Oleoresinous media

NMR has been primarily applied in archaeometric studies [40]. In contrast, NMR has had a restricted application in the art conservation field due to the complexity of the paint samples. This technique has been chiefly used for identifying highly polymeric materials, such as triterpenoid varnishes, oil, oleoresinous media, and synthetic media [41]. 

Electron paramagnetic resonance spectroscopy (EPR) (also called electron spin resonance spectroscopy, ESR) has been scarcely applied in the field of art and art conservation. Some work can be found in which EPR is used as complementary technique to SEM-EDX, NMR, and mass spectrometry (MS) for studying free radicals occurring in polymerization, pyrolytic, oxidative, and other radical degradative processes in artwork, as well as in the characterization of varnishes and oleoresinous media [42]. 

Nowadays, consumers would like those antioxidants present in food products not only to stabilise food lipids, but also to be absorbed through the intestinal wall and protect the lipids of blood plasma against oxidation. This effect is relatively evident in the case of tocopherols (which are liposoluble) or ascorbic acid (which is hydrophilic), but much less evidence is available on antioxidants of medium polarity, such as flavonoids, rosemary oleoresins or green or black tea catechins. 

Anothei fragrant oleoresin is storax. obtained from Uquidambar orientalis. a medium-sized tree growing in southwestern Asia. The resin is obtained by boiling the bark and wood of young branches. Il is used medicinally and also in incense. 

The effect of the resin, whatever its type, is to decrease the drying time of the paint, since the resins are hard in their normal states and only require solvent evaporation for drying. It should be noted that the addition of resin means that solvent (white spirit, turpentine or possibly aromatic hydrocarbons) will now be required to reduce the viscosity of the paint, though the low molecular weights of the oils, resins and oleoresinous products allow medium-high solids at application viscosity. 

Oil length n. Ratio of oil to resin in a medium. For an oleoresinous varnish, the oil length may be expressed in terms of parts by weight of oil to one part by weight of resin or, in American practice, in terms of USA gallons of oil per 100 lb of resin. Thus, a 25 gal varnish would mean, in American usage, a varnish composed of 25 USA... 

Alkyds, like oleoresinous varnishes, have an oil length and this is expressed as a percentage the number of grams of oil contained in 100 g of final resin. Below 45% oil it is a short oil alkyd, 45-60% medium oil and above 60% long oil. Long oil alkyds are soluble in aliphatic hydrocarbons, such as white spirit, while short oil alkyds require aromatic hydrocarbons (Tables 9.1 and 9.3). 

In physical form, oleoresins range from thin to viscous fluids, from semisolids to waxy or sticky pastes. Samples should be well mixed to ensure uniformity before testing. Initially, the sample should be evaluated for appearance (often characteristic), odor and flavor after dilution in a suitable medium. 

Regulatory Status. Use of the seed as a spice, natural flavoring, and natural seasoning ( 182.10), and the essential, natural extractive, and solvent-free oleoresins of the seed are GRAS ( 182.20). Fruits subject of a German therapeutic monograph in medium daily dose of 1.5 g for treatment of dyspeptic disorders (blumenthal 1). 

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