Tocopherol feeding studies

The tendency for radicals to form in freeze-dried raw milk, as measured by ESR spectroscopy, was found to be inversely related to the content of the natural antioxidant, a-tocopherol. Milks, with large variations in a-tocopherol concentrations, were obtained through a feeding study where diets included either a-tocopherol-poor roughage or a-tocopherol-sufficient roughage combined with intraperitoneal injection of rac-a-tocopherol acetate (20). The potential of ESR for detection of early events in oxidation is evident from this study, as tocopheryl radicals apparently did not interfere with the lipid and/or protein radicals. 

Consequently, soil samples from feedlots have a dual origin of toco-pherols. This is illustrated with the GC-MS data of a study done in the San Joaquin Valley of California (Fig. 5b, ). The y-tocopherol is derived exclusively from the vegetation fodder, while a-tocopherol is derived from both vegetation and the hydrolysis of the tocopheryl acetate feed supplement. Excess a-tocopherol acetate, not hydrolyzed in the animal gut, is also present. Because a-tocopherol acetate is relatively stable, its presence in soil dust samples indicates the level of its usage as a feed supplement. A significant metabolite of a-tocopherol elutes after the acetate and the... 

Figures 8-10 show the curves of tocopherol concentration in the residue (% w/w) vs the percentage of the distance on the evaporator (from the feed point) for feed flow rate ranging from 0.5 to 1.0 kg/h for the falling film molecular distillation unit. The initial tocopherol concentration was 8.50% (w/w). For a feed flow rate of 0.5 kg/h (Fig. 8), it can be observed that at the end of the distillation, the tocopherol concentration in the residue will be higher, at 150°C (about 15% [w/w]). At 160°C, at 80% of the distillation, the tocopherol concentration reaches a maximum and then decreases, because the tocopherols are already recovered in the vapor phase. Figures 8-10 show that by increasing the feed flow rate at the same temperature (160°C), the tocopherol concentration can increase until it doubles the initial concentration (for a feed flow rate of 0.6 kg/h). From this point, it decreases, requiring an increase in the temperature to concentrate more (for a feed flow rate of 1.0 kg/h at 170°C). For all feed flow rates (Figs. 8-10), at 180°C, practically all the tocopherols are found in the vapor phase. With this study, it is possible to observe which temperature is the best in order to recover the fatty acids (first step = 125°C) and, then, recover the tocopherols in the vapor phase (distillate) and the phytosterols in the liquid phase (residue) (second step = 170°C). At the lowest temperature (120°C) the tocopherol recovery was minimum (about 5%). By increasing the feed flow rate from 0.5 to 1.0 kg/h (100%), the quantity of tocopherol in the residue at 170°C, e.g., increases, which means that the process performance has decreased.

St. Laurent et al. (1990) investigated the effects on milk flavor of a-tocopherol supplementation (0, 700 or 3000 IU/day) to a feed consisting of grain mix, hay and pasture in herds with a chronic spontaneous oxidized flavor problem. a-Tocopherol supplementation resulted in improved milk flavor but no relationship was apparent between milk a-tocopherol levels and the extent of flavor improvement. In this study, the flavor problem decreased significantly when the cows subsequently got access to spring pasture. 

The feasibility of increasing the a-tocopherol concentration of milk by supplementation of the feed has been investigated in many studies (Dunkley et al., 1966, 1967 King et al., 1966 St. Laurent et al., 1990 Barrefors et al., 1995 Focant et al., 1998 Granelli et al., 1998). These studies showed that when feed was supplemented with varying levels of a-tocopheryl acetate, the a-tocopherol content of the milk was increased with consequent increased resistance to spontaneous and copper-induced oxidation. King et al. (1967) reported that when feed was supplemented to achieve an intake of 1 g a-tocopherol per day per cow, oxidation was effectively controlled in milk... 

The non-mevalonate route to terpenoids appears to be localized in the plas-tids. In plant cells, terpenoids are manufactured both in the plastids and the cytosol (Gray, 1987 Kleinig, 1989). As a general rule, the plastids produce monoterpenes, diterpenes, phytol, carotenoids and the side chains of plas-toquinone and a-tocopherol, while the cytosol/ER compartment produces sesquiterpenes, sterols and dolichols. In the studies discussed above, nearly all of the terpenoids labelled by deox30cylulose (Sagner et al, 1998b Eisenreich et al, 2001) and 2-G-methyl erythritol feeding (Duvold et al, 1997) or... 

Vitamin A with its five conjugated double bonds oxidizes to 5,8-epoxides (15) with subsequent loss of UV absorption at 325 nm. Thus, vitamin A was studied with the addition of various antioxidants (Table XI) in open bottles in thin layers. Although EMQ was the best, it is limited to use in vitamin A for animal feeds. AP activity was not great, but when added to a mixture of tocopherol, BHT, and diethanolamide, AP gave excellent protection. Klaui (16) has shown stability of vitamin A palmitate with tocopherol, AP, and an amine equal to 1300 h, compared to a control equal to 100 h. However, the antioxidants in the dry market form (beadlets) protect the vitamin A in the beadlets as well as the end use of the product. For example, spray-dried vitamin A can be pro-... 

Subramanian et al. [29] reported the application of dense membranes (not porous) in the study of permeation of different tocopherols. A membrane was used with an active layer of silicon and PI as a support layer (NTGS-2200, Nitto Denko, Japan). Experiments were carried out with high oleic sunflower oil with enriched tocopherol acid, with pressure and temperature ranging from 20 to 50 bar and 20°C to 50°C, respectively. Tocopherols showed preferential permeation when compared with triacylglycerols, corresponding to negative values of rejection (-30% to -52%). However, the concentration of tocopherols in the feed led to reduction in the rate of permeation of the same, but without significant effect on the total flow. The authors do not mention the characteristics of the membrane pore. 

On the basis of the various studies undertaken, the postnatal fall in the serum level may represent the effect on the premature infant of three unrelated factors (1) an inadequate supply of tocopherol in artificial formula feed. (2) excessive demand for tocopherol represented by the marked increase in body mass of the premature infant during the first several months of extrauterine life. (3) possible redistribution due to a rapidly expanded blood volume and accumulation of adipose tissue. 

An excellent example of the implementation of SCFF to obtain palmitic acid from a plant source is the work of Brunner and Machado [7,72]. They conducted a detailed analysis on the fractionation of fatty acids from palm fatty acid distillates (99 % FFA (mainly palmitic, oleic and linoleic acid), 0.9 % squalene and 0.1 tocopherol) starting with a phase equilibrium analysis through to pilot plant studies and experimental verification of the separation. They postulated, from the phase equilibrium studies, that squalene and palmitie acid would be preferentially extracted and verified their postulation experimentally. They also considered a pseudo-binary mixture separation where palmitic acid is to be separated from oleic and linoleic acid and showed, using separation factors that this is possible. On pilot plant scale they showed that such a separation is feasible and balanced yield and extraet quality. At their optimum conditions (373 K, 29 MPa, extract to raffinate ratio of 1.2) they obtained an extract where the palmitic acid content was enriched from 52.5 % in the feed to 74.4 % in the extract and the oleic and linoleic acid content enriched from 46.3 % in the feed to 59.0 % in the raffinate. Squalene was also enriched in the extraet Irom 0.6 % in the feed to 1.2 % in the... 

At present economic factors also preclude the feeding of tocopherol concentrates to meat animals. Large doses of this vitamin in the feed do increase fat stability, but most of it is excreted. Only a small fraction of that fed is absorbed from the digestive tract and stored in the fat. It is possible that deposition of either tocopherol or fatty acids or both may be influenced by the feeding of substances which can affect fat metabolism, but such studies are too few and in too early a stage to warrant any conclusions at present. 

Vitamin E (a-tocopherol) was extracted from feed and analyzed at the levels of 8-23 pg/mL on a Cjg column (A = 295 nm, ex 330 nm, em) with a 95/5 methanol/ water mobile phase [334]. Amaud et al. [335], chromatographically studied serum extracts for retinol, a-tocopherol, and ) -carotene on a C g column (A = 450nm, 325 nm or 292 nm) and published the retention times of these compounds in pure methanol and 17 other binaiy and ternary mobile phases including itietha-nol/acetonitrile/hexane, methanol/acetonitrile/cyclohexane, methanol/hexane, and methanol/acetonitrile/dichloromethane. Detection limits of 0.1-1.5 pM... 

It has been extensively shown that pecific feeding regimes can increase the concentrations of boh polyunsaturated lipids and pro-oxidative metal pedes, which boh make he milk more prone to autoxidation (6 7 8 9 10). Thus several studies have been perfomted to limit autoxidation in milk through optimized feeding (II 12). Moreover, numerous studies have shown that antioxidants in he feed are transferred to he milk and hereby improve he oxidative stability of milk. It has been reported hat increasing concentrations of dietary vitamin E can effectively reduce he intensity of oxidized flavor in milk (13 14). Recent studies confirm hat a-tocopherol protects milk fat from oxidation (IS). In contrast, earlier studies have not been able to show hat... 

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