Assessment of fresh star anise (Illicium verum Hook.f.) drying methods for influencing drying characteristics, color, flavor, volatile oil and shikimic acid

Abstract

In order to evaluate the effects of drying methods on the drying characteristics, quality (color, volatile oil (VO) content, shikimic acid (SA) content, trans-anethole content in the star anise volatile oil (TA-O)) and flavor components of star anise (Illicium verum Hook.f.), we tested five different methods (hot air drying (HAD), heat pump drying (HPD), far infrared radiation drying (FIRD), microwave drying (MD), and sun drying (SD)) with or without blanching to dry fresh star anise. Results showed MD had a shorter drying time than others, as well as the highest SA content (125.56 mg/g d.b.). HPD sample exhibited higher VO content (12.27% d.b.) and TA-O (113.30 mg/g d.b.) than those dried with other methods. HPD can improved the dominant flavor compounds of star anise, including trans-anethole (4165.46 mg/100 g d.b.), estragole (176.50 mg/100 g d.b.), linalool (280.69 mg/100 g d.b.), and (+)-limonene (471.18 mg/100 g d.b.). Samples treated with HPD-B had the highest comprehensive score (4.59) in the flavor principal component analysis. Therefore, HPD was more suitable for star anise drying as it maintaining quality. The better quality (higher flavor quality and better appearance) was found in HPD-B.