Significance iodine value

The classic chemical technique for measuring the degree of unsaturation in diene polymers is iodometry (iodine value) [102]. Kubo et al. [103] extensively measured the iodine value to determine the amount of residual double bonds present in the HNBR. However, this method exhibited significantly poorer precision as compared with IR and NMR spectroscopies [99-101]. Acid... 

Many of the tests described involve physical properties such as refractive index, viscosity or melting point of the fat, of the fatty acids or of the lead salts of the fatty acids. However, there were also many chemical tests such as Reichert, Polenske, iodine, saponification and acetyl values. These all gave information as to the composition of the fat, some information as to fatty acid composition, others as to other non-glyceride components of the fat. Thus the iodine value is a measure of unsaturated fatty acids in the fat, now obtainable in more detail from a fatty acid profile. Similarly the Reichert value is a measure of volatile fatty acids soluble in water. For most purposes this means butyric acid, and so the modem equivalent is the determination of butyric acid in the oil. The modem method for milk-fat analysis is thus carrying out the analysis in a similar way to the Reichert determination, but uses a technique that is less dependent on the exact conditions of the analysis and is thus less likely to be subject to operator error. The Reichert value could be useful, in theory, even if milk fat was not present. Lewkowitsch notes that some other oils do give high values. Porpoise jaw oil has a value almost twice that of milk fat, while some other oils also have significant values. It is unlikely that one would have come across much porpoise jaw oil even in 1904, and even less likely today. 

Pan-frying is a popular frying method at home and in many restaurants. The panfry stabilities of two oils with similar iodine values—mid-oleic sunflower oil (NuSun) and a commercial canola oil—were compared (121). Both oils have similar pan-fry stabihties, with few significant differences in the physicochemical properties during the heating process. 

Watermelon seed oil was prepared and evaluated for its physicochemical properties (22, 23). The seed oil consisted of 59.6% linoleic acid (18 2n-6) and 78.4% total unsaturated fatty acids (Table 4). The predominant fatty acid in the oil was linoleic acid, which was followed by oleic, palmitic, and stearic acids. Linolenic, palmitoleic, and myristic acids were minor constituents. The refractive index, acid value, peroxide value, and free fatty acids of watermelon seed oil were determined to be 1.4696 (25°C), 2.82 (mg KOH/g oil), 3.40 (mequiv oxygen/kg oil), and 1.41 (% as oleic acid), respectively. The saponification value of watermelon seed oil was 201 (mg KOH/g oil), and its iodine value was 115 (g iodine/100-g oil), which was significantly higher than pumpkin at 109 (g iodine/lOO-g oil) (22, 23). 

Melon, Cucumis melo, is a member of the Cucurbitaceae family and grows best in tropical regions. The pulp of the fruit has pleasant flavor and taste, and the seeds are generally treated as waste however, medicinal effects have been reported for the seeds (24, 25). Hexane-extracted seed oil of Cucumis melo hybrid AF-522 was determined to contain 64 g of linoleic acid per 100 g of total fatty acids (Table 4) (24). Significant amounts of oleic, palmitic, and stearic acids were also detected in the melon seed oil. The specific gravity (28°C), refractive index (28°C), and iodine value of the seed oil were 0.9000, 1.4820, and 112, respectively, under the experimental conditions (24). Earlier in 1986, Lazos (25) extracted the oil from Cucumis melo seeds and examined its physicochemical properties (25). Linoleic acid was the primary fatty acid and accounted for 64.6% of the total fat (w/w), along with 20.1% oleic acid, and 14.7% total saturated fatty acids (Table 4). Iodine value and refractive index (40°) of the seed oil were 124.5 and 1.4662, respectively. 

Significant differences in fuel standards also exist among different countries (2, 14-18 Table 1). In the European Union (EU), member countries have adopted a standard requiring an iodine value of less than 115 (15, 16), 120 (14), or 125 (18). This iodine value reflects the upper extreme iodine value of canola (low erucic acid rapeseed) oil. The American Society for Testing Measures (ASTM) and Italian National Standards Body (UNI) standards do not include iodine value (2, 17) and thus allow higher iodine value oils such as soy and sunflower. 

Table III gives the physical and chemical properties of the M. oleifera oil. Some of the properties of the oil depend on the extraction medium. The M oleifera oil is liquid at room temperature and pale-yellow in colour. Electronic nose analysis shows that it has a flavor similar to that of peanut oil. The melting point estimated by differential scanning calorimetry is 19°C (15). The chemical properties of the oil depicted in Table III below are amongst the most important properties that determines the present condition of the oil. Free fatty acid content is a valuable measure of oil quality. The iodine value is the measure of the degree of unsaturation of the oil. The unsaponifiable matter represents other lipid- associated substances like, sterols, fat soluble vitamins, hydrocarbons and pigments. The density, iodine value, viscosity, smoke point and the colour of Moringa oil depends on the method of extraction, while the refractive index does not. Varietal differences are significant in all physical characteristics apart from refractive index and density (2). The heating profile of the M. oleifera seed oil using the differential scanning calorimetry (DSC) conventional scan rate shows that there is one major peak B and, two small shoulder peaks A and C...

Einset et at. (1957) studied fish oils from 7 species and noted that the rate of autoxidation was directly correlated with the iodine value and inversely correlated with the tocopherol content. The disappearance of significant amounts of tocopherol lends support to the theory that it plays an important role in stabilizing fish oils. 

Because linolenic acid (a minor but significant component of soybean oil) with its n—3 (A 15) double bond furnishes undesirable flavours after oxidation and also because linoleic acid has a desirable dietary value considerable effort has gone into making catalysts with high linolenic/linoleic selectivity. For nickel catalyst this is only 2-3 but with copper catalysts it may be 15-20. Thus soybean oil, reduced to an iodine value of 110 for use as a salad oil, would contain <1% or 4-5% linolenate with copper or nickel catalysts respectively. 

According to this study, acid value, peroxide value and saponification value of the two types of oils are significantly different and the iodine values showed no signifieant differenee. Fatty acid compositions of the two types of oils were not significantly different enough to cause any nutritional changes. 

After water iodination values of thyroid hormones in adults indicated a significant increase of T4 (p <0.001), and a decrease of both T3 (p < 0.001) and TSH (p<0.001) mean values. 

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