Location: Healthy Processed Foods ResearchTitle: Pulsed vacuum drying (PVD) technology improves drying efficiency and quality of Poria cubes Author
|Zhang, Weipeng - China Agricultural University|
|Xiao, Hongwei - China Agricultural University|
|Zheng, Zhian - China Agricultural University|
|Chen, Chang - University Of California, Davis|
|Gao, Zhenjiang - China Agricultural University|
Submitted to: Drying Technology: An International Journal
Publication Type: Peer Reviewed Journal
Publication Acceptance Date: 10/9/2017
Publication Date: 1/20/2018
Citation: Zhang, W., Pan, Z., Xiao, H., Zheng, Z., Chen, C., Gao, Z. 2018. Pulsed vacuum drying (PVD) technology improves drying efficiency and quality of Poria cubes. Drying Technology: An International Journal. 36(8):908-921. https://doi.org/10.1080/07373937.2017.1362647.
DOI: https://doi.org/10.1080/07373937.2017.1362647 Interpretive Summary: Poria cocos (Fu-Ling) is one of the most frequently used traditional Chinese medicines (TCM) and extensively cultivated in Anhui and Yunnan province of China. The water-soluble polysaccharides in poria cocos have diuretic, antibacterial and immunomodulation functions. Due to the seasonal harvesting and perishable nature, fresh poria cocos must be dried so as to reduce or completely inactivate physiological, microbial, and enzymatic degradation and therefore extensively prolong its shelf life. Hot air (HA) dying has been widely used in business as it can reduce the drying time significantly compared to the natural open sun drying. However, poria cocos dried continuously by HA leads to increased moisture gradient caused by more moisture removal from the surface than the center, which reduces the product quality. The objective of this study was to examine the drying characteristics of Pulsed Vacuum Drying (PVD) system as an alternative drying technology for traditional Chinese herbs--poria cocos cubes. The research results indicate that PVD is a promising technology for poria cocos drying as it not only enhances the drying process but also improves the quality attributes of it.
Technical Abstract: The objective of this study was to examine the drying characteristics of Pulsed Vacuum Drying (PVD) system as an alternative drying technology for traditional Chinese herbs--poria cocos cubes. Poria cocos cubes in thin layer were dried at different temperatures (55, 65, 75°C), vacuum duration (5, 15, 25 min) and atmospheric pressure duration (4, 8, 12 min) to evaluate the operation conditions on the drying kinetics and quality attributes of poria cocos. The quality attributes included volume shrinkage ratio, firmness, water-soluble polysaccharide content. Volume shrinkage ratio was determined by image processing technology and analyzed by Bigot’s curves. The material internal temperature was also recorded during the whole drying process. Considering the drying rate and quality attributes, drying temperature of 65°C, vacuum pressure duration of 15 min, atmospheric pressure duration of 4 min were proposed as the most favorable drying conditions for drying poria cocos cubes. The current work indicates PVD is a promising technology for poria cocos drying as it not only enhances the drying process but also improves the quality attributes of it.