Effects of solid‐state fermentation (Aspergillus oryzae var. oryzae) on the physicochemical properties of corn starch

Abstract

The physicochemical transformations suffered by corn starch granules under the solid-state fermentative action of Aspergillus oryzae var. oryzae were studied. Light microscopy images showed that the starch granules became increasingly fractured and broke-down as fermentation time was longer. SEM micrographs showed that the mean particle diameter decreased linearly with the fermentation time, indicating a zeroth-order hydrolysis kinetics. The crystallinity content of fermented corn starch achieved a maximum value (39.72 AE 1.02) after 100 h followed by a reduction at longer fermentation times. The short-range ordering monitored by the absorbance ratio 1047/1022 from FTIR increased during the first 100 h, suggesting the formation of double-helix structures as long chains was hydrolyzed. DSC analysis showed the deterioration of the internal ordering of starch granules for long fermentation times, reflecting an extensive disruption of the granule integrity. Overall, the results showed that starch granules underwent strong, although slow, physicochemical changes as the solid-state fermentation evolved. Specifically, crystallinity increased about 25% and viscosity of 5% w/w gelatinized starch dispersion decreased about 85% in the first 100 h of fermentation. In addition, the gelatinization enthalpy decreased about 60.0% and the zpotential doubled during the fermentation process.

Changes in Structural and Physicochemical Properties of Corn Flour after Fermentation with Lactobacillus plantarum Y1

“…These results are in good agreement with findings of Reyes et al. [ 27 ] Also, Falade et al. found a greater enthalpy value for maize flour after fermentation with L. plantarum , indicating that higher energy is needed to disrupt starch granules of fermented corn flour.…”

“…[25] During fermentation, the amorphous zone was partially destroyed, and the proportion of crystalline zone increased, resulting in an increase in To, Tp, Tc, and ΔH, which is consistent with the conclusion of pasting properties mentioned above. These results are in good agreement with findings of Reyes et al [27] Also, Falade et al found a greater enthalpy value for maize flour after fermentation with L. plantarum, indicating that higher energy is needed to disrupt starch granules of fermented corn flour. [28]…”

Fabrication and Characterization of Starch Nanohydrogels via Reverse Emulsification and Internal Gelation

“…47 The ratio of the intensity of bands at 1047 and 1022 cm −1 (1047/1022) represented the ratio of ordered crystalline regions to amorphous regions in the starch. 48,49 The ratio of 1047/1022 among the three starch nanohydrogels was the highest in pea starch nanohydrogels and the lowest in potato starch nanohydrogels (Figure 6), which is consistent with the relative crystallinity results (Figure 4). The changes in the infrared (IR) ratio of 1047/1022 cm −1 following the retrogradation process suggest that the molecules of pea starch nanohydrogels with high-amylose starch more readily reassociate and reorganize into a more organized structure than the other two starches.…”

Solid State Fermentation of Turmeric Rhizomes with Aspergillus SP. To Improve Yield and Composition of Extracted Turmeric Oil

“…The secretion of hydrolytic enzymes in the process of metabolic fungi results in the cutting of the glycosidic bonds of starch compounds on the cell wall, causing the breakdown of complex compounds into simpler ones, namely glucose, and a decrease in starch content [29][30]. It is known from the research of Reyes et al [31] that the fermentation time of 3 days is sufficient to degrade starch granules in the material. The previous study used pure starch whereas this study used turmeric rhizome as the substrate, which is a complex medium.…”