## 3 Effect of Food Processing and Culinary Preparations on PAs, TAs and OAs
### Thermal Treatment  
Among the different food processing procedures and culinary preparations investigated, to date, the effect of thermal treatments on the concentration of PAs, TAs and OAs has been most studied (Figure 3). In this sense, the application of heat is a relevant point in food processing and culinary preparations, as it is applied in a wide variety of industrial processes to which many raw materials are subjected. Table 1 collects the works which have addressed the effect of thermal processes on the concentration of these alkaloids. As  
Figure 4: Overview of the occurrence and effect of food processing and culinary preparation on pyrrolidine (PAs), tropane (TAs) and opium (OAs) alkaloids according to the works included in this revision and currently available in the literature. Figure 3: Overview of the number of works currently available in the literature addressing the effect of different food processing and culinary preparations on the content of pyrrolidine (PAs), tropane (TAs) and opium (OAs) alkaloids. Data obtained from the Scopus, Web of Science and Google search engines from January 2012 to December 2022 (keywords used: transfer rate, food processing, alkaloids degradation, plant toxins, pyrrolidine alkaloids, tropane alkaloids, opium alkaloids, culinary process, alkaloids stability). observed, several heat treatments have been applied to different samples. For instance, milk processing involves the application of thermal treatments with different degrees of heat to eliminate pathogenic microorganisms (e.g., pasteurization, UHT, sterilization). Likewise, during tea manufacturing a drying step of the plant material is required. Additionally, the manufacture of bread and bakery and pastry products involve baking processes, in which high temperatures are reached. On the other hand, sometimes the intake of a product requires prior culinary preparation that involves heating, such as the preparation of a pasta dish, which requires a boiling procedure. Therefore, it is worth considering the effect of these thermal treatments carried out in food processing and culinary preparations on the stability of these alkaloids, so that the risk exposure of the population to these alkaloids through diet can be determined more precisely. The thermal stability of PAs is a matter of interest because if the necine base of their backbone structure becomes degraded with high temperatures, their toxicity could be greatly reduced, thus minimizing the risk associated with their oral intake. In this context, it is known that PANOs are unstable at volatilization temperatures, as they cannot be determined by gas chromatography [58; 59]. Likewise, thermal decomposition of PAs has also been described at these temperatures [58; 59; 60; 61]. However, the heat stability of PAs is not clear, since the available works that have addressed this issue show inconclusive and contradictory results among them. For instance, different PA intoxication cases caused by the intake of bread prepared with contaminated cereals and flours have been reported [62; 63; 64; 65]. Similarly, PA intoxication of puppies produced by the intake of contaminated cooked meat was also confirmed [66]. Accordingly, these works suggest the important heat stability of PAs against the high temperatures used in the baking and cooking processes. Likewise, the effect of other heat treatments, such as pasteurization and sterilization (UHT), on the PA content have been evaluated in milk samples [67]. The results obtained reveal that PA concentrations in the starting milk (thermized milk subjected to 68 \({}^{\circ}\)C during 13 s) remained the same as the pasteurized and sterilized milk. Thus, it was concluded that heat treatment had no influence on the PA concentration during milk thermal processing [67]. Therefore, a certain stability of PAs to milk processing can be assumed, as other authors have also detected PAs in heat-treated milk [68; 69]. [PERSON] et al.