Deep-freezing of potato starch.

Area of Science:

• Food Science
• Materials Science
• Biochemistry

Background:

• Starch is a vital biopolymer in food and industrial applications.
• Understanding starch's response to physical treatments like freezing is crucial for processing.
• Moisture content significantly influences starch's physical and chemical properties.

Purpose of the Study:

• To investigate the effects of deep-freezing and thawing on potato starch granules.
• To determine how varying moisture levels impact starch structural changes post-freezing.
• To correlate structural alterations with changes in starch properties.

Main Methods:

• Potato starch with different moisture contents (5%, 13%, 24%) was deep-frozen in liquid nitrogen and then thawed.
• Analyzed using cross-polarised light beam microscopy (CLBM).
• Utilized Fourier Transformation Infrared Spectroscopy (FT-IR), powder X-ray diffractometry, and non-contact Atomic Force Microscopy (nc-AFM) for structural analysis.

Main Results:

• Deep-freezing and thawing induced surface and internal structural changes in potato starch granules.
• Fourier Transformation Infrared Spectroscopy (FT-IR) spectra and X-ray diffractograms indicated internal alterations.
• Increased granule crystallinity was observed in moistened starch (24% moisture) after freezing and thawing.
• Minor effects were noted on aqueous solubility and gelation characteristics.

Conclusions:

• Deep-freezing significantly impacts potato starch structure, particularly at higher moisture levels.
• Moisture content is a critical factor modulating starch's response to cryogenic treatment.
• While crystallinity increases, the impact on solubility and gelation is minimal, suggesting retained functionality for some applications.