Extraction of protein from skim natural rubber latex using PEG as a surfactant via low speed centrifugation and continuous flow

Protein extractions from skim natural rubber latex using 3 %w/v polyethylene glycol (PEG6000) via both low speed centrifugation and continuous flow were investigated. In centrifugal extraction, when the speed was 1000 rpm, the extractable protein (EP) content in serum increased with processing time from 5 to 30 min and when the time was fixed at 5 min, EP content increased with centrifugal speed. In addition, further washing deproteinized chips with 2 %w/v SDS solution could remove proteins with efficiencies corresponding to the efficiencies of protein removals in latex phase, implying the role of PEG in protein reduction in both steps. In continuous flow extraction, EP content increased with increasing Reynolds number or increasing mean residence time of the flow to a maximum and then dropped. The efficiencies of the centrifugal extraction and continuous flow extraction were 55.2 and 33.7%, respectively. © 2013 Wiley Periodicals, Inc. J. Appl. Polym. Sci. 2014 , 131, 39900.     

Designing the optimal process target levels for multiple quality characteristics

The selection of the optimal process target has become an important research area in which the focus is to increase productivity and improve product quality. Although the quality engineering literature related to this issue contains a vast collection of work, some questions still remain unanswered. First, most previous studies have viewed this issue from a manufacturer's perspective. When designing the optimal process target in the early stage, the customer's perception of product quality needs to be incorporated. Secondly, many researchers have carried out their studies based on a single quality characteristic. From the customer's viewpoint, however, products are often judged based on more than one characteristic. To address these questions, this paper first studies a multivariate quality loss function to capture customer dissatisfaction with product quality, and then proposes an optimization scheme to determine the most economical process target levels for multiple quality characteristics. The optimization procedures are demonstrated in a numerical example, and the effects of process parameters are examined by conducting a sensitivity analysis.     

Isolation and Rheological Properties of Tamarind Seed Polysaccharide from Tamarind Kernel Powder Using Protease Enzyme and High-Intensity Ultrasound

Abstract: The effectiveness of using protease and combinations of protease and high-intensity ultrasound for high-purity, high-yield tamarind seed polysaccharide (TSP) production was investigated. Tamarind kernel powder (TKP) suspension was treated with protease alone at 0.16, 0.48, and 0.80 units/mL and with protease-ultrasound combinations over 3 different orders of sequence (before, simultaneous with, and after protease digestion) using combinations of 0.48 units/mL protease and high-intensity ultrasound at 25% and 50% amplitude for 15 and 30 min. The long protease digestion time could produce high-purity isolated TSP, but the polysaccharide yields were lower. The polysaccharide purity and yield were highly improved, even at a shorter protease digestion time, when the protease treatment was combined with high-intensity ultrasound. The increased amplitude level and sonication time decreased the average molecular weight of the polysaccharide. The rheological properties of the TKP and the isolated TSP, from nondestructive oscillatory measurements, demonstrated that the latter present a viscoelastic solution. The decreasing of protein content resulted in better elasticity of the solution. The power law model could be used to fit the down curve between shear rate and shear stress data. The consistency coefficient (K) increased while the flow behavior index decreased with the increased purity of the polysaccharide as a result of increasing increased digestion time, enzyme concentration, sonication power, and sonication time.     

Effect of Hydroxypropyl Methylcellulose on Rheological Properties, Coating Pickup, and Oil Content of Rice Flour-Based Batters

Rice flour-based batter is an alternative for wheat flour-based batter for consumers with wheat allergy or wheat intolerance. Further advantage of rice flour in batter is its ability to reduce oil uptake. However, due to its low-protein content, high amylose, and small granule size, rice flour-based batter possesses poor adhesion property. The aim of this study was to investigate the effect of the addition of hydroxypropyl methylcellulose (HPMC); a hydrocolloid, on rheological properties, coating pickup, and oil absorption of HPMC-rice-based fried batter. Rheological properties of rice flour-based batters containing HPMC with different degrees of substitution (DS) and concentrations were determined. In steady-shear measurements, the addition of HPMC; E4M (DS = 1.9) and K4M (DS = 1.4), led to the increase of apparent viscosity, yield stress, and consistency index. K4M rice flour batters showed shear-thickening behavior (n > 1) with syneresis. HPMC increased the complex modulus (G*) of batters, where storage moduli (G′) were higher than loss moduli (G″). The crossover points increased with increasing HPMC concentration. HPMC addition increased the coating pickup of fresh carrot sticks and less coating loss was observed with K4M. Rice batter formulated with 0.5% E4M provided deep-fried crust with 26% lower oil content compared to the control crust.     

Determining optimal process mean of two-market products

The determination of the optimal mean for a manufacturing process involves a complex and financially important decision. This study examines a situation where a product is classified into two grades with respect to market specifications. It is reasonably assumed that each grade has its price and manufacturers cannot produce every item to a good grade due to the uncontrollable variation of product performance. This study attempts to determine the optimal process mean that gives a maximum profit to the manufacturer. The expected profit function for such situation would consider the profit associated with all product grades as well as the loss to the consumer upheld by the modern concept of Taguchi’s loss function. A method for identifying the optimal process target that reflects such a situation is given by an optimization model. Numerical examples are provided to illustrate the use of the model. Finally, discussion and conclusion are given.     

Taro Colocasia esculenta (L.) Schott Amylopectin Structure and Its Effect on Starch Functional Properties

Flour extracted from small‐, medium‐, and large‐corm taro Colocasia esculenta (L.) Schott cultivated in central Thailand had similar proximate composition, comparable calcium oxalate and amylose content, but different starch granule size and average chain length of amylopectin. Starch from the larger corm taro had a smaller average granule size and a lower average amylopectin chain length (CL_avg), a lower average external chain length (ECL_avg), and a lower average internal chain length (ICL_avg) when compared to that from the smaller corm taro. The solubility of taro starch was inversely proportional to CL_avg, ECL_avg, and ICL_avg. Starch having a shorter CL_avg, ECL_avg, and ICL_avg had a higher peak viscosity and breakdown. The onset (T_o), peak (T_p), and conclusion temperatures (T_c) of starch gelatinization and the extent of starch paste retrogradation did not correlate with the amylopectin structure.     

The impact of computer-mediated immediate feedback on developing oral presentation skills: An exploratory study in virtual reality

Feedback plays a central role in learning. Crucial to this is the nature and timing of the feedback. This experimental study explores the efficacy of immediate computer-mediated feedback within a virtual reality environment designed to facilitate the development of pre-university students' presentation skills. Two conditions were established to assess the efficacy: immediate computer-mediated feedback; a control condition of delayed expert-mediated feedback. Results showed improvement but no statistically relevant difference in performance gains between the two conditions, suggesting both can facilitate learning. Furthermore, students perceived the environment to be an effective and motivating platform in which to practise presentation skills. For educators seeking viable alternatives to face-to-face presentation practice and feedback, the finding that immediate computer-mediated feedback is potentially as effective in aiding presentation performance is crucial for two reasons: first, it expands practice opportunities for students; second, it could result in less pressure on resources, including time and staffing.     

Processing of Kaolinite and Alumina Loaded in Natural Rubber Composite Foams

Composite natural rubber foams were successfully prepared from the vulcanization of natural rubber in a sulfur curing system. The natural rubber matrix phase was added with chlorinated polyethylene, kaolinite, and alumina. The morphology of natural rubber composite foams was altered when a gas was generated at the vulcanization temperature of 150°C to obtain open and closed cell structures. Furthermore, the kaolinite and alumina reinforced the mechanical properties and increased the thermal resistance of the composite foams. The composite foams were light in weight and had good thermal, mechanical, and electrical properties, suitable for energy absorption, thermal insulation, and structural uses.     

X-ray Diffraction Pattern and Functional Properties of <Emphasis Type="Italic">Dioscorea hispida</Emphasis> Dennst Starch Hydrothermally Modified at Different Temperatures

Starch from Thai yam Dioscorea hispida Dennst was hydrothermally modified at its original moisture content (∼13%, w/w) and 90 °C to 130 °C for 10 h. X-ray diffraction analysis of the modified starch showed that the crystallographic pattern of the starch was altered from type B in native starch to type C in the starch modified at 90 °C and to type A in those modified at 100–130 °C. Along with the change in crystallographic pattern, decreases in granule swelling, starch solubility, and amylose leaching were observed. Up to the modification temperature of 100 °C, a reduction in the estimated degree of crystallinity and an increase in peak viscosity were noted. Seven percent starch gel of all modified starches, except for that modified at 130 °C, showed higher complex moduli over 0.001 to 10 Hz in dynamic shear test when compared with 7% native starch gel.     

Automatic Optical Inspection of Solder Ball Burn Defects on Head Gimbal Assembly

Journal of Failure Analysis and Prevention - The detection of low-quality solder joints in hard disk drive manufacturing is a time-consuming, error-prone and costly process that is often performed...