Rheological characterization of egg yolk processed by spray-drying and lipid-cholesterol extraction with carbon dioxide

The present work studies the rheological properties of avian egg yolks processed by spray-drying and by lipid-cholesterol extraction with CO₂ under near-critical conditions. The results have been compared with those obtained from native egg products in order to analyze the effect of processing on the microstructure and rheological properties of egg yolks. The rheological study included linear viscoelasticity measurements by means of dynamic oscillatory shear and creep tests, which provided information about the unperturbed structure of the material, as well as steady-state flow measurements. The thermal denaturation of proteins, which was produced during the spray-drying of egg yolk, was responsible for the dramatic change from fluid to gel-like behavior. The thermal denaturation of proteins promotes the formation of a gel-like network, which may be attributed to exposure of internal hydrophobic groups that favor protein aggregation. Lipid (and cholesterol) extraction from yolk increased the viscoelasticity functions and flow properties due to the increased protein concentration.     

Effects of the degree of unsaturation of coexisting triacylglycerols on cholesterol oxidation

In order to evaluate the effects of the degree of unsaturation of triacylglycerols on cholesterol oxidation, mixtures of purified sardine oil triacylglycerols (iodine value, IV=182.6) and cholesterol; of partially hydrogenated sardine oil triacylglycerols (IV=174.5) and cholesterol; and of fully hydrogenated sardine oil triacylglycerols (IV=92.0) and cholesterol were incubated at 25°C in the dark. The oxidative stability of the samples decreased with increasing degree of unsaturation of the triacylglycerols in the sample mixtures; the induction period for peroxide values (PV) of the sardine oil triacylglycerols and cholesterol was shorter than that of the partially hydrogenated sardine oil triacylglycerols and cholesterol. Certain polyunsaturated fatty acids (PUFAs) in the constituent fatty acids of sardine oil triacylglycerols started to decrease after a shorter induction period compared with that of the partially hydrogenated triacylglycerols. The prominent cholesterol oxides accumulated in the samples were 7β-hydroxycholesterol, 7-ketocholesterol, β-epoxide and cholestane triol. The tendency for accumulation of cholesterol oxides in the time course coincided with the changes in PV as well as the decrease in PUFAs. Cholesterol was oxidized in conjunction with autoxidation of coexisting fish oil triacylglycerols. Although lowering the degree of unsaturation of fish oil triacylglycerols was effective in prolonging the induction period of cholesterol oxidation, the rate of cholesterol oxidation in the cholesterol oxides' formation phase after the induction period was not affected by the difference in the proportion of highly unsaturated fatty acids in the natural and partially hydrogenated triacylglycerols of fish oils.     

Medication Adherence and Diabetes Control in Urban African Americans With Type 2 Diabetes.

In 181 urban African Americans with Type 2 diabetes, medication adherence was assessed using a measure designed specifically for an urban, impoverished sociodemographic population. Hemoglobin A1c, blood pressure and cholesterol levels, medication-related beliefs, and depression were assessed. Seventy-four percent of the sample reported adherence to diabetes medication. Adherence, adjusted for age, was associated with lower hemoglobin A1c. The specific behaviors associated with poorer diabetes control were forgetting to take medications and running out of medications. Knowledge of blood glucose goals differed for adherers and nonadherers. Blood pressure and cholesterol medication adherence rates were not associated with actual levels of blood pressure or lipids, respectively. These data suggest that specific medication-taking behaviors are important to diabetes control and constitute logical targets for interventions. (PsycINFO Database Record (c) 2010 APA, all rights reserved)     

Evaluation of Frying Oil Filtration Systems

Three heated oil filtration systems were evaluated: (1) paper filter; (2) paper filter plus diatomaceous earth (DE); and (3) depth filtration with a filter pad under positive pressure. Methods 1 and 2 are traditional methods. Results on tallow-cottonseed oil (90:10) and hydrogenated soybean shortening indicated that depth filtration was more effective at maintaining lipid oxidation products at low levels than methods 1 and 2. Levels of free fatty acids did not appear to differ markedly between treatments in both comparisons of depth filtration with traditional methods. Mineral analysis of both heated oil filtrate and residue removed from oil by filters revealed that depth filtration was more effective at removal of pro-oxidant transition metals than were methods 1 and 2.     

Use of cyclic anhydrides to remove cholesterol and other hydroxy compounds from fats and oils

A method for removing cholesterol from animal fats has been developed based on the reaction between the hydroxyl group of cholesterol and cyclic anhydrides. The reaction forms monoesters with acyl chains having a terminal free acid group. The conversion of cholesterol into an acid derivative makes it possible to remove the cholesterol from fats by extraction with aqueous alkali. A study of the reaction in model systems showed that optimal conditions were a molar ratio of cholesterol to succinic anhydride of 1∶3 at 135°C for several hours. Acid catalysts increased the rate of the reaction, and acetic was selected not only because of its catalytic power but also because its reflux prevented the distillation of the cyclic anhydride from the reaction mixture. If all the cyclic anhydride was added at the beginning of the reaction, animal fats such as lard, tallow and milk fats were reduced in their cholesterol content by about 40%. A study of the reaction mechanism showed that the cholesterol reduction could be increased to 60–70% by altering the amount and the addition sequence of cyclic anhydride. The effectiveness of acid catalysts was related inversely to the negative logarithm of their acid dissociation constant (pK), but as their effectiveness increased, so did their tendency to form other, unwanted esters of cholesterol. A mixture of monoethyl fumarate and acetic acid sped the reaction, compared with acetic acid alone, with minimal formation of cholesteryl acetate. Studies with¹⁴C-cholesterol showed little formation of products other than cholesteryl hemiscuccinate during the reaction. The procedure removed some of the tocopherol from the fat but had no other detectable effect on fat stability. The procedure also can be used to concentrate the lactone precursors from milk fat.     

Male-stimulated female maturation inSchistosoma: A review

InSchistosoma mansoni and other schistosome species, pairing of the female with a male partner is necessary for the completion of reproductive morphogenesis and growth. Permanent contact with a male is also necessary for the maintenance of reproductivity in the sexually mature female. This phenomenon appears to be unique within the animal kingdom. The mechanism of male-stimulated female reproductive development in schistosomes remains unknown however. In this paper, the theories for the nature of the process are reviewed briefly, recent findings are added, and the biological and technical problems associated with its study are highlighted.