Scanning electron microscopy

Scanning electron microscopy of porridge samples was performed using the methods described by Hu et al. (2011) with some modifications. The morphological changes in porridge were observed using a scanning electron microscope (SEM; Inspect F, FEI, Japan) at 5.0 kV. The porridge was freeze-dried by a freeze-drying machine (CleanVac, Hanil Science Industrial Co., Ltd., Korea). Each sample was cut using a surgical blade (Surgical Blade Stainless No. 11, Feather Safety Razor Co., Ltd., Czech) and rice cross-sections were observed. Each sample was attached to an SEM stub using double-sided carbon tape. The stub and sample were coated with a thin layer of silver (ca. 5 nm) for 3 min by a sputter coater (SPI-Module, SPI Supplies, USA). The samples were observed at 1,000× magnification and photographed.