# Infrared Thermographic Signal Analysis of Bioactive Edible Oils Using CNNs for Quality Assessment
## 2 Nutritional and Health Challenges of Edible Oils
### Sunflower Seed Oil: Nutritional and Functional Profile  
Sunflower oil is one of the most widely consumed and used vegetable oils because it is appreciated for its light taste, favourable fatty acid composition, and high oxidative stability [62]. Over time, sunflower oil evolves into a product with both nutritional and functional value, thanks to its high content of polyunsaturated fatty acids, especially linoleic acid, and significant concentrations of natural antioxidants such as vitamin E [63]. From a nutritional point of view, sunflower oil has a total absence of carbohydrates, sugars, proteins, and fibres, while providing the same energy content as olive oil entirely from lipids. These lipids include approximately 10 g of saturated fats, 20 g of monounsaturated fats, and 70 g of polyunsaturated fats, with linoleic acid being the dominant polyunsaturated fatty acid. The oil is an exceptional source of vitamin E, offering 41 mg per 100 g, which corresponds to 207% of the RDA. The complete nutritional composition is summarised in Table 2.  
Chemically, sunflower oil has a predominantly triglyceride composition, in which the glycerol backbone is esterified with fatty acids. The main constituents include linoleic acid (C18:2, omega-6), a polyunsaturated fatty acid essential for human health, and oleic acid (C18:1, omega-9), a monounsaturated fatty acid that contributes to lipid stability and cardiovascular benefits. Equation (2) represents a typical triglyceride molecule found in sunflower oil:  
\[C_{57}H_{104}O_{6} \tag{2}\]  
with a molecular weight of approximately 885.4 g/mol. The oxidative stability of the oil shows a high content of topcpherd, in particular \(\alpha\)-tocopherol, which plays a key role in protecting polyunsaturated fatty acids from lipid peroxidation. This oxidative stability is quantified through parameters such as peroxide value (PV) and anisidine value (AV), while the oil's susceptibility to rancidity can be assessed through the Totox index, shown in Equation (3):  
\[Totox=2*PV+AV \tag{3}\]  
where lower values indicate better stability. From a physical standpoint, sunflower seed oil has a density of approximately 0.92 g/cm\({}^{3}\) at room temperature, a parameter that slightly decreases with an increasing temperature. The kinematic viscosity at 40 \({}^{\circ}\)C is typically in the range of 35-40 mm\({}^{2}\)/s and follows an approximate inverse relationship with temperature, modelled by Equation (4):  
\[\eta(T)=\eta_{0}*e^{(-\beta T)} \tag{4}\]  
where \(\beta\) is a temperature-dependent constant, \(\eta\)(T) is the dynamic viscosity at temperature T, and \(\eta_{0}\) is the reference viscosity. Because of its high smoke point and relatively balanced fatty acid composition, which prevents thermal degradation, sunflower seed oil has exceptional thermal resilience. The nutritional effects of sunflower oil also depend on the presence of phytosterols, which are naturally occurring compounds that help reduce the intestinal absorption of cholesterol [64]. In dermatology and cosmetics, sunflower oil has strong moisturising and antioxidant properties [65]. Linoleic acid helps maintain the integrity of the skin barrier by reducing transepidermal water loss (TEWL), while tocopherols neutralise reactive oxygen species (ROS), thus preventing premature skin ageing. The oil has the distinction of having anti-inflammatory effects useful in the treatment of eczema and psoriasis. Physicochemical properties, including high biocompatibility and oxidative stability, make sunflower oil suitable for use in oral emulsions, soft-gel capsules, and topical formulations [66]. The oil helps make fat-soluble drugs easier to dissolve and absorb, which is especially helpful for creating health products and supplements for heart health. In conclusion, sunflower seed oil presents a compelling combination of nutritional richness, chemical stability, and multifunctional applicability, supporting its widespread use in dietary, cosmetic, and pharmaceutical fields.