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The well-organized chitosan film on mica surface has drawn wide attention for its potential applications and studies on the process of self-assembly. In this article, atomic force microscopy was used to investigate the ultrastructure of the self-assembly of chitosan molecules with calcium ions in different concentrations. It was showed that calcium ions might affect the self-assembly of chitosan to a certain extent, and chitosan molecules gathered from fibrils to circular, and finally formed to film with the increasing concentration of calcium ions. Further, the formation mechanism of Ca(II)-chitosan conjugates was adapted to explain the effects of calcium ions on the self-assembly of chitosan. These results and the related analysis would be valuable for guiding the pattern of chitosan self-assembly with a potential application in food packaging science and engineering.

The aim of this study was to demonstrate the effect of different treatments on collagen self-assembly, the morphological and the qualitative analysis of collagen assembly were measured by atomic force microscopy. Collagen samples were treated with 0.02%, 0.04%, 0.10% and 0.20% glutaraldehyde individually at the first steps. Meanwhile, the other experimental groups were treated with 0.05%, 0.10%, 0.20% riboflavin, respectively, the structural change of the collagen network with 15, 30, 45, 60 min UV365 exposure and the fluorescent irradiation as the control group in turn was investigated by atomic force microscopy. The width and height of collagen assembly increased with the concentration of glutaraldehyde, which were changed from 36.45 ± 4.45nm to 64.35 ± 2.58nm and 2.26 ± 0.19nm to 4.93 ± 0.29 nm, respectively. The effect of different UV365 irradiation time on the height of collagen was greater than the effect on the width, the width and height of collagen were varied from 41.36 ± 4.30nm to 55.47 ± 4.53nm and 3.10 ± 0.39nm to 6.20 ± 0.85nm, which were changed 25.44% and 50.00%, respectively. The concentration of riboflavin was more efficiently than irradiation time, and the maximum width and height of collagen reached 106.98 ± 3.37nm and 11.17 ± 1.33 nm, respectively, the control group without a significant change at the fluorescent irradiation by the time. This optimized cross-linking method with riboflavin/UV365 would have great potential for tissue engineering in clinic and food packaging science.

The effects and safety of electron beam irradiation (EBI) treatment on the detoxification of aflatoxin B1 (AFB1) in the peanut meal were evaluated in this article. The AFB1 degradation was predominantly affected by both initial AFB1 and water concentrations. The degradation of AFB1 in the selected concentrations (0.5–5 ppm) was proven to follow pseudo first-order reaction kinetics (R2 > 0.95). The AFB1 degradation was faster when the initial concentration was 5 ppm and the moisture content was 21.47%, in comparison with the initial concentration of 1 ppm and 0.5 ppm and the moisture content of 14.32% and 8.74%, respectively. The Ames and cytotoxicity tests were employed to evaluate the residual toxicity of EBI-treated peanut meal. The mutagenic activity of EB-treated samples was completely lost compared with that of untreated samples and the degradation products in peanut meal has almost no cell toxicity.