Lipase-assisted concentration of n-3 polyunsaturated fatty acids in acylglycerols from marine oils

Preparation of n-3 polyunsaturated fatty acid (PUFA) concentrates from seal blubber oil (SBO) and menhaden oil (MHO) in the form of acylglycerols was carried out by hydrolysis with a number of commercial microbial lipases. The lipases tested were Aspergillus niger, Candida cylindracea (CC), Chromobacterium viscosum, Geotrichum candidum, Mucor miehei, Pseudomonas sp., Rhizopus oryzae, and Rhizopus niveus. After lipase-assisted hydrolysis of oils, free fatty acids were removed, and fatty acid composition of the mixture containing mono-, di-, and triacylglycerols was determined. All lipases were effective in increasing the n-3 PUFA content of the remaining acylglycerols of both SBO and MHO. The highest concentration of n-3 PUFA was provided by CC lipase; 43.5% in SBO [9.75% eicosapentaenoic acid (EPA), 8.61% docosapentaenoic acid (DPA), and 24.0% docosahexaenoic acid (DHA)] and 44.1% in MHO (18.5% EPA, 3.62% DPA, and 17.3% DHA) after 40 h of hydrolysis. Thus, CC lipase appears to be most suitable for preparation of n-3 PUFA in the acylglycerol form from marine oils.     

Experimental investigation into glass fiber/epoxy composite laminates subjected to single and repeated high-velocity impacts of ice

Many engineering components in aerospace structures which are made from polymer composite materials are often damaged during service life due to hail ice and bird impact. This study examines the damage which may be incurred by a single and repeated high-velocity impact of 11.7 g cylindrical-shaped ice on glass fiber/epoxy laminated composite panels carried out on a 20-mm diameter smooth barrel gas gun. The laminates were made from E-glass fiber/epoxy resin with 0/90, ±45, chopped strand mat (CSM) and unidirectional fiber orientation and in different stacking sequence. The impact velocity was in the range of 130–140 m/s and the resulting damage extension zones from ice projectile impacts were measured. Damage extension was successfully identified in all specimens subjected to high-velocity ice projectile impact. Results showed specimens with ±45 orientation and CSM fiber exhibited the lowest damage extension. The results also revealed that specimens with plain weave 0/90 lay-up of glass woven roving show the highest damage extension. Extended damages were observed in composite panels under repeated ice projectile impacts. Study of the stacking sequence effect indicated significant role played by presence of ±45 reinforcement in reducing the damage extension in the laminated plates. Delamination constituted the major damage mechanism for most specimens tested followed by matrix and fiber fracture.     

Meat flavor volatiles: A review of the composition,techniques of analysis,and sensory evaluation

Flavor is an important quality attribute which relates to the organoleptic characteristics of meat. Although perception of flavor is a complex phenomenon, odor is the most important single factor contributing to the overall characteristics of flavor. A large number of compounds have been identified in the volatile fraction of red meats and poultry. An overview of the chemical constituents present in the volatiles of beef, pork, mutton, and chicken is presented according to species and arranged by chemical class — hydrocarbons, alcohols, acids, aldehydes, ketones, sulfides, heterocyclic compounds, etc. The volatile components of cured and uncured pork are compared. The field of meat flavor is assessed in terms of what has been accomplished and the direction in which it may proceed. Techniques for analysis of these volatiles are briefly described.     

Antioxidant Potential of Pea Beans (Phaseolus vulgaris L.)

ABSTRACT: Four bean varieties ( Phaseolus vulgaris L.) (white kidney, red pinto, Swedish brown, and black kidney) and their hull fractions were extracted with 80% acetone and evaluated for their phenolic contents and antiradical activities. Total phenolic content of bean hulls and whole seed extracts ranged from 6.7 to 270 and 4.9 to 93.6 mg/g extract as catechin equivalents, respectively. Trolox equivalent antioxidant capacity (TEAC) assay revealed that the antioxidant capacity of red, brown, and black whole seed extracts was in the same order of magnitude with little variation. TEAC values of red and brown whole seed extracts were superior to that of black whole seed extract. On the basis of the total phenolic content and TEAC values, it can be deduced that colored beans possess superior antioxidative activity compared with white beans. The hydrogen peroxide scavenging capacity of different bean extracts ranged from 58% to 67% at 50 ppm and 65% to 76% at 100 ppm. The corresponding superoxide radical scavenging capacity was 24% to 29% at 50 ppm and 53% to 60% at 100 ppm. The 2,2–diphenyl-1–picrylhydrazyl (DPPH) radical scavenging capacity of black bean whole seed extracts was 22% at 50 ppm, whereas the other extracts showed 100% scavenging of this radical at both 50 and 100 ppm levels. The hydroxyl radical scavenging capacities of the bean extracts at 50 and 100 ppm were 12% to 29% and 32% to 49%, respectively. All extracts used prevented human low-density lipoprotein (LDL) cholesterol oxidation by 61.4% to 99.9% at 2 to 50 ppm level as catechin equivalents.     

Natural antioxidants in tree nuts

The levels of natural antioxidants and phytochemicals present in tree nuts are reported. Where possible, the health claims by Food and Drug Administration and European Food Safety Authority and health effects of tree nuts are provided. The content and recommended dietary allowances of nutrient antioxidants (such as vitamins A, C, E, and the mineral selenium) present in various tree nuts are compared. Antioxidant activity and phytochemicals present among tree nuts have been thoroughly reviewed. Research findings from over 65 references, many of which have been published within the last 10 years, have been compiled and reported.     

An investigation on the effect of SBS+Vacuum bottoms residue modification on rheological characteristics of asphalt binder

In this research, the effect of adding SBS and vacuum bottoms residue on 60/70 neat asphalt binder have been carried out using classic and superpave testing methods. Adding SBS led to increase of softening point, elastic recovery and viscosity of asphalt binder. Besides, SBS reduced the penetration and ductility of specimens. Results of dynamic shear rheometer indicated that G^* and G^*sinδ reduced by adding the SBS content before and after aging while δ and G^*/sinδ parameters increased. Therefore, adding SBS improves the permanent deformation and fatigue resistance of neat asphalt binder.     

Multi-walled carbon nanotube-filled polypropylene nanocomposites: high velocity impact response and mechanical properties

Polymer nanocomposites containing 0.75, 1.0 and 1.5 wt% of multi-walled carbon nanotubes (MWNTs) in a polypropylene (PP) matrix were studied in relation to their low and high velocity impact performances. PP nanocomposites reinforced MWNTs were prepared via melt compounding in an internal mixer followed by injection molding. Transmission electron microscopy analysis confirmed well dispersed 1?wt% MWNT in the polymer nanocomposites. The same analysis showed agglomeration and cluster formation in 1.5?wt% MWNT specimens. Results showed increase in Izod impact strength in nanocomposites containing 1?wt% MWNT, which attained the highest value (with 33.4?% increment). A single stage gas gun was used to carry out high velocity impact test in velocity range of 20?C150?m/s using hard steel hemispherical tip projectile of 11.34?g weight and 8.1?mm diameter. Results showed better ballistic limit velocity (the average of highest impact velocity causing perforation but unable to go through and lowest impact velocities with no residual velocity recording) and energy absorption for specimens, each containing 1?wt% MWNT, showing the highest value (with 100?% increment), compared with neat PP. Considerable increases were observed in tensile and flexural strengths and modulus for the MWNT-containing specimens as compared with neat PP.     

Progressive collapse analysis of steel frames: Simplified procedure and explicit expression for dynamic increase factor

Progressive collapse refers to a phenomenon in which local damage in a primary structural element leads to total or partial structural system failure. When investigating the progressive collapse of structures, nonlinear dynamic procedures lead to more accurate results than static procedures. However, nonlinear dynamic procedures are very complicated and the evaluation or validation of the results can become very time consuming. Therefore, it is better to use simpler methods. For static analyses, the gravity force applied to the removed column bay should be multiplied by a constant factor of two. However, using a constant dynamic increase factor (DIF) is only appropriate for elastic systems. According to the optimal design of structures, the assumption of elastic behavior after column removal is conservative. Thus, it is necessary to establish an expression for DIF that considers inelastic responses. In this paper, a simplified analysis procedure for the progressive collapse analysis of steel structures is presented using the load displacement and capacity curve of a fixed end steel beam. The results of the proposed method are in good agreement with nonlinear dynamic analysis results. Also, the capacity curve, obtained by dividing the accumulated area under the nonlinear static load displacement curve by the corresponding displacement of the column removed point, is used to predict the progressive collapse resistance of the column removed structure. Finally, an explicit expression for the DIF is established for elastic-perfectly plastic and elastic plastic with catenary action behavior.