, there was a reduction in the specific volume, an increase in crust and crumb firmness, and a change in alveolar structure – resulting in denser breads with a less soft texture.
"However, adding the aqueous extract [SFE] managed to preserve the structure and texture of the breads, keeping them close to those of traditional wheat bread. This indicates that adding SFE is an effective strategy for maximizing the nutritional benefits and minimizing the adverse sensory effects of sunflower seed flour," argues Mesquita.
The researcher explains that the aqueous extract is obtained by dissolving SF in water and filtering it without the need for other physical or chemical processes. He ponders whether SFE can replace SF entirely or be mixed with it in different proportions, which the bakery industry will be able to investigate to determine the ideal formulation.
Sustainable innovation
The study is part of a broader initiative to repurpose industrial by-products. "Transforming waste into products is a fundamental strategy for promoting a circular economy and reducing resource waste. As well as being a cheap raw material, partially defatted sunflower seed flour contributes to human health and environmental sustainability. It therefore covers the three pillars of the circular economy: economic, social, and environmental," says Mesquita.
The circular economy proposes replacing the traditional production and consumption model, which is based on the "extract, produce, discard" logic, with a system that aims to keep resources in use for as long as possible, extract the maximum value from them while in use, and regenerate them at the end of each cycle. Mesquita's study fits perfectly with this concept: an industrial by-product that was previously underutilized is transformed into a functional ingredient for nutritious bread, promoting sustainable innovation and reducing waste.
The work involved researchers from the Multidisciplinary Laboratory of Food and Health (LabMAS) at the School of Applied Sciences of the State University of Campinas (FCA-UNICAMP) in Limeira and the Laboratory of Food Technology and Nutrition at the Federal University of São Paulo (UNIFESP) in its Baixada Santista campus. The work received support from FAPESP through six projects ( 13/04304-4 , 20/15774-5 , 18/14582-5 , 20/08421-9 , 15/00658-1 , and 19/13496-0 ). Mesquita was later awarded a Young Researcher Grant for the project "Sustainable Innovations: The Biorefinery Revolution through the Valorization of Macroalgae Using Renewable Solvents Toward a (Green/Blue) Economy" .
About São Paulo Research Foundation (FAPESP)
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