A Comparative Study on the Oxidative Stability and Physicochemical Properties of Cashew Nut and Pequi Almond Oils from the Brazilian Cerrado

The study of the physical-chemical characteristics and oxidative stability of oils such as cashew nut oil (CNO) and pequi almond oil (PAO), both products of the Brazilian Cerrado, is fundamental to understanding their nutritional value, shelf life, safety, and possible applications in food, cosmetics, and health. Thus, this study aimed to investigate the physicochemical characteristics and oxidative stability of CMO and PMO. CMO showed high oxidative stability and physicochemical characteristics compatible with high-quality refined oils, with moisture content within the ideal range (788±13mg/kg), low acidity (0.58±0.03 mg KOH/g; 0.30±0.02% oleic acid), refractive index (1.4679, 25°C), and specific mass (0.9127±0.0001 g/cm³) typical of matrices rich in oleic acid. In contrast, PAO showed higher acidity (12.54 ±0.47 mg KOH/g; 6.30±0.24% oleic), related to the partial hydrolysis of triacylglycerols and hydrolytic acidity, a consequence of the degree of ripeness and storage conditions of the fruits, in addition to moisture close to the limit for semi-refined oils (1165±24 mg/kg). CNO presented a light yellow-green color (L*(61.61), a*(-12.15) and b*(51.71)), associated with the presence of β-carotene (15.69 to 21.23 mg/kg), α-carotene (21.36 to 25.08 mg/kg) and chlorophylls (59.84 to 62.44 mg/kg), compounds that contributed to its bioactive potential. PAO presented a moderate yellow-green color (L*(59.7), a*(-5.63) and b*(40.67)), showing a predominance of yellow, associated with higher concentrations of β-carotene (25.22 to 28.71 mg/kg), α-carotene (19.02 to 29.07 mg/kg), and chlorophylls (94.8 to 102.45 mg/kg), pigments that reinforced its antioxidant activity. Both oils showed high resistance to oxidation (CNO: 18h, and PAO: 13h, RANCIMAT 110°C), and reduced formation of secondary oxidative products (CNO: 0.14±0.02mg MDA/kg, PAO: 0.23±0.04 mg MDA/kg), indicating chemical integrity and possible application in foods and functional products. Infrared spectroscopic characterization confirmed similar profiles characteristic of triacylglycerols for both oils, with bands at 3000–2800 cm⁻¹ (C–H), 1740 cm⁻¹ (C=O of esters), 1460–1375 cm⁻¹ (CH₂ and CH₃), as well as signals at 1230–1160 and 1100–1000 cm⁻¹, attributed to C–O and C–O–C. In PAO, the formation of a new band in the region of 1720–1740 cm⁻¹ is observed, related to the emergence of free carbonyls and lipid degradation products during oxidation processes in vegetable oils. These results show the predominance of triacylglycerols, low oxidative degradation, and high chemical integrity, consolidating CNO as a matrix with greater stability compared to PAO, both with potential for application in food and functional formulations of technological and nutritional interest.