Abstract:

In order to obtain Castanea henryi crisp ball products with a fast drying rate and high quality by microwave, a single factor experiment was used to explore the effects on dry basis moisture content, dry basis water loss rate and sensory quality of different microwave power, loading and microwave power per unit load, ie microwave power density (Mp₀). The results showed that both the microwave power and loading had a significant influence on the drying time, higher the microwave power would lead to higher vacuum degree and faster the drying. In the test range, the Mp₀ was the decisive factor affecting the moisture removing properties of cooked chestnut. When the Mp₀ was 5.5 W/g, the optimal sensory quality score of the ripened chestnut was 80 points, high expansion, brittleness rate and porosity was 2.92, 3.51 N and 61.4% respectively, water activity was less than 0.3. Based on the relationship between moisture ratio and time of microwave moisture removing of wild chestnut, Matlab software was used to determine the drying properties accorded with Page equation, and the model fitting degree was very high (0.99), indicating that the equation could clarify the stage of microwave moisture removing of chestnut crisp ball. The results would provide theoretical references for the drying production of chestnuts. The random distribution of the particle moisture content of the sample after drying conformed to the sixth-order polynomial distribution, which was consistent with the average moisture content, indicating that the model be used to improve the quality stability of dried C. henryi crisp balls by phased varying power microwave

Key words: Castanea henryi crisp ball, microwave power density, moisture content after pre-drying, dynamic model