Effect of microwave freeze-drying on microbial inactivation, antioxidant substance and flavor quality of Ashitaba leaves (Angelica keiskei Koidzumi)

Abstract

To decrease microbial quantity and conserve antioxidant substances of Ashitaba leaves, microwave freeze-drying was conducted at 1, 1.5, and 2 W/g in pilot scale. After drying, microbial inactivation and quality parameters of color, chlorophylls, flavonoids, moisture content, and flavor of dried Ashitaba leaves were evaluated. After drying, the highest contents of chlorophylls and flavonoids maintained 14.62 g/kg and 15.75 mg/g, respectively; microbial colonies decreased by about 2-log; various tastes of dried sample were improved. It could be a suitable dehydration in processing of Ashitaba leaves.

Keywords:

• Ashitaba leaves
• microwave freeze-drying
• microbial inactivation
• quality

Additional information

Funding

We acknowledge the financial support from National Key R&D Program of China [Contract No. 2017YFD0400901], Jiangsu Province (China) Agricultural Innovation Project [Contract No. CX(17)2017], Jiangsu Province (China) “Collaborative Innovation Center for Food Safety and Quality Control” Industry Development Program, Jiangsu Province Key Laboratory Project of Advanced Food Manufacturing Equipment and Technology [Contract No. FMZ201803], all of which enabled us to carry out this study.