Determination ofN-(Carboxymethyl)fumonisin B₁in Corn Products by Liquid Chromatography/Electrospray Ionization–Mass Spectrometry

Abstract

It is well-known that fumonisin B(1) (FB(1)) in corn meal decreases during baking, frying, and cooking, but it is still not exactly clear how heating affects the formation of N-(carboxymethyl)fumonisin B(1) (NCM-FB(1)), the reaction product of FB(1) and reducing sugars. In model experiments corn grits were spiked with FB(1) (2 mg/kg) and D-glucose (50 g/kg) or sucrose (50 g/kg) and manufactured into extrusion products at various temperatures (160--180 degrees C) and moisture levels (16--20%). A liquid chromatography/electrospray ionization-mass spectrometry method using isotopically labeled fumonisin FB(1)-d(6) as an internal standard was developed for the determination of NCM-FB(1). For sample cleanup solid-phase C18 cartridges were used. The detection limit achieved with this method was 10 ng/g (signal-noise ratio = 3:1) using the protonated molecule [M + H](+) signal of NCM-FB(1) (m/z 780) in the selected ion monitoring mode. Low concentrations of NCM-FB(1) (29-97 ng/g) were detected in all samples spiked with D-glucose and FB(1), whereas those spiked with FB(1) and sucrose showed only NCM-FB(1) in samples produced at 180 degrees C (NCM-FB(1) = 27 ng/g). Various corn-containing food samples from the German market were analyzed for the presence of NCM-FB(1), FB(1), and hydrolyzed fumonisin B(1) (HFB(1)). All samples were contaminated with FB(1) (22--194 ng/g) and HFB(1) (5--247 ng/g). Six of nine samples contained NCM-FB(1) in low concentrations ranging from 10 to 76 ng/g. From these data and the low toxicity of NCM-FB(1) it can be concluded that the significance of NCM-FB(1) in food seems to be a minor one.

Effects of thermal food processing on the chemical structure and toxicity of fumonisin mycotoxins

“…While, from a structure-function standpoint, this reaction sequence is intriguing toxicologically (see below), little to no NCM-FB1 or NDF-FB 1 has been found in corn [95,99] or nixtamalization products [95]. At higher temperatures, e. g., under extruding conditions (see Table 2), only low concentrations (27 -97 lg/kg) [81] of NCM-FB 1 were detected in a product made from cornmeal spiked with 2 mg/kg FB 1 .…”

“…Both found significant reductions of fumonisin concentration in the extruded product, however, the amount of reduction depended on the type and amount of sugar added. Extruding corn grits that were spiked with 2 mg/kg FB 1 resulted in a 68 -77% reduction of FB 1 with added sucrose and in a 85 -93% reduction of FB 1 with added glucose (parameters see Table 2) [81]. Castelo et al [56] found a fumonisin reduction of 45 -71% when glucose, 30 -53% when fructose and 19 -39% when sucrose was added.…”

“…Seefelder et al [81] and Castelo et al [56] studied the effects of added sugars on fumonisin levels in extruded corn grits. Both found significant reductions of fumonisin concentration in the extruded product, however, the amount of reduction depended on the type and amount of sugar added.…”

“…The combined effect of nixtamalization and cooking on fumonisin levels has been investigated by several research groups and, in each case, the concentration of fumonisins in the product was less than in the uncooked corn. Dombrink-Kurtzman et al [93] showed that nixtamalization reduced the FB 1 concentration in tortillas by 81.5% and that the FB 1 and HFB 1 were mainly found in the steeping and washing water [93]. Cortez-Rocha et al [78] observed a 39% reduction of FB 1 concentration when raw corn was nixtamalized (1,2% Ca(OH) 2 , 55 min, 95 -1008C).…”

Recent advances in mycotoxin determination in food and feed by hyphenated chromatographic techniques/mass spectrometry

“…The same group also proposed this method for the determination of N-(carboxymethyl)-fumonisin B1 (NCM-FB1), the degradation product formed by reaction of fumonisin B1 with reducing sugars, in corn products (Seefelder, Hartl, & Humpf, 2001). By using D 6 -FB1 as internal standard, they obtained a LOD of 10 ppb by monitoring the protonated ion of NCM-FB1.…”