Olive tocopherol content

Olive oil contains a-tocopherol in the range of 12-190 mg/kg. According to one report (43), olive oil tocopherols were found to consist of 88.5% a-tocopherol, 9.9% (3--f y-tocopherol, and 1.6% 8-tocopherol. Tocopherol content can be used to detect adulteration of olive oil with seed oils. 

Tocopherol Content. Tocopherols can be determined by colorimetry or GLC (90), or by HPLC (91, 92). Added tocopherols are not permitted in virgin olive oils and crude olive-pomace oils (12). Added ot-tocopherol is allowed in refined olive oil, olive oil, refined olive-pomace oil, and olive-pomace oil to restore natural tocopherol lost during refining with a maximum level of 200 mg/kg of total ot-tocopherol in the final product (12). 

Psomiadou, E., Tsimidou, M., and Boskou, D. 2000. a-Tocopherol Content of Greek Virgin Olive Oils. J. Agric. Food Chem. 48 1770-1775. 

The main component of the tocopherol mixture is a-tocopherol which makes up 95% of the total. The other 5% of the mixture consists of (J>- and y-tocopherols. All tocopherols occur in the free (non-esterified) form. The vitamin E(mg) PUFA(g) ratio in olive oil is approximately 1.8. In countries with a high annual per capita consumption, a significant percentage of the daily requirement for vitamin E is covered by olive oil. Refined, bleached, and deodorised olive oils have markedly reduced tocopherol content because of losses during processing. 

Lo Curto, S., Duco, L., Mondello, L., Errante, G. and Russo, M.T. (2001) Variation in tocopherol content in Italian virgin olive oils. Ital. J. Food Sci, 13, 221-226. 

Komsteiner et al. [158] studied the tocopherol content of oils extracted from different nuts and found that vitamin E content was highest in hazelnut oil (33.1 mg/lOOg), followed by, in descending order, almond > peanut > pistachio > pine nut > walnut > Brazil nut > pecan > cashew > macademia. Hazelnut oil has been reported to contain the highest a-tocopherol level among nut oils [3,158]. Depending on the variety, hazelnut oil also contained-two to three times more a-tocopherol than olive oil [100,127,157]. 

That tocopherols are apparently nature s choice of antioxidant is demonstrated in Fig. 4, which is similar to a correlation observed by Hove and Harris (1951). Here the total tocopherol content of oils from babasu (1), beechnut (2), carrot (3), castor bean (4), cacao (5, 6), coconut (7, 8), corn (9, 10), cottonseed (11-13), hazelnut (I4, 15), linseed (16), oat germ (17), okra seed (18, 19), olive (20-25), palm (26-28), peanut (29-33), pecan (34, 35), poppyseed (36), rapeseed (37), rice bran (38), safflower (39), sesame (40, 4I), soybean (42-44), sunflower (45), and wheat germ (46-50), as reported by Lange (1950), have been plotted against their total linoleic plus linolenic acid content as reported by Hilditch (1956). The linoleic, plus linolenic acid content of oils from the same species varies, sometimes threefold. It is unfortunate that the content of tocopherol, linoleic acid, and linolenic acid have seldom been determined on the same sample. If Fig. 4 could have been prepared from such data, the correlation would probably be even more dramatic. 

Determination of vitamin E isomers in seeds and nuts Determination of tocopherol and tocotrienol in rice bran Investigation of vitamin E content in olives Determination of tocopherol and tocotrienol in olive oils... 

Sensidoni, A., Bortolussi, G., Orlando, C. and Fantozzi, P. (1996) Borage oil (Bortago officinalis L.) an important source of gamma linolenic acid. II. Tocopherols and chlorophyll content and sensorial analysis of borage oils extracted by different techniques and blended with extra virgin olive oil. lnd. Aliment., 35, 664-669. 

For olive oil, total tocopherol level is ca 100-150 pg/g and a-tocopherol is the dominant (>90%) tocopherol present (Van Niekerk and Burger, 1985 Kamal-Eldin and Andersson, 1997). a-Tocopherol values of virgin olive oils from Greece ranged between 98 and 370 pg/g, while the sum of other vitamers was <50 pg/g. Smallsized Greek olives had slightly higher contents of a-tocopherol than medium-sized olives, at 239 and 198 pg/g, respectively (Psomiadou et al., 2000). 

The aim of this work was to develop a simple, environmentally sound and fltst method for the extraction and determination of squalene in an olive biomass using the PFE technique, and investigate if this technique could be a viable processing technology for the extraction of squalene from olive oil pomace. The effects of different solvents and mixtures of solvent, extraction temperature and extraction time were also evaluated for their influence on yield of squalene. Squalene in the olive biomass extracts were quantified by liquid chromatography with UV absorbance and fluorescence detection. In addition, the proposed method was used to determine the content of a-tocopherol in the olive biomass. 

Estimation of true vitamin E in foods requires quantitative determination of all its components since they vary in their biological potency. This vitamin consists of four tocopherols (a, jS, y, and 6) and four tocotrienols (a, jS, y, and d), but the three major constituents responsible for vitamin E activity are the a-, jS-, and y-tocopherols. While these compounds are fluorescent, their esters must be reduced to free alcohols for total tocopherol assays. Total vitamin E can be directly obtained through fluorimetry, but the determination of individual components is carried out using LC with fluorimetric detection. This procedure has been used to determine the composition of vitamin E in seed oils from maize, olives, soya beans, sesame, safflower, and sunflower by measuring the content of all the four tocopherols plus a-tocotrienol. The simultaneous determination of tocopherols, carotenes, and retinol in cheese has been carried out using LC with two programmable detectors coimected in series, a spectrophotometer and a fluorimeter. Carotenes have been determined photometrically, and fluorimetric measurements have been obtained for tocopherol and retinol. 

The fate of endogenous antioxidants in vegetable oils, especially tocopherols, due to microwave heating has also been studied. In com and soybean oils, 90% of the original tocopherol level was retained after 8-10 min of microwave heating, however, in olive, palm and flaxseed oils the content of tocopherols was decreased substantially. When soybean oil was heated for 12 min, 40% of the total tocopherols was lost, but microwave treatment for 6 min retained 90% of their original amounts (Yoshida et al, 1990 1995). 

Oils that have undergone lipid peroxidation may have adverse physiological effects if consumed. Eor example, Eder (1999) found that oxidized oils in a diet could diminish the ability of rat heart and liver tissues to desaturate fatty acids. Work by Sheehy et al. in 1994 showed that the consumption of thermally oxidized sunflower oil by chicks reduces the tissue content of a-tocopherol and increases the susceptibility of tissues to lipid peroxidation. The addition of vitamin E to refined olive oil increases the stability of the oil under pro-oxidant conditions and decreases the oxidative damage caused by adriamycin in rats (Quiles et al., 1999). 

Not to be forgotten in this section, is the unsaponifiable fraction, which corresponds to the non-glyceride constituents of oils. In general, oils contain between 0.2 and 1.5% unsaponifiable compounds. The relevance of unsaponifiables is based on their chemical composition. They are employed in cosmetics as antioxidant and vitamin actives because of their tocopherol and carotene content and as anti-ageing agents—their sterol content. We would like to emphasize the cosmetic properties of the unsaponifiable fractions of soya, olive and avocado oils. 

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