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Photodegradation of cassava and corn starches
A C Bertolini1, C Mestres, J Raffi
1Institut National de la Recherche Agronomique, Rue de la Géraudière, B.P. 71627, 44316 Nantes, France.
Journal of Agricultural and Food Chemistry
|March 23, 2001
Summary
UV light causes photochemical degradation in sour cassava starch, altering its structure and improving baking expansion. This process involves photodegradation of photosensitive compounds and free radical mechanisms.
Area of Science:
- Food Science
- Photochemistry
- Polymer Science
Background:
- Sour cassava starch (Polvilho azedo) exhibits unique baking expansion properties.
- These properties are linked to photochemical degradation during sun-drying and heterolactic fermentation.
Purpose of the Study:
- To investigate the impact of UV irradiation on cassava starch structure.
- To compare these effects with corn starch and dextrins.
- To elucidate the mechanisms behind UV-induced starch modification.
Main Methods:
- Exposure of cassava starch, corn starch, and dextrins to sunlight and 360 nm UV irradiation.
- Analysis of structural changes and photodegradation of starch and lactic acid.
- Spectroscopic investigation of photosensitive and fluorescent compounds.
Main Results:
- Cassava starch contains photosensitive compounds degraded by UV light (360 and 290 nm).
- UV irradiation depolymerized both cassava and corn starches, involving free radical mechanisms.
- Lactic acid present in the starch was also photodegraded.
- Photodegradation is attributed to UV absorption by fluorescent and non-fluorescent chromophores.
Conclusions:
- UV irradiation significantly modifies cassava starch structure through photodegradation.
- The findings explain the role of photochemical processes in sour cassava starch's baking properties.
- Understanding these mechanisms can inform starch modification for improved food applications.