Partial enhancement of soluble fiber through pyrodextrinization of the residual starch in cassava pulp: Developing a novel dietary fiber with modified functional and improved prebiotic properties

A novel cassava pulp–derived dietary fiber (CPDF) was developed by converting the residual starch in cassava pulp (CP) into resistant maltodextrin (RMD) through pyrodextrinization and enzymatic hydrolysis. This process produced a novel dietary fiber product with distinct properties, containing both insoluble fiber and high levels of soluble fiber. The effects of pyrodextrinization temperature were investigated at 140, 160, 180, and 200 °C. The CPDF product obtained from pyrodextrinization at 200 °C (pH 3 for 4 h) and subsequent enzymatic hydrolysis (CPDF-200) exhibited a significant soluble fraction content of 25.8 g per 100 g of product (43.3 % yield). Nuclear magnetic resonance spectra and high-performance liquid chromatography analyses confirmed the presence of RMD in the soluble fraction. Fourier transform infrared spectral analysis revealed a decrease in α-configuration and an increase in β-configuration of glycosidic bonds in the final product. The CPDF products were finely powdered, brown fibrous materials. As the pyrodextrinization temperature increased, the color darkened and the average particle size and the degree of crystallinity decreased. Functional properties, including water-holding capacity, oil-holding capacity, swelling capacity, and bulk density, also changed. Notably, CPDF-200 enhanced prebiotic potential by promoting Limosilactobacillus reuteri TBRC291 growth more effectively than CP without pyrodextrinization. The innovative application of pyrodextrinization and enzymatic hydrolysis to the residual starch in CP enhanced the soluble fiber content in the newly developed dietary fiber, offering a promising strategy for upcycling agricultural by-products into value-added functional foods.