Abstract:
Aflatoxin B
1 (AFB
1) with strong carcinogenic, teratogenic and mutagenic properties is mainly produced by
Aspergillus flavus. Maize, due to its high moisture content, is prone to
Aspergillus flavus growth and subsequent AFB
1. Both ultraviolet irradiation and cold plasma are non-thermal physical techniques with fungal inactivation and mycotoxin degradation capabilities. Ultraviolet combined with cold plasma technology can overcome the limitations of individual technologies, such as low penetration depth and inefficiency. However, there is little research on the effect of ultraviolet combined with cold plasma on degradation of AFB
1 in maize. Therefore, this article aims to explore the degradation efficacy, products and pathways of AFB
1, as well as effects on maize kernels quality treated by ultraviolet combined with cold plasma. AFB
1 standard was spiked onto glass dishes and maize kernels, respectively. The residual AFB
1 content was quantified after different ultraviolet combined with cold plasma treatment durations (5, 10, 15, 20, 25, 30 min). Liquid-chromatography mass spectrometry (LC-MS) was employed to analyze the potential structure of degradation products and degradation pathways. A comparison was mad on the moisture content, fatty acid value, color parameters (
L*,
a*,
b* and △
E value), starch gelatinization properties, starch content, protein content, surface seed coat microstructure, and cross-sectional microstructure of endosperm starch granules of maize kernels before and after ultraviolet combined with cold plasma treatment. A systematic investigation was implemented to explore the effect on the quality of maize kernels. The results showed that ultraviolet combined with cold plasma treatment effectively degraded AFB
1, with degradation rates increasing progressively with prolonged treatment time. On glass substrates, the degradation rate of AFB
1 reached 98.96% after 30 min treatment. For maize kernels, which required turning to expose both sides, the degradation rate was 39.40% after a total treatment time of 60 min (30 min per side). A slower degradation process was observed in the complex food matrix. LC-MS analysis identified 11 major degradation products. The peak areas of most degradation products initially increased and then decreased, indicating their further degradation. This trend was more pronounced for products 1-6 compared to products 7-11. The primary reaction sites involved the furan ring, methoxy group, lactone ring, and carbonyl group of AFB
1. Structural modifications occurred at known toxicogenic sites of AFB
1, suggesting a potential reduction in toxicity. However, further toxicological assessment was required. Degradation pathways were proposed, suggesting initial formation of six products (products 1-6) via substitution, addition, or demethylation reactions. Product 6 underwent furan ring cleavage to form an intermediate (C
16H
14O
7), which subsequently yielded products 7-11 through oxidation, demethylation, demethoxylation, and ring-opening reactions. Regarding maize quality, ultraviolet combined with cold plasma treatment caused a significant decrease (
P<0.05) in moisture content and fatty acid value, which was actually of benefit to the long-term storage stability of maize kernels. Starch gelatinization properties were slightly altered, with breakdown value, peak viscosity, trough viscosity, and final viscosity all showing a trend of initially decreasing followed by an increase. Meanwhile, the setback value, pasting time, and pasting temperature remained largely unaffected (
P>0.05). These phenomena did not cause quality of maize deterioration. Moreover, color, starch content (including amylose and amylopectin), protein content, and the microstructure of surface seed coat and endosperm starch granules showed no significant changes (
P>0.05). Overall, ultraviolet combined with cold plasma treatment did not adversely affect quality of maize kernels. In conclusion, ultraviolet combined with cold plasma technology can effectively degrade AFB
1 while ensuring maize kernels do not exhibit significant deterioration in quality. The finding can provide a theoretical reference for the application of ultraviolet combined with cold plasma in the control and detoxification of AFB
1 in maize.