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Title: Reduced toxicity of fumonisin B1 in corn grits by single-screw extrusion

Author
item Voss, Kenneth
item BULLERMAN, LLOYD - FOOD SCI/UNEB,LINCOLN,NE
item BIANCHINI, ANDREIA - FOOD SCI/UNEB,LINCOLN,NE
item HANNA, MILFORD - FOOD SCI/UNEB,LINCOLN,NE
item RYU, DOJIN - FOOD SCI/TX WOMANS UNIV

Submitted to: Journal of Food Protection
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 5/2/2008
Publication Date: 10/1/2008
Citation: Voss, K.A., Bullerman, L.B., Bianchini, A., Hanna, M.A., Ryu, D. 2008. Reduced toxicity of fumonisin B1 in corn grits by single-screw extrusion. Journal of Food Protection. 71(10):2036-2041.

Interpretive Summary: Fumonisins are toxins produced by a group of related molds of the Fusarium species that contaminate corn. Fumonisin B1 (FB1) is the most common. It causes animal diseases and, although the impact of FB1 on human health is unclear, evidence suggests that it increases the risk of certain cancers and birth defects. Minimizing exposure to fumonisins is therefore desirable. One approach is to use processing and cooking methods that reduce fumonisin concentrations in the feed or food product. Extrusion cooking combines high heat and pressure and has been shown to reduce FB1 concentrations in corn. The amount of fumonisin reduction achieved is increased if glucose is added to the raw material. However, the types of chemical reactions that occur in the corn during extrusion are poorly understood and the toxicity of extrusion products has not been tested. To do so, one batch of corn grits was spiked with 30 ppm FB1 and two batches of grits were fermented with fumonisin-producing fungi (FB1 concentrations were: low-level = 33 and high-level = 48 ppm). Portions of the three batches of spiked or fermented grits were extruded without glucose. Additional portions of each were extruded with glucose supplementation. Extrusion without glucose reduced fumonisin B1 concentrations by 10 to 30 % whereas extrusion with glucose reduced fumonisin B1 concentrations by 75 to 85%. The nine contaminated preparations were fed to rats to assess their toxicity and, with one exception, they caused significant kidney lesions. In contrast, the kidney effects found in the rats fed the low-level (30 ppm FB1) fermented grits extruded with glucose were significantly less severe. This indicates that extrusion with glucose can safely reduce fumonisin exposure and toxicity under some circumstances and suggests that more studies are needed to optimize the process.

Technical Abstract: Extrusion cooking under conditions of high heat and pressure reduces the concentration of fumonisins in corn-based products; however, the toxicity of heretofore uncharacterized fumonisin reactions products in extruded materials has not been determined. Uncontaminated corn grits, grits spiked with 30 mg/g FB1, and two batches of grits fermented with F. verticillioides M-2552 containing 33 µg/g (Batch 1) or 48 mg/g FB1 (Batch 2) were extruded in the with and without glucose (10%, dry weight basis) supplementation. Equivalent weights of the non-extruded and extruded materials were fed to male Sprague-Dawley rats for three weeks. Two control groups were fed either non-extruded (negative control) or extruded (extrusion control) uncontaminated grits. The groups fed the non-extruded spiked or fermented grits, the spiked or fermented grits extruded without glucose, and the spiked or the more highly contaminated Batch 2 of fermented grits extruded with 10 % glucose supplementation exhibited significantly decreased kidney weights and moderately severe microscopic kidney lesions that were consistent with the effects of fumonisin exposure. Kidney weights of rats fed Batch 1 of the fermented grits extruded with 10 % glucose supplementation were however not decreased. Furthermore, kidney lesions in this group were significantly less severe (scored as minimum to mild) than those found in the other test groups. Decreased toxicity could be attributed to the lower FB1 concentration (4.8 µg/g) of Batch 1 grits after fermentation with glucose compared to the non-extruded Batch 1 grits (33 µg/g) and all other spiked or fermented materials (9.5 to 48 /g FB1). Together, these findings confirm that extrusion with glucose supplementation more effectively decreases FB1 concentrations than extrusion alone and indicate that extrusion with glucose supplementation can reduce in vivo toxicity, likely by promoting the formation of less toxic FB1-glucose reaction products, Thus, this study suggests that extrusion with glucose supplementation is a potentially useful approach for reducing the fumonisin concentrations and toxicity of products prepared from corn contaminated with fumonisins.