## 4 Conclusions  
The effect of food processing and culinary preparation on the content and stability of natural toxins, such as PAs, TAs and OAs, is a research field that, to date, has been scarcely studied, since there are not many works published addressing this issue. However, the works that do exist show that this research topic is increasingly booming and that they constitute a research line of great interest for future work with many challenges to be resolved. Accordingly, to date, the effect of thermal treatments on the concentration of PAs, TAs and OAs has been well studied, including the investigation of the infusion rate of these compounds during the preparation of tea and herbal tea infusions with boiling water. Currently, knowledge about the effect that thermal treatments have on the content of these alkaloids, including the detection of their transformation products, is very limited and inconclusive. One of the reasons for the great controversy of results is the lack of well-designed studies, with exhaustive controls of all the variables involved in the process. In fact, almost all the works addressing this issue did not provide kinetic or thermodynamic data related to the thermal degradation process of these alkaloids. These studies are necessary to perform a more real assessment of the population's exposure to these toxic alkaloids. Currently, in the case of PAs, it seems that thermal treatments have a more pronounced effect in the stability of PANOs, while PAs are more stable compounds. TAs and OAs also seem to have a certain sensitivity to heat, as reductions in their content have been reported at high temperatures. Nonetheless, to date there are no conclusive findings, and it is worth considering that the reduction observed in these compounds in many cases is due to their interconversion or transformation into other products. Accordingly, PANOs can also be degraded by heat into their corresponding free base primary PAs, maintaining the total levels of PAs. Likewise, complex TAs, such as atropine and scopolamine, can be degraded to low molecular weight TAs or other degradation products (e.g., aposcopolamine and apoatropine) which are even more toxic. Moreover, another relevant point which is worth considering is the TA chirality issue, as some works have described racemization processes due to heat. Therefore, it is not only important to determine the stability of these alkaloids, but also to evaluate the production of transformation products and evaluate their toxicity. In fact, if toxic degradation products are formed, they should also be considered in the legislation of these alkaloids to establish maximum concentration limits for them to ensure the health of consumers. On the other hand, the effect of fermentation has been studied to a lesser extent, and only in the case of TAs and PAs, more so in the latter. It seems that fermentation may contribute to reducing the content of these alkaloids due to microbial activity; however, due to the limited available data more studies are needed to draw reliable conclusions and to understand the microbial action mechanism on these alkaloids. Regarding the transfer rate of these alkaloids, it seems that many parameters may influence the process. Moreover, the published works reveal that the analysis of infusions is most suitable than the dried products to avoid an overestimation of the real intake and exposure of consumers to these alkaloids. Moreover, it has been highlighted that to determine the content of these alkaloids it is preferably to prepare infusions according to the vendor's instructions in order to assess realistic consumer exposures. Accordingly, the limits set in the legislation should be revised considering these aspects. Finally, the effect of grinding, washing and soaking has been little reported and only in the case of OAs, so it could be interesting in future work to carry out more studies concerning the effect of these preparations on the different types of alkaloids.