In a recent article published in the journal Foods, researchers developed novel types of gluten-free sourdough bread with a pseudocereal formulation containing Moringa oleifera, an unconventional crop that promotes health.
Study: Development of Functional Gluten-Free Sourdough Bread with Pseudocereals and Enriched with Moringa oleifera. Image Credit: Created with the assistance of DALL·E 3
The Rise of Gluten-Free Options
Bread is a dietary staple consumed widely across the world. While most people can consume wheat-based breads, people with celiac disease cannot. Others avoid gluten for lifestyle reasons and gluten sensitivity, which has increased the market for gluten-free products in recent years. As a result, pseudocereals, including buckwheat, quinoa, and amaranth, which are naturally gluten-free, have also garnered much attention.
Why Moringa and Sourdough?
Researchers postulate that the addition of the Moringa plant's leaf extract to bread could be safe for consumption for both healthy and celiac populations. In addition, sourdough fermentation could enhance protein digestibility, total phenolic compound (TPC) content, antioxidant properties, the availability of micronutrients, and functional characteristics of bread.
How the Bread Was Made and Tested
In the present study, researchers evaluated whether enriching gluten-free sourdough bread made of pseudocereals with Moringa oleifer leaf powder enhances its nutritional properties, especially its protein, amino acids, soluble fiber, and essential mineral(s) content.
They prepared six gluten-free bread formulations, of which three were control breads, having quinoa, amaranth, or brown rice sourdoughs, abbreviated as Q, A, and BR. The other three breads were also quinoa, amaranth, and brown rice sourdoughs but comprised Moringa oleifera extract at a concentration of 6% in the flour, abbreviated as QM, AM, and BRM.
All six types of gluten-free sourdough bread were compared to gluten-free commercial bread (COM) on several parameters.
For bread preparation, the researchers performed a spontaneous ferment every 24 hours for five days at 25–26°C, wherein they added a 50:50 ratio of water and flour, following the Tomić et al. method.
Nutritional Breakdown: Protein, Fats, and More
During the analysis, they determined the moisture, protein, total fat, ash, total dietary, soluble, and insoluble fiber composition of these breads (in grams per 100 gm of bread) using the standard methods outlined by the Association of Official Analytical Chemists (AOAC) and their pH, total titratable acidity (TTA), lactic and acetic acids content.
Further, they evaluated bread's colorimetric parameters, including lightness, yellowness, and redness coordinates (L*, b*, and a*), saturation (C*), and tone (h*). The antioxidant activity of the breads was determined using four different assays.
The Folin−Ciocalteu method described by Singleton and Ross was used to determine the TPCs in bread, and their sucrose, maltose, D-glucose, and D-fructose (total sugar content) were also analyzed. Likewise, they used the Minekus et al. method to evaluate the mineral bioaccessibility of all bread samples. Further, the team determined bread's fatty acid and amino acid profiles and folate content.
Taste Test and Consumer Acceptance
A total of 35 panelists performed the sensory analysis of all types of bread using hedonistic tasting, evaluating their color, appearance, aroma, juiciness, texture, taste, general acceptance, and intention to purchase. They rated each bread sample on a scale of 1-5, where a score of one and five indicated they did not like the bread at all and liked it very much, respectively.
During statistical analysis, a two-way ANOVA test helped examine the differences in the amino acids, fatty acids, proximate composition, mineral bioaccessibility, antioxidant capacity, folates, and TPC content across all bread samples studied. The post hoc HSD Tukey test was used to compare least mean squares, where p < 0.05 was considered statistically significant.
In the control bread, Q bread had the highest amount of protein and BR the lowest. Since quinoa and Moringa oleifera are both high in protein and sourdough fermentation increased protein digestibility, QM bread attained the highest protein content, equivalent to 6.76 g/100 g.
Even the fat content of quinoa is higher than that of brown rice and amaranth, and including the moringa leaf further increases it. Thus, both Q and QM bread had high total fat (6.07 g/100 g); however, they were lower than the COM bread, having a total fat equivalent to 3.25 g/100 g.
The QM bread had the highest content of total, insoluble, and soluble dietary fiber, while the COM bread had the lowest. The high fiber content of the moringa leaf powder increased it further (24.97 g/100 g).
Moringa oleifer also increased the ash content of reformulated bread significantly, especially in the QM bread (2.33 g/100 g), while the COM bread obtained a much lower ash content (0.01 g/100 g).
The carbohydrate content of bread depends on the amount of moisture, ash, fat, fiber, and protein. Since bread enriched with Moringa leaf had a higher lipid, ash, fiber, and protein content, they had low carbohydrate content, with the lowest level observed in the AM bread (36.27 g/100 g). Overall, the A bread had the highest carbohydrate content, equivalent to 48.98 g/100 g.
The BR bread had the highest pH; however, in general, the bread enriched with Moringa leaf, due to its high mineral content, had significantly lower pH values (p < 0.05) than the control bread.
The addition of moringa leaf markedly decreased the lightness coordinate (L*) and tone (h*) parameters; however, conversely, it markedly increased the redness coordinate (a*). Moreover, it slightly decreased the saturation (C*) and yellowness coordinate (b*) values.
The color darkening observed after adding Moringa leaf could be considered a positive point, as gluten-free breads typically have a poor color. It also improved the aroma and texture but did not enhance acceptability among the consumers, who preferred the sensory attributes contributed by the pseudocereals alone.
Furthermore, adding Moringa leaf significantly increased the TPC and antioxidant activity of the bread to 64.54%, 96.37%, and 71.15% in QM, AM, and BRM, respectively. The increase in the TPC of all six formulated gluten-free breads was statistically significant compared to COM bread (p<0.05).
Notably, the AM bread had the highest total folate content, antioxidant capacity, and TPCs due to the high content of moringa compounds, equivalent to 32.90 mg GAE/g DW, and bioactive compounds in amaranth, such as p-hydroxybenzoic acid, vanillic, rutin, and gallic acids.
Regarding mineral bioaccessibility, BR bread had a higher content of iron (Fe) and calcium (Ca) minerals, which are especially important for celiac patients who have these micronutrient deficiencies. The BR bread obtained greater mineral bioaccessibility mainly due to its low phytic acid content. The control bread with sourdough also had higher bioaccessibility of most minerals, including Fe, Ca, Mn (manganese), Zn (zinc), Sr (strontium), S (sulfur), and B (boron).
All psuedocereals, quinoa, buckwheat, and amaranth, are rich sources of amino acids. Thus, Q, A, and BR bread had high amounts of methionine, phenylalanine, cysteine, and hydroxyproline, equivalent to 66.79, 213.73, 69.04, and 0.26g/100 g, respectively. Given its high content of all folate-mono glutamates, BRM bread could be great for a celiac patient who typically has folate deficiencies.
In the sensory evaluation, the QM bread obtained the highest score on attributes of aroma and texture, while the A bread emerged as the winner in terms of appearance, flavor, color, and acceptability. The BRM bread scored lowest on aroma, taste, and overall acceptability.
Conclusive Health Benefits and Future Prospects
According to the authors, it is the first time that a gluten-free sourdough bread containing pseudocereals has been fortified with Moringa oleifera, a drought-resistant and highly productive crop with several health benefits.
Incorporating Moringa notably increased nutritional richness, particularly in terms of protein, amino acids, and essential minerals. In addition, it enhanced the levels of soluble dietary fiber in breads, which has health benefits. Accordingly, bread fortified with moringa leaf had high antioxidant capacity, TPCs, folate content, phenylalanine, and cysteine amino acids content, all sugars, and fatty acids, such as docosahexaenoic acid (DHA).
Furthermore, a tasters' panel found this novel formulation acceptable and agreed that it met the requirements for labeling it as a functional food.
Overall, reformulated gluten-free sourdough bread with pseudocereals and enriched with Moringa could promote the health of all people. They could be most beneficial for people with celiac disease who have nutritional inadequacies due to their dependence on gluten-free bread.
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