Protein-lipid complexes are known to result from complex molecular interactions which contribute to physiochemical and functional properties of foods. To identify the interactions of food proteins with lipids and the associated changes in properties, the following factors were investigated: incubation temperature, pH, type of lipids (phospholipid, triglyceride and fatty acids) and different proteins (ovalbumin and soybean glycinin). The effects of lipids on physiochemical and functional characteristics of ovalbumin and glycinin were investigated using polyacrylamide gel electrophoresis (PAGE), fluorescence, differential scanning calorimetry (DSC), Fourier transform infrared (FTIR) spectroscopy, and emulsification and gelation properties. / The results showed that pH, temperature and the type of lipids affected both ovalbumin-lipid interactions and physiochemical properties of ovalbumin. Changes in the electrophoretic behavior of ovalbumin were related to the presence of lipids, and the relative fluorescence of ovalbumin decreased in the presence of lipids at different pH values. In addition, lipids increased the stability of ovalbumin as revealed by the thermal denaturation (Td) and by the enthalpy transition (DeltaH). FTIR spectra in the amide I absorption region revealed that lipids affected the secondary structure of ovalbumin. Changes in the integrated intensity of the amide II band between (1520--1555) cm -1 in the presence of D2O showed that H-D exchange of ovalbumin decreased in the presence of lipids. Emulsifying properties, gel strength and water holding capacity (WHC) of ovalbumin increased significantly (P < 0.05) in the presence of lipids. Scanning electron microscopy (SEM) showed difference in the microstructure of ovalbumin gel in the presence of different lipids. The more pronounced effect of lipids was observed with lecithin and the lowest was with stearic acid. The order of magnitude for the effects of lipids on physiochemical and functional properties of ovalbumin was: lecithin > cocoa butter > oleic acid > linoleic acid > linolenic acid > stearic acid. It is likely that the degree of polarity of lipids play an important role in protein-lipid interactions and in the enhancement of the functional properties of ovalbumin. / The effects of soybean oil (SO), soybean lecithin (SL) and a mixture of both (SOL) on physiochemical and functional properties of soybean glycinin were studied at pH 8.0, with incubation at 40°C. Changes in the electrophoretic behavior were related to the presence of lipids. Relative fluorescence of glycinin decreased in the presence of lipids. Lipids increased the thermal stability (Td) of glycinin from 89.7°C to 92.0°C, 94.3°C and 93.4°C with SO, SL and SOL respectively. FTIR spectra indicated changes in both; the secondary structure and H-D exchange of glycinin in the presence of lipids. Gel strength, WHC and emulsifying properties of glycinin increased significantly (P < 0.05) in the presence of lipids; the order of consequence increase was: SL > SOL > SO. SEM showed difference in the microstructure of glycinin gels with the different lipids used. Overall, the results demonstrate both quantitative and qualitative effects on the physiochemical and functional properties of ovalbumin and glycinin as a result of protein-lipid interactions.

The house cricket, Acheta domesticus (L.), is an insect which has received, up until recently, very little attention as a physiological subject. This is no doubt due to the fact that it has been of little economic importance in Europe or North America. However, its potential as a laboratory test animal has been pointed out by several authors (Stone, 1953; Ghouri and McFarlane, 1958; Ritchot, 1960 ). Several factors enhance its utility - it is easily reared; it is a large enough insect in all stages of its life history to require no special handling, techniques; it has a sufficiently short life history; and finally it is not commonly subject to diseases or parasites in the laboratory.

The hen's egg consists mainly of water with its solid portion composed of proteins, fats, carbohydrates and minerals. Although the yolk and albumen are approximately equal in their content of proteins, carbohydrates and minerals, the yolk contains practically all the lipids. Consequently, very little is known about the lipids of the albumen whereas the lipids of the yolk have been studied extensively. Fresh egg yolk contains 33% lipids (66% on a moisture free basis) and about 16% protein (Romanoff and Romanoff, 1949). These lipids consist of neutral glycerides, phospholipids and sterols. The exact chemical structure of the egg yolk lipids is still uncertain mainly because of the extreme difficulty encountered in any attempt to isolate them in a pure state. [...]

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This project was initiated in an attempt to determine the effects of fermented dairy products on plasma cholesterol concentrations. The literature indicates that bacteria, in the small intestine, could modify circulating cholesterol levels through their effects on bile acid excretion. As a result, cholesterol is mobilized for de novo bile synthesis. Furthermore, bacterial fermentation in the small intestine produces short chain fatty acids which affect cholesterol production by the liver. A cross-over, placebo-controlled study was thus conducted on 13 hypercholesterolemic men to establish the effect of kefir, a fermented milk, on cholesterol levels. Subjects consumed kefir or milk for periods of four weeks separated by a four-week washout period. There was no effect on plasma total cholesterol, high-density lipoprotein cholesterol, or triacylglyceride levels upon treatment with kefir. Milk significantly decreased myristic acid (p < 0.01) and palmitoleic acid (p < 0.05) concentrations. Fractional synthesis rate of cholesterol was significantly greater after kefir supplementation than after milk supplementation (0.057 vs 0.042g/day). The effect seen on fractional synthesis rate of cholesterol may be the result of a significant decrease in low-density lipoprotein cholesterol concentration (p < 0.05) during milk supplementation. However, it was concluded that the bacterial content of kefir may have been too low to produce any significant effect on blood lipid parameters.

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