Oxidation encapsulated lipids

Meat products have to be stabilised in some cases, as meat lipids contain no natural antioxidants or only traces of tocopherols. Most muscle foods contain, however, an efficient multi-component antioxidant defence system based on enzymes, but the balance changes adversely on storage. The denaturation of muscle proteins is the main cause of the inbalance as iron may be released from its complexes, catalysing the lipid oxidation. Salting contributes to the negative effects of storage, as it enhances oxidation. Using encapsulated salt eliminates the deleterious effect of sodium chloride. 

Effect of Water Activity. A preliminary study was done to determine the a at which encapsulated orange peel oil was the most stable to oxidation. Figure 1 summarizes the results of this study. The formation of the limonene oxidation product, limonene oxide, was the slowest for the powder adjusted over Mg(NO3)2 (a 0.536). While the levels of oxidation product do not follow in exact order of a, it is evident that better storage stability correlates with a higher a of the powder. This relationship was not anticipated. Literature on lipid oxidation (2, 2) indicates that there is an optimum a for product... 

Grattard, N., Salaun, F., Champion, D., Roudaut, G., and Le Meste, M. (2002). Influence of physical state and molecular mobility of fieeze-dried maltodextrin matrices on the oxidation rate of encapsulated lipids. J. FoodSci. 67, 3002 3010. 

The effects of water on the destruction of the protective food structure in some specific dehydrated foods is probably involved in prevention of lipid oxidation in heated meat systems (Karel, 1986). In systems in which there are both surface lipids and lipids encapsulated within a carbohydrate, polysaccharide, or protein matrix, the surface lipids oxidize readily when exposed to air. The encapsulated lipids, however, do not oxidize until the structure of the encapsulated matrix is modified and/or destroyed by adsorption of water as shown by Simatos and Karel (1988). In some IM meats, muscle may be considered as being encased in or surrounded by a humectant matrix. However, free lipid may be left on the surfaces. The unwarranted overuse of lipids, which often happens in the indirect drying process to improve heat transfer and to prevent burning, is detrimental to the products. Prevention of this structural change is of considerable... 

Oxidation of encapsulated lipids in freeze-dried products (after sublimation stage) Tc... 

Water Activity The role of water activity in determining shelf life of the spray-dried powders is of interest. It is well documented in the literature that lipid oxidation is slowest at the monolayer (water activity ca. 0.2) and will increase on either side of the monolayer. Anker and Reineccius [86] found that shelf life of orange peel oil encapsulated in gum Arabic increased with water activity within the range of water... 

Smaller droplets (larger interfacial area) increase the exposure of the encapsulated BLI to reactive molecules, so would be expected to reduce their chemical stability. Despite this, comparisons of BLI degradation rates at different particle sizes are relatively few and the postulated relationship is not always seen. For example, Kiokias and co-workers (2007) did not report any effects of droplet size (d3 =0.5-2 pm) on the rate of lipid oxidation in model food emulsions as a function of temperature, while Let and co-workers (2007), and Nakazawa and co-workers (2008) showed fine to3 fatty acid-rich oil and methyl linolenate emulsions oxidized more slowly than coarse ones (d32=0.5-1.5 pm and median=0.02-1 pm, respectively). Droplet size distribution affects not only the chemical stability of BLI and the physical stability of the EBDS but also the bioavailability of BLI within the EBDS. 

The Jing group investigated their poly(L-lysine)-6-poly(L-phenylalanine) vesicles for the development of synthetic blood, since PEG-lipid vesicles were previously used to encapsulate hemoglobin to protect it from oxidation and to increase circulation time. They extended this concept and demonstrated that functional hemoglobin could be encapsulated into their vesicles. The same polypeptide material was also used to complex DNA, which caused the vesicles to lose their... 

Probucol, another di-r-butyl phenol, is an anti-atherosclerotic agent that can suppress the oxidation of low-density lipoprotein (LDL) in addition to lowering cholesterol levels. The antioxidant activity of probucol was measured, using EPR, with oxidation of methyl linoleate that was encapsulated in liposomal membranes or dissolved in hexane. Probucol suppressed ffee-radical-mediated oxidation. Its antioxidant activity was 17-fold less than that of tocopherol. This difference was less in liposomes than in hexane solution. Probucol suppressed the oxidation of LDL as efficiently as tocopherol. This work implies that physical factors as well as chemical reactivity are important in determining overall lipid peroxidation inhibition activity (Gotoh et al., 1992). 

Imagi, J. Muraya, K., Yamashita, D., Adachi, S., and Matsuno, R. 1992. Retarded oxidation of liquid lipids encapsulated in matrixes of saccharides or proteins. Biosci. Biotech. Biochem. 56, 1236-1240. 

However, numerous challenges exist in the production, transportation, and storage of fatty acid fortified functional foods, since these lipids are extranely susceptible to oxidative deterioration. Encapsulation of bioactive lipids has been found to be an excellent method for their stabUization." ... 

Chemical stability may also be surface-related. The lipid exposure at the surface influences the oxidation sensitivity of cholesterol in a dairy-type powder. An encapsulating procedure using gelatine during the drying process enhances the chemical stability of... 

Soft butters have been produced by feeding encapsulated polyunsaturated oils in order to overcome the problem of biohydrogenation (Barbano and Sher-bon, 1980 Kuksis and McKarthy, 1964 Scott et al., 1972a,b Storry et al., 1974, 1980). Using encapsulation techniques the 18 2 content of butterfat can be increased from 2-3% to 35% but problems of oxidative stability arise (Edmunson etal., 1974). The effect of feeding protected lipids on the composition of the milk fat globule membrane has been reported (Smith etal., 1977) (Table 3.159). 

According to the glass transition theory, lipids are dispersed in the free volume of the food matrix composed of carbohydrates and protein polymers. In the rubbery state, the lipids react readily with oxygen and become oxidized. In the glassy state, however, the lipids are stable to oxidation because they are encapsulated and there is no free volume. The glass transition temperature, which determines when the food matrix changes from one state to the other, increases with a decrease in moisture and water activity. In many foods the... 

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