Enhancement of quality attributes of dried Poria cocos Wolf cubes by stress sweating combined with steam pretreatment

Abstract

The effect of different pretreatment namely natural sweating (NS), steam treatment (S), and stress sweating combined with steam treatment (SS) on the quality attributes (water-soluble polysaccharide, total triterpene content, alcohol-soluble extractive values, and broken rate) and drying characteristics of Poria cocos Wolf (PCW) cubes were investigated. The results showed that NS and SS pretreatment resulted in a noticeable weight loss, while S pretreatment resulted in a significant weight gain by PWC cubes. Such treatments as NS, S, and SS did not significantly affect the drying time of PCW cubes. SS pretreatment greatly improved the water-soluble polysaccharide content and alcohol-soluble extractive values of dried products by 1.54 and 1.68 times, respectively. NS pretreatment for four days resulted in the highest content of total triterpenes, i.e. 6.46 mg/g d.b. of dried PCW cubes, while S pretreatment significantly reduced the broken index. A comprehensive evaluation method was used to quantify the feasibility of NS, S, and SS pretreatments in terms of drying time and quality attributes. Samples subjected to SS pretreatment were characterized by the highest comprehensive score. The results of this study showed that the selection of the appropriate treatment may help to improve the material quality and drying characteristics.