First report on degradation of Alternaria toxins in apple juice by UV-C treatment

Toxic metabolites of <i>Alternaria</i> spp. are considered as "emerging mycotoxins" and have not been yet regulated by legislation in many countries. <i>Alternaria</i> species can grow and produce these mycotoxins in various products including fruits and fruit juices. In the present study, UV-C treatment (3971.09 J m^-2, 1-8 h) was used for the first time to degrade <i>Alternaria</i> toxins [tenuazonic acid (TeA), alternariol (AOH) and alternariol monomethyl ether (AME)] in apple juice. The effect of the treatment on quality characteristics of apple juice was also evaluated. UV-C treatment was very effective in degrading toxins. AME was the most affected toxin (decreased by half) after a treatment for 1 h. Degradation rates of 90.52, 77.01 and 75.92% were observed in the levels of TeA, AOH and AME, respectively, at the end of treatment for 8 h. Soluble solid content, pH and titratable acidity values did not change significantly after UV-C treatment, however turbidity values increased by 92% at the end of treatment. One of the major effects of UV-C treatment was on the color of the apple juice. Transmittance value at 440 nm increased while <i>a</i> ^* and <i>b</i> ^* values decreased significantly (<i>p</i> < 0.05) which shows that UV-C had a deleterious effect on color pigments of the juice. Significant decreases were observed also in phenolic content and antioxidant activity of the UV-C treated juice. These results demonstrate that UV-C is quite effective in degrading <i>Alternaria</i> toxins in apple juice but has detrimental effects on some quality characteristics, especially for prolonged treatment periods.