## 3 Effect of Food Processing and Culinary Preparations on PAs, TAs and OAs
### Fermentation  
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 (Figure 3). Nonetheless, the evaluation of this food processing procedure is also of high interest, as there are many raw materials which undergo a fermentation process to obtain different commercial products, such as yogurt, cheese, beverages, etc. Accordingly, it is also important to consider how this process may affect the content of these toxins, since depending on the fermentation conditions and the type of microorganisms used as the starter culture the content of alkaloids may be affected. In this sense, some works have evaluated the effect that fermentation may have on the content of these alkaloids (Table 2). In the case of PAs, the effect of fermentation has been determined in mean prepared from contaminated honey [86; 87]. In one of these works, it was observed that after the fermentation process, significant amounts of PAs were still present in the final product [86]. Conversely, [PERSON] et al. (2013) observed a reduction in PAs (about 30% and 70%) in the meal samples prepared in comparison with the levels determined in raw honey [87]. However, the authors did not confirm if this reduction was due to a degradation caused by the fermentation process or if it was caused by a dilution effect of the whole process [87]. Nonetheless, the effect of fermentation on the content of PAs has also been assessed in yoghurt and cheese, observing in both cases a reduction in the initial PAs levels from the starting milk [67]. In the yoghurt, a reduction of 27% in the total content of PAs was determined after 6 h of fermentation at 42 \({}^{\circ}\)C. Regarding cheese, a reduction of 14% was observed during the cheese making process [67]. It was observed that the reduction did not vary from the first step (from milk to whey) to the second (from whey to cheese). Therefore, the reduction was attributed to microbial activity [67]. Likewise, the effect of cheese ripening on the PA content was also evaluated during a 6-week period [67]. The PA content decreased by 38% during the ripening process. Overall, it was concluded that the decrease observed in the PA content of the fermented dairy products was due to the microbial activity, but no mechanism for the microbial action was detailed in this work [67]. Therefore, it could be interesting to investigate the specific effect of bacterial cultures used for commercial dairy processing on PA concentrations. In contrast, [PERSON] et al. indicated an increase in the content of PAs and PANOs during the fermentation step of tea manufacturing, observing a marked increase in the content of PANOs [72]. However, the authors did not specify the reason for this phenomenon and mentioned moisture issues during the rolling step of tea manufacturing. Therefore, due to the sparse and inconclusive data available at present, more studies about the effect of fermentation on the PA content are required because is not possible to determine the effect of fermentation on these alkaloids in a reliable way with the available data in the literature. Nonetheless, such as in the case of thermal treatments, these works have not performed an exhaustive control of the parameters affecting the fermentation process. Likewise, they have not delved in the action of microorganisms. Therefore, these aspects should be considered for future works addressing this treatment.