The presence of calcium oxalate is the major obstacle in flour processing of Amorphophallus muelleri tuber since the calcium oxalate can induce skin irritation and is harmful to kidneys. The development of a rapid analytical method to detect calcium oxalate in Amorphophallus flour is required. This research was intended to evaluate the use of some analytical methods (FTIR, SEM-EDS, XRD, XRF, and titration methods) in calcium oxalate detection in Amorphophallus muelleri flour prepared from different treatments (soaking in water (W), solution of sodium bisulfite 1000 ppm (B), solution of sodium chloride salt 3% (S), solution of sodium bisulfite 1000 ppm and sodium chloride salt 3% (BS)). Results showed that the presence of oxalate in Amorphophallus flour can be detected in the FTIR spectra from the C=O group at a wavenumber of 1610 cm-1. SEM images confirmed that calcium oxalate in Amorphophallus flour existed as raphide crystals in which their quantity can be estimated by the EDS feature of SEM. The presence of calcium oxalate crystals in Amorphophallus flour can be differentiated from other salts present in the flour by XRD. XRF can be used as a rapid analytical tool to detect the presence of calcium oxalate in Amorphophallus flour. The potassium permanganate titration technique can be used as a reference method for other rapid analytical methods in detecting calcium oxalate in Amorphophallus flour.

Pre-gelatinization by using an autoclave is the simplest lab-scale method for preparing instant flour from adlay. The effect of heating temperatures (60 °C, 80 °C, and 100 °C) on the structural and pasting properties of pre-gelatinized adlay flour was studied. Moreover, the sensory acceptability of instant porridge prepared from this flour was investigated. Results showed that the shapes of starch granules of pre-gelatinized adlay flour started to disappear at a temperature of 80 °C. However, the crystallinity of the flour gelatinized at 60 °C was higher than that of flours gelatinized at other temperatures. The treatment increased water absorption, water solubility, and swelling power of pre-gelatinized adlay flour. It changed the pasting properties of pre-gelatinized adlay flour and decreased the lightness of pre-gelatinized adlay flour. Overall, the panelists preferred the instant porridge made from pre-gelatinized adlay flour prepared from 100 °C