## 4 PAH Occurrence and Formation in Processed Meat, Edible Oils, and Cereal-Derived Products
### Features Underlying PAH Formation in Meat and Meat-Derived Products  
In the case of meat and meat-derived food products, domestic preparation options involve thermal processing, such as smoking, drying, barbecuing, roasting, baking, frying, or grilling [1, 23, 27, 107, 139]. Figure 4 provides an overview of the elements modulating PAH levels in meat and meat-derived products undergoing thermal processing. Further, a detailed interpretation is supplied for the corresponding factors involved in PAH formation and occurrence. Smoke curing, comprising direct and indirect smoking, produces the highest PAH content compared with other processing techniques [27, 140]. Direct smoking consists of the thermal degradation of wood and is further divided into cold smoking (15-30 \({}^{\circ}\)C) and hot smoking (80 \({}^{\circ}\)C) [27, 141]. By contrast, indirect smoking is based on smoke generation (friction, touch, steam) techniques [27, 142] and aims to reduce PAH contamination in food [143]. For instance, industrial smoking resulted in lower BaP, BaA, BaF, and Chr levels compared to traditional smoking in meat sausages and pork ham [39]. A similar outcome was reported for \"Petrovska klobasa\" dry fermented sausages, attaining considerably lower PAH contents by industrial smoking compared to traditional smoking [144]. The positive effect of the indirect process was also revealed in Frankfurter sausages cured by friction smoke and steam smoke, showing diminished contamination in comparison to traditional smoking [142]. In addition to smoke curing, techniques entailing thermal processing include direct and indirect (electric grilling, pan grilling) contact between the product and the heating source [15, 103]. A charcoal grill yields a greater BaP content in pork bacon, as opposed to a modified charcoal grill, which enables direct contact with the product but avoids fat dripping onto the heating source [103]. On the other hand, infrared and electric grills render BaP undetectable in grilled bacon [103]. Similarly, PAH formation was higher in  
Figure 4: Flowchart showing the representative factors influencing PAH formation in meat and meat-derived products undergoing thermal processing. be beef grilled on a stone barbeque than on a wire barbeque [98]. In the same vein, the classic barbeque produced higher PAH content than the electrical oven in grilled duck meat and skin [145]. Generally referred to as \"doneness\", cooking intensity translates into the extent of exposure of food materials to the heating source. Hence, time-temperature settings synergistically modulate PAH formation [7]. The progressive rise in PAH levels over the course of a prolonged processing time and an increased temperature has been ascribed to the formation and accumulation of additional PAHs in meat products [146; 147; 142; 145; 148; 149]. The cooking degree of beef steak, including rare, medium, well done, and very well done, generates a directly proportional level of PAH accumulation [98]. Correspondingly, done-ness had a significant effect on promoting PAH content in charcoal-grilled meat samples, with chicken displaying higher contamination than beef for both medium and well-done cooking levels [150]. In meat model systems (lyophilized ground beef), PAH levels increased gradually as a function of both temperature and time. However, temperature had a greater effect than time [7; 148]. In addition, grilled meat subjected to a temperature gradient (heating to 320 \({}^{\circ}\)C followed by a steady decrease to 200 \({}^{\circ}\)C) resulted in elevated PAH accumulation during the initial heating stage [99]. In this regard, the preboiling or partial cooking of meat products might minimize the time of the subsequent cooking stage (involving high temperatures) [7]. [PERSON] et al. (2015) evaluated how cooking time affected contamination with PAHs in a variety of fried, grilled, barbecued, toasted, and roasted animal and plant food products. They noted overall increased PAH levels, attributed to a 50% increase in cooking time [151].