9%. For these experiments, we used a QM-DK low temperature

planetary ball-mill (Nanda, Nanjing, China) equipped with an insulation cover and an air cooling machine that used R22 as a cryogen. The weight ratio of starch to balls (Φ10 mm:Φ20 mm = 2:1) in the ceramic (500 mL) and stainless steel pots (500 mL) were 15:1 and 20:1 (w:w), respectively. Each container was filled to approximately one third of their capacity. During milling, the balls were rotated horizontally at a constant milling speed of 500 rpm for up to 5 h. The ball-milling rotational direction was changed every 30 min. The ball-milling process was carried out at 5–10 °C and the temperature was maintained by the air cooling system to prevent overheating of the starch samples. After the treatment, the samples were sealed in a bag for analysis. The particle size distribution of the CP-868596 ic50 starch samples was determined using a Malvern Mastersizer S (Malvern Instruments, Ltd., UK) laser scattering

analyzer at room temperature, as described by Edwards et al. with a few minor modifications [9]. Briefly, ethyl alcohol was used instead of water as the dispersing reagent (refractive PD0325901 index = 1.36). We then computed D(v, 0.1), D(v, 0.5) and D(v, 0.9) from each distribution, each representing the particle diameter including the cumulative volume of the particles (10%, 50% and 90%, respectively). The size dispersion was evaluated using the dispersion index, referred to as the span, by the following Eq. (1): equation(1) Span=D(v,0.9)−D(v,0.1)D(v,0.5) Cold water solubility (CWS) of the maize starch was determined according to Singh with minor modifications [10]. Briefly, 2 g (dry weight basis) sample was dissolved

in 100 mL deionized water. The solution was heated to a constant temperature (30 °C or 40 °C) science for 20 min with continuous stirring in order to avoid agglomeration, centrifuged at 3000 × g for 20 min, and then the supernatant was removed and dried at room temperature. The resulting residue was placed in a drying oven at 110 °C until we obtained a constant weight. The CWS was calculated by the following Eq. (2): equation(2) CWS%=Grams of solid in supernatant×4Grams of sample×100 X-ray diffraction (XRD) analyses of test samples were performed using a Rigaku D/max-2500 V diffractometer (Rigaku, Tokyo, Japan) under the following conditions: X-ray tube – Cu Kα (Ni filter), 40 kV, 30 mA, 1°/1° divergence slit/scattering slit, and a 0.3 mm receiving slit. The relative intensity was recorded at a scattering angle range (2θ) of 4–37° with a scintillation counter at a scanning speed of 0.02°/min. The smoothened resultant diffractograms by 15 points using the Origin 7.5 software (Originlab Corporation, Northampton, USA) and then finally calculated the relative crystallinity.