Phenolic Compounds,Antioxidant Activity,and Medium Chain Fatty Acids Profiles of Coconut Water and Meat at Different Maturity Stages

Coconut is grown in tropical and subtropical areas worldwide. The endosperm (water and meat) is consumed and processed in different forms. This study investigated the antioxidant activities and identified the phenolic compounds existing in the water and meat of coconut fruits at three different maturity stages, i.e., 180, 190, and 225 days after pollination from two planting areas in Thailand. Total phenolic content and antioxidant activity indices increased as the coconut matured from 180 to 190 days after pollination and then decreased or remained unchanged at 225 days after pollination. Catechin and salicylic acid were the major phenolic compounds found in the water, while gallic, caffeic, salicylic, and p-coumaric acids were found in the meat. The fat content of the meat increased significantly with maturity stage. Medium chain fatty acids profiles were also analyzed. The results are important for producers, processors, and consumers to realize an optimal quality and functionality of coconut water and meat when used for specific purposes.     

Improvement of plane stress solutions using adaptive finite elements

Abstract

A finite element method is combined with an adaptive meshing technique to improve the accuracy of the finite element solution. The effectiveness of the combined method is evaluated by a plane stress problem that has an exact solution. The problem is that of a panel with a circular cutout subjected to an applied load. The result demonstrates that the adaptive meshing technique can reduce the numbers of the finite elements, the analysis computational time, and improve the accuracy of the analysis solution.     

Combined Streamline Upwind Petrov Galerkin method and segregated finite element algorithm for conjugate heat transfer problems

A combined Streamline Upwind Petrov-Galerkin method (SUPG) and segregated finite element algorithm for solving conjugate heat transfer problems where heat conduction in a solid is coupled with heat convection in viscous fluid flow is presented. The Streamline Upwind Petrov-Galerkin method is used for the analysis of viscous thermal flow in the fluid region, while the analysis of heat conduction in solid region is performed by the Galerkin method. The method uses the three-node triangular element with equal-order interpolation functions for all the variables of the velocity components, the pressure and the temperature. The main advantage of the presented method is to consistently couple heat transfer along the fluid-solid interface. Four test cases, which are the conjugate Couette flow problem in parallel plate channel, the counter-flow in heat exchanger, the conjugate natural convection in a square cavity with a conducting wall, and the conjugate natural convection and conduction from heated cylinder in square cavity, are selected to evaluate efficiency of the presented method.     

Morphological evolution of NiO-ScSZ composite in a high-temperature reducing atmosphere

The microstructural change in composite of nickel oxide and scandia-stabilized zirconia (NiO-ScSZ) under a reducing atmosphere was observed by scanning electron microscopy (SEM). The morphological transformation was noticeable after high-temperature treatment with the formation of two peculiar microstructures; i.e., fibrous zirconia and metallic nickel with wrinkled surface. It was suggested that partial reduction of the nickel species dissolved in ScSZ lattice triggered the formation of these characteristic morphologies. The growth of fibrous zirconia appeared to be promoted via interfacial reaction between the metallic Ni particles and the zirconia phase. The agglomeration of metallic nickel proceeded by the reduction at high temperatures and then the surface was transformed to the wrinkled morphology. The unique wrinkled pattern was often observed for the large agglomerated nickel particles. This drastic change in Ni-ScSZ microstructure upon the high-temperature reduction degraded the electrochemical performance of solid oxide fuel cells.     

Production of oligosaccharides from coconut meal by subcritical water treatment

Coconut meal, a by‐product from coconut milk production, was hydrolysed via subcritical water treatment at various maximum temperatures in the range of 100–300 °C using a batch‐type vessel under nonisothermal conditions. The effect of the treatment temperature and time was evaluated using the severity factor (R₀) as a parameter. The highest yield of mono‐ and oligosaccharides (28.3 g/100 g dry coconut meal) was obtained at lnR₀ = 10.4 (maximum temperature of 250 °C within the treatment time of 14 min). At higher temperature, degradation of the saccharides was observed and a large quantity of 5‐hydroxymethyl‐2‐furaldehyde was detected. The hydrolysates contained mannose, glucose and manno‐oligosaccharides with various degrees of polymerisation. The yield and ratio of saccharide components were affected by variation of the ratio of coconut meal to water used in the subcritical water treatment.     

Compositions,flavour and antiradical properties of products from subcritical water treatment of raw Isada krill

Comparative analysis of subcritical water (SCW) treatment and ambient pressure boiling one of raw Isada krill was performed for the nutritive, flavour and antiradical properties of krill extracts and residues as well as the molecular mass and odour intensity of the extract. SCW treatment was performed for 10 min in a batch‐type vessel in the temperature range of 100–240 °C, using a 1:1 weight ratio of raw krill to water. Higher protein and lipid contents were obtained by SCW treatment relative to boiling. The lipid content of the SCW extracts increased with increasing treatment temperature. Protein was the main component in these extracts, and the highest protein content was achieved by SCW treatment at 200 °C. High‐molecular‐mass species decomposed under SCW treatment at high temperatures with consequent generation of smaller molecules. The antiradical activity of the SCW extract, determined by DPPH and ABTS assays, increased with increasing treatment temperature. The krill extracts and residues exhibited shrimp‐like flavour, and the most desirable flavour was obtained by SCW treatment at 140 °C or 160 °C for 10 min. The treatment would be applicable for the production of seasonings from Isada krill.     

Computer-augmented preliminary design of aircraft wing structures

A computer system to aid in the preliminary design of aircraft wing structures for minimum weight is described. The system was developed to utilize effectively the best attributes of both computers and the human mind in the iterative process of analyzing highly redundant trial structures and using these results to select new trial structures with the objective of minimizing weight. The computer is used for the routine data processing, and the designer performs those tasks which require judgement and intuition. Cathode ray tube graphical displays are provided for checking input data and for evaluating results. From given basic information on the wing structure, loads, and material properties, a finite element model is developed, analyzed, modified to eliminate violations of design criteria, and optimized to obtain the structural configuration of least weight. The optimization proceeds automatically, but the designer may monitor progress with the aid of tabular and graphical displays and modify the direction in which the optimization is proceeding. The impetus for this work was provided by a need for such a system in teaching structural design to aeronautical engineering students. The modular system was developed for the Control Data Corporation 6400/6500 computer installation at Purdue University using the Purdue Interactive Remote Access Terminal Environment (PIRATE).     

Flexible and Tough Poly(lactic acid) Films for Packaging Applications: Property and Processability Improvement by Effective Reactive Blending

This study demonstrates a practical means to overcome inherent brittleness problem of poly(lactic acid) (PLA) and make PLA feasible as packaging material. PLA with suitable processability is utterly required for package manufacturers, where flexible, tough PLA film is essential for packers and end users. Highly flexible PLA films with 60‐fold increase in elongation at break (Eb) over that of the neat PLA were successfully produced by integrating effective reactive blending and economical film blowing process. The ‘two‐step’ blending was used to prepare PLA compound; poly(butylene adipate‐co‐terephthalate) (PBAT – another biodegradable polymer) was first blended with 0.5–1% chain extender (epoxy‐functionalized styrene acrylic copolymer) (ESA), followed by subsequent blending with PLA in twin‐screw extruder. Blown films of reactive blend of PLA/PBAT/ESA (80/20/1) showed impressively high Eb of 250% versus a very low Eb of 4% for the neat PLA. Resulting blown films still possessed high modulus of 2 GPa, yield stress of 50–60 MPa and good toughness of ~100 MPa. Significant enhancement in the film's ductility was attributed to homogeneous blend with developed fine strand‐like structure as a result of effective in situ compatibilization and good interfacial adhesion between the PLA and PBAT. PLA/PBAT/ESA blend also offered improved processability. Resulting films had acceptable haze of ~10% for common packaging, and clearer film close to PLA (≤2%) could be obtained by designing PLA skin layers in multilayer structure. Films of PLA/PBAT/1%ESA exhibit potential as packaging material; their mechanical and optical properties are comparable with or even exceed some existing films used in the market. Copyright © 2015 John Wiley & Sons, Ltd.     

Minimally-destructive evaluation of durian maturity based on electrical impedance measurement

Electrical impedance spectroscopy was investigated to model the dry matter content of durian using partial least squares regression. Measurements of the impedance were taken on the stem and the rind of durian samples at various stages of maturity based on the number of days after anthesis. Plots of the relationship between resistance and reactance, and the change in impedance and capacitance with respect to frequency in a range of 1–200 kHz were explored to determine the optimal frequencies associated with variation in the number of days after anthesis. The impedance parameters at frequencies of 1, 41 and 200 kHz were employed to model the dry matter content of the pulp. The reactance of the cross section of the stem and the capacitance of the rind were found to predominantly contribute to the prediction of the dry matter content. Selected impedance parameters using a stepwise regression could be used to classify durian samples into an immature class and mature class with less accuracy of 83.3%.     

Carbohydrate content and composition of product from subcritical water treatment of coconut meal

Coconut meal, a by-product from coconut milk production, was treated with subcritical water at 100–200 °C for 30–240 min in a batch-type reactor. The analysis focused on the content and constituent neutral sugar of the soluble carbohydrate in the liquid products. The carbohydrate is composed of both monosaccharides and oligosaccharides. Treatments at 100–150 °C gave a small amount of a carbohydrate (3.5–5.1 g/100 g dry coconut meal). At 175 °C, the carbohydrate content increased from 4.9 to 9.6 g/100 g dry coconut meal (p < 0.05) for 30–240 min of treatment, but the value decreased from 10.6 to 6.1 g/100 g dry coconut meal for 30–240 min of treatment at 200 °C. The soluble carbohydrate contained mannose, glucose, galactose and arabinose. A response surface methodology study indicated that 13.9 g/100 g dry coconut meal of mannose in the soluble carbohydrate could be produced at 227 °C in 3 min.