Estudio de la reducción química y biológica de hongos y micotoxinas en pan

Food spoilage caused by molds that produce mycotoxins is of primary concern and represents an important food safety problem. Cereal grains and their processed food products, such as bread, are frequently contaminated with mycotoxigenic fungi. Therefore, in this PhD Thesis, the occurrence of 17 mycotoxins in 80 samples of bread loaf and the risk exposure of the population to these toxic compounds were determined. Aflatoxins (AFs), zearalenone (ZEA) and enniatins (ENs) were detected respectively in 20%, 65% and 96% of bread samples analyzed. The presence of these mycotoxins and, above all, the samples in which AFs and ZEA, exceeded the maximum limits established, raised the interest of reducing these compounds. In particular, two natural alternatives to the conventional preservatives were studied: isothiocyanates (ITCs) in active packaging and lactic acid bacteria (LABs) as starter cultures. ITCs are originated from the hydrolysis of glucosinolates (GLSs), which are found in mustard, broccoli, cauliflower, cabbage, etc. Different packaging with ITCs and mustard flour were evaluated for their ability to extend the shelf life and reduce the presence of mycotoxins in cereals contaminated by Aspergillus parasiticus or Penicillium expansum. Furthermore, the potential of AITC to react with ZEA and α-zearalenol (α-ZOL) was determined; reaction products were characterized and bioaccessibility and bioavailability of the mycotoxins and adducts with AITC were studied. LABs were added during the baking process to extend the shelf life and reduce the production of AFs in bread contaminated with A. parasiticus. Finally, the ability of different LABs to reduce the bioaccessibility of aflatoxins B1 (AFB1) and B2 (AFB2), through a model of in vitro dynamic, digestion was studied. Among the ITCs, only AITC extended the shelf life and reduced AFs in bread contaminated with A. parasiticus and patulin (PAT) produced by P. expansum. Among the two mustard flours studied, the oriental mustard flour was more effective in reducing AFs while the yellow flour in the reduction of PAT. AITC can react directly and reduce α-ZOL and ZEA in vitro at levels up to 97%, forming adducts ZEA/α-ZOL-AITC. A reduction of mycotoxins and their reaction products was observed after simulated digestion. Reaction products of mycotoxins with AITC were more bioavailable compared to the isolated mycotoxins. The use of LABs in bread fermentation increased the shelf life of bread and reduced the formation of AFs. Finally, some of the bacteria studied were able to reduce the bioaccessibility of AFB1 and AFB2 contained in contaminated bread up to 99%.