scholarly journals Response Surface Method in Evaluating the Extrusion Effects on Molecular Degradation and Physical Properties of Sago Starch

Author(s):  
Ansharullah Ansharullah ◽  
Sri Wahyuni ◽  
. Tamrin ◽  
Muhammad Natsir

This study was aimed to measure the effect of extrusion on the molecular degradation and physical characteristics of the sago starch by employing response surface method. The starch was extruded in a twin screw extruder with moisture contents of 25, 32.5, and 40%; melt temperature of 86, 95 and 104oC; and screw speed of 100, 150, and 200 rpm. The extruded products were then analyzed for degree of molecular degradation, reducing sugars of the water soluble materials, water solubility index (WSI), water absorption index (WAI), enzyme susceptibility, gelatinization endothermic energy (∆H), and specific mechanical energy (SME). Increased mechanical and thermal energy input received by the products in the extruder gave rise to a significant degradation of the molecular weight of the macromolecules. It was believed that granule structures of the extruded starch have been reshaped. The extrusion process conditions did not significantly affect the WSI, WAI, reducing sugar content, and ∆H. All extruded samples had a much lower gelatinization endothermic energy than native starch.

Author(s):  
Helena Poy ◽  
Estela Lladosa ◽  
Carmen Gabaldón ◽  
Sonia Loras

AbstractRice straw (RS) is a promising feedstock for transformation into biofuels and bioproducts due to its high sugar content and worldwide availability. However, a pretreatment step is necessary in order to disrupt the RS complex lignocellulosic matrix. The aim of this work was to study RS pretreatment with the ionic liquid 1-ethyl-3-methylimidazolium acetate ([Emim][OAc]) to maximize the enzymatic hydrolysis yield. For this purpose, a response surface method (RSM) based on a central composite design (CCD) was used, with temperature (53–137 °C), time (0.3–6.2 h), and solid loading (3.3–11.7% dry weight) as process variables. The analysis of variance (ANOVA) results suggested that temperature was the most significant factor affecting the fermentable sugar yield of [Emim][OAc]-pretreated RS samples. The selected conditions for this pretreatment were 120 °C, 5 h, and 5% (w/w), obtaining 29.8 g/L of potentially fermentable sugars. In these conditions, maximum delignification was achieved (64.9%) as well as maximum reduction of the crystallinity index (62.2%), as determined by X-ray diffraction analysis. Fourier-transform infrared spectroscopy (FT-IR) and scanning electron microscopy (SEM) analysis were used to confirm the RS amorphous structure after the pretreatment with [Emim][OAc] and showed that it had a more disordered and accessible structure.


2014 ◽  
Vol 134 (9) ◽  
pp. 1293-1298
Author(s):  
Toshiya Kaihara ◽  
Nobutada Fuji ◽  
Tomomi Nonaka ◽  
Yuma Tomoi

Materials ◽  
2019 ◽  
Vol 12 (21) ◽  
pp. 3552 ◽  
Author(s):  
Chun-Yi Zhang ◽  
Jing-Shan Wei ◽  
Ze Wang ◽  
Zhe-Shan Yuan ◽  
Cheng-Wei Fei ◽  
...  

To reveal the effect of high-temperature creep on the blade-tip radial running clearance of aeroengine high-pressure turbines, a distributed collaborative generalized regression extremum neural network is proposed by absorbing the heuristic thoughts of distributed collaborative response surface method and the generalized extremum neural network, in order to improve the reliability analysis of blade-tip clearance with creep behavior in terms of modeling precision and simulation efficiency. In this method, the generalized extremum neural network was used to handle the transients by simplifying the response process as one extremum and to address the strong nonlinearity by means of its nonlinear mapping ability. The distributed collaborative response surface method was applied to handle multi-object multi-discipline analysis, by decomposing one “big” model with hyperparameters and high nonlinearity into a series of “small” sub-models with few parameters and low nonlinearity. Based on the developed method, the blade-tip clearance reliability analysis of an aeroengine high-pressure turbine was performed subject to the creep behaviors of structural materials, by considering the randomness of influencing parameters such as gas temperature, rotational speed, material parameters, convective heat transfer coefficient, and so forth. It was found that the reliability degree of the clearance is 0.9909 when the allowable value is 2.2 mm, and the creep deformation of the clearance presents a normal distribution with a mean of 1.9829 mm and a standard deviation of 0.07539 mm. Based on a comparison of the methods, it is demonstrated that the proposed method requires a computing time of 1.201 s and has a computational accuracy of 99.929% over 104 simulations, which are improvements of 70.5% and 1.23%, respectively, relative to the distributed collaborative response surface method. Meanwhile, the high efficiency and high precision of the presented approach become more obvious with the increasing simulations. The efforts of this study provide a promising approach to improve the dynamic reliability analysis of complex structures.


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