Proportion Of Large Vesicles Research Articles

Manufacture and Incorporation of Liposome-Entrapped Ethylenediaminetetraacetic Acid into Model Miniature Gouda-Type Cheese and Subsequent Effect on Starter Viability, pH, and Moisture Content.

Liposome-encapsulated ethylenediaminetetraacetic acid (EDTA) was incorporated into a model miniature Gouda-type cheese (20 g) in order to assess its effect on rennet gelation, starter viability, pH, and moisture content. EDTA was encapsulated within 2 different food-grade proliposome preparations, Pro-Lipo Duo and Pro-Lipo C (50% and 40% unsaturated soybean phospholipids and 50% and 60% aqueous medium, respectively), using the following high-shear technologies: Ultra-Turrax (5000 rpm), 2-stage homogenization (345 bar), or microfluidization (690 bar). Liposome size distribution was affected by the high-shear technology employed with the proportion of large vesicles (>100 nm) decreasing in the order microfluidization < 2-stage homogenization < Ultra-Turrax. All EDTA-containing liposomes were stable during 28 d refrigerated storage, with no significant (P ≤ 0.05) change in size distribution or EDTA entrapment efficiency (%EE). Liposome composition affected the entrapment of EDTA, with Pro-Lipo C having a significantly greater %EE than Pro-Lipo Duo, 63% and 54%, respectively. For this reason, Pro-Lipo C EDTA liposomes, with and without EDTA, were incorporated into model miniature Gouda-type cheese. Addition of liposome-encapsulated EDTA to milk during cheese making did not impact pH or rennet gel formation. No differences in composition or pH were evident in liposome-treated cheeses. The results of this study show that the incorporation of liposome-encapsulated EDTA into milk during cheese manufacture did not affect milk fermentation, moisture content, or pH, suggesting that this approach may be suitable for studying the effects of calcium equilibrium on the texture of brine-salted cheeses.

Structural destabilization of synaptosomal particles by lysis and sequential chemical treatments.

Synaptosomes from rat brains were subjected to a sequence of treatments: osmotic lysis, buffered saline wash, nonionic detergent, EGTA and EDTA. After each treatment, particulate samples were fixed in 2% glutaraldehyde-1% formaldehyde and centrifuged to form pellets which were then processed for and examined by electron microscopy. Five morphological classes of synaptic particle were defined in terms of character and presence of synaptic vesicles, flocculent and stranded material, designated as intervesicular scaffolding (IVS), and presynaptic membrane. During osmotic lysis, the presynaptic compartment was altered by loss of most, but not all, small synaptic vesicles, by increase in proportion of large vesicles, and by disappearance of the presynaptic densities. The retention of vesicles was interpreted in terms of IVS struts interconnecting anchorage sites on synaptic vesicles and the presynaptic junctional membrane. Treatment of lysed synaptosomes with nonionic detergent or EGTA resulted in loss of vesicles and IVS from the junctional region in most particles. The apposition of pre-and postsynaptic junctional membranes along the synaptic cleft was disrupted more by EGTA than by detergent. The final result of the sequential treatments was a sediment containing a high proportion of synaptic particles, about half of which had lost their presynaptic junctional membranes.