Exploring the effects of spontaneous and solid-state fermentation on the physicochemical, functional and structural properties of whole wheat flour (Triticum aestivum L.)

Abstract

The effects of fermentation on various physicochemical and functional properties of whole wheat flour (Triticum aestivum L.) were investigated in this study. Firstly, changes in pH and total titratable acidity (TTA) were observed during spontaneous and solid-state fermentation. Spontaneous and solid-state fermentation led to a decrease in pH and a rapid increase in TTA, indicating effective acidification due to organic acid production. Both fermentation approaches significantly influenced the total starch and amylose content of wheat. The total starch content was decreased accompanied by a significant increase in apparent amylose content. This phenomenon was attributed to starch hydrolysis facilitated by microbial enzymes and organic acids, resulting in a higher amylose/amylopectin ratio. Chemical composition and mineral content of whole wheat flour were also affected. Fermentation led to reductions in moisture, crude fat, and crude protein content, while ash content increased. Furthermore, fermentation significantly impacted the soluble and total dietary fiber content of whole wheat flour, with an increase in soluble dietary fiber and a decrease in total dietary fiber. These changes were attributed to increased synthesis of non-cellulosic polysaccharides and β-glucans during fermentation. Moreover, fermentation resulted in reductions in gluten content, alterations in functional properties such as water and oil absorption capacity, changes in protein solubility, and modifications in gel texture properties. Finally, X-ray diffraction (XRD) and scanning electron microscopy (SEM) revealed minimal changes in the crystalline structure and morphology of starch granules during fermentation, with some signs of surface erosion and degradation, particularly in solid-state fermented samples. The results highlight the potential benefits of fermentation for improving the properties of whole wheat flour. This study contributes to a better understanding of the effects of fermentation on whole wheat flour, offering insights for the development of novel and improved whole wheat flour-based food products.