Comparative evaluation of CO sub(2) drying as an alternative drying technique of basil (Ocimum basilicum L.) - The effect on bioactive and sensory properties

In this study the potential of employing CO sub(2) drying as an alternative to conventional drying techniques of basil was evaluated, with the aim of preservation of native bioactive and sensory properties of basil. For that purpose, optimal CO sub(2) processing conditions were established and compared to air-dried and freeze dried basil samples. The contents of bioactive compounds (polyphenols, chlorophylls, ascorbic acid) and antioxidant capacity were determined spectrophotometrically and using high performance liquid chromatography (HPLC-PDA) analysis. Color analysis and essential oil content were also determined, while consumer evaluation of sensory properties was conducted using hedonic scale preference analysis. According to the obtained results, freeze drying was recognized as the most suitable technique for preservation of color, essential oil content, bioactive compounds and antioxidant capacity of basil. The essential oil content of basil ranged from 0.21 to 0.96%, and decreased upon prolongation of CO sub(2) drying time. Among 4 identified phenolic acids (rosmarinic, chicoric, caftaric and caffeic), rosmarinic acid was the most abundant in all samples. Longer CO sub(2) drying duration (4 h) also exhibited the most detrimental effect on the polyphenolic compound content and antioxidant capacity of basil. The taste and appearance of CO sub(2) dried basil were scored higher in comparison to air-dried basil, but further optimization of CO sub(2) drying is needed to improve its aroma properties. Based on the obtained results, employing shorter CO sub(2) drying time (2, 3 h) and pressures of 80-100 bar at 40 degree C might be a good alternative to freeze drying of basil.