Microwave drying of germinated brown rice: Correlation of drying characteristics with the final quality

• Published in: Innovative food science & emerging technologies Vol. 70; p. 102673
• Main Authors: Shen, Liuyang, Gao, Ming, Zhu, Yong, Liu, Chenghai, Wang, Lei, Kamruzzaman, Md, Liu, Chai, Zheng, Xianzhe
• Format: Journal Article
• Language: English
• Published: Elsevier Ltd 01.06.2021
• Subjects: Drying characteristics; Gamma-aminobutyric acid (GABA); Germinated brown rice (GBR); Microwave drying; Visual color; LSG; MR; SSG; BI; Microwave drying; w.b; GAD; Drying characteristics; DR; UC; SE; SG; Germinated brown rice (GBR); AV; DSC; GBR; Visual color; GABA; DSG; SEM; Gamma-aminobutyric acid (GABA); HPLC
• ISSN: 1466-8564; 1878-5522
• DOI: 10.1016/j.ifset.2021.102673

Drying characteristics influence the formation of quality including visual color and gamma-aminobutyric acid (GABA) of germinated brown rice (GBR) subjected to microwave drying. In microwave drying, microwave intensities induced microscopic pores inside GBR to enhance the drying rate in initial stage, while rising temperatures caused gelatinization of starch granules to hinder the drying rate in later stage. The higher microwave intensity resulted in the greater non-uniformity of temperature inside the grain layer, which dominated the moisture content and final quality indexes of GBR. However, the coupling effects of temperature rising and moisture reducing failed to stimulate the glutamate decarboxylase (GAD) activity for the GABA synthesis, but may cause the degradation of GABA. The non-uniformity of microwave drying influenced the evaluation of GABA content in the dried GBR, and the suitable average grain temperature of 64–67 °C may retain relatively high GABA content. The critical temperature for preventing the serious browning and charred kernels inside the grain layer was 132 °C and 170 °C, respectively. Microwave intensity of 3–4 W/g may be suitable for drying of GBR considering high drying efficiency and product quality. •Microwave drying characteristics of GBR were evaluated comprehensively.•Critical temperature to avoid visual color deterioration of GBR was 132 °C.•Average grain temperature of 64–67 °C was suitable to retain GABA content.•Microwave intensity of 3–4 W/g may be suitable for drying of GBR.