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Li X.,Academy of the State Administration of Grains | Sakurai N.,Hiroshima University
Natural Products Journal | Year: 2012

The contents of cell wall polysaccharides in pericarp tissues of immature Hayward kiwifruit were determined during development. Two methods employed to remove starch from the crude cell wall preparations were enzymatic digestion (porcine pancreatic α-amylase and Pseudomonas iso-amylase, Method 1) and dimethyl sulfoxide extraction (DMSO, Method 2). Method 2 was more effective in removing starch than Method 1. After extensive removal of starch, cell wall materials were successively extracted with 50 mM EDTA, followed by 4% and 24% KOH. The hot EDTAsoluble (pectic) and alkaline-soluble (hemicellulosic I and -II) polysaccharides were further treated with enzymatic digestion. In subsequent amylase digestions of fractions derived from cell walls previously subjected to the two methods the glucose content was further depleted by 28-77% (Method 1) and 85-91% (Method 2) in the pectin fraction, and 51- 86% (Method 1) and 45-91% (Method 2) in the hemicellulose fractions, suggesting starch in the crude cell walls was not released by initial enzymatic treatment or DMSO extraction. Moreover, the crude cell walls yielded α-amylase activity upon extraction by 1 M NaCl, further suggesting that starch is present in the cell walls. Methylation analysis of the starch fraction revealed a molar ratio of 0.2~0.6:3.8~11.6:1 for T-Glc, 4-Glc and 4,6-Glc. The red-violet starch-iodine complex had an absorption maximum of 550~565 nm. These results provide evidence for an amylopectin-type starch present in the cell walls of immature kiwifruit. © 2012 Bentham Science Publishers. Source


Wu Z.,Academy of the State Administration of Grains | Li X.,Academy of the State Administration of Grains
Journal of the Chinese Cereals and Oils Association | Year: 2013

The moisture sorption isotherms of milled rice and soybean respectively from eleven and ten varieties were determined under RH 11%~96% and different temperature (10, 20, 25, 30 and 35°C) conditions and were fitted by CAE equation. For milled rice, the determination coefficient (R) >0.9911, and mean relative percentage error (MRE) < 5.048%. For soybean, R2 > 0.9777, MRE < 10.778%. As well as for soybean, the parameters in CAE model for both milled rice desorption and adsorption isotherms showed appreciable difference, consistent with a hysteresis between desorption and adsorption behavior at lower ERH. The deduced CAE models for both desorption and adsorption of milled rice or soybean were respectively used to make curve graphs for searching equilibrium absolute humidity of the grain with particular moisture at certain temperature. To the purpose of decreasing grain temperature or moisture content, or increasing grain moisture content, one can choose the curve graph for equilibrium absolute humidity of the desorption or adsorption, and quickly make decision on grain aeration operation in a depot after referring to the absolute humidity of atmosphere at that particular RH and temperature. Source


Li X.,Academy of the State Administration of Grains | Jiang P.,Academy of the State Administration of Grains
Computers and Electronics in Agriculture | Year: 2016

Wheat samples with low (4.97-6.08%), normal (10.11-11.04%), and high (20.7-22.72%) initial moisture content (IMC, wet basis) were used to determine the rate of moisture adsorption by the gravimetric method at 10, 20, 25, 30, and 35 °C under 65%, 86%, and 100% relative humidity (RH), respectively. A moisture diffusion equation was modified to fit the relationship between the moisture ratio of samples and exposure time. From 65% to 100% RH, the IMC of wheat samples was inversely related to the moisture adsorption rate at temperatures from 10 to 35 °C. Moisture adsorption rates of samples increased with increasing temperatures. The moisture adsorption rate of samples with the same IMC increased with increasing RH at a given temperature. A single wheat kernel was considered geometrically to be a finite homogeneous slab shape, and the analytical solution of the partial differential equation for moisture diffusion was given. The effective moisture diffusivity was calculated using the slope method by plotting the experimental data in terms of ln (MR) versus rewetting time. In the range of 10-35 °C, the effective moisture adsorption diffusivity of wheat kernels with normal moisture was 1.681 × 10-8-1.516 × 10-7 m2 h-1, and their activation energy was 23.651-28.434 kJ mol-1. For the same IMC, the effective moisture diffusivity of wheat kernels tended to increase with increasing temperature at a given RH, but decreased with an increase in RH at a given temperature. Activation energy and the pre-exponential factor of Arrhenius equation (D0) tended to decrease with increasing RH. With similar initial moisture content, winter wheat and spring wheat exhibited similar effective moisture diffusivity. © 2016 Elsevier B.V. Source


Wu Z.,Academy of the State Administration of Grains | Li X.,Academy of the State Administration of Grains | Guo D.,Institute of Grain Storage | Wang S.,Institute of Grain Storage
6th International CIGR Technical Symposium - Towards a Sustainable Food Chain: Food Process, Bioprocessing and Food Quality Management | Year: 2011

An equilibrium moisture content (EMC) and equilibrium relative humidity (ERH) model called CAE fitted to the moisture sorption data of shelled corn from ten Chinese maize varieties with the determination coefficient (R 2)>0.9914 and mean relative percentage error (MRE)<7.19%. The parameter B1 in the CAE model for shelled corn desorptive and adsorptive isotherms showed appreciable difference, consistent with a hysteresis between their desorptive and adsorptive behaviors in lower ERH. The measured sorption isotherms among shelled corn varieties had no significant difference, in accordance with the similar parameters of CAE model. It is concluded that the shelled corns from different varieties have similar hygroscopic properties, but their adsorptive and desorptive behaviors should be differentiated from. The deduced CAE models for shelled corn adsorption and desorption were respectively used to show the variations of equilibrium absolute humidity and equilibrium RH of shelled corn at particular moisture content (m.c.) with temperature. The variation of equilibrium absolute humidity of shelled corn with temperature could clearly indicate the influence of a change in grain temperature on drying or moisture-adsorbing state of grains during aeration. Referring to the absolute humidity of atmosphere at particular RH and temperature, one can quickly make decision on grain aeration operation in a shelled corn depot. Source


Li X.,Academy of the State Administration of Grains | Jiang P.,Academy of the State Administration of Grains
Journal of the Chinese Cereals and Oils Association | Year: 2015

The paper has presumed that the Equilibrium Moisture Content (EMC) of grain was both the polynomial function of relative humidity (RH) and the linear function of temperature. Here an EMC/ERH model has been developed with C1~C7 as parameters. The model was used to fit the measured EMC/ERH data of the Chinese varieties including 17 rough rice, 11 milled rice, 14 wheat, 16 shelled corn, and 10 soybean which have a determination coefficients above 0.994, mean relative error (MRE) <3.46%, better than the commonly cited models such as Modified-Chung-Pfost (MCPE), Modified-Halsey (MHAE), Modified-Henderson (MHE), Modified-Guggenheim-Anderson-deBoer (MGAB) and Modified-Oswin (MOE). In comparison of the isotherms derived from the polynomial model, there were apparent hysteresis between desorption and adsorption for cereal grains, while no significant hysteresis for soybean. The relatively safe storage moisture content derived from the developed desorption polynomial equation at 30℃ was below 14% for cereal grain and 11.47% for soybean. © 2015, Editorial Department, Chinese Cereals and Oils Association. All right reserved. Source

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