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- Author or Editor: A. Cencič x
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Vegetables are the major source of dietary nitrate, with wide variations in nitrate content. The presence of nitrate in vegetables is often associated with harmful effects on human health, i.e. with toxic effects of methaemoglobinaemia and the possibility of causing an endogenous formation of carcinogenic N-nitroso compounds. However, it is also associated with beneficial health effects, since nitrate represent an important alternative pathway to bioactive NO and its important physiological roles in vascular and immune function. In this review the concentrations of nitrate in different vegetables from different countries are given. Furthermore, the reasons for the different contents of nitrate in vegetables, the daily intakes and comparisons to the acceptable daily intake (ADI) values, legislation, metabolism and toxicology of nitrate are described as well as harmful and beneficial effects of nitrate on human health.
The influence of three milling techniques (MT1: industrial roller-grinder, MT2: grain hammer crasher, and MT3: traditional millstone) and two baking methods (BM1: industrial oven, BM2: traditional ceramic stove heated by wood (log fire oven)) on mycotoxin deoxynivalenol (DON) and nivalenol (NIV) levels in bread were investigated. The DON and NIV concentrations in wheat grain, flour, and bread were analysed using high performance liquid chromatography with UV-detection methods. The 2 500 kg lot of wheat grain containing 1 400–1 900 μg kg −1 deoxynivalenol and 130–200 μg kg −1 nivalenol was divided into sub-lots which were processed to get three types of flour (F1: industrial bread flour, F2: industrial wholegrain flour and F3: traditional wholegrain flour). The concentrations of DON and NIV measured after milling the grain according to MT1 (yielding F1) amounted to 310–370 \g kg −1 and <50–70 μg kg t1 , respectively. After applying MT2 to the grain (yielding F2), the DON and NIV levels were measured to be 1 060–1 400 μg kg −1 and 60–87 μg kg −1 , respectively. Applying MT3 (yielding F3) produced a DON level of 1 100–1 770 μg kg − 1 and a NIV level of 80–95 μg kg −1 . Six types of bread were baked from the three types of flour according to BM1 or BM2, and the mycotoxin levels were analysed. The average reduction in DON concentration after baking (70 min at 195–235 °C) was 47.2% for bread baked in the industrial oven and 48.7% for bread baked in the log fire oven. Concentrations of DON in bread prepared by the industrial MT1 were under the permitted limit of 500 μg kg −1 stated in EC (2006) regulation, despite the fact that the bread was baked from grains highly contaminated with mycotoxins. In the bread baked from traditional wholegrain flour, mycotoxin concentrations were higher (850–950 μg kg −1 ).
