Pulsed vacuum drying (PVD) technology improves drying efficiency and quality of Poria cubes

ABSTRACT

The objective of this research was to examine the drying characteristics of pulsed vacuum drying (PVD) system as an alternative drying technology for a functional food—Poria cocos. Poria cubes in thin layer were dried at different temperatures (55, 65, and 75°C), vacuum duration (5, 15, and 25 min), and atmospheric pressure duration (4, 8, and 12 min) to evaluate the operating conditions on the drying kinetics and quality attributes of P. 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, and atmospheric pressure duration of 4 min were proposed as the most favorable drying conditions for drying Poria cubes. The current work indicates PVD is a promising technology for P. cocos drying as it not only enhances the drying process but also improves the quality attributes of it.

KEYWORDS:

• Poria cocos
• pulsed vacuum drying
• shrinkage
• texture

Additional information

Funding

This research is supported by National Key Research and Development Program of China (No. 2017YFD0400905), the National Natural Science Foundation of China (No. 31201436, 31501548), the Project in the National Science & Technology Pillar Program during the Twelfth 5-year Plan Period (2015BAD19B010201). Moreover, Dr. Weipeng Zhang thanks China Scholarship Council for supporting his overseas research in UC, Davis. (No. 201606350187).