Vitamin oxidative stability

Stability. Ascorbic acid, a white crystalline compound, is very soluble ia water and has a sharp, acidic taste. In solution, the vitamin oxidizes on exposure to air, light, and elevated temperatures. Solutions of ascorbic acid turn yellowish, followed by development of a tan color. Ascorbic acid is stable to air when dry but gradually darkens on exposure to light. 

Al-Mabruk R M, Beck N F G and Dewhurst R J (2004), Effects of silage species and supplemental vitamin E on the oxidative stability of milk , Journal of Dairy Science, 87, 406 112. 

Oxidatively stable raw materials are necessary to obtain a profitable shelf life of the products (Sheard et al., 2000). When fed above requirement levels, vitamin E increases the oxidative stability in fresh pork and pork products considerably (Jensen et al., 1998). Selenium is also involved in reducing lipid oxidation there is no evidence, however, that supplying additional selenium above the requirements improves pork quality (NRC, 1998). 

A widespread method for determining the induction period for autoxidation of oils and fats consists of passing a continuous stream of air through the heated sample and collecting the volatile acids evolved in a water trap, where they are determined on a real time basis. The time plot usually presents a flat appearance for a certain period and then takes off in an accelerated manner. This test is the basis of several national and international standards (e.g. AOCS Cd 12b-92—oil stability index" ISO 6886—accelerated oxidation test for oxidative stability of fats and oils ) and the design of the Rancimat equipment, where the end determination is based on conductivity measurements . In addition to oxidation stability as determined by the Rancimat method and POV, which negatively affects virgin olive oil stability, other nonstandard properties were proposed for better assessment of the quality of this oil, namely LC determination of Vitamin E (21), colorimetric determination of total polar phenols and UVD of total chlorophyll. ... 

Charmley, E., Nicholson, J.W.G. 1995. Influence of dietary fat source on oxidative stability and fatty acid composition of milk from cows receiving a low or high level of dietary vitamin E. Can. J. Anim. Sci. 74, 657-664. 

Morrissey, P.A., Buckley, D.J., Galvin, K. 2000. Vitamin E and the oxidative stability of pork and poultry. In Antioxidants in Muscle Foods. Nutritional Strategies to Improve Quality (E.A. Decker, C. Faustman, C.J. Lopez-Bote, eds.), pp. 263-287, John Wiley, New York. 

The quality of a refined oil is usually evaluated by traditional quality parameters such as a low residual FFA content, a high oxidative stability, a light color, and a neutral odor and taste. In addition, high-quality food oils should contain low transfatty acid (TEA) levels, high amounts of natural antioxidants and vitamins, low levels of polymeric and oxidized triacylglycerols, and no contaminants (pesticides, polycyclic aromatic hydrocarbons, dioxins and polychlorinated biphenyls, etc.) (Tables 5 and 6). 

Halbaut L, Barbe C, Aroztegui M, de la Torre C. Oxidative stability of semi-solid excipient mixtures with corn oil and its implication in the degradation of vitamin A. Int J Pharm 1997 147 31 0. 

Buckley, D.J., Morrissey, P.A., and Gray, J.I. 1995. Influence of dietary vitamin E on the oxidative stability and quality of pig meat. Journal of Animal Science 73 3122-3130. 

It appears from Figs. 9.5 and 9.6 that there is a huge variation in colour stability between meat from different sources. A range of intrinsic factors influence the oxidative balance in raw meat and thereby the colour stability of the meat (Bertelsen et al., 2000). Thus the oxidative stability of muscles is dependent on the composition, concentrations, and reactivity of (i) oxidation substrates (lipids, protein and pigments), (ii) oxidation catalysts (prooxidants such as transition metals and various enzymes) and (iii) antioxidants, e.g., vitamin E and various enzymes. For review see Bertelsen et al. (2000). 

Yoshida, H., Tatsumi, M., and Kajimoto, G. (1991a). Relationship between oxidative stability of vitamin E and production of fatty acids in oils during microwave heating, JAOCS, 68, 566. 

Gamboa et al. (2011) also microencapsulated vitamin E using spray chilling. However, their aim was to microencapsulate tocopherol using chemically interesterified low trans fat. Besides characterizing the microparticles, the authors used the tocopherol-loaded microparticles in a food matrix and analyzed the sensory acceptance of the product. It was observed that microparticles obtained by spray chilling presented satisfactory release profile. The use of microparticles loaded with tocopherol did not compromise the sensory characteristics of the product. In both studies (Albertini et al., 2008 Gamboa et al., 2011), there was no description of the oxidative stability of vitamin E after the encapsulation. 

The d-form of the vitamin is the most active. Any studies of vitamin supplementation, and their subsequent effects in various muscle foods, must acknowledge the form of tocopherol fed before conclusions can be drawn regarding dietary uptake and antioxidant efficiency, d-a-tocopherol or its ester is more readily assimilated into tissues than the racemic (dl) form (Hidiroglou et al., 1988). Burton et al. (1988) have demonstrated that the uptake of the free phenol and acetate forms of d-a-tocopherol are equivalent. Marusich et al. (1975) reported that dl-a-tocopherol and dl-a-tocopheryl acetate were equivalent in terms of uptake by chicken liver and breast muscle, and resulted in similar oxidative stabilities within the tissue types. 

O Keefe and Noble (1978) supplemented catfish diets with 0, 5,10, 20, 40 or 80 mg dl-a-tocopheryl acetate per 100 g dry diet. All levels of supplementation >10 mg dl-a-tocopheryl acetate/kg diet demonstrated a positive effect on minimizing oxidation of fillets during frozen, and frozen/ refrigerated storage. The maximum benefit was observed at the level of 40 mg dl-a-tocopheryl acetate/kg diet. In rainbow trout, tissue tocopherol levels increased with dietary supplementation of 500 or 1000 mg dl-a-tocopheryl acetate/kg diet (Eoggio et al., 1985). Tissues subsequently obtained from supplemented fish and stored at —80°C for 4 months demonstrated reduced TEA values over those from controls. However, there was no difference in oxidative stability between vitamin E and control fillets stored at —20°C for 10 months. Interestingly, supplementation of vitamin E did not significantly affect sensory attributes of fresh or frozen trout fillets. 

The relative merits of vitamin E supplementation for delaying warmed-over flavor (WOF) in muscle foods have been investigated. Webb et al. (1972) studied the effects of a-tocopheryl acetate supplementation on oxidative stability and flavor of broiler parts, which were pre-cooked, frozen and then re-heated. The supplementation of broilers with 11 or 22 lU a-tocopheryl acetate for 36 days resulted in pre-cooked meat with lower TEA values than that from non-supplemented birds. However, a sensory panel could not detect any treatment difference in flavor assessment. The panel did, however, corroborate a positive effect demonstrated... 

The fact that exogenous addition of vitamin C is widely used in the food industry for antioxidant purposes demonstrates the potential for improving oxidative stability of animal-based foods by increasing its endogenous concentration. However, the principal difficulty appears to be in increasing tissue concentrations of this vitamin. Most studies published to date have not presented data on tissue accumulation the instability of ascorbic acid in feeds is also a practical problem. Muscle contains very low concentrations of this vitamin (Pardue and Thaxton, 1986) Dorr and Nockels (1971) were unable to increase ascorbic acid content in chicken muscle with dietary supplementation. 

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... 

Traces of heavy metal ions can act as catalysts for fat or oil oxidation. Their binding by chelating agents increases antioxidant efficiency and inhibits oxidation of ascorbic acid and fat-soluble vitamins. The stability of the aroma and color of canned vegetables is substantially improved. 

Several comprehensive reviews have been published on the existing chromatographic methods for the analysis of lipophilic antioxidants (tocopherols, tocotrienols, and carotenoids) in various sample matrices (Abidi, 2000 Aust et al., 2001) on electrochemical approaches in the sensing of natural or biological antioxidants and antioxidant capacity (mainly polyphenols and vitamins C and E) using cyclic voltammetry on flow injection analysis (FIA) with amperometric detection in food and biological samples (Blasco et al., 2007) and on chemiluminescence (CL) and fluorescence (FL) methods for the analysis of oxidative stability, antioxidant activity, and lipid hydroperoxide content in edible oils (Christodouleas et al., 2012). 

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