title: Effects of pH and Temperature on the Stability of Fumonisins in Maize Products.
abstract: This paper is a study of the stability of fumonisins in dough based on maize flour prepared in a phosphate buffer with a pH of 3.5, 5.5 or 7.5 and baked at a temperature within the range of 100-250 °C. Buffers with various pH values were tested, since it is well-known that pH may significantly influence interactions of fumonisins with other substances. A standard analytical procedure was used to determine the concentration of free fumonisins. Hydrolysis in an alkaline medium was then applied to reveal the hidden forms, while the total fumonisins concentations was determined in another measurement. The total concentration of fumonisins was statistically higher in pH = 3.5 and pH = 5.5 than the concentration of free fumonisins; no similar difference was found at pH = 7.5. The applied phosphate buffer pH 7.5 may enhance solubility of fumonisins, which would increase extraction efficiency of free analytes, thereby decreasing the difference between concentrations of total and free fumonisins. Hydrolysed B₁ fumonisin (HFB₁) and partially hydrolysed B₁ fumonisin (isomers a and b: PHFB1aand PHFB1b, respectively) were the main investigated substances. For baking temperatures below 220 °C, fumonisins were slightly more stable for pH = 5.5 than for pH = 3.5 and pH = 7.5. In both of these latter cases, the concentration of partially hydrolysed fumonisins grew initially (up to 200 °C) with an increase in the baking temperature, and then dropped. Similar behaviour was observed for free HFB₁, which may suggest the following fumonisin degradation mechanism: initially, the tricarballylic acid (TCA) groups are removed from the molecules, and next, the HFB₁ molecules disintegrate.
authors.affiliation: Department of Food Analysis, Prof. Waclaw Dabrowski Institute of Agricultural and Food Biotechnology, Rakowiecka 36, 02-532 Warsaw, Poland. marcin.bryla@ibprs.pl.
authors.forename: Marcin
authors.initials: M
authors.lastname: Bryła
authors.affiliation: Department of Chemistry, Poznan University of Life Sciences, Wojska Polskiego 75, 60-625 Poznan, Poland. agat@up.poznan.pl.
authors.forename: Agnieszka
authors.initials: A
authors.lastname: Waśkiewicz
authors.affiliation: Department of Food Analysis, Prof. Waclaw Dabrowski Institute of Agricultural and Food Biotechnology, Rakowiecka 36, 02-532 Warsaw, Poland. krystyna.szymczyk@ibprs.pl.
authors.forename: Krystyna
authors.initials: K
authors.lastname: Szymczyk
authors.affiliation: Department of Food Analysis, Prof. Waclaw Dabrowski Institute of Agricultural and Food Biotechnology, Rakowiecka 36, 02-532 Warsaw, Poland. renata.jedrzejczak@ibprs.pl.
authors.forename: Renata
authors.initials: R
authors.lastname: Jędrzejczak
mesh_terms: D003296:Cooking; D005433:Flour; D005506:Food Contamination / Q000032:analysis; D037341:Fumonisins / Q000032:analysis* / Q000737:chemistry; D006863:Hydrogen-Ion Concentration; D006868:Hydrolysis; D013696:Temperature; D003313:Zea mays / Q000737:chemistry*
chemical_list: D037341:Fumonisins
keywords: LC-TOF-HRMS; conjugated fumonisins; fumonisins; maize products; pH and temperature conditions; stability of fumonisins