Submitted to: Industrial Crops and Products
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 12/22/2008
Publication Date: 7/1/2009
Citation: Sessa, D.J., Palmquist, D.E. 2009. Decolorization/Deodorization of Zein via Activated Carbons and Molecular Sieves. Industrial Crops and Products.
Interpretive Summary: Commercially available zein products produced in the USA all possess yellow color and an off odor that deters their usage in food systems as well as in the medical, pharmaceutical and cosmetic industries. Activated carbons (ACs) are effective for purifying zein, but, use of this adsorbent binds too much protein along with the contaminants. Statistical analyses of the binding characteristics of protein and contaminants with a series of different ACs demonstrated that AC from coconut hulls gave good adsorptions of contaminants with the least adsorption of protein. Based on AC principles of adsorption, zeolites, clay-based particles acting as a porous molecular sieve, proved to be alternative adsorbents that bound lesser amounts of protein compared to AC usage relative to contaminants adsorptions. This information is basic to the selection of column media for a pilot scale operation to purify zein products. These findings will benefit farmers, corn ethanol producers, food service, medical, pharmaceutical and cosmetic industries.
Technical Abstract: A series of commercial activated carbons generated from different media and selective microporous zeolites with different pore sizes were used in a batch system to sequester the low molecular weight odor and color contaminants in commercial zein products. Because the adsorbents can also adsorb proteins as well as the odor and color components, a statistical evaluation of the batch adsorption data was performed to determine the activated carbon medium and zeolite pore size that gives the least protein adsorptions relative to the odor and color component adsorptions. Adsorptive properties of the activated carbons and molecular sieves were performed by spectral analyses. Wavelength 280nm measures absorbance of the tyrosine component of zein protein and absorbance at wavelength 325nm is a measure of the off-odor contributor previously identified as diferuloylputrescine. Its removal coincides with removal of the color components attributed to xanthophylls. Our findings demonstrated that activated carbon generated from coconut hulls and zeolite 5A (5 angstrom pore size) achieved our objective. This information is basic to selection of column chromatographic media to be used for the purification of commercial zein products.