Comparative analysis of innovative and conventional oil extraction techniques on yield and phytochemical profiles of Citrus aurantium L. seed oil and seed nutritional value

Abstract

Citrus aurantium L. seeds (CAS), one of the major food by-products in Iran from crops of industrial interest, were evaluated as a potential industrial oilseed for pharmaceutical and dermocosmetic applications. Three innovative extraction techniques (ultrasound-assisted extraction, pressurized solvent extraction, and a combined pressurized solvent-ultrasound-assisted method (PSUA)), were optimized to enhance oil yield. For comparison, traditional methods (Soxhlet, maceration, and cold pressing) were also conducted. The extraction yield, oil quality parameters (acidity, peroxide, iodine, and saponification values), and fatty acid (FA) composition were analyzed to assess the efficiency of each technique. Additionally, the phytosterol content and both ¹H and ¹³C NMR profiles were examined for the oil obtained through cold pressing, along with the CAS nutritional value, antioxidant capacity, and vitamin E profile of seeds. The results demonstrated a high carbohydrate and fat content, along with notable antioxidant and vitamin E levels. The major fatty acids identified included three unsaturated (linoleic, oleic, and α-linolenic acids) and two saturated (palmitic and stearic acids) FAs. Across all extraction methods, the PSUA technique (5 min, 2 bar, at 25 °C) emerged as the most efficient, providing a higher extraction yield, shorter processing time, reduced solvent usage, and superior oil quality with a higher content of unsaturated FAs. Phytosterol analysis revealed significant levels (357.6 ± 0.48 mg/100 g oil) of compounds, such as β-sitosterol, campesterol, stigmasterol, and ∆5-avenasterol. Additionally, ¹H and ¹³C NMR proved to be effective for FA qualitative analysis, with the ¹³C NMR spectrum confirming the FA chains identified in the ¹H NMR analysis.