Study on the effects of different drying methods on physicochemical properties, structure, and in vitro digestibility of Fritillaria thunbergii Miq. (Zhebeimu) flours

• Fritillaria thunbergii had a higher active component when hot air-dried at 60 °C.
• F. thunbergii hot air-dried at 60 °C had more resistant starch.
• Microwave drying caused significant damage to the crystal structure of starch.
• Hot air drying at 60 °C is an effective method of drying F. thunbergii.

This study was designed to investigate the effects of different drying methods on the main components, crystal properties, morphological properties, and in vitro digestibility properties of Fritillaria thunbergii Miq. flour. The results showed that the total peimine and peiminine contents ranged between 0.093% and 0.245%, insoluble amylose from 4.57% to 10.93%, and the water-binding capacity (WBC) from 144.09% to 192.28%. Compared with the sun-drying method, microwave drying significantly decreased the total peimine and peiminine content, protein, soluble amylose, resistant starch (RS), solubility, swelling power, and relative crystallinity, while increasing the insoluble amylose content and WBC. The microwave-dried sample showed significant changes in starch content, as evident from the scanning electron microscopy (SEM), X-ray diffraction (XRD), and Fourier transform infrared (FT-IR) spectroscopy findings. Low levels of rapidly digestible starch and glucose and high RS levels were found in the hot air-dried and freeze-dried samples. Thus, F. thunbergii flour can be used as medicinal excipients, as health products, and in paints by these results. Furthermore, this flour finds more uses when subjected to chemical or physical treatment in medicinal, paint, and food processors.

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