The effects of water activity (aw, 0.994-0.90 identical to 0.4-14.0 (-)MPa water potential), temperature (4-45 degrees C), and pH (3.6, 5.5, 7.0), and their interactions on growth of isolates of Fusarium moniliforme and Fusarium proliferatum were determined in vitro on a maize extract agar medium. Growth of two isolates of F. moniliforme and four isolates of F. proliferatum were significantly influenced by water activity regardless of solute type used (NaCl, glycerol, or glucose). However, at steady-state aw levels, growth was optimum at 0.994-0.98 aw and reduced significantly at 0.92 aw. Further detailed studies with one isolate of F. moniliforme (25N) and two isolates of F. proliferatum (73N, 131N) showed that growth occurred over the range of 0.994-0.90 aw in the temperature range 20-35 degrees C with slight differences between species. Growth did occur at 4 degrees C and 0.994-0.96 aw, but no growth was recorded at 40 and 45 degrees C regardless of aw. Profiles of aw x temperature relations for growth of these two species were constructed from these data for the first time. Optimum pH and temperature for growth was 5.5 and 25 degrees C for both isolates of F. proliferatum, and pH 7.0 and 30 degrees C for the isolate of F. moniliforme. However, for the latter isolate at < 0.98 aw, optimum pH and temperature for growth changed. The effects of pH, temperature, and aw for single, two-way and three-way interactions were all found to be statistically significant for these three isolates. The ecological significance of this information for understanding these important fumonisin-producing fungi is discussed.

The fate of deoxynivalenol (DON) and ochratoxin A (OTA) during the breadmaking process was studied. In particular, toxin content was analysed in mixed baking ingredients before kneading, after fermentation and proofing, and finally after baking. Fermentation and proofing were carried out at 30 C for 1 h, while baking was performed at different temperature levels (from 170 to 210 C) and baking times from 45 to 135 min, in a full factorial design. DON increased from unkneaded mix to fermented dough, and decreased due to baking; this trend depended on the initial concentration of DON in the flour. The level in the bread was significantly lower than in the initial mix of ingredients. In contrast, deoxynivalenol-3-glucoside (DON-3-G) content increased both during kneading and fermentation, and also during baking. Moreover, the results confirmed the high stability of OTA as no significant change in its content could be observed as a result of the breadmaking process. As conclusion, the design of bakery product processes may help to control DON in final products, because although quite stable, its levels can be reduced to some extent. However, high levels of DON-3-G were released during baking, and this point should be further investigated. Mycotoxins have been always considered as stable compounds; however, in depth knowledge of the processing steps that may lead to some reduction (although limited) and those which can stimulate their release from conjugated forms, will definitely help in their control in finished foodstuffs.

This review focuses on the fumonisin-producing Fusarium species and the ecophysiology of these species. The effects of environmental biotic and abiotic factors on germination, growth, and fumonisin B1 production by Fusarium verticillioides and Fusarium proliferatum have been investigated under laboratory, field, and storage conditions. An understanding of the factors involved in production of fumonisins is the first step in preventing accumulation of these toxins.

Beer is the most consumed alcoholic beverage in the world. Its contamination with mycotoxins is of public health concern, especially for heavy drinkers. Beer production implies a variety of operations which might impact the initial level of mycotoxins in a positive or negative way. The complexity of these operations do not give to the brewer a complete control on chemical and biochemical reactions that take place in the batch, but the knowledge about mycotoxin properties can help in identifying the operations decreasing their level in foodstuffs and in the development of mitigation strategies. This review discusses available data about mycotoxin evolution during malting and brewing process. The operations that may lead to a decrease in mycotoxin load are found to be steeping, kilning, roasting, fermentation and stabilization operations applied over the process (e.g. clarification). Also, other general decontamination strategies usually employed in food industry, such as hot water treatment of barley, ozonation or even the use of lactic acid bacteria starter cultures during malting or fermentation are considered.

The effect of different water activities (aw, 0.968, 0.956, 0.944, 0.925) and temperature (25 degrees C and 30 degrees C) on colonization and production of fumonisin B1 (FB1) and B2 (FB2) on sterile layers of maize by Fusarium proliferatum and F. moniliforme isolates was determined over periods of 6 weeks. Generally, both F. moniliforme and F. proliferatum grew faster with increasing aw and best at 30 degrees C. All three isolates produced more FB1 than FB2 regardless of aw or temperature. Very little FB1 and FB2 were produced at 0.925 aw, with maximum produced at 0.956 and 0.968 aw at both temperatures tested. Most FB1 and FB2 were produced by F. moniliforme (25N), followed by F. proliferatum isolates (73N and 131N). At all aw levels and both temperatures there was an increase in FB1 and FB2 concentration with time. Statistical analyses of aw, temperature, time, two- and three-way interactions showed some significant differences between isolates and FB1 and FB2 production.

The stability of deoxynivalenol (DON), deoxynivalenol-3-glucoside (DON-3-glucoside), 3-acetyldeoxynivalenol (3-ADON), 15-acetyldeoxynivalenol (15-ADON), de-epoxy-deoxynivalenol (DOM-1) and ochratoxin A (OTA) during thermal processing has been studied. Baking temperature, time and initial mycotoxin concentration in the raw materials were assayed as factors. An improved UPLC-MS/MS method to detect DON, DON-3-glucoside, 3-ADON, 15-ADON and DOM-1 in wheat baked products was developed in the present assay. The results highlighted the importance of temperature and time in mycotoxin stability in heat treatments. OTA is more stable than DON in a baking treatment. Interestingly, the DON-3-glucoside concentrations increased (>300%) under mild baking conditions. On the other hand, it was rapidly reduced under harsh conditions. The 3-ADON decreased during the heat treatment; while DOM-1 increased after the heating process. Finally, the data followed first order kinetics for analysed mycotoxins and thermal constant rates (k) were calculated. This parameter can be a useful tool for prediction of mycotoxin levels.

Deoxynivalenol (DON) and ochratoxin A (OTA) are mycotoxins produced by fungal species which can contaminate, alone or simultaneously, cereal-based products such as bread. Due to the increasing interest in the beneficial effects of dietary bran, bran bread has attained high consumption. Usually, the higher mycotoxin concentrations in cereals are found in the external layers of the grain (bran), leading to higher concentration of DON and OTA in breads with added bran. Moreover, the use of sourdough in breadmaking is increasing, but no studies about its effect in the mycotoxins content exist. The objective of this study was to determine the variation of concentration of these mycotoxins during the breadmaking process including the following factors: two initial mycotoxin concentrations in the initial mix of ingredients, four different bran contents, and use of sourdough. OTA was confirmed to be quite stable during the breadmaking process, regardless of the assayed factors. DON concentration during breadmaking was not significantly affected by bran content of bread. However, it was significantly affected by kneading and fermentation steps in opposite way depending on sourdough use and flour contamination level: if DON reduction occurs during fermentation, this leads to a safer situation, but the possible increase in DON should be considered with care, as it can compensate the expected dilution effect by recipe. Finally, the results on deoxynivalenol-3-glucoside (DON-3-G), although preliminar, suggest an increase of this toxin during fermentation, but mainly during baking.

The effects of water activity (aW, 0.994-0.85 = 0.4-21.0 (-)MPa water potential), temperature (5-42 degrees C), and their interactions on microconidial germination of three isolates each of Fusarium moniliforme and Fusarium proliferatum were determined in vitro on a maize meal extract medium. Temporal germination rates of microconidia of isolates of both species were significantly influenced by both aW and temperature. Germination was very rapid at > 0.94 aW with an almost linear increase with time. Germination rates of microconidia of F. moniliforme were slower than those of F. proliferatum isolates at marginal aW levels and 5-25 degrees C, while at higher temperature (30-37 degrees C), the former germinated more rapidly than the latter. The aW minima for germination of isolates of both species was 0.88, with none occurring at 0.85 aW over a 40-day incubation period. At 37 degrees C, isolates of F. moniliforme had slightly lower aW minima than those of F. proliferatum. The narrowest range of aW for germination was at 5 degrees C, and none occurred at 42 degrees C. The effect of aW x temperature interactions on the lag phases (h) prior to germination and the germination rates (h-1) were estimated using the Gompertz model and the Zwietering equation. This showed that lag phases were shorter at 25-30 degrees C and 0.994-0.98 aW, and were increased to 10-500 h at marginal temperatures (5-10 degrees C) for F. proliferatum and longer for F. moniliforme. At marginal aW levels (0.92-0.90), lag times were increased to > 250 h. Germination rates (h-1) were different for the two species. Microconidia of F. moniliforme germinated optimally at 25-37 degrees C and 0.96-0.98 aW, but this changed to 30 degrees C at 0.90-0.94 aW, while germination of microconidia of F. proliferatum remained optimum at 30 degrees C, regardless of aW. There were statistically significant (P < 0.01) effects of aW, temperature, isolate, and two- and three-way interactions for F. proliferatum, but there were no intraisolate effects for F. moniliforme. The ecological significance of these data for understanding colonization patterns of these important fumonisin-producing fungi are discussed.