The effect of osmosis pretreatment on hot-air drying and microwave drying characteristics of chili (Capsicum annuum L.) flesh

Authors

  • Dandan Zhao,

    1. College of Food Science and Nutritional Engineering, China Agricultural University; National Engineering and Technology Research Centre for Fruits and Vegetable Processing; Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture, Beijing, China
    Search for more papers by this author
  • Cuiping Zhao,

    1. College of Food Science and Nutritional Engineering, China Agricultural University; National Engineering and Technology Research Centre for Fruits and Vegetable Processing; Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture, Beijing, China
    Search for more papers by this author
  • Hongyan Tao,

    1. College of Food Science and Nutritional Engineering, China Agricultural University; National Engineering and Technology Research Centre for Fruits and Vegetable Processing; Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture, Beijing, China
    Search for more papers by this author
  • Kejing An,

    1. College of Food Science and Nutritional Engineering, China Agricultural University; National Engineering and Technology Research Centre for Fruits and Vegetable Processing; Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture, Beijing, China
    Search for more papers by this author
  • Shenghua Ding,

    1. College of Food Science and Nutritional Engineering, China Agricultural University; National Engineering and Technology Research Centre for Fruits and Vegetable Processing; Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture, Beijing, China
    Search for more papers by this author
  • Zhengfu Wang

    Corresponding author
    • College of Food Science and Nutritional Engineering, China Agricultural University; National Engineering and Technology Research Centre for Fruits and Vegetable Processing; Key Laboratory of Fruits and Vegetables Processing, Ministry of Agriculture, Beijing, China
    Search for more papers by this author

Correspondent: Fax: 86 10 62737434x601; e-mail: wzhfuwzhfu@163.com

Summary

Chili flesh pretreated with or without osmotic dehydration (OD) was dried in the hot-air drying (AD) oven at 50–80 °C or in the microwave drying (MD) oven at 60–180 W. Results showed that the samples osmotically treated in mixed solution (10% salt + 50% sucrose) had the best dehydration effect as compared with single salt or sugar solutions. During the drying process, osmotically treated samples had one falling-rate period and their effective moisture diffusivities (Deff) showed a rapidly linear increase with the decrease in moisture content, while directly drying samples showed a three-phase falling-rate period and their Deff increased gradually at the initial period and then rapidly at the final period. When the moisture content decreased, the activation energy increased gradually; however, for AD after OD, it decreased. Among all the processes, MD at 60 W after OD presented the largest vitamin C retention rate and the best colour difference, needing less drying time.

Ancillary