Oxidized fats

Ethylene-propylene (EPDM) Oxidizing agents Dilute acids Amines Water (Mostly any HR fluid) Oils Hot cone, acids Very strong oxidants Fats fatty acids Chlorinated hydrocarbons... 

There has not been found any substantial difference between the effects of irradiation on the lipid fraction of complex foods and that on model systems analogous to to fats. The autooxidation products of either natural fats or of model systems on irradiation are the same as those present in oxidized fats that... 

Figure 25.9 The relative contributions of the thermal Ep (1), prompt Ep (2), and nitrous oxide Fat (3) mechanisms as well as reburn Er (4) to the emission index and the net emission index found from Eq. (25.2) (symbols 5 — Eno ) predicted by RRA analysis for methane-air diffusion flames at p = 1 bar and oxidizer and fuel stream temperatures of Tf = To = 300 K...

Several methods have been introduced which express the degree of oxidation deterioration in terms of hydroperoxides per unit weight of fat. The modified Stamm method (Hamm et at 1965), the most sensitive of the peroxide determinations, is based on the reaction of oxidized fat and 1,5-diphenyl-carbohydrazide to yield a red color. The Lea method (American Oil Chemists Society 1971) depends on the liberation of iodine from potassium iodide, wherein the amount of iodine liberated by the hydroperoxides is used as the measure of the extent of oxidative deterioration. The colorimetric ferric thiocyanate procedure adapted to dairy products by Loftus Hills and Thiel (1946), with modifications by various workers (Pont 1955 Stine et at 1954), involves conversion of the ferrous ion to the ferric state in the presence of ammonium thiocyanate, presumably by the hydroperoxides present, to yield the red pigment ferric thiocyanate. Newstead and Headifen (1981), who reexamined this method, recommend that the extraction of the fat from whole milk powder be carried out in complete darkness to avoid elevated peroxide values. Hamm and Hammond (1967) have shown that the results of these three methods can be interrelated by the use of the proper correction factors. However, those methods based on the direct or indirect determination of hydroperoxides which do not consider previous dismutations of these primary reaction products are not necessarily indicative of the extent of the reaction, nor do they correlate well with the degree of off-flavors in the product (Kliman et at. 1962). 

In addition to the previously mentioned chemical tests, methods based on the carbonyl content of oxidized fats have also been suggested (Henick et al 1954 Lillard and Day 1961) as a measure of oxidative deterioration. The procedures determine the secondary products of autoxidation and have been reported to correlate significantly with the degree of off-flavor in butter oil (Lillard and Day 1961). The methods, however, are cumbersome and are not suited for routine analysis. 

Other benefits of guggulsterone supplementation include reduced blood cholesterol and triglyceride levels, increased fat oxidation (fat burning), increased energy, and better post-training recovery during diet restriction phases. Reduced acne has been noted. 

Hydroperoxide Levels. In thermally oxidized fats hydroperoxides are usually very low. At higher temperatures, oxidation proceeds rapidly and the rate of hydroperoxide decomposition exceeds that of hydroperoxide formation (17,18). For example, when ethyl linoleate was oxidized at 70°C, peroxide content reached a maximum of 1777 meq/kg after 6 hr then decreased to 283 meq/kg after 70 hr. At 250°C, on the other hand, peroxide value reached a maximum of only 198 meq/kg after 10 min, and was zero after 30 min. 

Other traditional methods available for monitoring the extent of lipid oxidation include the Anisidine value, the Kreis test (Mehlenbacher, 1960), methods based on the carbonyl content of oxidized fats (Henick et al., 1954 Lillard and Day, 1961), and measurement of oxygen uptake either by manometry or polarography (Tappel, 1955 Hamilton and Tappel, 1963). 

As indicated, a variety of aldehydes have been demonstrated in oxidized fats. Alcohols have also been identified, but the presence of ketones is not as certain. Keeney (1962) has listed the aldehydes that may be formed from breakdown of hydroperoxides of oxidized oleic, linoleic, Iinolenic, and arachidonic acids (Table 2-23). The aldehydes are powerful flavor compounds and have very low flavor thresholds for example, 2,4-decadie-nal has a flavor threshold of less than one part per billion. The presence of a double bond in an aldehyde generally lowers the flavor threshold considerably. The aldehydes can be further oxidized to carboxylic acids or other tertiary oxidation products. 

Carbonyl compounds in oxidized fats and oils are the secondary oxidation products that originate from decomposition of hydroperoxides. They usually have low threshold values and hence are responsible for off-flavor development in oxidized oils. Therefore, content of carbonyl compounds corresponds with sensory data. 

Body lipids are mobilized during exercise and are oxidized readily during strenuous exercise like gafloping. Physically conditioned horses oxidize fat more efficiently than nonconditioned horses. Hyperlipidemia is an important clinical problem in small pony breeds. It is most common in mares in late gestation and lactation and occurs when the animal is in negative energy balance. 

Fig. 10.2 Schematic view of Fat metabolism Linked to various Tissues Liver oxidizes fats, produces ketones, exports triglycerides.

Pure crystalline vitamin A occurs as pale yellow plates or crystals. It melts at 63 to 64°C and is insoluble in water but soluble in alcohol, the usual oiganic. solvents, and the fixed oil.s. It is unstable in the presence of light and oxygen and in oxidized or readily oxidized fats and oils. It can be protected by the exclusion of air and light and by the presence of antioxidants. 

Oxidized fats with their attendant health risks are reduced. 

The use of ozonated air did not produce any decrease in L. monocytogenes concentration in DCH or the PS samples (data not shown). No significant differences were observed when comparing the untreated to the treated samples. In addition, the treatment produced high fat oxidation. Fat showed a yellow colom after 5 h from the start of the treatment. 

Roffo, A.H. Experimental gastric cancer from ingestion of heat-oxidized fats Bol. Inst. Med. Exptl. Estud. Cancer 19 (1942) 503-530, see Chem. Abstr. 37 (1943) 63358. 

Fig. 16 Effects of amiodarone, perhexiline, and diethylaminoethoxyhexestrol (DEAEH) on mitochondrial function. After crossing the outer membrane, the uncharged secondary or tertiary amine (A) of amiodarone, perhexiline, or diethylaminoethoxyhexestrol (DEAEH) is protonated in the acidic intermembrane space. The positively charged molecule (AH ) is then electrophoretically pushed by the mitochondrial membrane potential into the matrix. High intramitochondrial concentrations inhibit both B-oxidation (causing steatosis) and oxidative phosphorylation, thus causing the accumulation of electrons in the respiratory chain and increasing the mitochondrial formation of ROS. The latter oxidize fat deposits, causing lipid peroxidation, which, together with ROS-induced cytokine production, could cause steatohepatitis.

The biological properties of thermally oxidized fats have been studied for many years. Evaluation of laboratory-heated and commercially-used fats in diets for animals have included feed consumption, weight gain, and feed efficiency ( l-4), pathology ( 5- ), organ weights (, 10), enzyme assays (11), and total lipid... 

Rat heart cells in culture, exposed to thermally oxidized fat components, (37) took up and incorporated more exogenous... 

The most consistent change in cultures exposed to heated fats was associated with intracellular lipid accumulation, which occurred rapidly (Figure 6). Prolonged exposure produced abnormal spherical cells filled with lipid droplets. They contained constricted, centrally located nuclei. Karyorrhexis and karyolysis were observed, and vacuolation and a network appearance were pronounced due to oxidized fat (Figure 7). The pyknotic nuclei as a percentage of the total number of cells in 20 random fields were increased due to heated fat fractions (Table IX), and accompanied the cytoplasmic changes seen earlier. Lipid droplet accumulation was estimated as shown in Table X, and the free fatty acids from the fresh fats induced less lipid accumulation. Nevertheless, the values for 00 were as high as those for HCO. 

Toxic properties of thermally oxidized fats are concentrated in the non-urea adductable monomers and dimers (45, 46). Usual... 

Alteration of tissue fatty acid concentration by oxidized fats may indicate the impairment of transport and enzyme systems by effects on lipoprotein synthesis and function (31). Clark et al. (49) showed that lipoproteins are susceptible to alterations of both structure and function by reaction with agents that pro-... 

The cytotoxicity studies associated with oxidized fats indicate that they interfered with cellular metabolism and differ-... 

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