Drying sea buckthorn berries (Hippophae rhamnoides L.): Effects of different drying methods on drying kinetics, physicochemical properties, and microstructure

Zhihua Geng; Lichun Zhu; Jun Wang; Xianlong Yu; Mengqing Li; Wenxin Yang; Bin Hu; Qian Zhang; Xuhai Yang

doi:10.3389/fnut.2023.1106009

Drying sea buckthorn berries (Hippophae rhamnoides L.): Effects of different drying methods on drying kinetics, physicochemical properties, and microstructure

Front Nutr. 2023 Feb 8:10:1106009. doi: 10.3389/fnut.2023.1106009. eCollection 2023.

Authors

Zhihua Geng¹, Lichun Zhu¹, Jun Wang², Xianlong Yu³, Mengqing Li¹, Wenxin Yang¹, Bin Hu^{1

4}, Qian Zhang¹, Xuhai Yang^{1

5}

Affiliations

¹ College of Mechanical and Electrical Engineering, Shihezi University, Shihezi, China.
² College of Food Science and Engineering, Northwest A&F University, Yangling, China.
³ Shandong Academy of Agricultural Machinery Sciences, Jinan, China.
⁴ Xinjiang Production and Construction Corps, Key Laboratory of Modern Agricultural Machinery, Shihezi, China.
⁵ Engineering Research Center for Production Mechanization of Oasis Special Economic Crop, Ministry of Education, Shihezi, China.

Abstract

Sea buckthorn berries are important ingredients in Chinese medicine and food processing; however, their high moisture content can reduce their shelf life. Effective drying is crucial for extending their shelf life. In the present study, we investigated the effects of hot-air drying (HAD), infrared drying (IRD), infrared-assisted hot-air drying (IR-HAD), pulsed-vacuum drying (PVD), and vacuum freeze-drying (VFD) on the drying kinetics, microstructure, physicochemical properties (color, non-enzyme browning index, and rehydration ratio), and total phenol, total flavonoid, and ascorbic acid contents of sea buckthorn berries. The results showed that the IR-HAD time was the shortest, followed by the HAD, IRD, and PVD times, whereas the VFD time was the longest. The value of the color parameter L* decreased from 53.44 in fresh sea buckthorn berries to 44.18 (VFD), 42.60 (PVD), 37.58 (IRD), 36.39 (HAD), and 36.00 (IR-HAD) in dried berries. The browning index also showed the same trend as the color change. Vacuum freeze-dried berries had the lowest browning index (0.24 Abs/g d.m.) followed by that of pulsed-vacuum-(0.28 Abs/g d.m.), infrared- (0.35 Abs/g d.m.), hot-air-(0.42 Abs/g d.m.), and infrared-assisted hot-air-dried berries (0.59 Abs/g d.m.). The ascorbic acid content of sea buckthorn berries decreased by 45.39, 53.81, 74.23, 77.09, and 79.93% after VFD, PVD, IRD, IR-HAD, and HAD, respectively. The vacuum freeze-dried and pulsed-vacuum-dried sea buckthorn berries had better physicochemical properties than those dried by HAD, IRD, and IR-HAD. Overall, VFD and PVD had the highest ascorbic acid and total phenolic contents, good rehydration ability, and bright color. Nonetheless, considering the high cost of VFD, we suggest that PVD is an optimal drying technology for sea buckthorn berries, with the potential for industrial application.

Keywords: drying kinetics; physicochemical properties; pulsed vacuum drying; sea buckthorn berries; vacuum freeze-drying.

Grants and funding

This work was supported by the High-level Talents Research Start Project of Shihezi University (RCZK201918), the Xinjiang Production and Construction Corps Financial Technology Plan Project (Grant No. 2021CB042), the Xinjiang Production and Construction Corps Key Laboratory of Modern Agricultural Machinery (BTNJ2021004), and the Engineering Research Center for Production Mechanization of Oasis Special Economic Crop, Ministry of Education (Grant No. PMOC2021A06).