Plantain starch granules morphology, crystallinity, structure transition, and size evolution upon acid hydrolysis

Area of Science:

• Food Science
• Materials Science
• Biochemistry

Background:

• Native starches possess unique crystalline and morphological structures.
• Acid hydrolysis is a common method for modifying starch properties.
• Understanding starch hydrolysis kinetics is crucial for optimizing its applications.

Purpose of the Study:

• To investigate the hydrolysis kinetics of plantain native starch using sulfuric acid.
• To characterize the structural and morphological changes in plantain starch during acid hydrolysis.
• To correlate hydrolysis time with changes in starch crystallinity, thermal properties, and granule morphology.

Main Methods:

• Plantain native starch was subjected to hydrolysis using sulfuric acid for 20 days.
• Hydrolysis kinetics were modeled using a logistic function.
• X-ray diffraction (XRD) was used to analyze changes in starch crystallinity.
• Differential scanning calorimetry (DSC) assessed thermal transitions.
• Scanning electron microscopy (SEM) examined starch granule morphology and size distribution.

Main Results:

• Hydrolysis followed a logistic function, with zero-order kinetics in the first 7 days, then slower kinetics.
• XRD revealed increased crystallinity in the first 7 days, followed by a decrease.
• DSC indicated a sharp structural transition around day 7, attributed to molecular rearrangement and erosion.
• SEM showed degradation of granule morphology from oval to irregular shapes, with broadening of size distribution due to fragmentation and agglomeration.

Conclusions:

• Plantain starch hydrolysis exhibits distinct kinetic phases and significant structural alterations.
• The initial 7 days are critical for structural changes, involving molecular rearrangement and erosion.
• Acid hydrolysis modifies plantain starch morphology and size, impacting its physicochemical properties.