Abstract: Based on the cooked purple sweet potato slices (CPSPS), the effects of microwave power, loading and slice thickness on the drying characteristics, its effective moisture diffusion coefficient (EMDC) of water and color of CPSPS were studied. SPSS software was applied to analyze data and optimize the mathematical model of PSPS drying. The result showed that microwave drying process of PSPSs can be divided into three stages: rising rate drying period, constant drying rate stage and falling rate drying period. Microwave power, loading and slice thickness have a certain influence on the microwave drying characteristics of CPSPS. However, the effect of slice thickness was less significant than microwave power and loading. EMDC increased with the increase of microwave power and slice thickness and the decrease of loading. The maximum EMDC was 1.135 4×10-8 m2/s and the value of Ea was 4.893 8 W/g. Of the six models, the Modified Page model had the highest coefficient of determination R2 (0.999 7), the lowest chi-square χ2 (0.000 5) and root mean square RMSE (0.006 1), and it is the optimum model of the PSPS in microwave drying.
HE K, YE X, LI X, et al. Separation of two constituents from purple sweet potato by combination of silica gel column and high-speed counter-current chromatography [J]. Journal of Chromatography B, 2012, 881: 49-54.
TRUONG V D, DEIGHTON N, THOMPSON R T, et al. Characterization of anthocyanins and anthocyanidins in purple-fleshed sweet potatoes by HPLC-DAD/ESI-MS/MS[J]. Journal of Agricultural and Food Chemistry, 2010, 58(1): 404-410.
YANG J, GADI R L. Effects of steaming and dehydration on anthocyanins, antioxidant activity, total phenols and color characteristics of purple-fleshed sweet potatoes (Ipomoea batatas) [J]. American Journal of Food Technology, 2008, 3(4): 224-234.
ZHANG Z F, FAN S H, ZHENG Y L, et al. Purple sweet potato color attenuates oxidative stress and inflammatory response induced by D-galactose in mouse liver[J]. Food and Chemical Toxicology, 2009, 47(2): 496-501.
WANG S M, YU D J, SONG K B. Quality characteristics of purple sweet potato (Ipomoea batatas) slices dehydrated by the addition of maltodextrin[J]. Horticulture, Environment, and Biotechnology, 2011, 52(4): 435-441.
AHMED M, AKTER M S, LEE J C, et al. Encapsulation by spray drying of bioactive components, physicochemical and morphological properties from purple sweet potato[J]. LWT-Food Science and Technology, 2010, 43(9): 1 307-1 312.
GIRI S K, PRASAD S. Optimization of microwave-vacuum drying of button mushrooms using response-surface methodology[J]. Drying technology, 2007, 25(5): 901-911.
FIGIEL A. Drying kinetics and quality of vacuum-microwave dehydrated garlic cloves and slices [J]. Journal of Food Engineering, 2009, 94(1): 98-104.
GB 5009.3—2010,食品中水分的测定[S]. 北京:中国标准出版社, 2010.
FALADE K O, SOLADEMI O J. Modelling of air drying of fresh and blanched sweet potato slices [J]. International Journal of Food Science and Technology, 2010, 45(2): 278-288.
WANG Z F, SUN J H, LIAO X, et al. Mathematical modeling on hot air drying of thin layer apple pomace [J]. Food Research International, 2007, 40(1): 39-46.
WHITE G M, ROSS I J, PONELET C G. Fully exposed drying of popcorn [J]. Transactions of the American Society of Agricultural Engineers, 1981, 24(2): 466-468.
CHKIR I, BALTI M A, AYEDA L, et al. Effects of air drying properties on drying kinetics and stability of cactus/brewer’s grains mixture fermented with lactic acid bacteria [J]. Food and Bioproducts Processing, 2015, 94: 10-19.
BAINI R, LANGRISH T A G. Choosing an appropriate drying model for intermittent and continuous drying of bananas [J]. Journal of Food Engineering, 2007, 79(1): 330-343.
O’CALLAGHAN J R, MENZIES D J, BAILEY P H. Digital simulation of agricultural dryer performance [J]. Journal of Agricultural Engineering Research, 1971, 16(3): 223-244.
WANG Z, SUN J, CHEN F, et al. Mathematical modelling on thin layer microwave drying of apple pomace with and without hot air pre-drying [J]. Journal of Food Engineering, 2007, 80(2): 536-544.
ERTEKIN C, YALDIZ O. Drying of eggplant and selection of a suitable thin layer drying model [J]. Journal of Food Engineering, 2004, 63(3): 349-359.